© Erwin Puts
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Chapter 6: LEICA lens reports

6.1 State of the art designs.

Leica lenses have been produced since 1925 and somewhere in the year 2000 the 4.000.000 mark will be reached. The durability of these lenses is so high that many of them are still available on the second hand market. Most of the lens types (aperture/focal length versions) can be bought new too. The Leica user then has a bewildering choice or 'embarrass de riche' from more than 150 different types and versions. The Leica afficionado will identify and discuss with great enthusiasm the differences in character that every lens design is presumed to possess. In a sense that is true. Every lens has its specific aberration correction, as this is derived from the overall characteristics, aperture, focal length and physical dimensions). In the individual reports I will describe and explain the character of the lens, mostly based on the measurable properties. It is possible, when closely looking at the performance profile or fingerprint, to identify groups of lenses, which share many characteristics.

It is well known that any lens, when stopped down to 1:5.6 or 1:8.0 will deliver image quality that is commendably good. Of course, when the negative is enlarged more than 8 times and/or the picture is made under heavy duty circumstances (strong highlights, high contrast and oblique light rays striking the lens) big differences can be detected without much effort. For many a Leica user, there is a fun factor involved when using older lenses. And it gives indeed much satisfaction, to use an older Elmar or Summar for photographing those typical Parisian scenes, and getting fine images, that are a pleasure to look at. Lens performance and manufacture has improved over the years and so a Summar is not as 'good' (optically and mechanically) as the current Summicron. If you look critically at comparison pictures, the difference is evident. How you appreciate or value this difference, is an entirely personal matter. The chapter about image evaluation ( you will enjoy the photography with Leica lenses more when you look at the progress that is possible. A perennial topic is the comparative evaluation of lenses from different manufacturers. I would prefer to discuss this issue in a balanced way. There are two polarised views, both of which I think are unproductive and not true. One states that Leica lenses can never be challenged by other marques and the other assumes that there no differences of any importance. In the chapters on optical design I showed how a designer or a team analyses the task, defines the goals and finds a solution. I also exposed to some length that aberrations and their control are universally discussed and studied. In fact many design departments all over the world use the same design program (Code V). It is rational to assume that, given the same set of requirements, the solutions will be found in the same direction. And in the past, it would not have been different, even if the methods and tools were different.

As lenses are manufactured for a long period, they reflect the state of the art at the beginning of the design, some exceptional designs excepted. It would be difficult to improve significantly on the Noctilux lens, even today, as long one has to stay within the parameters set by that lens. But generally designs do improve. This progression is not orderly, but happens in bursts and jumps. Sometimes a design is a quantum leap ahead of the predecessor and competitor, sometimes the differences are more subtle or the balance of characteristics is different. At every point in time, you could make a cross-section of designs and note that a particular lens is better or not as good as the comparative lens. And this applies to the lens lines of all leading marques. I noted that a lens can be evaluated at 30 or more parameters. It is a bit naive to assume that all parameters of all lenses of one manufacturer at all times are above all the others.

The question if Leica is better or as good as other leading marques, should be rephrased to what specific lens at what period are you referring to. Today as in the past, Leica has produced lenses whose performance profile is comparable to others on the market and it would be most unbelievable if that were not the case. Leica has always stressed the importance of the image quality at the wider apertures and tuned the design and manufacture of lenses (aberration control, mechanical tolerances) to this goal. Their definition of optical quality has progressed through the years and so have the designs and the lenses. Lenses like the Apo-Summicron-M 1:2/90 ASPH, the Elmarit-M 1:2.8/24mm, the Apo-Elmarit-R 1:2.8/180mm and Apo-Telyt 1:4/280mm, to cite only a few examples, redefine the notion of image quality at wider apertures in 35mm photography. The optical performance in itself is not the only aspect to look at. Leica can design a lens with 9 lens elements, with about equal performance to a lens from another manufacturer, who needs 16 lens elements to accomplish the same. The Leica lens will have more consistent performance at wider apertures, sample for sample, as tolerances are smaller and the chances for error are less. We should enjoy the quality of Leica lenses, evaluate the performance with an appreciative, yet critical eye and at the same time admire the accomplishments of the optical industry as a whole.

 

6.2 The question of focal length

The choice of the specific focal length of a lens is sometimes a mystery. Leitz used for its medium telephoto lens the 90mm, but only once the 85mm. In photography we are used to series of numbers like shutter speeds and apertures, which generally obey a factor of 2 for its progression. The aperture series of 1.0; 1.4; 2.0; 2.8; 4.0; 5.6 is well known and we see clearly that the numbers itself double in two steps. The increment here is the square root of 2, which is +1.4 or an addition of 40% per step.

These steps are quite large and so we can imagine a series of numbers with smaller increments. For photographic purposes an increment of 26% or even 12% will suffice, but for increments in focal length a step of 6% is customary. With such an increment (for the mathematically inclined: an increment of 1.059 or log 0.025) we can generate a series which covers all possible focal lengths.

 

Table 6.

 

If we look at this table carefully, we will find any focal length that has been chosen by Leica. It is clear that the choice of a focal length is governed by a table like this. It is also interesting to note that the value of 50 is not part of the series, but 53 is. And the true focal length of many 'standard' lenses of 50mm (indicated) is 52mm! Why a designer would choose 90mm or 85mm is not clear. Presumably the calculations dictate a certain physical volume or a certain front lens diameter, which is convenient or necessary. A second consideration when discussing lenses is the angle of view or angular coverage. I would like to draw attention to the fact that the negative format is 24x36mm, which gives three different angles of view. As any lens produces an image circle, in which the rectangular format of the negative has to be fitted, we have a diagonal, a horizontal and a vertical angle of view. For a 50mm lens the diagonal angle of view is 45, but the horizontal angle is 41 and the vertical only 28. For the 35mm lens the numbers are, 64, 56 and 37. It is evident that the horizontal angle of view is more important than the diagonal, so the next table gives these figures for the Leica lenses. When taking photographs, we habitually look at the horizontal line to see what part of the scene is covered by the lens. This intuitive gaze, corresponds to the horizontal angle, which is invariably smaller than the quoted diagonal and can explain the disappointment sometimes noted with the covering power of a wideangle lens in practical situations.

Focal length	Horizontal angle	Diagonal angle
15	97	110
19	87	96
21	79	92
24	74	84
28	63	76
35	52	64
40	48	57
50	39	45
75	26	32
80	25	30
90	22	27
100	20	25
105	19	23
125	16	20
135	15	18
180	11	14
200	10	12
210	9.5	12
250	8.5	9
280	7	8.5

 

The horizontal angle of view of 90°, is particularly interesting as you can cover a rectangular courtyard or room with such an angle in one picture. The focal length needed to cover this angle is approx. 18mm and if we would build a series from here in equal steps, we would get 18mm, 25mm, 35mm, 50mm, 70mm, 100mm, 140mm, 200mm, 280mm, 400mm, 560mm, 800mm. The lenses for the M-body are quite close, with the exception of the 21mm and the 90mm: we have 24, 50, 75, 135, and with Visoflex lenses: 200, 280, 400, 560 and 800!. The R-series is 19, 24, 50, 100, 180, etc: here the 80 and 90 are the odd ones. A second option would be to use a 10° increment, so starting with 90° the series would be: 80°,70°, 60°, 50°, 40°, 30°, 20°, and the focal lengths would become: 18mm, 21mm ,25mm, 31mm ,39mm ,50mm, 67mm,102mm. If a 90° angle is the base angle, it is not surprising to imagine that half that figure (45°) has also some relevance. Now a full frame 35mm negative has a diagonal of 43mm, which covers an angle of 53°. We can calculate that a coverage of 45° needs a focal length that is 20% larger, or 43 + 9mm = 52mm! Here lies a partial explanation for the choice of .i.; for the 52mm focal length for the Elmax/Elmar.

 

6.3 50mm

The focal length of 50mm has been designated as the 'standard' for the 35mm format. There are however, no hard or fast rules here. The statement is derived from the notion that the standard lens should have a focal length equal to the diagonal of the negative area. For a 24x36mm negative the diagonal is exactly 43.27mm. In reality most standard lenses of 50mm focal length are closer to 52mm. That is a difference of almost 10mm and too large to be inconsequential. A second, related explanation, has it that the angle of view of the standard lens (about 47 degrees) corresponds with a natural viewing angle of the human eye. That again is a myth and cannot be supported by research. The angle of view of the eye where good discrimination of details is maintained, is about 20 degrees. And the total angle is 140 degrees. The angle of 45 to 50 degrees has no special significance for the human eye. There is a psychological and a technical argument that can explain the preference for the 50mm length. If we look at a print with dimensions 15 x 20cm (diagonal 25cm) at the closest normal viewing distance (25cm) the eye is located at the so-called centre of perspective, corresponding to the optical centre of the taking lens. From that location of the eye , we look at the picture as if we were standing in the centre of the negative at the sharpness plane. At this distance the eye can capture the whole print area without eye movement, providing for easy viewing. Technically the focal length of 50mm is a very good compromise between high speed, small dimensions and excellent optical correction. In the world of the microscope lenses, where Barnack looked for a suitable lens, the focal lengths of 42mm to 60mm were available with good corrections. This might have inspired .i.; to search for a solution within this range. The 50mm focal length, combined with an aperture of 1:2 has been the workhorse of all Leica photographers since the early thirties. It is quite amazing to reflect on the enduring popularity of the 1:2/50mm lens, when one considers the big advances in emulsion sensitivity. When the Summar was introduced a film with a nominal speed of ISO 50 (Kodak Verichrome) , was the fastest that could be bought.

In the mid-fifties the ISO400 speed barrier had been broken by the Kodak Tri-X, which was rated at 200ASA at first, but here a safety margin had been built-in. Since then this combo: the ISO400 film and a 1:2/50mm lens covers most demands and has recorded the most compelling images in photography. In the early fifties and sixties the ultimate object of desire for any 35mm photographer, who liked or needed to practise the art of the artless snapshot (Henri Cartier-Bresson-style) was a standard lens with an aperture of 1,4. Any additional photon that could be captured on emulsion while shooting in 'available darkness' was most welcome.

The slender depth of field at that large aperture added quite often impact and drama to the image. The need for such a large aperture became imperative after the candid pictures of Erich Salomon of Ermanox-fame. The 35mm worker got what he demanded in the early fifties as coated 1,5/50 designs from several manufacturers, including Leitz became available. These lenses indeed did capture some of the additional photons. But the photons on their way through the many glass elements wandered around not fully controllable. Aberrations abounded and the image quality, to be polite, was just acceptable. The Leitz Summilux 1,4/50, introduced in 1959 for the M series camera was the first to offer a higher level of image quality. A redesign , offering very good quality, was introduced in 1961 and is still in production. The Leicaflex user had to wait till 1970 before she could capture scarce photons. A redesign in 1978 improved the quality. In the meantime the emulsion technology made some quantum leaps in speed/granularity relationship and the ubiquitous electronic flash lessened the need for high speed optics. Some even predicted the demise of this type of lens. More so as the 50mm fixed focus lens is nowadays often being replaced by a 'standard zoom' of 28/35mm to 70mm focal length.

The 50mm focal length has lost a bit of its status as the premium lens for 35mm photography. The 35mm focal length will cover a horizontal angle of 53o and as the format diagonal has also a full angle of 53o , there seems to be a natural match. Some would regard this 35mm medium wide angle lens as the best suited for Leica RF photography. In my personal view (no scientific arguments involved here), the 50mm lens is still one of the most versatile lenses to use. It is well suited to a wide range of subjects and situations, from environmental portraits, to documentary photography and landscapes. In fact hardly a subject exists that cannot benefit from being recorded by a 50mm lens.

 

6.3.1 3.5/50, Anastigmat/Elmax,1925

The first lens, designed by Max Berek for the 'Barnack-Leica'. The original sheet with the calculations have the signature of with a date of Oct 7, 1922. That is some years before the actual production. In those days, that is a customary time lapse. (see page xx). The intriguing fact is the construction of 3 lenses and 5 elements, the last lens, composed of three elements. The usual explanation for this design is the avoidance of the Tessar patent. But this patent expired in 1921 or 1922. So with a presumed introduction date of 1924/1925, would not find himself in legal trouble, if he would adopt a 'classical' construction. The number of lenses produced (Anastignat and Elmax together) is well below 2000. And less than a year later the Elmar was computed and produced. It is most unlikely that if a patent problem would exist in march 1925 (introduction of the Leica camera), it would have been solved a few months later and could be anticipated by . The remarkably quick introduction of the Elmar, after the short production run of the Elmax, is a mystery that will probably never be solved. The patent issue, if one existed is only part of the answer. The Elmar delivers different image quality, and that may be the true answer.

The complex three- element last component is difficult to produce and may not have been the solution looked for.

 

Figure 85: diagram 43

At full aperture the overall contrast is low to very low, with coarse detail rendered a bit softly. The performance from centre to corner is very even, but there is evidence strong astigmatism and field curvature. Quite fine detail is detectable and especially in the centre is of very good quality. Stopped down to 1:5.6 overall contrast improves visibly and now we have a remarkably good image quality over most of the picture area. The difference between the tangential and sagittal structures is quite large, which does soften the rendition of fine detail in the zonal areas. The Elmar has a more balanced performance in this respect. This behaviour might have provided Berek with the argument to redesign the Elmax.

 

6.3.2 3.5/50,Elmar,1925, 3.5/50,Elmar,1932 and later years

This lens is part of the Leica legend and myth too. The original drawings of Max .i.; have a date of May 6th, 1925 for this lens. The Elmar has been in production for more than 35 years in countless versions, that make it a collector's delight and nightmare. Almost half a million have been produced, which is more than 12% of all Leica lenses ever produced till 2000. Optically the lens has had minor updates, which did not change its overall character. Changes recorded are differences in radius of surfaces, differences in distance from position of aperture to first lens, etc. The application of coating did not enhance the performance very much as its moderate aperture and low number of air-glass surfaces could control flare and unwanted reflections very well. The serial number, quoted often as the start of the coated versions (581501) is not fully correct. While Leica could use the coating technique from October 1941, (from serial number 580401) it is most likely that this technique has been reserved or lenses, issued to military organizations. In an internal note we read that coated lenses will not be made available for amateur users, only for 'Kriegsberichterstatter'. (war correspondents and official war photographers).

 

Figure 86: diagram 44

 

Figure 87: diagram 46

On axis and till an image height of 6mm, object outlines and coarse detail are rendered with low to medium contrast. In the field, outside this circle, the performance drops significantly. Finer detail is reproduced quite softly, caused by a fair amount of astigmatism, curvature of field and chromatic aberrations. When stopping down to 1:5.6, the image quality improves markedly and now the lens has medium contrast over most of the image field. The zonal errors however remain and reduce the definition of fine detail in the outer zones. Overall the Elmar is a fine performer and is quite able to defend its reputation, at least when stopped down moderately. We should however put the performance in its proper perspective.

Compared to the current Elmar-M 1:2.8/50mm it is of low contrast and it lacks the crisp and transparent recording of very fine detail.

 

6.3.3 2.8/50,Elmar,1957

This lens was redesigned with the new Lanthanum glasses, used also in the Summicron version and the LaK9 glass can be found in the first and last element.

Analysis by modern computer based design programs of the original Elmar configuration show that the basic design is difficult to improve upon. A tribute to the old masters no doubt.! If advances are to be made, the only route is the glass selection. Inevitably, older glass types were removed from the catalogues and so the designers were forced to adapt to these circumstances. But modern optimization analysis also shows that the gains are relatively modest and so it may be no surprise that the image quality of this lens is quite stable over the years. Of course newer glasses and specifically the coating of surfaces give a modest gain under adverse conditions. In many situations, the use of new glass types will not improve the basic performance of a lens, as the designer will adapt the lens specifications to the characteristics of the new glass in order to preserve the original image quality. The classical four-element/three group design of the Elmar can just cope with the most important aberrations. And we know that doubling the aperture will increase the effect of aberrations by at least 6 to 8 times. The designer has however limited optical means to correct this higher level of optical errors. The Leitz designers used the new glass to improve the lens, but the progress is modest. The moving tube for the collapsible mount made the lens mount a bit unstable and Leitz indeed designed a newer rigid version with much better image quality. This elusive Elmarit 1:2.8/50mm never went beyond prototype status, but should have been an excellent design.

 

Figure 88: diagram 47

At full aperture the lens has a low overall contrast, lower than that of the Summicron and the Elmar 3.5 version. Coarse detail is reproduced with soft edges and finer detail is blurred in the outer zones (beyond image height of 8mm). The aperture of 1:2.8 does overstretch the design and spherical aberration and flare (due to coma) do lower the contrast. It delivers however an even performance over most of image field, which improved rapidly when stopping down. At 1:4 the performance is very good and better than that of the original Elmar 1:3.5/50mm at 1:4. Overall contrast becomes medium and now we have a very good centre quality, with he outer zones still trailing behind. Compared to the Summicron (I), there is an interesting difference in fingerprint. The Elmar has the edge in the centre of the picture and the Summicron is better in the field. At 1:8 we find very fine imagery (as good as that of the Summicron (II) from 1957). The performance characteristics show the limit of a four-element design with the glass types then available. Vignetting and close-up performance.

 

6.3.4 2.8/50,Elmar-M, 1994

Introduced in 1994 as a special lens, only to be sold in combination with the M6J body, it has evolved into a normal , but underrated, catalogue item since 1996.

Production however was continued during 1995. The image quality of this completely redesigned lens is amazingly good and now the position of the stop is between the second and third element. One might assume that the 4 element design has been fully explored and in a sense that is the case. Still the Leica designers could extract more performance out of the design, showing that improvements are always possible. The ergonomics of the Elmar-M do limit its use. The external design very closely resembles the previous version, and inherits its small aperture ring and distance ring, presumably necessary for the compact size when collapsed. The lens mount is non-rotating.

 

Figure 89: diagram 48

At full aperture the Elmar-M adds medium to high overall contrast to the image.

Fine detail is rendered crisply over most of the film area and fine detail is recorded with great clarity and sharp edges. This behaviour is interesting when compared to the Summicron (III) from 1969, at aperture 2.8. The overall performance is comparable, with the Summicron having an advantage in contrast. But in the field (zonal areas from image height 9mm) the Elmar has clearly the edge. The Summicron has better imagery in the centre (contrast and rendition of fine detail), but the Elmar records fine textures with greater clarity in the field. Stopped down to 5.6 or 8.0, the Elmar improves visibly with a higher contrast and consequently better rendition of (now) very fine detail. The fingerprint difference with the Summicron holds at these apertures too. Only in the extreme corners the Summicron has an advantage. Compared to the older Elmar, we see the progress when we look at the capabilities of recording fine detail, which is excellent with the new version and moderate with the previous version. Vignetting is more visible with the Elmar-M than with the previous version and identical to the current Summicron (IV), stopped down to 1:2.8. Close-up performance, even at full aperture is excellent with the Elmar-M, but less so with the previous Elmar-version.

 

6.3.5 2,5/50,Hektor,1930

The Hektor is the first attempt by .i.; to design a high speed lens, with minimal means. A 'compounded triplet' as this one has six air-to glass surfaces and should reduce unwanted reflections and flare. The three cemented doublets are introduced to create glass types with characteristics, that were not available then. called this an 'Anastigmat', and he reserved the term for a lens with relative small field curvature, and good correction of the astigmatic image planes (saucers). This design generates a moderate form of spherical aberration, what can be noticed when stopping down.

The plane of sharpness shifts because of this effect, which may be noticed when taking pictures at closer distances at different apertures. The Hektor is very interesting in its use of a so-called Merté surface, a special optical design employed with the cemented surface in the centre doublet. Zonal spherical aberration is reduced by this solution and gives the lens part of its character. The patent description of this lens identifies it as a 1:1.8 design. however presumably would not go this far and reduced the aperture to 1:2.5. The Merté-surface is very sensitive to fabrication errors and when even higher speed lenses were required, the Summar was introduced.

 

Figure 90: diagram 49

The design is also very sensitive to production tolerances. One might be tempted to regard this lens as a bridge between the Elmar and the Summar and provided the Leica user with a higher speed lens to cope with slow film speed and low light. The Hektor 50 and 73 were designed in parallel and the Hektor 50mm could be a costeffective derivative of the 73mm version. Aperture stops went to 1:18. At full aperture overall contrast is low with coarse detail reproduced cleanly on axis and quite soft in the field. Stopped down to 1:4 improves contrast substantially and in the centre (image height of 9mm) fine detail is clearly defined, albeit with blurred edges.

In the outer zones performance drops visibly. At 1:5.6 the outer zones start to improve and at 1:8 we find really good quality, comparable to the current Elmar-M 1:2.8/50mm at 1:3.5. As a more apt comparison we may say that the Hektor from aperture 4 is better than the contemporary Elmar 1:3.5/50mm. Specifically in the field, the image quality is of a higher level. Field curvature and astigmatism are corrected to a higher degree, and the Hektor has a gentle drop in performance when traversing from centre to edge. The Elmar has slightly higher overall contrast, but a weaker performance over the whole picture area. Vignetting of the Hektor is high with 1.5 stops, as compared to the Elmar with 1 stop.

 

6.3.6 2.0/50, Summar, 1933

The first high - speed lens for the Leica, again designed by .i.;, closely followed the pattern set by the 6 element Cooke design, and gave the Leica truly available light capabilities. The aperture of 1:2 was 1 2/3 stops faster than the Elmar 1:3.5/50mm and now the Leica user could truly 'fix the shadows' as a famous and accurate definition of photography has it. The Summar has been produced in collapsible and (rare) rigid versions, both with the same optical cell. In 1938 the Summar had a price tag of 157 Reichsmark, against the Elmar 3.5/50 of 77 Reichsmark. A 1:2/50mm is still the workhorse under the standard lenses and it may be amazing that after 70 years many photographic situations can be handled with this aperture.

 

Figure 91: diagram 50

The Summar 1:2/50mm exhibits a low contrast image at full aperture, with a strong presence of astigmatism in the outer zones and a fair amount of veiling glare. The edges of the fine detail outlines are blurred, which give the impression of a slight unsharpness. Coarse detail is clearly visible with good edge contrast. The performance on axis (till an image height of 4-6mm) is quite commendable. The rendition of fine detail in the image field (zones and edges) rapidly becomes fuzzy and very soft. On axis we can detect 80 to 100 linepairs/mm, a Figure that appears quite high. Here we may note another general topic. Performance on axis has never been a big problem for lens designers since the early '30s, as the axial area is almost aberration free, by nature so to speak. References in the literature to high resolution Figures in the centre of the lens/image are not a very useable measure for real-world optical performance. Introduce a lower contrast , add some flare and some zonal aberrations and the centre performance, as recorded on film, will drop dramatically.

Stopping down to 1:4.5 the image quality improves a bit , but reluctantly, and at this aperture the overall contrast is slightly higher and now we have very good imagery spreading into the outer zones. Quite fine detail is clearly detectable, but still with a shade of fuzziness. The amount of vignetting is on the high side with 1.7 stops.

Allowing some vignetting is a well-known tool of the lens designer to improve the image quality as the extreme corner rays are excluded form the image formation process. At 1:5.6 overall contrast improves another step, but rendition of fine detail in the outer zones of the field hardly improves, a sure sign that the residual aberrations are still large. At 1:8 we have excellent performance till image height 9mm, after which quality drops visibly.

 

6.3.7 2.0/50,Summitar,1939

Leitz however, kept on studying and improving the design and so gained valuable experience, which they used to good effect when they introduced the Summitar 1:2/50mm in 1939. With he Summitar, Leitz designed its first seven element- four group design, that shows many characteristics with the early Summicron version.

Aperture stops went to 1:12.5, as with the Summar. Later versions went to 1:16.

There is some discussion if this restricted range of stops has any relation to the level of aberration correction. It is presumed that a lens with small aperture diameters would show diffraction and other errors. There is no factual basis for such a assertion. It is possible that problems with the mechanical accuracy of the aperture stop to cover a range from 1:2 to 1:16 are part of the answer. The Summitar is supposed to have a large front diameter to reduce vignetting, but read the test.

 

Figure 92: diagram 51

This lens has somewhat higher contrast and noticeably less vignetting, partly due to a bigger front lens . Its general characteristics wide open closely follow the Summar.

Its central area of good definition is larger as is the reduction of astigmatism. Most importantly the Summitar improves rapidly on axis on when stopping down and at 1:2.8, we get medium overall contrast and clearly visible recording of fine detail, but edges stay on the soft side. The outer zones are flare prone and of very low contrast with blurred corners. At 1:4 we find very good imagery in the centre, but the outer zones improve very reluctantly when stopping down. At 1:8 the optimum is reached and fine detail is recorded with good clarity, albeit soft edges. After 1:11 performance drops as contrast is reduced. Compared to the Summar, the improvements are a higher overall contrast, very good quality in the central area of the image and a more powerful rendition of coarse to fine detail. The definition of finer structural details is on the same level as that of the Summar. The alleged improved colour correction is difficult if at all to detect. Vignetting is about 1.5 stops at full aperture, only slightly lower by the way than with the Summicron (I).

 

6.3.8 2.0/50,Summicron collapsible, 1953

After the introduction of the Summitar, the 'Leitz Rechenbüro' continued to explore this design as it was clear that the competition would not sleep and a high quality 2/50 lens was of utmost importance for the critical Leica user. In those days the limits of the diameter of the lens mount of the current models became painfully clear. When wider apertures were needed or a higher level of correction , the diameter simply was too small. The patent literature of the four-tap bayonet mount for the later M-models, specifically mentions the reduced vignetting as one of the prime characteristics. The first Summicron version closely followed the design parameters of the Summitar and the increase in image quality was slight. It is a low contrast lens, and shares the optical 'fingerprint ' with its predecessor

Figure 93: diagram 52

As suitable glass types seemed to be the biggest obstacle for the advancement of new designs, Leitz set up its own glass laboratory and around 1953. The first fruit of that effort was the introduction of the Summicron 1:2/50mm (collapsible). Its design was completed in 1949 and employed the new lanthanum ('rare earth') glass, which was being offered by the British firm Chance Brothers Glass and a new computation became necessary in 1952 when Schott glass had to be incorporated. The Summicron design was first 'tested' in a Summitar* disguise. Two small batches were produced, one from 812242 to 812323 and one from 812341 to 812360, both series are from September 1950. The first batch, assigned to the Summicron is from #920.000, is dated late 1951. This lens employed LaK9 glass for three of its seven elements. Leitz documentation show that the lens was designated as SummiKron too, implying that 'cron' might be derived from Kron-glas (Crown glass). At full aperture overall contrast is low to medium, and coarse detail is rendered with good clarity over most of the image field, corners excepted. The fingerprint of this lens is almost identical to that of the Summitar. Very critical inspection will reveal some finer differences. The Summitar has slightly better centre performance, whereas the Summicron has a more even performance over the whole image area. One might assume that the designers paid more attention to an even coverage as this lens was supposed to be the prime lens for the Leica system. Stopped down to 1:2.8 the Summicron clearly distances itself from the Summitar at the same aperture. Contrast improves, and the even coverage of coarse and finer detail is crisper. At 1:4 very fine detail is resolved over most of the image area with good clarity and very fine detail becomes visible, but with fuzzy edges, due to a trace of astigmatism and field curvature. At 1:5.6 a faint improvement in the outer zones can be detected. The lens is sensitive to flare and bright light spots have extended blurred edges. Vignetting is about 1.6 stops at full aperture and is gone at 1:5.6.

 

6.3.9 2.0/50,Summicron, 1957

This Summicron version has a slightly different optical cell than the collapsible one and improved performance. Now 4 lens elements are from the LaK9 type. The distance between the first and second lens element (the air lens) has been increased form 028mm to 1.52mm and the shape of the second element is different too. It has been build it two versions, the standard version, designated as the Rigid version to distinguish it from the Collapsible version. The minimum focusing distance is 1 meter. A second version with an extended close focus range (from 88cm till 48 cm) and an removable spectacle rangefinder attachment has been produced. This version has the designation DR (Dual Range) or NF (Near Focus). Both the Rigid and the DR version have identical optical cells and so have absolutely identical performance.

 

Figure 94: diagram 53

The rigid version of the Summicron 1:2/50mm arrived on the market in 1957, but was on the drawing board several years earlier. It utilized the optical improvements that were made available with the wider throat for the M-body. Increasingly Leitz realized that the inherent instability of the moving tube of the collapsible types was a negative factor for the required optical improvements. The rigid version of the Summicron is the first Leica lens with image characteristics pointing into the future direction. The designers now were free to use the wider bayonet throat of the Mbody and did not have to compromise for the use on the thread-mount bodies.

Overall contrast at full aperture is medium and fine detail is recorded with crisp edges over a large part of the image area (till image height 12mm). Most noticeable difference with the collapsible version is the greater transparency and clarity of the image and a marked improvement in the definition of fine to very fine detail , after stopping down one or two stops. The aperture of 1:4 brings a quite visible improvement in contrast and the centre performance now spreads into the zonal areas. Very fine detail is rendered with quite crisp edges and extremely fine detail is visible, but a bit blurred by flare and low contrast. At 1:5.6 we get excellent performance with only the outer zones and corners lagging behind. Close-up performance is acceptable at full aperture, but for best results one should stop down to 1:4 or smaller. This also helps extend the depth of field, often necessary when photographing at close distances when the subject has depth in space. This Summicron captures a level of very fine detail that is beyond the recording capabilities of the predecessors. Vignetting is at the same level as the first version.

 

6.3.10 2/50,Summicron-R, 1964

The first Summicron for the Leicaflex, introduced in 1964 was a Canadian design, as was the Elmarit-R 1:2.8/90. (the 35mm, the 135mm and he 180mm were of Wetzlar origin). This Summicron could be focused till 50cm, a must for a reflex lens and can be compared to the 1 meter limit with the rangefinder version. This additional focusing range asked for a different type of correction. Curvature of field had to be small at full aperture and focus shift should be contained as well. The higher contrast of this lens, when compared to other lenses, including the competition, was quite noticeable. Research had indicated that film-emulsions could deliver a higher sharpness impression and a higher level of recording of fine detail if the acutance (or micro-contrast) was enhanced. Lenses that could use this characteristic with success had to be of higher contrast than was customary in those days. The introduction of the Summicron-R with enhanced contrast was the result of reflection and study of these imaging characteristics.

 

Figure 95: diagram 56

With its lower level of astigmatism, spherical aberration and field curvature, this lens has a medium to high overall contrast at full aperture, more so than the RF-version at that time (the then current Summicron (II) for the M-system). Stopped down however the M-version gave better results. This comparative evaluation indicates that any lens is a compromise between several competing demands. It is true that today, designers with a different approach, expanded theoretical understanding and sophisticated tools are able to balance these conflicting characteristics to a higher degree. The reader will become convinced (I do hope at least) that any lens (at least in the Leica world) has its own unique personality. A global merit Figure for the evaluation of a Leica lens does not suffice to get to the finer points that characterizes and differentiates the Leica lenses. Some of the lens elements for this lens have been produced by the Leitz factory in Rastatt, where spectacle glasses were also made.

The Summicron-R (I) has better overall performance than the Summicron (II) for the rangefinder system: generally we note a higher contrast in the field and a much better reduced level of flare. At full aperture we note a medium to high overall contrast, and a crisp definition of fine detail over a large part of the image area.

Stopping down improves the performance somewhat. From 1:4 the Summicron (II) for the M improves more than the Summicron-R (I) and might be the better performer as this lens had a more favourable optical response to the aperture becoming smaller. The improved image quality at the wider apertures, however, gives the R-version a wider usefulness. Here again we note as so often, that it is not so easy to give one overall performance measure to appraise a lens. Too many variables have to be balanced and the compromise will be different from lens type to lens type. The bad guys with high speed lenses are flare, low contrast, coma and spherical aberration and the design history of the high speed lens is a battle on many fronts.

 

6.3.11 2/50,Summicron (III), ,1969

The seven-element Summicron 1:2/50mm was followed in 1969 by a six element version. It shared many design characteristics with the first Summicron-R 1:2/50mm, which was introduced in 1964. The sixties were a period of rapid changes in photography and the criteria of lens evaluation evolved. It was established that good contrast at the limit of the resolving power of the film-emulsion provided better image quality than a high resolving power with lower contrast. The Leitz Summicron-R and the Nikkor-H 2/50mm were probably the first lenses to be designed according to this rule. Both were six element lenses and these designs replaced the previous seven-element constructions, which were generally of lower contrast. The lens elements 4 and 5 are separated by an air lens with a thickness of 0.07mm!

Figure 96: diagram 54

At full aperture overall contrast is high; outlines and coarse detail is rendered with good edge contrast over most of the image field, the corners excepted. Crisp definition of very fine detail is visible on axis, but becomes soft when going to the outer zones of the image. This performance at 1:2 is better than of the 7-element version at 1:2.8. Effectively the user wins a full stop. As astigmatism and field curvature are better controlled, close up performance is very good and better than with the previous version. One of the reasons of the improved correction is a slightly larger diameter of the last lens element. The DR-version had a mechanical construction, that needed a smaller diameter of this lens, and this caused some edge rays (with a beneficial effect on the performance) to be cut off from the image plane.

At 1:2.8 the contrast improves significantly, but the rendition of very fine detail trails a bit behind. This characteristic holds when stopping down further: excellent quality on axis with a clear definition of very fine detail and a more restrained rendition of the very small textural details in the outer zones of the image. At 1:5.6 the previous Summicron (II), is at the same level of performance, but the impression of clarity and high contrast of the newer one, gives it the definite advantage. Vignetting is slightly higher, when compared with the second version. Distortion is absolutely zero, making this lens good for recording of plane surfaces with scientific precision.

 

6.3.12 2/50, Summicron-R (II), f, 1976 & 2/50,

Summicron-M (IV, 1979 Both lenses are identical in design and (almost) in performance. The small differences can be attributed to the mount that is dedicated to the use of an automatic diaphragm in the R-version and a rangefinder coupling in the M-version. Both are Canadian designs as were the predecessors. Both versions share the same glass types and design. The lens diagrams do show some differences in shapes of the rims of the lens elements, but these are necessitated by the different mounts and have no significance for the image quality. Many modern lenses after 1950 are based on the six-element double-Gauss design, and without any doubt, this lens-type is the best studied type in the world. It has excellent potential for high quality imagery, but as with every design it has its limits, due to a fair amount of oblique spherical aberration (a fifth-order aberration). This error is very difficult to balance with third order aberrations, let alone to correct completely. The wider the aperture , the more disturbing this error becomes. Around 1980, this design type reached its current zenith and I may add, that significant improvements are unlikely, unless the designer departs from the basic layout.

 

Figure 97: diagram 57 (R)

 

Figure 98: diagram 55: M

Five surfaces are flat, a measure, that reduces the ability for aberration correction and at the same time simplifies the production and assembly of the lens. Both lenses have improved imagery and this is an outstanding tribute to design optimization, that would have been impossible in the pre-computer period. The improved performance has been made possible through a higher correction of coma, and field curvature. At full aperture the M-version has the same overall contrast as the previous one, but the most visible improvement is the crisp and clear rendition of the extremely fine details on axis, which give the definition of the image a sparkling clarity. At 1:2.8 the contrast of the fine details improve, as do the outer zones and at 1: 4 we have an outstanding image quality, with only the outer zones a trace behind the centre. The Summicron (III) at the same aperture exhibits a softer image in the field. At 1:5.6 the overall contrast is slightly reduced, and the definition of the fine textural details in the field has improved a bit. Here we note that the user of these lenses should study his subjects and demands very carefully: for best overall contrast the optimum aperture is 4, but for best definition of very subtle textural shades of grey or colour, 5.6 might be more appropriate. Scientific tests can indicate these differences as measured values, but the user may or may not be able to see or appreciate them.

Photographic technique is the limiting factor here. I will note this aspect often in the course of these reviews. Vignetting is at the same level as the Summicron (III). Close up performance is much improved as is flare reduction (the lower amount of came helps here a lot). Drawing (distortion) is non-existent. Most of the above remarks apply to the R-version too. The R version at full aperture has somewhat lower contrast over the whole image field than its M-version. One should however not overestimate these differences. I made careful comparisons with both lenses and saw a fractional difference when shooting in normal day light situations. When taking pictures in twilight and similar low contrast environments the difference may be of more importance. At 1:5.6 the situation is reversed. Now the R-version has the higher contrast and gives a truly outstanding performance on axis (up to an image height of 9mm). The outer zonal areas have a somewhat lower performance as one looks at the very fine textural details. The M-version has a somewhat more even performance over the whole image field, but with a lower overall contrast. Both lenses offer sparkling clarity of extremely fine details, but if one wishes to differentiate the R version has a slightly flatter definition in the field. Stopped down to 1:5.6 the R-version shows that typical dip in performance in the outer zones, that many Leitz lenses of these generations share. R- and M-version deliver outstanding performance at a close-up distance of 1 meter, when stopped down a bit. This phenomenon does show, as so often, that many classical legends, are no longer valid.

The old adagio , that a lens can only be corrected for infinity and therefore should drop in performance when closer distances are used, has of course a theoretical justification, but not always a practical relevance. Many current Leica lenses do prove that at closer distances, performance can be as good as at infinity, which by the way is not true mathematical infinity, but a value like 100 times the focal length. (See design chapters).

 

6.3.13 1.5/50, Xenon,1935/1936 & 1.5/50,Summarit, 1954

Most lens aberrations grow disproportionatetely when the aperture is doubled. When designers were still struggling to get decent performance out of an 1:2/50mm design, it seemed a bit rash to introduce a 1.5 lens. Remembering the slow film speeds of those days and the advent of the colour slide films with even lower sensitivity and the drive of the Leica photographer to capture scenes, illuminated by the faintest trace of light, a 1.5 lens makes sense, even if it is a designer's nightmare. Why Leitz have opted for the Schneider lens and did not wait for the Berek solution that was being created in the same period, is a mystery, but it might be that the introduction of the Zeiss Contax RF with a good 1.5 lens, was seen as a commercial challenge. It is sometimes asked why a designer would choose a 1.5 aperture and not the 1.4 aperture, as there seems to be only a small difference between both apertures. First of all, we have to realize that aperture stops and their values are subject to issues of tolerance, just like focal lengths. Secondly, a difference in aperture of 5 or 10%, is for a designer sometimes the borderline between a good and a bad design, as this additional amount of rays might introduce aberrations, that are very difficult to correct. To give a practical example: the diameter of a 1.5 aperture is 21.3mm and for a 1.4 aperture it is 22.7mm. Such a difference might be quite large in the world of optical design. The Leitz Xenon allowed the user to expand his practical picture taking opportunities into hitherto uncharted realms. Apertures till 1:9 only. Weight is 300grams.

 

Figure 99: diagram 59

The performance of the lens at full aperture is however barely acceptable for the intended use. Finer detail in the centre area (about 5 mm image height) is recorded with good visibility, but the very low contrast and strong presence of coma, especially in high contrast situations reduce the useful recording capabilities. A high speed lens with 10 air-glass uncoated surfaces has a high level of internal flare, that tends to lighten the deeper shadow areas in a picture, and thus give the impression of being able to penetrate the shadows, where in fact the only effect they have is a bit higher density in the otherwise blank areas of the negative. On the other hand the coma introduces flare patches around specular highlights. The quite dreamy and romantic atmosphere of pictures taken with high speed lenses at wider apertures in those days visible in many picture examples. Stopping down improves the image quality very reluctantly. At 1:2.8 we find an overall performance that will bring in the finer details within visible range, but with soft edges. In the outer zones definition of fine detail is quite soft. At 1:5.6 performance evens up and quite fine detail is rendered with still blurred edges. Close distance performance at the wider apertures is very weak and one has to stop down to 5.6 and smaller to get good results.

The Summarit 1:1.5/50mm is a coated version of the Xenon. The anti-reflection coating as a tool in the lens designers toolbox is effective when the design is trimmed to the use of coating. Coating can reduce reflections and enhance the effectiveness of transmission, but only to a certain extent. The overall contrast at full aperture is very low. The centre area (image height about 4 to 5 mm) has the (usual) familiar high resolution from 80 to 100lp/mm, which is, however, a theoretical figure as flare and the residual zonal aberrations degrade the recording capacity significantly. Stopping down improves contrast and after 1:5.6 we see a quite good image quality that invites sympathy , but is not equal to the contemporary lenses of lower speed. The inherently higher correction of aberrations in the lower speed designs does show.

Generally the image quality of the Summarit is close to that of the Xenon, which should come as no surprise, as both share the identical formula. Apertures now till 1:16. Weight is 300grams

6.3.14 1.4/50, Summilux (I), 1959

The first Leica lens in the 1.4/50mm category was a redesigned version of the Summarit with newer glass types. This lens was introduced in 1959, designed by ELW and had the shortest life span of any Leica lens as it was replaced in 1961 by a much improved version, the still current Summilux-M 1:1.4/50mm. The first Summilux has low overall contrast at full aperture, quite visible vignetting (more than 2 stops) and on axis coarse detail is rendered with good clarity but soft edges, rapidly becoming blurred when approaching the corners of the image area. At 1:2 the contrast becomes medium and fine detail is now quite visible, albeit with some fuzziness. The outer zones , from image height 6mm, stay soft and fine detail is recorded with fuzzy edges.

 

Figure 100: diagram 60

This characteristic of good on axis and weaker performance in the field holds till 1:8, where the performance evens up over the whole image area. At 1:4, contrast improves again and the definition of the major outlines becomes crisp as is the rendition of finer detail on axis. Stopping down to 1:5.6 brings some marginal improvement. At apertures 8 and 11, we have optimum image quality of a high order. For serious close-up performance you have to stop down to 2.8 - 4. Flare is present at the wider apertures and produces the well-known blurry patches of light around bright light spots. Compared to the Summarit, this Summilux has visibly higher contrast and definition of fine details. At 1:2.8, the Summarit has improved, but the Summilux is at the same aperture still better. These remarks are relative and I also have to remark that the contemporary Summicron (II) at all apertures, including 1:2, has the better imagery overall. Everything is more relative than one might care to know about and, as a comparison the other way around, we may say that the Summilux (I) is at all apertures better than the Summitar.

 

6.3.15 1.4/50,Summilux (II), 1961

A truly excellent 1:2/50 lens can be realized relatively easily with a double-Gauss design, as we noted during the Summicron discussion. Often it is assumed that the one additional stop to the aperture of 1:1.4 is a matter of smooth transition. Add one lens element to correct the increased level of aberrations, tolerate somewhat more image degradation at the wider apertures and all is well? In fact the jump from 2 to 1.4 is a step into another dimension, as going from the molecular to the atomic level.

As the aperture increase with a factor 2 , all aberrations will grow with a factor of 22 and 23 . The battle with this new level of optical errors would be easier to win, if the volume of the lens were of no importance. But it is and especially with the M-series large lenses are not feasible ergonomically and presumably economically too.

 

Figure 101: diagram 61

This second (Canadian) design has a higher overall contrast at full aperture and on axis very fine detail is rendered with high edge contrast. This second version has excellent image quality on axis, but performance takes a visible dip in quality when going to the outer zones. Coarse outlines and medium fine detail is crisply rendered, but finer detail becomes progressively softer and fuzzier when extending into the outer zones. Stopping down to 1:2.8 improves overall contrast. Image quality in the field is however visibly lower and the outer zones stay weak, with very fine detail below the threshold of recording capability. This behavior is typical of very wide aperture lenses and is an indication that there are some nasty aberrations operating at this level. Stopping down to 1:4 and 1:5.6 bring small improvements and the overall characteristic of excellent on-axis performance, combined with a weaker performance in the field does not change. At apertures 1: 8 and 1:11 the performance becomes first class and extends over the whole image area. This second version shows its advantages specifically when the wider apertures are used. Stopped down the differences are quite subtle. Vignetting is on the same level as the first version.

Close-up performance is very good from 1:2.8. Strong light points are recorded with fuzzy rings of halo and high contrast scenes generate a veiling glare over the whole image area, lowering micro-contrast and thus soften the definition of the finer details. Compared to the Summicron-M (III), its contemporary, we may note the same general fingerprint. The Summilux verson performs as a Summicron (III) lens opened up one stop.

 

6.3.16 1.4/50,Summilux-R (I), 1970

The Summilux-R 1:1.4/50mm has been introduced at the Photokina 1970. It constitutes a Wetzlar design and has an interesting performance profile. At full aperture it is of slightly lower contrast than the M-version and its on axis performance extends over a wider area. It also shows reduced astigmatism and field curvature, giving it improved image quality. The M-version shows better flare reduction thanks to the better correction of coma. On this level the designer has clearly to balance requirements against possibilities. At 1:2 the Summilux-R improves and is now as good and even a bit better than the Summicron-R (I) (higher contrast, crisper rendition of fine details). Stopped down to 1:5.6 its overall performance is improved visibly, thanks to a high contrast. The definition of very fine detail in outer zones of the image field is a bit weak and brings in very fine detail with good clarity .

At this aperture the Summicron-R (I) has a larger focus shift, that reduces the definition of small details at very big enlargements. During its production, the Summilux underwent several detail changes in glass type, without altering its fingerprint.

 

Figure 102: diagram 62

Around 1980 there is a change in production method, and lenses are no longer classified in groups of focal length (as with the M-lenses), but a compensation method is used to adjust the correct focal length with lens thicknesses and distances.

Elpro-close-focus attachments can be used with the Summilux-R without problems.

 

6.3.17 1.4/50,Summilux-R (II), 1998

This eight-element design shows a significant improvement over all previous 1.4 designs. The performance in the field is quite visibly enhanced and this is the first 1.4-Leica lens, that delivers outstanding image quality when stopping down. In this respect it is better than the current Summilux-M-version and even brings current Summicron quality and more to a 1.4 design.

 

Figure 103: diagram 63

At full aperture the new Summilux-R exhibits medium to close-to-high contrast that is visibly above the lower contrast of the seven element predecessor. This is quite a performance as conventional wisdom will tell you that more lens elements will degrade contrast. The additional eight element was needed for correction of field curvature. Fine detail is very clearly rendered with crisp edges with only a faint trace of astigmatism and field curvature in the centre over an image area with image height of 9mm. From there the quality very gradually drops, as compared to a drastic drop in previous designs. At 1:2 overall contrast improves and the optical performance is as good as that of the current Summicron lenses at their full aperture. In fact performance from 1:2.8 to 1:4 is almost identical to the current Summicron. Very fine detail is recorded with excellent clarity and crisp outlines from centre to well into the outer zones. In the far corner area a slight drop in performance can be noted.

Stopping down from 1:2.8 to 1:4 gradually brings in exceedingly fine details that are now recorded with that lucid clarity that characterizes modern Leica designs. At 1:5.6 the Summilux surpasses the level of image quality of the current Summicron. From f/11.0 diffraction starts to lower the contrast of very small image details. Close-up performance (+1 meter distance) is at all apertures excellent. Deliberate two stops underexposure failed to bring out strong vignetting. Veiling flare at full aperture is negligible. Suppression of light halos around small subject details is excellent and careful comparison shots with the Summilux-M 50mm showed the R version to have a slight edge. The sharpness-unsharpness gradient is quite smooth and subject shapes are very well preserved in the unsharpness zones.

The new Summilux-R 1:1,4/50 offers excellent image quality and Leica R users can now shoot in available darkness and fully exploit the capabilities of modern emulsions. For my comparison shots I use Kodachrome 25 and 64, as these films still give the best microcontrast (read edge contrast) for the definition of extremely fine image details. Stopped down one stop and the new Summilux-R has that enviable balance of lucidly rendered crisp detail and smooth gradient of colour hues within small subject areas that is Leica's current . The image recording capabilities of this lens far exceed the one offered by all current ISO400 films and are on a par with the best of the ISO100 films. Kodachrome 64 would be an excellent companion.

In comparison to the Summicron-R 2/50 the new Summilux is a better lens. Optical aberrations( especially curvature of field and astigmatism) are tightly controlled, and from 1:2 the Summilux jumps ahead of the Summicron-R. Compared to the current Summilux-M the differences at full aperture are quite visible. On axis performance is more or less equal, but the R-version wins in the field, ad significantly so! And when stopping down forges ahead with superior performance in the field Summarizing: the 1./50 Summilux-R (II) defines the current state of the art of large aperture standard lenses. It outclasses the 1.4/50 Summilux-R (I) by a comfortable length. It edges ahead of the Summicron-R (II) and visibly improves on the Summilux-M (II) 1.4/50. Non-scientific comparison pictures with the Summicron-M (IV) show comparable performance in most picture taking situations. If you need to record the finest possible details and shades in small textures, the Summilux-R (II) has to be stopped down to 1:2.8 and at medium apertures, the Summilux-R (II) has no competition.

 

6.3.18 1.4/50mm Summilux-M ASPH, 2004

The evolution of the high-speed standard lens came to a virtual halt in the late seventies. The reason is quite simple: the classical design for most 35mm lenses was a derivative of the double Gauss lens, as exemplified by the Biotar lens. In my report of the new Summilux-R 1: 1.4/50mm (II) in 1998 I noted that the era of the Double Gauss lens was not yet over. We were encountering a certain plateau however. In 1980 Dr. Mandler had written the definitive book about the stare of the art and the potential of the DG class of lenses. His conclusion was that for most lenses for general photography with focal lengths from 35mm to 90mm, the DG type was eminently suited and could not be improved upon within normal economical and manufacturing constraints. But the design has its inherent limitations. Very highspeed lenses could not be corrected fully for the oblique spherical aberration in the sagittal direction, astigmatism and curvature of field. These aberrations produced a low contrast reproduction of fine details and a soft edge contrast for subject outlines in the outer zones of the image area. The wider the aperture, the more pronounced these effects could become. In addition the improvement of performance at smaller apertures was quite modest because the balance of the aberration correction was naturally focussed on the image quality at the wider apertures. In addition, the focus shift could lower the quality of the image in the centre of the image.

These limitations made the design of a truly outstanding high-speed lens, based on the DG design an enigma. And in fact development of wide aperture lenses stopped around 1980. With eight elements the development potential was exhausted. The choice of glasses and especially the modern glass types could be beneficial, but not enough to give a radical improvement. The Canon FD 1: 1.2/55mm Aspherical design did demonstrate this, but with eight elements, one grounded aspherical surface and a floating element, it was very bulky and outrageously expensive. Wide open the overall definition showed the faint softness of the image that is the main characteristic of all very high-speed lenses at full aperture. If you look critically at the image, you have the impression that you just missed the critical focus plane.

However good the image quality wide open, there is always a visible improvement when stopping down to f/2 and f/2.8. It is as if the image snaps into focus with high contrast.

To be fair, it should be noted that most users of high-speed lenses do not use the wide apertures quite often and when then in conditions where the finest optical quality is not the overriding concern of the photographer.

In recent years we have seen only two new designs that show a marked improvement on the predecessors: the Leica Summilux-R 1:1.4/50mm (II) from 1998 and the Voigtländer Nokton 1:1.5/50mm Aspherical for Bessa and Leica cameras.

The new Summilux-R 1:1.4/50mm showed a significant improvement in the stopped down performance, based on a higher level of correction of the secondary spectrum and the reduction of astigmatism and curvature of field. The thick centre element (behind the stop) functions as a field flattener. The sharpness impression at the wider apertures was also improved, especially in the middle zones of the image. The overall performance wide open did follow the pattern described above and high contrast imagery can be expected from f/2. From 2.8 the quality is better than what can be expected from the Summicron-R. 2/50mm. Wide open the Summilux-R is remarkably free from veiling glare, flare around bright light sources and secondary reflected images The Nokton has the classical double Gauss design with six elements and two aspherical surfaces on the last lens element. This lens shows improved performance in the outer zones when stopping down and a fair to modest contrast wide open.

Excellent performance can be expected from f/3.5. At wider apertures we see a tendency to veiling glare and overall contrast is fair to medium. As a corollary the definition of fine detail is on the soft side, but quite evenly distributed over most of the image area. Astigmatism and curvature of field are partly responsible for this behaviour.

It has however the edge on the Leica Summilux-M 1:1.4/50mm, a design from 1962, modelled on the classical lines with seven elements and an air spaced lens between the second and third element. This lens has good contrast wide open, but the performance in the outer zones there is a fair amount of astigmatism and there is also some curvature of field. Definition in the centre of the image is very good, even wide open, but on stopping down the outer zones cover the finer details with low contrast. The intended use for this lens is the reportage and documentary photography with high-speed film, as the Kodak Tri-X (in this year 50 years old incidentally), where the coarser grain does boost the edge contrast and suppresses the reproduction of really fine detail.

 

Contrast versus resolution

There is a persistent story that one can optimize a lens for high contrast or high resolution. There is a certain truth in this assertion, but one has to understand the facts. The choice is only relevant for systems with a high amount of spherical aberration. In this case the rays from a point in object space do not converge to a point in image space, but the bundle of rays forms a pipe of light that is converging to a certain location on the optical axis where the waist of the pipe is smaller and then starts to widen. It is obvious that the location with the narrowest waist has the best contrast, but this is not the location of the film plane. Around the film plane we find a wider bundle of rays, but more dispersed and here we find the location with best resolution. In the past high-speed lenses al had a fair amount of spherical aberration and then the designer could select the back focal length such that the film plane was near the location of best resolution or best contrast. But the difference between both choices was quite minor in practice. Currently all Leica lenses have a very low amount of spherical error and then the choice is not relevant: all lenses have automatically a high contrast and a high resolution.

 

New approaches and a new vision

The first fundamental departure from the DG design was introduced with the Summilux-M 1:1.4/35mm Aspherical in 1989. In the patent literature (#5.161.060) the designers stress the fact that the new design gives a markedly improved performance in the outer zones of the lens. They also note that the employment of aspherical surfaces must be fully integrated in the whole design and must be part of the basic specifications. Here we detect the design principles of Mr Kölsch: you need to understand the basic problem of a lens first in order to find a sensible and fruitful solution. If a lens exhibits astigmatism as example, it makes no sense to let the computer find solutions, but you must first understand on a theoretical base why this astigmatism occurs, what lens surfaces are responsible for its magnitude and what is the best and most simple solution. This approach: to find the best and most simple solution for a design problem is the basis of all current Leica lenses. It is better to search for one special glass type with the required characteristics in one of the many lens catalogues and to understand it's potential for the solution for the problem at hand, than to use two separate elements whose combined power might provide a solution too.

When I discussed future trends in optical design with the Leica designers in 2000, the natural question to ask was whether a future 1.4/50 design for the M series could be derived from the Summilux-M 1.4/35 ASPH. The answer was that it might be possible, but not at that moment. The Summilux design transposed to a 1.4/50mm lens would become too large and require a level of tolerances that was impossible to hold in series production, even with the high level of careful manual assembly and frequent inspections that is the hallmark of the Leica Manufaktur. Two years later the optical cell with the eight elements and some exotic glass types was ready and delivered breathtaking performances on paper. At that moment in time it was not yet feasible for production as the mechanical problems were not solved and the size of the lens was an additional hurdle to take. It was a clear design goal that the new lens should be as compact as the current Summilux-M 1.4/50mm. But the designer had an ambitious vision: this lens was to become the best high-speed standard lens in the world, a true demonstration of Leica's optical ability in this field. For this goal the lens needed to perform above normal requirements in the near focus range and a floating element would be necessary. We know that a lens can be optimized for one distance only. This distance is normally the infinity position or in more practical terms one thousand times the focal length. But even at a distance of one hundred times the focal length (in this case 5 meter), the performance has not dropped to a level that is detectible. But at a close range and particularly at wider apertures one might begin to see a drop in contrast and a very slight haze that seems to reduce the clarity of the image. High-speed lenses in particular are prone to this effect, due to the presence of spherical aberration, astigmatism and curvature of field. If you are not a professional optical designer, there are many aspects you take for granted, but are a nightmare for the designer. The performance of a lens can be fully described by looking at the aberration distribution in the entrance and exit pupils. Here distortion and spherical aberration are two sides of one coin. Improve one and automatically degrade the other. But near distance performance needs to be distortion free and also deliver a crisp image. For a designer this is quite demanding a task.

 

The size problem

But the most demanding of all tasks is the combination of a small size with excellent image quality. I am now seriously designing lenses, as this is the only way to start to understand the problems and challenges of the optical designer. Modern optical design programs are extremely capable and you can ask the program to find the best lens design for a certain level of performance and selection of glass types. But invariably the optimization program will create a lens that is large and as soon as you restrict the physical dimensions of the lens, the performance drops significantly and all your work is for nothing. Then there is only one option: to make manual adjustments and very slowly proceed to a practical solution. As photographers we are justified to have simple demands: small size lenses and superb performance. But we do not appreciate fully the achievements of the designer when we do not have a clue how difficult it is to combine size and performance. The image quality of the new Summilux-M 1:1.4/50mm ASPH would be outstandingly good when fitted in a big mount, but is spectacularly good when one considers the size.

The addition of a floating element in the same space of the previous Summilux-M can be regarded as a triumph of mechanical engineering. The task here is twofold: find a mechanical solution (in this case finding the correct specifications for the pitch and thread of the mating parts: you need to combine accuracy and smoothness) and find one that can be manufactured in a consistent way. In the past, the prototype stage is the platform to find out if the lens can be manufactured at all to the required specifications. But it is up to the manufacturing department to find a way to manufacture and assemble the parts in a cost effective way. This did not always function in the past: and many lenses had to be changed during series production to accommodate to the harsh realities of the limits of the workers at the assembly stage.

The famous wooden hammer, often seen as the symbol of superior craftsmanship at the assembly stage is in fact the remedy for the shortcomings at the prototype stage.

The current approach within the Leica optical design department is to order parts from the series production to be used during the prototype stage. So they accommodate to the realities of production tolerances and not the other way around.

This is a most sensible approach and explains why the period between finalizing the prototype and the start of the series production is very short. Normally it takes Leica a long period to go from prototype to series production, a delay that was acceptable in the old times, but now is no longer an option, given the aggressive pace of new developments.

 

On test.

Let me be clear and honest: it is impossible for a 1.4 lens to deliver at that aperture the same image quality as what we can expect from the best 1:2 lenses at f/2. The increase in magnitude of aberrations and the additional types of aberrations (fifth and seventh order) forbids this level of quality. In particular the spherical aberration in the sagittal direction is a bad guy. This said, I have to note that the performance at 1.4 that we get form the new Summilux-M 1:1.4/50mm ASPH is very, very close to the performance of the best f/2 design (read Summicron).

At full aperture the overall contrast is high, with a faint hint of softness still hovering over the image. Astigmatism is very well controlled and the curvature of field is very flat, bringing a visibly enhanced image impact in the outer zones of the picture area.

There is a small amount of coma detectible in small bright spots and specular highlights, but much less than in the previous design.

I made the test pictures with Fuji Provia 100F and 400F. Colour rendition of the new Summilux is outstandingly good. Especially in areas with dim light, the colours are bright and clean and quite saturated. With other high-speed lenses the colours in low light illumination look a bit underexposed and flat. They lack the sparkle of bright light illumination. Here the new Summilux sets a very high standard. And in combination with the excellent reproduction of high lights and reflections in bright surfaces, the images with this lens have a very fine and subtle three-dimensional effect that enhances the lifelike quality of the pictures.

Flare suppression is outstandingly good and even better than that of the Noctilux or the Summicron. It is almost impossible to create secondary reflections, even with bright sources in the picture or even worse, just outside the picture but shining into the front surface of the lens. In this last situation, you may see some smeared out bands of light in the outer zones, Of course, no lens with this aperture and front lens diameter is fully immune to flare and veiling glare but this lens is quite close to being for most intents and purposes flare free. You can see this when you make pictures where very bright windows figure prominently in the scene and the windows are decorated with small objects. Normally these objects are washed out and over saturated, but with the Summilux ASPH they retain shape and colour fidelity, a most remarkable performance.

Definition of very fine detail is quite good, but still has a somewhat soft edge. In night scenes the images retain their contrast and outlines of small subjects are clearly reproduced, but very fine detail is lost in the very low micro contrast of the subject textures.

Stopping down to f/2 adds crispness to the very fine detail and from this moment on the Summilux is ahead of the Summicron-M 2/50mm. The jump in quality when going from 1.4 to 2 is however a subtle one and not as visible as with all other highspeed designs. It is easy to assume that a picture made at 1.4 was made at smaller apertures. In this respect this is the first lens where you do not have to accept a compromise quality because of the high speed. The visible advantage of the Summilux is the excellent quality over the whole image area, where very fine detail is reproduced with clarity and crispness.

At f/2.8 the micro contrast of the extremely fine detail is enhanced, because now the effects of the higher order aberrations (residual errors are extremely small now) are neutralized. From here to f/8 image quality is extremely high and comparable with the best Leica lenses in the range (24, 90 and 135). The inevitable drop in contrast at smaller apertures is due, as always, to the effect of diffraction.

Vignetting is on paper on the high side with 2 stops at full aperture, but in practice the darkening of the corner-edges is not so pronounced that is should be a problem.

Distortion is just visible, but not of relevance for most scenes, unless you do reproduction.

The floating element improves the quality in the near focussing range. Reduction in image quality will normally occur around the distance of 3 meters and less with highspeed lenses. The floating element does correct this reduction quite effectively, but to a certain limit. When you are in the close up distances from 0.7 to about 1 meter, the floating element can improve matters quite a bit, but then at the wider apertures we get soft images. For best quality in this focusing range, we need to stop down to /5.6 or smaller to get good imagery. We should not imagine that with the floating element, we get a high-speed lens with near macro capabilities. We should stay realistic in our demands. What the floating element accomplishes, is a visual improvement of the quality in the outer zones and a contrast improvement from 1 meter to 3 meters, where the wider apertures will now perform at the optimum of the lens.

Bo-ke aficionados will have mixed feelings about the performance of the lens. The unsharpness gradient is relatively smooth in the near focus range when the fore- and background planes are close to the sharpness plane. But when the distance between main subject and fore-/background increases the unsharpness subjects lose shape and form. Especially when the unsharpness areas are backlit, the shapes become very harsh and rough. This behaviour is due to the reduction of the astigmatism and curvature of field as is a small price am gladly willing to pay. With careful selection of the background and at full aperture, you can produce very intriguing natural portraits.

 

Conclusion

The new Summilux-M 1:1.4/50mm ASPH is the best high-speed general-purpose lens in the Leica range. Its wide-open performance is outstandingly good (in some respects like flare even better than the Sumicron at f/2). Stopped down it is better than the Summicron 2/50mm. It can be used as the universal standard lens and can be deployed without any restrictions in image quality at all apertures and over the whole image field. If you want only one lens for your M camera, this one should be the prime choice. I still have the opinion that the focal length of 50mm is the best single lens for the M (I am an old fashioned M3 user with 50, 90 and 135mm as the prime lenses) and offers a wide range of possibilities for picture taking.

Handling is superbly smooth and the size of the lens fits in well with the camera and the finger controls of the average user. The screwed finger grip allows for one finger fast focussing and the telescopic lens hood has a lock to prevent accidental moving.

This is nice to have but not essential. The smoothness of the focussing mount is the most important aspect. Using the prototypes, you could notice some rough spots, but in the production versions, these are gone. The finish is of a very high standard and the aperture click stops match the quality of the rest of the lens.

This lens has optical qualities second to none and is a triumph of optical and mechanical engineering mastery. It even adds some new pictorial tools in the plasticity of the reproduction and the fine colour rendition in dim light and shadow areas.

 

Comparisons

The previous Summilux-M is clearly outclassed on all counts. As the Nokton is a small improvement on the older Summilux-M, this one too is not a serious competitor to the new Summilux-M 1:1.4/50mm ASPH, except on the matter of price. More interesting is the comparison to the current Summicron-M. The close up performance of the Summicron is definitely better than that of the new Summilux and if you do not need the high speed, it still has its virtues. The Noctilux-M is more difficult to profile. If you look at the objectified performance criteria, the Noctilux at the wider apertures is no match for the new Summilux-M. But then we have the more subjective considerations. Here the Summilux offers the real life dimension, where the Noctilux is more dreamlike and painterly in its reproduction of the scenes.

The Nokton colour rendition is leaning to the pastel colours where the Summilux is more saturated. The drawing of the Noctilux is with a thick pencil where the Summilux uses a very thin tipped point. It is up to every photographer to make the choice. I can only try to describe the differences, objective as well as subjective, What about the Elmar-M 1:2.8/50mm, This could be the perfect companion to the new Summilux-M: it offers excellent close up imagery even at full aperture, it is very compact and has excellent overall performance.

I often get questions like this: if you only had to use one lens, which one would you choose. The answer was not that easy. But now it is: the Summilux-M 1:1.4/50mm ASPH.

 

Glass types

The glass selection for the new Summilux is very interesting. There is one glass element in the new lens, whose cost is higher than the cost of all seven glass elements in the previous model of the Summilux. One may ask whether the mechanical parts have been reduced in engineering quality to compensate for the high glass cost. There is indeed a persistent story among Leica aficionados that the new generation of lenses may be optically superior, but the mechanical quality is inferior to older generations. This is not the case. In the new Summilux, there has been advanced engineering to account for the additional movement of the last lens group, the floating group. The total movement is about 2 mm and the effect can be seen from 5 meters. The employment of automated machining is the reason that the lens can be in the same price league as the previous version. And as the lens elements, in combination with the mechanical components, can be made to a higher level of precision, the costly manual adjustments during assembly can be forgotten.

The new glasses used in the new Summilux are very sensitive and very difficult to machine. In fact, the glass is very soft, which makes it difficult to get a smooth surface on nanometer level. The glass is also very sensitive to atmospheric influences and after being polished may not be in the open air for more than a half hour. The manufacturing process has been adapted to this requirement and the glass is coated immediately after the final machining. This also implies very good and thin coating layers. In fact the new Leica process of 'cold' coating is needed to accomplish this.

One of the new glasses has an interesting story. The original glass lab of Leitz was very productive and creative and has produced numerous receipts for special glasstypes. But the glass lab was a research facility and not a production factory.

When glasses were needed in substantial quantities, Leitz had to persuade glass manufacturers to adopt the glass in their catalogues. In the past Schott was often the partner in this business. Later that role was adopted by Corning, a company that almost became the main supplier of Leitz glass. But Corning has stopped making the

Leitz glasses.

Leica however needed that special glass, formulated by the old Leitz lab in order to get the required optical characteristics. Leica approached Schott and they agreed to manufacture that glass type. It can now be found in the regular Schott catalogue.

As a matter of interest, it may be noted that almost every glass now employed by Leica is eco-glass, or lead-free glass. The change from old glass types to newer ecoglasses implied in many cases a reformulation of the optical formula to hold the required image quality. In normal practice this change is not important, as one does not notice any difference.

If you take a good look at the lens diagram, you will note that the rear diameter is not very large, less indeed than with the Summicron 2/50mm. Therefore the first lens element needs to be of high refractive power to bend the rays sufficiently to get through the aperture opening. Lens elements two and three correct the color aberrations and are also responsible for the flat field of the image. The color correction is excellent, but not of APO calibre. Some red and green color fringing can be detected at high magnifications. The aspherical (fourth) element does correct the fifth order spherical aberration (oblique spherical in the sagittal (horizontal) direction). Element five and six are needed to get the rays to enter the last group almost horizontally. This is a requirement to enable the last group to become 'floating'.

One question that may be asked is why the original layout of the Summilux 35mm asph has not been used. The negative front element will disperse the rays to such a wide angle that the diaphragm opening cannot capture them. Therefore a strong converging lens was needed as the first element.

 

Performance issues.

Some comments have been made why I did not compare the Summilux 50 with the 35mm version. The obvious answer is that the angle of field of the 35mm is so much wider than that of the 50mm, that a real comparison is not possible. The design choices are totally different. But many persons consider the 35mm wide angle as the true standard lens for the Leica. I declared the Summilux 50mm ASPH as the best Leica standard lens. This does beg the question. The verdict is difficult as the Summilux 35mm ASP is an outstandingly good lens. But with a gun pointed at my head I would say that the new Summilux 50mm is slightly ahead at the widest apertures, especially in the zonal sections of the lens. The image area is normally divided in four sections (the centre, a circular segment from centre to the vertical edge of the negative format, another segment from the vertical edge to the horizontal edge of the format and lastly the corners. Everything from the centre to the corner is designated as the 'image field'. Or as the 'Feld' in German To avoid confusion with the normal photographic parlance where the field is interpreted as the location where you take the photographs, I will use the concept of the zonal sections of the lens. The question has also been asked where the new Summilux-R stands in the performance league. If we set the previous Summilux at the beginning of a line and the new Summilux ASPH at the end of the line, the current Summilux-R would by on a point, located at about two thirds of the line segment from the start point.

What are the more subjective differences between the old and new versions of the Summilux-M? If you are familiar with Dutch painting, one could say that the older Summilux paints as Rembrandt, where the new one paints like Vermeer. This is an especially apt comparison as both painters lived in the same period. Rembrandt has been famous for his atmospheric and emotionally charged paintings. Vermeer on the other hand has been called the first optical painter as he painstakingly captured the finest possible detail with his fine brushes and used special techniques to bring the specular high lights to life.

On a more quantitative level, I made pictures with the older version of the Summilux at 5.6 and with the new version at 1.4. Even experienced users could not see a difference. I did check this again at the optical bench and indeed here the same conclusions holds. The new one is almost four stops ahead of the previous version.

This is an incredible result, given the fact that the older Summilux got very high praise in the past for its performance. There is on the other hand a fair amount of discussion in the newsgroups, whether the performance of the new lens is not hyped-up or sexed-up (to use the language of the spin doctors in the political arena).

Many people were and are very happy with the image quality of the seven-element Summilux-M. So what is the fuss about? Just marketing speak from Leica and some overcritical zealots? Let me say this: the original Porsche 911 sports car was and is a great driving machine. Driving one is a fine experience and may recall the glorious days of the real men, who could handle an unpredictable beast and knew exactly where the limits were of cornering and road holding. The newest Porsche 911 is a vastly improved car that still captures the original atmosphere, but is improved in every screw and detail.

Now road holding and cornering and braking are impeccable and the important performance parameters have been significantly improved. The older one is a very fine vehicle, but the newer one is simply better. You can be very happy with the older 911, but the new one out-engineers and out-performs the older one In photographic terms: the older Summilux can deliver fine images, and if you are happy with them, stay at all means with the older version. If you however wants to take pictures at f/1.4 with the uncompromising quality, previously associated with an excellent f/2 lens, there is no way but to buy the new Summilux. I did an additional, special check between both versions on the bench to try to find the important differences that are relevant for picture taking in real life. First of all there is a major difference in the edge contrast at the low frequencies: where the older one at 10 linepairs/mm has a quite soft representation of the black line pattern, the new one shows lines with excellent edge definition. The overall impact is an image that is really crisp and powerful, where the older lens delivers an image that is more modest, more reduced in its drawing and contrast. At the finer frequencies, let us say, 30 to 60 lp/mm, the older one has a quite fuzzy representation of the lines in the sagittal direction and even become blurred. The new one has very good micro contrast and shows the fine lines with good clarity and separation. With hand held shooting, one is hardly able to capture these fine details and so one does not see them in the picture. And what you do not see, does not exist; that is the adopted view! If you were to use the new lens only and exclusively at shutter speeds of 1/30 and less, the chances are high that vibration will blur the edge contrast and reduce the impact of the image. When using a good high speed film, like the new Kodak BW400CN, that has excellent fine grain, and allows a higher shutter speed, the difference is easier to see, if you do your own printing. (the natural gradient is not steep to allow printing on color paper!). Best is of course a medium speed film, like TMax100 or Delta100. And if you are a fan of slow speed films like Technical Pan, the differences between the old and new version are quite easy to see. But even with Tri-X 400, the new version delivers images with much higher impact and tighter grain. You will not see this clearly when you concentrate on the small circle in the centre of the image. But when you look for significant details at a location half way the axis point and the edge of the vertical delineation of the negative format, the older one will disappoint you, where the new one will show quite fine texture in the subject details.

The current view of a high-speed lens is to use it only at low shutter speeds in scare ambient light. Under these circumstances any performance advantage may be lost, depending on the workmanship of the photographer. If you do care for the best images, even in adverse conditions, one would yearn for the highest quality lens.

Indeed if you use the lens at widest apertures to be able to use a slower speed film or a higher shutter speed or to take advantage of the limited depth of field, one is not inclined to compromise.

The 1.4 lens has always been the lens to judge the standing of a lens line. If you read the older literature of a fine manufacturer like Canon, you will notice that they regard the 1.4 design as the pivotal lens for the photographer, but only if the quality is uncompromisingly good. As a matter of interest, I checked the current Canon 1.4/50mm AF design for comparison. Overall this is an excellent lens, very close in performance to the current Summilux-R. The drawback is a quite high level of distortion, even more than that of the Canon 1.4/35mm ! There is also a trace of coma and the oblique spherical aberration in sagittal direction (the killing aberration for all high speed Double Gauss designs). The Canon philosophy then allows a higher level of distortion to compensate the other lens errors. For the intended use of the 1.4 lens, this is good thinking. But Leica engineers would not agree, as they know things can be done better. The new Summilux-M ASPH is the proof.

 

6.3.19 1.2/50, Noctilux, 1966

In 1966 the Noctilux 1:1.2/50mm was presented to the market and this lens, with two aspherical surfaces became famous at the same moment. It was not the first lens with such a wide aperture, but all previous efforts to construct a lens with a truly useful aperture around 1:1.2 or wider did fail. Some manufacturers tried the route of many lens elements, but the nine element designs were heavy and of very low contrast. The more sedate seven element designs were often 1.4 designs, opened up a half stop. The Noctilux was the first lens, that specifically had been created to provide a high contrast mage at the aperture of 1:1.2. As spherical aberration and coma are, among others, responsible for low contrast on -axis, the Leitz designers tried two different routes: new glass types or even special glass constructions (see picture of Marx) and/or aspherical surfaces. (see chapter 1.2).

 

Figure 104: diagram 64

 

Figure 105: Marx pictures on CD

The grinding of a non-spherical surface was extremely difficult and in those days (without CNC-equipment) had to be done manually. We must realize that the amount of asphericity is very small and the deviation from the spherical surface is measured in microns) To get to this level of precision by manual means is close to impossible and even with a specially trained operator Leitz had to accept a fair proportion of out-of-tolerance lens elements. And at the assembly stage, the narrow tolerances and precision required to put this lens together were additional cost enhancing factors. Commercially the Noctilux was not the success Leitz had hoped for.

The Noctilux is quite remarkable in its characteristics. At full aperture it delivers medium to high overall contrast with coarse detail rendered quite crisply. Comatic flare is also very well suppressed, but in the field the astigmatism is not. Finer details are not resolved at all and you have to stop down to 5.6 and smaller to get outstanding imagery, that is even better than that of the then current Summicron 1:2/50mm. There is a widespread misunderstanding concerning the characteristics of the Noctilux. This lens is supposed be tuned for good performance at full aperture exclusively and in the (assumed necessary) design compromise, stopped down performance is supposed to be of lower quality. The Figures and my tests do not support this description. Stopped down the Noctilux is excellent and from 5.6 to 11 we have imagery of a very high order and very fine textural details are now rendered with good clarity. At full aperture the lens exhibits a medium to high overall contrast on axis with a fairly rapid drop in the field, where only subject outlines and coarse detail is rendered with good visibility. When stopping down from 1.2 to 1.4 and 2 overall contrast improves visibly . On axis the image quality increase rapidly , but in the field performance improves more reluctantly. At 1:2.8 we find almost the same performance as with the Summilux 1:1.4/50 design, which has a slight advantage. In fact we may say that from apertures 1:2.8 the Noctilux and the Summilux are equal in performance. At 1.4 the Summilux is on axis, a bit ahead of the Noctilux and this comparison shows the very great challenge the Leitz designers had to face. To increase the aperture by half a stop, they had to accept a much higher level of aberrations that could only be checked by a very creative use of optical design and technology. The understanding of the complexities of aspherics in design and production was greatly enhanced by the Noctilux, but the production problems made it a challenging lens for the Leitz factory. Given the much higher aberration content, is no mean feat to design a lens that performs as good as an excellent 1:1.4 design as the Summilux is. Vignetting is more than 3 stops, distortion is visible and for good close-up performance, the lens has to be stopped down at least 3 stops. The Noctilux has a lower level of flare than the Summilux at the wider apertures, giving pictures in high contrast situations and when strong point sources of light are shining indirectly into the lens, a particular clarity that might be referred to as the hallmark of the Noctilux. Leitz invested considerable research into the design of a Noctilux R 1:1.2/50mm in the early eighties. The physical constraints (throat diameter among others and the space needed for the mechanism of the automatic diaphragm) limited the usefulness of this lens, and the project was cancelled.

 

6.3.20 1/50,Noctilux,1976

In 1976 a new version of the Noctilux was manufactured, now of Canadian design and with the maximum aperture yet another half stop wider. Employing spherical surfaces and using a new Leitz designed glass type, the 900403, the 1:1/50mm Noctilux-M was the first lens to deliver useable image quality at this wide aperture.

As with the earlier Noctilux, some myths around the lens have to be discussed and discarded. The comment that this aperture even surpasses the sensitivity of the eye is not very well researched. The maximum aperture of the eye is between 1:2 and 1:3 as the pupil of the eye has a maximum diameter of about 8mm. To find an animal with an eye, that has a really fast aperture, we have to turn to the cat, whose maximum aperture is 1:0.9!! . A second myth, we have already encountered when discussing the properties of the earlier Noctilux 1:1.2/50mm. The new Noctilux improves on stopping down and at apertures around 5.6 surpasses by a small margin the performance of the current Summilux-M and is close to the performance of the current Summicron-M. The inherently higher correction of the Summicron-M gives the pictures taken with this lens a higher clarity and an almost brittle edge contrast.

Comparison pictures with the Noctilux show a somewhat softer definition at the level of very fine detail. The suggestion that the Noctilux should only be used at full aperture as this is the aperture where this lens should deliver its best, is not supported by the facts. The Noctilux at full aperture delivers a low to medium overall contrast (due to comatic flare) , and subject outlines are rendered with clear edges on axis. In the field, outlines are more blurred coarse detail becomes soft. Stopping down to 1:1.4 improves contrast substantially and now we see Summilux quality at its 1.4 aperture. At the edges the Noctilux-M is a bit below the performance of the Summilux, due to a higher level of field curvature. At 1:2 the Noctilux-M fingerprint is similar to the Summilux-M, but the Summicron-M has the best overall performance at that aperture. From 1:2.8 the Noctilux-M has excellent on axis performance with a smooth definition of fine detail and a gradual softening of details when going to the corners.

 

Figure 106: diagram 65

Vignetting is with 3 stops on the same level as the predecessor and distortion is slightly less. There is some evidence of colour errors : small bright spots show outer fringes that are blue, with an internal core that is red-yellow Close up performance (around 1 to 1.5 meter) gives good imagery when stopped down to 1:4 and smaller.

The lens can cope very well at full aperture with strong light points in the image and secondary images are very well suppressed. This is a demanding lens to use at full aperture as its shallow depth of field (only 10 cm at a distance of 2 meter) asks for accurate focusing, which is not easy in the available darkness where the Noctilux will be employed often. Some users also have to adjust their expectation level for the image quality at full aperture which is impressionistic rather than scientific. Out-offocus objects retain their subject outlines and a gradual transition from the sharpness plane to the unsharp fore- and background add to the illusion of depth.

 

6.3.21 4/28-35-50,Tri-Elmar, 1998, New version 2000

The Tri-Elmar lens for all M bodies, from the M3 till the most recent one, is a landmark design in optical and mechanical construction. The shift in focal length goes from 35-50-28, and this sequence is necessitated by the frame-selector mechanism. The use of the Tri-Elmar-M expands your style of photography into unknown territory and helps to refocus your vision, even when attached to a 40 year old M3. This is an engineering feat of daunting complexity. And last but not least, Leica M users now have a zoom lens with optical quality that challenges the best lenses in the world. It is obvious that a maximum aperture of 1:4 has its limitations.

We should however note that subjects with deep shadows, illuminated by a heavy overcast sky require exposures of 1/30 at 1:4 when using 100ISO film. The Tri- Elmar-M still has some margin to go before hand-held shutter speeds prohibit picture taking. And then a small tripod or fill-in flash will assist us in expanding our limit. The three ring construction (ring for distance, ring for change of focal length and ring for aperture change) is a bit unfamiliar at first. The ring for distance setting is quite close to the body and your fingers almost naturally fall around the focal length ring so you are changing the focal length when you intend to adjust the distance. After a while you get the knack for it. The new version, introduced at Photokina 2000 has the same optical cell, but improved ergonomics, with a focusing tab and improved selection mechanism for the focal lengths. It is also smaller than the predecessor with a 49mm mount and a slightly shorter mount. Mechanical complexity. In order to grasp and appreciate the mechanical complexity of this lens, let us first review the basics of zoom lens design.

From its optical design the Tri-Elmar is a true zoom lens. A zoom lens alters the focal length of the optical system and thus changes the magnification of the image when you take pictures from a fixed standpoint. The designer accomplishes this by employing two groups of lens elements, a back and a front cell. When both groups are shifted relative to each other and relative to the film plane the focal length is changed. The front group also moves axially for the adjustment of the distance setting. The demands on the mechanical engineering are extremely high. The Leica M employs a mechanical linkage to bring in the correct frame masks when changing lenses. So the "zoom lens" must have a mechanical linkage too, in order to activate the correct frames when changing focal length. And this lens must be designed such that at the three focal positions the accurate focal length must be set. The designer has to take into account the demands of all M bodies, including the M3. Every M body has a coupling arrangement between the lens and the appropriate frame in the viewfinder. These frames are spring actuated with different tensions and the sequence is 35, 50, 28. As can be seem from the illustrations, the two cells move over a bigger distance when going from the 50 to the 28 position than when going from the 35 position to the 50 position. The relative movement between the two cells and with respect to the film plane is mechanically compensated by cams with different curves. The change from 50 to 35 and from 50 to 28 requires the same distance on the focal-length setting ring, but the internal movements are quite different, where the shorter distance requires a steeper curve. This results in different forces to overcome and these forces need to be linked to the tensions of the frame actuating springs. If we then think about the required precision as the lens needs to stay accurately focused when changing focal length, we can appreciate the quality of the precision mechanical engineering involved in the Tri-Elmar. Every one of the three focal positions is individually tuned to a very high degree of accuracy when the lens is mounted. It may be noted that the Tri-Elmar is the lens where the art and tradition of precision mechanical engineering and mounting is at its current zenith.

 

Figure 107: diagram 130 A, B, C The performance of the Tri-Elmar-M.

At 50 mm: on axis and over most of the image area the lens gives a high contrast image with very fine detail crisply rendered. In the outer zones (at an image height of about 12mm) the contrast drops a little and textural details become slightly softer.

The corners are soft with fine detail just visible. Stopping down to 1:5.6 enhances the contrast and definition somewhat. This performance level holds till 1:11 when the overall contrast drops a bit. Close-up capabilities (1,0 meter) are very good with a high contrast image showing crisply rendered fine detail over most of the whole image field. At 35mm: at full aperture the contrast now is just a bit lower and very fine detail is a bit softer. Very fine detail is visible over the whole image field. Quite remarkable here is the uniform quality over the whole picture area. This performance level holds till 1:11 when the overall contrast drops a bit. The close-up performance again shows a high contrast image with excellent detail rendition over the whole film area. At 28mm: At full aperture fine detail is rendered with medium to high contrast in the centre and drops a little in the outer zone. Very fine detail is clearly visible and becomes somewhat softer in the outer zones. This performance level holds till 1:11 when the overall contrast drops a bit. At close-up distance the image is of the same high contrast and evenness of field as the other settings. Here as with the 35 and 50 setting stopping down brings in contrast but the correction of aberrations is already on such a high level that image outlines and fine textural details improve a little. The distortion at the 28 setting is more visible than at the 35 and 50 settings. It depends on the kind of subject area if the effect is acceptable. Vignetting for the 50 and 35 position is quite low (1 stop in the corners) and about 1.5 stop for the 28mm setting.

Flare is very well controlled and its absence, especially when specular highlights are in the picture, enhances the clarity and crispness of the overall image and the rendition of depth and textural tonality. As a general statement one may conclude that the performance when compared to the current 28, 35 and 50 Leica M lenses at their 1:4 setting is outstanding. And like it or not the Tri-Elmar is better than most of the previous generations of the 28, 35 and 50mm Leica lenses.

 

6.4 15 to 21mm

The focal lengths from 15mm to 21mm offer many interpretative opportunities for interesting images. One should realize however, that an angle of view of about 100o, is quite challenging from the viewpoint of perspective and subject. Optically the design of a very wide angle lens, is equally demanding. The very wide angle introduces many daunting aberrations, that need attention and the cosine-fourtheffect brings lots of vignetting. To make the problem manageable, the designers at first opted for a fully symmetrical design, as in this case several aberrations cancel out each other, simplifying the task. But a symmetrical design implies that the focal length is the same as the physical lens, bringing the lens very close to the film plane.

That is OK for a rangefinder, (within limits!), but not practical for a SLR-camera, where a swinging mirror needs space too. One does not realize often how cramped the space is behind the lens and in front of the film plane. Retro focus designs can be used to get more room behind the lens, but one has to leave the symmetrical construction, which introduces now problems from an aberration perspective. The change from symmetrical to retro focus for the Leica R dropped the maximum aperture from 3.4 to 4 in the case of the Super-Angulon and the change to a retro focus design for the Leica-M in the case of the 28mm, brought a slight performance drop at first.

 

6.4.1 8./15,Hologon

1972 In 1972 the Hologon 1:8/15mm from Zeiss had been added to the M-lens line.

It offered virtually distortion less imagery and a fairly even illumination. If necessary, a graduated filter can be used when the residual vignetting is really disturbing. On axis definition is very good with a crisp recording of outlines and coarse detail. The recording of the finer details in the field is on the soft side and its potential for high quality images is limited. As this lens will be used to record subjects close to the lens or for architectural spaces the excellent definition of coarse detail should suffice. If bigger enlargements (above 12x) are required, the limits of definition become visible and the overall image becomes softer. In those days, the creative potential for such a lens was quite limited and in my view still is. The learning curve of the lens is quite high, but if the user has familiarised himself with its characteristics, pictures with a high attention value can be produced. The Hologon has serial numbers from the Zeiss range and seems to have been completely outsourced as Leitz did not allocate serial numbers from their range for this lens. Only a few hundred have been produced.

 

6.4.2 3.5/15, Super-Elmar-R, 1980

In 1980 Leitz offered a new 15mm lens for the R-series. The optical cell is identical to the Zeiss Distagon-T 3.5/15 and has a floating element to improve performance at closer ranges. There is very good image quality at a distance of 50cm. This design has a correction philosophy similar to the 19mm lens. A deliberate amount of astigmatism above image height of 12mm is used to correct field curvature. The filter revolver has slight changes in the spectral characteristics of the filters, compared to the Zeiss version, to bring them in line with the other Leica lenses with the same feature.

 

Figure 108: 6.4.2.A Super Elmar

At full aperture overall contrast is medium and fine detail is crisply rendered on axis till an image height of 10 -12mm. Vignetting is relatively low with 2 stops, but distortion is quite visible. Stopping down to 1:5.6 improves contrast and the definition of very fine detail on axis. In the field there is a moderate performance gain. Due to the very curved front lens the Super-Elmar-R is flare-prone and sensitive to reflexes of secondary images.

 

6.4.3 1:2.8/15mm Super-Elmarit-R ASPH General remarks

The very wide angle of this lens and its short focal length bring advantages and restrictions. The extended depth of field makes the concept of 'boke' obsolete for this lens. Even unsharp areas in front and beyond the sharpness field ('plane' would be the wrong word here) retain shapes and details and have a very smooth migration curve. On the other hand, the assumption that the lens is an easy one for pictorial representation is wrong. This is definitely not a convenient landscape lens. The large and extended foreground pushes main subject areas into the vanishing background.

So you need to be careful when and where to deploy the lens. It is at its best when the sense of shape needs to be defined or when the overwhelming surroundings of some magnificent room or corridor or interior is to be visually communicated. In short a visually sensitive photographer with a keen and empathic eye can do wonders with the lens.

It is also very good for closing in on groups of people who share some activity. The lens has back element focusing and is indeed incredibly smooth in its movement.

The internal filter revolver is the same from the previous Elmar 15 and must be used as the filter element is part of the optical design. It focuses to 18cm.

At full aperture we have a medium to high contrast image with excellent definition of very fine detail over an image circle of 12mm radius (24mm image circle in diameter).

The outer zones and the corners are progressively softening but even in the extreme corners coarse detail is quite visible. When reading this one should reflect on the extreme angle of field. For this angle the definition over the whole image field is close to outstanding. A slight fuzziness at the edges of fine detail delineation softens the overal image a bit.

Distortion is very well corrected and even persons at the edges of the image retain their normal body contours. (Ever looked at the elongated faces and bodies of persons when using a 12 mm or some other 15mm lens). Architectural straight lines are straight lines with a just visible distortion in the outer zones of the image.

Astigmatism and colour fringing are for all practical purposes non-existent. For really demanding work (above 50 times enlargements of slides, there is some colour fringing from 9mm radius). Vignetting is of course visible but not objectionably so.

In darker grey areas it is not visible, but white areas or blue sky do show light fall-off.

Flare is commendably low: secondary images are not to be seen and the veiling glare in contre-jour shots is confined to very small areas around the bright spots themselves.

A good example is a picture of very fine telegraph or electricity lines against a light grey or white sky: if the lines are clearly differentiated and keep their own colour (no greying) then the lens is OK. There is absolutely no decentring, which is some act given the large diameter of the lens elements.

At f/4 the lens visibly crispens and the circle of best performance grows to 30mm, that is close to covering the whole format. Edges of fine detail now are clean-cut and overall contrast is high. The typical Leica sparkle in the highlights and bright spots is evident and the fine differentiation of the whitish hues (on Kodak E100VS) adds to the image.

Further stopping down is not necessary for image quality and or depth of field. Till f/16 the lens can be used, but at apertures from f/11 the overall image is softer.

At 5,6 and 8.0 the lens is at its optimum and hs that typical Leica fingerprint of crisp and clean details with excellent clarity of shadow and highlight hues and outstanding colour reproduction, with a high fidelity reproduction of fine gradation of hues in small subject areas.

At closer distances the contrast drops in the zonal areas outside a small center circle.

But stopping down to f/8 brings the quality you need. So when using the lens at distances closer than 1 meter you should stop down to f/8 for best imagery.

Leica yes or no?

The lens is a Schneider design. It is worth stressing that Leica did not accept the design as Schneider provided initially but commented on the quality and wanted a performance that is in line with the Leica philosophy. So it happened. Whoever designed and manufactures the lens is of no importance. The imagery is as Leica wants it, given their own goals and aspirations.

Comparisons.

The inevitable comparison is with the previous (Zeiss) design. The Zeiss design has less overall contrast at all apertures and especially the definition of very fine detail is much lower. The new Schneider design is quite crisp and clean in its detail rendition, which is the result of a better mastery of the higher frequencies.

The Zeiss Super-Elmar 3.5/15mm As example: At f/8 the older Elmar design has about 90% contrast in the centre for the 10 lp/mm. The newer Super Elmarit has above 95%, which is visible. Even more important is the 40 lp/mm: Elmar in the centre: 40% at f3.5 and 55% at f8 versus Super-Elmarit 65% at f2,8 and 70% at f8. That is clearly visible progress.

The other comparison is the Voigtlander 4.5/15mm. This is in fact a comparison that is optically and theoretically questionable. A compact symmetrical design for the RF scene with a modest aperture of 4.5 is not to be compared to a big retrofocus design with an 2.8 aperture. Even so, much interest does exist. So even if not allowable, I will stick my neck out.

The Voigtlander at 4,5 has a visibly lower overall contrast and general image quality is below what you can expect of the SE 15 at its full aperture of 2.8. The imagery of the Voigtlander is a bit dull, lacking the sparkle of the SE 15, an indication of a highly corrected lens even at the 30 and 40 lp/mm level of performance. Distortion of the V is a bit higher and so is light fall off. Where the SE 15 can be used for scientifically correct architectural pictures, the Skopar is best used for the more casual shots.

Overall

The best proof of the capabilities of the new SE 15 is the fact that slides taken with it do not show as taken with a 15mm. They are natural looking in its perspective and clarity. Fine details exude when enlarging or looking closer at the image.

But remember that a slight dislocation of the camera will introduce natural distortion. My usual trick is to ensure that one vertical and one horizontal line in the image align with the viewfinder frame.

 

6.4.4 2.8/16,Fish-Eye-Elmarit-R, 1975

This type of lenses has been designed at first for scientific and technical purposes where hemispherical recording is required. The Leitz version is identical to the Minolta version and has been built in Japan. The circular angle of view is 180o, which requires an extreme refraction of the rays. Eleven elements are needed to cover the full 24x36mm format with a horizontal angle of 137o and a vertical one of 86o. To stretch the circular image to the rectangular format extreme pincushion distortion has to be fed into the design. For best performance the large front element should be completely hemispherical to collect as much light as possible. A normal assessment of image quality is obviously impossible. For its intended application the centre performance will satisfy modest requirements.

 

Figure 109: 6.4.3.A

 

6.4.5 2.8/19, Elmarit-R, 1975

Leitz Canada computed the Elmarit-R 1:2.8/19mm , which arrived on the market in 1975. At full aperture contrast is low to medium, definition of coarse detail is very good, and very fine detail is rendered with slightly fuzzy edges in the centre of the image. In the outer zones performance drops as astigmatism is used to balance field curvature. Stopping down does improve contrast (which becomes high) and on axis performance, while the image quality in the field improves very reluctantly. At 1:5.6 and 1:8 performance is good with a crisp rendition of fine detail on axis and a quite soft reproduction of small detail in the field. Vignetting is high with 2.5 stops and distortion quite visible in the periphery and at close distances. The distortion type is a bit weaving and its changes direction abruptly. Close-up performance is not so good, as this design has no floating element. You need to stop down to 1: 11 to get an even performance over the whole image field. At the middle apertures this lens is better than the Super-Angulon-R 1:4/21, with less field curvature, visibly improved rendition of fine detail in the outer zones and corners and better close-up performance. The lens is flare sensitive, as is the Super-Angulon. The large front lens of both these retro-focus designs does contribute to the occurrence of this phenomenon. In general picture taking situations, this 19mm lens offers good imagery.

 

6.4.6 2.8/19,Elmarit-R, 1990

The new version of the 19mm does include a floating element (rear lens focusing!)for improved close-up performance as this was one of the weaker points of the previous version The mechanical construction of a floating element is demanding. As example: the lens moves only 0.7mm from infinity to .5 meter. From 3 to 2 meter the lens moves 0.05mm! The mechanical movements are very small and need a high precision construction to function properly after many years of use. Between this version and the older one, there is a time span of 15 years.

 

Figure 111: diagram 5

 

Figure 112: 6.4.5 A floating

And a change in generation of designers. The new one has at full aperture high contrast and outstanding performance on axis with a clear and crisp rendition of very fine details. In the field the performance drops gradually to weak, with fine detail now recorded very soft and with blurred edges. At full aperture the new is as good as the previous one at 1 :4 to 1 :5.6. And at 1 :5.6 the current 19mm version reaches its own optimum with outstanding imagery over the whole image field. This lens shows the progress the Leica designers have made with retro-focus type of lenses.

 

6.4.7 4.0/21,Super-Angulon, 1958

Very wide angle lenses with acceptable apertures for the 35mm format were very difficult to design, as the oblique aberrations (coma and lateral colour)and distortion on one hand and the light fall off on the other hand challenged the designers beyond imagination. A wide angle of view could be created with a symmetrical design and a small aperture. The use of a symmetrical design was imperative as several aberrations cancel out with symmetry. It is clear that the aberrations, introduced in the front part of the lens, will be fully corrected by the same aberrations, but of negative magnitude, present in the rear part. The designer then was free to pay attention to other problematic errors. You could correct the natural vignetting (cosine-fourth effect) by allowing a strong amount of distortion, which is unacceptable. At about the same time, designers at Zeiss and Schneider found the identical solution. By using the properties and relationship between the entrance and exit pupil, one could enlarge the apparent pupil diameter for oblique rays and so reduce the vignetting. A large front and rear element is typical for this type of designs. Leitz adopted the Schneider version and used the same name. 'Super-Angulon' sounds a bit heavy as it seems to refer to a super-lens, which the first Angulon was not.

 

Figure 113: picture from HOVE archive

The deployment of a 21mm is tricky, due to its large foreground and tendency to perspective distortion, when the lens is angled to the object. Artistically it is challenging lens and only a few photographers can really produce arresting pictures with such a lens. Jeanloup Sieff and Bill Brandt come to mind, both of which did not use the 21mm for landscapes or interiors, but for nude studies. I specifically mention these examples with the intention that the Leica photographer will break out of the conventional mould and use the lenses based on inherent characteristics and optical qualities. At full aperture the overall contrast is low and there is strong vignetting, with a hot spot in the centre of the image even at aperture 1:8. The definition of coarse to fine detail is on the soft side, but the performance is very even over most of the picture area, excepting the edges. Stopping down improves the definition of fine detail and at 1:8 we see a crisp rendition of fine to very fine detail over the entire field, with the excepting of the extreme corners. Flare is very well repressed and night shots with this lens show well contained halos around point light sources. After 1:11 we note a reduction of contrast due to diffraction. For best close up performance some stopping down is advisable.

 

6.4.8 3.4/21, SuperAngulon, 1963 & 3.4/21,Super-Angulon-R, 1965

In 1963 the Super-Angulon 1:3.4/21mm superseded the 1:4 model. The same optical cell has been used for the M and R versions. It is a complex design with 9 elements, each of which is made from a different glass type. This lens could only be used on the R-body with the mirror out of the way. Vignetting now is much less with this redesign and at 1:8 the picture area is now even illuminated. Flare is higher at full aperture than with the 1:4 version. Contrast is medium and coarse detail is rendered crisply on axis (image height 9mm) with the outer zones becoming progressively softer.

 

Figure 114: picture from HOVE archive

Very fine detail is just under the threshold of reproduction. Stopping down to 1:4 brings a visible improvement and now this lens is better than the predecessor and at 1:5.6 the rendition of very fine detail is quite clear, but with blurred edges. At 1:8 the optimum is reached and very fine detail is now reproduced over most of the image area with soft edges. As is typical of many lenses from this period, the textural details are recorded with a certain softness that gives the impression at bigger enlargements that the plane of focus has been missed. It is true that the extended gradient between sharpness and unsharpness gives a pleasing effect to the pictures at the detriment of a clearly defined plane of critical sharpness. This is part of the fingerprint that defines the Angulon lenses overall.

 

6.4.9 4/21,Super-Angulon, 1968

This lens is a new design of the retro-focus type and a half stop less than the symmetrical predecessor. This is a wise precaution, as even at this reduced aperture, the new design is not the equal of the symmetrical version of the same specifications.

At full aperture overall contrast is low and the definition of coarse detail is soft , with the exception of the centre where we find a cleaner definition. At 1:5.6 and 1:8 performance is fair with a crisper rendition of fine detail on axis and a very soft reproduction of small detail in the field. Flare level is high at full aperture and for high quality in the close up range, we need to stop down a few stops. The designers evidently grappled with the intricacies of the retro-focus design, which was introduced only a few years earlier by Angenieux. The improved grasp of the design we see with the first and specifically the second version of the 19mm. The time span between the first retro-focus design and the state-of-the-art design is almost 25 years and is a good indication of the research needed to improve a design substantially.

These rays of light are really stubborn!

Figure 115: 6.4.8 lens

 

6.4.10 2.8/21, Elmarit, 1980

he first retro-focus design from Leitz in the 21mm focal length class, is of Midland origin and shows family resemblance with the 2.8/19mm for the R, which is also a Midland design. The gradual change from symmetrical to retro-focus types for the M-body, was necessary since the introduction of the M5. The second, more disguised argument for the change to this newer type of designs is the optical potential of these designs. As soon as the designer has familiarized himself with the inherent characteristics of retro-focus designs, (s)he has more opportunities for correction.

The M-version could not grow to the physical dimensions of the R-19mm and this restricted the designers somewhat. The M-21mm is of similar quality as the R-19mm, which has a still wider angle of view.

 

Figure 116: diagram 10

At full aperture the M-21 has a low to medium overall contrast, crisp rendition of fine detail on axis (image height 6mm), with a fairly rapid drop in the field. The lens is flare sensitive, has vignetting of 2.5 stops and visible distortion. Stopped down to 1:4 improves contrast slightly and so does performance in the field. At 1:5.6 the reproduction of very fine detail is brought within visibility range over most of the image area. The delineation of small textural details is fuzzy and we need to stop down to 1:8 to get a clear recording on axis. In the field the softness is retained however. This lens is a good performer, but it is not a leading edge design. .

 

6.4.11 2.8/21,Elmarit ASPH, 1997

The combination of aspherics and more insight into the principles of the retro-focus design, made possible a quantum leap in performance with the 2.8/21 asph. At full aperture overall contrast is high and very fine detail is rendered with crisp outlines over a larger part of the centre (till image height 9mm). In the outer zones performance gently drops and becomes very soft in the extreme corners. As comparison: image quality at full aperture is better than that of the previous version at 1:4.5. Vignetting is visible with 2 stops and distortion is measurably on the same level as with the M-21, but as the distortion curve has a different shape, it is less noticeable. Stopped down to 1:4 the field improves visibly and at 5.6 extremely fine detail is recorded over the whole picture area with high edge sharpness on axis and more softness in the outer zones. This lens offers clean definition of fine detail and clarity of small textural areas, which add to the pristine image quality.

Figure 117: diagram 11 The second version of the R-19mm offers the same level of performance and here we see the choices of the Leica designers. The R-version is physically larger which supports a better correction of aberrations. The M-version has to be smaller and here the employment of an aspheric surface makes sense.

 

6.5 24 - 28mm

 

6.5.1 2.8/24,Elmarit-R, 1974 11221/11257

The 24mm focal length is a relatively recent addition to the Leica lens lines. It seems to sit a bit uncomfortable between the 21mm and 28mm lenses. In fact it is a fine compromise. The horizontal angle of 74 that coupled to the main motive at closer distances, will wrap around the subject and enhance the feeling of being in the scene.

The 21mm is often a bit to far-off and the 28mm has a too narrow perspective to really encapsulate the subject. As is the case with many lenses, a learning curve is unavoidable. The Elmarit-R 1:2.8/24mm is often referred to as a Minolta lens. The true background is a bit more complicated. The original design is a Minolta computation with Minolta glass and glass from other manufacturers. The computation had been adopted by Leitz. The lens is completely built in Germany.

 

Figure 118: diagram 12

 

Figure 119: 6.5.1 A front floating

This lens has a medium overall contrast with clean rendition of the fine details on axis (image area of 6-9mm). In the outer zones the performance drops and now coma and flare become quite visible. Coma will always soften the details and lower the contrast. Most users assume that coma is only operative when strong light sources are present, but that is not true. Stopping down to 1:4 evens up performance to the edges, but the fine textural details stay soft, due to a strong presence of astigmatism and field curvature. At 1:5.6 the contrast in the outer zones improves a bit and this level of quality is available at 1:8 too. At the level of reproduction of coarse to fine details this lens offers commendable image quality, but stopping down does not reduce the residuals enough to bring high edge contrast to the really fine details. Vignetting is 2 stops, but distortion is pronounced. At the middle apertures the R-24 is better than the Angulon 4/21 or the first R-28mm. Performance is always relative. The R-24 employs a floating element, which brings excellent image quality to the close focus range.

 

6.5.2 2.8/24,Elmarit ASPH, 1998

Once in a while, all parameters fall into place with that indefinable fit, that characterises the presence of a successful creation.

 

Figure 120: diagram 13

 

Figure 121: 6.5.2 A aspheric element

The Elmarit-M 24mm is without any doubt a masterpiece of optical engineering and within the Leica M range a landmark design. At full aperture the lens exhibits a very high contrast image from centre across the whole field. Only the far corners drop in contrast and produce soft details. On axis (till image height of 12 mm) the outlines of subject shapes and details are delineated with superb edge contrast and extremely fine details are crisply and clearly rendered. In the rest of the field the very fine details are crisply etched in the emulsion with extremely fine details visibly rendered but with softer edges. Exceedingly fine detail is just rendered above the threshold of visibility, but with slightly lower contrast. Going from centre to corner the contrast drops a bit, but while a bit soft these details are still visible. Stopping down 1:4 overall contrast improves and exceedingly fine detail now is clearly visible. Corners still lag a bit but centre performance is at its optimum. This aperture can be called the optimum. Stopping down to 1:5.6 we see that the finest details crispens a bit on axis, but overall contrast in the field is lower. It is a matter of priorities which aperture is optimum. I would say that at 1:4 this lens is at its best At 1:8 corners continue to improve where the centre now drops in contrast. At 1:16 the overall image contrast is lower and very fine detail suffers as diffraction effects set in. At close range (around 1 to 2 meters) this excellent performance is preserved. A wide angle lens like a 24 is less usable if the close up performance would not equal the infinity setting. Due to aberrations we need to stop down to 5,6 to get the best of performance in the close up range. Flare suppression is perfect. Night pictures with Kodachrome 64 show excellent gradation in strong highlight sources and distance point sources are clear and without any halo Vignetting is about 2 stops and distortion is visible. There is some confusion about the effects of distortion in the corners. Flat objects will be rendered almost geometrically correct, but it is with three-dimensional objects that distortion becomes visible. The M-24 excels in his respect with a gentle transition in the depth-distortion. Pictures taken with the M-24 have outstanding definition of fine detail in the foreground, with an added sparkle and clarity for luminous pictures.

 

6.5.3 6.3/28,Hektor,1935

In the thirties, optical expertise with really wide angle lenses was limited and the focal length of 28mm was about the widest that could be employed with acceptable results in the 35mm format. A small aperture helped to reduce the effect of aberrations.

Vignetting is quite high with 3 stops and most certainly is allowed as an aid in correction of optical errors. The current M-28 has vignetting of less than a stop at this same aperture. Progress in optical construction can be noted in many different aspects of lens performance. At full aperture overall contrast is low, and on axis (image height 3 mm) fine detail is recorded with soft edges. In the field image quality drops significantly, but outlines and coarse detail are clearly visible. Finer detail however is fully blurred and introduce a kind of background noise, that degrades the overall quality. Stopping down does not bring much improvement and we need to stop down to 1:16 to get a reproduction of detail and outlines that will stand bigger enlargements.

 

Figure 122: diagram 14

The rendition of fine colour hues in small detail is quite good and gives this lens in standard picture taking situations a pleasing look. As soon as light sources enter the front lens the veiling glare gives the overall picture a washed out look. This lens delivers remarkably good imagery when stopped down an/or used in not too demanding circumstances. The overall image is however a bit dull and fine detail is softly rendered without the clarity and bite we do note in current lenses.

 

6.5.4 5.6/28, Summaron, 1955.

Twenty years after the first 28mm design, the Summaron has a maximum aperture that is only half a stop wider. Image quality is however vastly improved. At full aperture we have high overall contrast and a crisp rendition of very fine detail over a large part of the picture area (till 12mm image height). In the outer zones performance drops rapidly. At 1: 8 we see identical performance and closing one more stop brings a drop in contrast and a further drop when going to 1:16. From 5.6 to 8 this lens delivers excellent image quality. Vignetting is 2.5 stops and distortion nonexistent. Flare is also well suppressed, but the lens is not immune to its effects.

 

Figure 123: diagram 15

 

6.5.5 2.8/28, Elmarit (1),1965 Germany and Canada.

 

Figure 124: diagram 16

Of symmetrical design, this lens has a bit more distortion and with 2.6 stops vignetting at full aperture looks the same as the predecessor. The full aperture is two stops wider however and then we can appreciate the raw figures. At full aperture the on axis performance is good with a clear definition of fine details, but going to the corners the image becomes progressively softer. At 1:4 corners improve rapidly, contrast becomes medium and fine detail is now crisply rendered over a substantial part of the picture area. At 1:5.6 quite fine detail becomes visible with somewhat fuzzy edges and now only the corners and edges of the picture lag behind. Image quality is comparable to the Summaron at full aperture. Performance levels off at 1:8.

 

6.5.6 2.8/28, Elmarit (2), 1972

Canada manufacture. This Midland design is a retro-focus construction and the change was needed for the M5. It equals, but did not surpass the quality of the previous, symmetrical design. The performance description of the first version is applicable here too.

 

Figure 125: diagram 17

Differences in fingerprint are the more pronounced difference between centre and field performance. The M-28 (2) is of lower contrast in the outer zones and even stopped down to 1:8 renders fine detail with fuzzy edges. Vignetting is reduced to 2 stops and distortion is very small.

 

6.5.7 2.8/28 Elmarit-M (3), 1979 (new focusing mount from # 3037401 Canada mnf)

 

Figure 126: diagram 18

A much improved design became available after only a few years. In 1979 the second Canadian Elmarit-M 1:2.8/28mm arrived on the market and this lens set the standard for the 28mm focal length for years to come. At full aperture overall contrast is medium to high and very fine detail is crisply rendered in the centre area (image height 9mm). Beyond that the definition becomes progressively softer. Outlines however are delineated with high edge sharpness till the corners and it is these image details that are responsible for the overall impression of the picture. At 1:4 and 1:5.6 performance improves slowly, with a higher overall contrast and a crisper definition of very fine detail over most of the image area. At 1:8 extremely fine detail is captured on film with very clean edges on axis and a more fuzzy look in the field.

Two stops vignetting and negligible distortion are in the same league as the predecessor. Close up performance is very good when stopped down to 5.6. This lens has excellent overall image quality that will challenge many higher speed film emulsions.

 

6.5.8 2.8/28 Elmarit-M (4), 1993.

 

Figure 127: diagram 19

Primary goal of this redesign, now with Solms signature, was improved image quality and smaller physical dimensions. Both demands are in fact contradictory and it is slight surprise that in actual picture taking, the advance is readily seen. The front lens is unusual with its plane front surface , which might help reduce the flare tendency.

At full aperture the lens is indeed sparklingly clear, even in high contrast situations.

Generally this lens is one full stop ahead of the predecessor and at 1:2.8 is as good as the previous one at 1:4. At full aperture a high overall contrast is combined with a crisp definition of really fine detail over most of the picture area (image height 16mm). In the outer zones we detect a veil of softness that overlays the finest textural structures. At 1:4 the performance in the field improves, but now we note a slight reduction in contrast on axis. For all intents and purposes stopping down is only needed for extension of the depth of field range. The specific fingerprint of this lens is a high correction of the oblique sagittal rays, which does improve the rendition of fine gradations in tiny object areas. Close up performance has been improved too and now the full aperture can be used at 1 meter without reservation.

Vignetting is a bit lower with 1.8 stops and distortion will be observable in critical work. This is an outstanding lens with a clear rendition of very fine details in deep shadows and highlights alike with a retention of crisp outlines in high contrast situations. The old myth that in high contrast lighting a lens with low contrast is of advantage, as this characteristic is supposed to compensate for the extended brightness range, finds its Waterloo with this lens.

 

6.5.9 2.0/28 Summicron-M ASPH, 2000

Leica designers, when creating lenses for the M-system, have to face two conflicting demands: the physical size of the lens should be small, as it may not obscure the viewfinder and should fit the size of the body and the image quality must be the highest attainable within the size limitations. A physically small lens puts constraints on the optical capabilities of the design. The use of aspherical surfaces has made the task of the designer somewhat easier. With the new Summicron-M 2/28 ASPH, the designer had to work within the physical dimensions of the Elmarit-M 1:2/8/28mm and fit in a full stop more and realize more performance. The result is a superb lens.

A lens with an aperture of 1:2 with the same dimensions as a 1:2.8 lens is in itself a feat to be proud of and when the performance at full aperture is as good as that of the Elmarit-M at 1:2.8, we have an outstanding example of the Solms design philosophy.

The optical construction with one moulded glass (blank pressed) aspherical surface (the front surface of the last element) follows the lay-out as first introduced with the Summilux-M 1:1.4 ASPH. The front section of the optical system (before the aperture) is closely related to this Summilux. The first cemented group now has separate elements, which enables additional degrees of freedom for aberration correction. Based on the computed performance indicators, vignetting at full aperture is fractionally higher than with the 2.8-version, and distortion is very low.

Given the small size this is a quite remarkable feat. The calculated MTF graphs do indicate that at full aperture the Summicron-M 2/28 ASPH is even better than the Elmarit-M 1:2.8/28 at 2.8 and has better on axis performance than the Summicron- M 1:2/35 ASPH at 1:2. As with the Elmarit-M 1:2.8/90 - Apo-Summicron-M 1:2/90 pair, the newer lens at its full aperture has better performance and a full stop gain in light transmission. In the past, a faster lens at its widest aperture would not be as good as the less fast lens at its full aperture, but this rule of thumb no longer is valid with the new generation of Leica designs. The Summicron-M 2/28 ASPH and the Summicron-M 2/90 ASPH redefine the classical Summicron image quality and both are the benchmark lenses for the M-system. When current thinking indicates a levelling off in optical quality, these new Leica designs forcefully demonstrate that the creativity of optical designers defies this view.

 

Introduction and background

A few years ago in Solms, I was shown a certain lens, a compact 1:2.0/28mm lens for M. It was a prototype, to be sure, but it was ready for production, all optical computations and tests were done. On my question why this lens never made it to the production stage, Mr. Kölsch answered, that he expected more performance from a new lens of these specifications. So a new design was created from scratch: the Summicron-M1:2/28mm ASPH., scheduled for delivery early in 2001 The optical prescription of the lens is quite fascinating. It fits in the genealogy of the seminal Summilux ASPH, a design that decisively departs from the classical Double- Gauss formula. This design-type, now more than a 100 years old, has been stretched to the limits and a performance plateau has been reached. The new Summilux design, incorporates the negative front and back surfaces and the aspherical surface.

It is probably the first lens that has been designed specifically around the use of aspherics. Retrofocus designs are a second approach to step out of the shadows of the Double-Gauss formula. More lens elements can potentially improve performance, as more parameters can be controlled. The new Summicron-M 1:2/28mm ASPH picks up design elements of both: the lens group in front of the aperture is an enhancement of the Summilux (front group) design and the lens group behind the aperture fits into the retrofocus family and is a derivative of the 2.8/28 formula. We should not press the point, however, as a lens design is a creative whole and not a mix of ready-made components. The message should be that the new Summicron is based on the best design principles currently available in Solms thinking. The location of the aspherical surface is different and probably decisive for this design

The ergonomics.

The new 2/28 is indeed a very compact lens, comparable to the current 2.8/28 version. Measurements are (2.8 version in parentheses): length from flange: 41mm (41.4mm), overall diameter: 53mm (53mm), front diameter: 49mm (48mm). Both lenses use filtersize E46.

For a lens with twice the speed this is a remarkable feat. This design indicates the direction of future Leica M designs: compact and high speed and high performance.

The somewhat weak performance of the old Summilux 1.4/35mm could be excused with reference to its compactness, which forced the designers in those days to find a compromise between size and performance. Now the circle has been squared.

The lens operates very smoothly, and the aperture ring clicks with just the right amount of resistance and fluidity. When taking pictures with the new Summicron 28, I was amazed how quickly I could focus with the focusing tab and I have to confess that I hardly missed a shot, when focusing moving objects. The depth of field with a 28mm lens, even at an aperture of 1:2 exceeds of course the DoF of the Summicron 50 by a factor of 2, which brings real advantages in street shooting.

 

The performance

At full aperture this lens exhibits a high contrast with crisp definition of exceedingly fine detail over most of the image field, softening in the field from image height of 9mm. A faint trace of astigmatism and field curvature can be detected. Stopping down to 2.8 improves the center area (diameter 12mm) and also brings in a higher microcontrast in the outer zones. Corners however lag a bit and stay soft with a limited definition of coarse detail. Stopped down to 4, contrast becomes very high and the optimum is reached with a very even performance over the whole image area, excepting the extreme corners. At 5.6 we se a small drop in microcontrast of the fine textures and from 8, the overall contrast drops a bit. We have to put this in perspective, of course as we relate it to the optimum aperture. At 5.6 and smaller, the Elmarit-M 2.8/28 is a bit behind the new Summicron 28.

Distortion is about the same as with the Elmarit 28mm and vignetting is just visible with 2 stops in the corners at full aperture, about the same as the Elmarit at 1:2.8. In general use, this falloff can be neglected: even on slide film one has some difficulty noticing the darkening of the extreme corners.

Close up performance at 0.7 meters and full aperture shows excellent performance with high contrast rendition of very fine detail Night pictures retain high contrast in the shadow areas, and (when exposure is right) finer gradations in the highlights are recorded as well. At least with slide film and Black and White. Bright light sources have cleanly delineated outlines, indicating effective elimination of halo effects. Coma cannot be detected in these situations (light points in the image field).

Flare is very well suppressed in daylight shooting too, in contre-jour situations and when the sun strikes the front lens obliquely. Of course: you can construct situations where secondary images and veiling glare is quite visible, but even here the images retain contrast and some saturation. A lens shade is needed, when the light sources may shine in or close to the front lens. I will give this topic a separate treatment.

Leica has redesigned the front part of the lens where the shade is attached for easier handling. All wide angle lenses suffer the same problems here. It is a tribute to the design team that they have given this topic additional attention.

The transition from the sharpness plane to the unsharp areas is relatively smooth, but really out-of-focus areas show the tendency to break up details in coarse and fuzzypatches. There is a certain harshness in the out of focus rendition that is typical of modern Leica lenses. It is related to the level of aberration correction.

 

The comparison

The Elmarit 28 at 1:2.8 is slightly behind the Summicron at 1:2, specifically in the contrast in the field. At 2.8 the Summicron is ahead of the Elmarit at 2.8, again in the field and in the rendition of very fine details. This advantage is not lost at smaller apertures. So we may say that the Summicron at 2 is already ahead of the Elmarit at 2.8 and never loses this advantage. Given the very high performance of the Elmarit, these differences at the smaller apertures are not very great, but they are there for the discerning user to exploit.

Compared to the Summicron 2/35 ASPH, the new Summicron 2/28 wins in the department of definition of very fine detail, where the 35mm is of slightly lower contrast. The Summicron 35 however wins in the area of distortion. Stopped down the 35mm lens is a bit softer overall, but we are here discussing differences on a very high level of performance.

If we take a helicopter view of the Summicron line for the M, we can note that the Apo-Summicron-M 2/90 ASPH. is the best overall and at full aperture, closely followed by the new Summicron 2/28 ASPH. The Summicron 2/35 ASPH is third with a somewhat lower overall contrast and a softer rendition of very fine detail at all apertures. The Summicron 2/50 upholds its reputation at smaller apertures, but begins to show its age at full aperture performance. Well even Pete Sampras can be beaten by a younger player

Conclusion

With the Summicron-M 2/28 ASPH Leica adds a very potent lens to the stable of current M-lenses. Its a full stop ahead in performance compared to the Elmarit-M 2.8/28. The significance of this evolution is not to be underestimated. In the very recent past, it has been normal experience, when comparing lenses, that a faster speed lens would be not as good as the not so fast lens in the same focal length class, and would become better when stopping down, surpassing he less faster alternative because of its inherently higher level of correction. Now we have a lens in the 1:2 category that is even better, objectively, when compared to the 1:2.8 version. The same trend I noted with the Apo-Summicron-M 2/90 ASPH, a lens that is also better at full aperure than the excellent Elmarit 2.8/90mm. It is really progress when we now have transferred the outstanding performance of a 2.8 design to a 2.0 lens. It is to be expected that Leica will improve the performance of a lens, when introducing a successor version. The magnitude of the improvement however is such that we may note a new paradigm for Summicron-class lenses.

 

6.5.10 2.8/28 Elmarit-R, 1970

This lens is of Wetzlar origin, and should be one of the lightest lenses for the Rsystem with less than 300grams. It is also very compact and has vignetting of 2 stops.

It is of comparable performance of the contemporary M-28 (2), with a slight advantage for the R version in the field, where details are rendered with higher contrast. At full aperture we have low to medium overall contrast and the rendition of fine detail on axis (to image height 6mm) is quite clear, becoming very soft when approaching the corners. Stopping down enhances micro-contrast, but the definition of image details improves marginally.

 

Figure 128: diagram 20

There is a fair amount of field curvature and this limits the improvements when stopping down. At 5.6 the depth of field covers some of the detail softness in the zonal areas and fine detail is now rendered with clean edges. Close up performance is fair at best and stopping down a few stops is necessary for good imagery. Wide open the lens is flare sensitive and small bright spots have extended blur patches. During its course of life, there have been some changes in balance between centre and edge performance. For really critical work, this lens should be used stopped down to middle apertures.

 

6.5.11 2.8/28,Elmarit-R, 1994

A 1.4/28 has been designed around 184. B846. Problem is again the small diameter of the bayonet. Vignetting can be reduced by enlarging front lens. Test pictures show a nice quality in the centre. But bad in the corners.

 

Figure 129: diagram 21

 

Figure 130: 6.5.10A rear floating

The current R-28 has been introduced in 1994 and is a more advanced design. It has a floating element to improve close distance performance and also to assist the overall level of correction. Its level of performance is very close to that of the 1993 version of the M-28. At full aperture it is about equal to the M-version and almost two stops ahead of the previous R-28. .At 1:2.8 high overall contrast is combined with a crisp definition of very fine detail over most of the picture area (image height 16mm). In the field the fine textural structures are rendered with soft edges. In the corners coarse detail is blurred but detectable. At 1:4 the performance in the field improves and at 1:5.6 the on axis performance (image height 9mm) sets a new standard and surpasses even the M-28. As with the M-version we note a high correction of the oblique sagittal rays, which does improve the rendition of fine gradations in tiny object areas. Close up performance has been improved too and now the full aperture can be used at 1 meter without reservation. Vignetting is?????????? This is an outstanding lens, that in some areas even surpasses the Mversion, which lacks the mechanically complex floating-element construction.

 

6.5.12 2.8/28, PC Super-Angulon-R,1988

With large format-studio cameras, it is very easy to control the perspective by changing and shifting the lens board and film holder relative to each other. The large format lens covers a wider image circle than is needed for the format to get good illumination and definition when shifting the lens relative to the film plane. The same principle is being employed by the so-called perspective-control (PC) lenses for the Leica R. The diagonal of the 35mm format is 43mm and most lenses cover an image circle, just sufficient to illuminate the full picture format. The Super-Angulon has an image circle of 62mm, which allows some shift in the position of the lens, relative to the film-area. (see picture here). The angle of view is effectively 93 is normal for a 21mm focal length. The trick of the lens is to have a larger angle of view for the effective focal length of 29mm. Movement in the vertical and horizontal direction is 11mm, and diagonally 9.5 mm.

 

Figure 131: 6.5.11 SA

The PC-28 at full aperture has medium contrast, less so than the current Elmarit-R 2.8/28. Performance is very good up till image height of 9mm. There is strong vignetting of more than 3 stops. Stopping down to 5.6, the contrast improves markedly and is now even better than that of the R-28mm. Definition of fine detail improves to an image height 26mm and on axis very fine detail is rendered quite crisply. This performance is partly due to a very good correction of the field curvature. necessary for the movements. Using the PC option forces the user to stop down to 1:11. Full aperture will be used mainly for focusing. There is the normal slight barrel distortion which grows when the PC option is used. The PC 28/28 employs a floating element for improving the quality at the closer distances.

 

6.6 35 to 40mm

Whatever the more philosophical arguments for the prima-donna role of the 35mm lens in the Leica RF world (natural perspective, angle of view suitable for intimate life-shots and story telling), the optical reason is quite simple. An angle of view of 64 relatively large aperture, small physical dimensions and modest optical lay-out and still ensuring good optical quality. The 35mm focal length has been produced in many variations and optical designs and has proved to be very demanding in its correction, if really outstanding image quality is required. The 1.4 aperture has been offered in 1961 already, but while delivering good imagery stopped down, at full aperture is was overstretched. In fact the 1.4 Summilux is almost identical to the later Summicron 2.0, and this lens can be seen as a Summilux with a smaller aperture. The first Summilux aspherical is a radically different optical design and delivers outstanding performance, beyond what is possible with a design based on the double-Gauss formula.

 

6.6.1 4.5/35 ,Elmar,1934/35

This snapshot lens had been announced as early as 1935, and officially postponed as a production model. A few samples have surfaced, probably as prototypes, as no serial numbers have been ever allocated for this lens. The optical cell is identical to the normal Elmar 3.5/35mm and all comments made for this lens, apply here too.

 

6.6.2 3.5/35, Elmar, 1930

This is the first interchangeable lens that Berek designed for the Leica, a year later followed by the 90mm and 135mm. It is also used in the Stereo attachment. It is a classical Elmar construction, but now the aperture is located behind the second element. It has vignetting of 2 stops and has visible light fall off, even at 1:8. Some distortion can be seen. At full aperture is has low overall contrast and a clear definition of coarse detail on axis, becoming rapidly very soft. At 5.6 the contrast in the field improves and the centre area of good definition expands to an image height of 6mm, where fine detail is rendered with fuzzy edges. In the field however, the fine detail is blurred and difficult to detect. At 1:8 the image quality improves markedly, with the outer zones still of low contrast.

 

Figure 132: diagram 25

The pictures that Paul Wolff produced with this lens are made mostly stopped down and at the smallest apertures this lens is a commendable performer.

 

6.6.3 3.5/35, Summaron, 1948

This lens is the first new design after the war. It is of double-Gauss construction and has been introduced in 1948. Many sources give 1946 as the earliest date, with serial # 601001, but the factory records indicate that this batch was reserved for the Elmar 50mm. See the Appendix for a more detailed discussion. At full aperture the performance is visibly improved when compared to the Elmar 35mm. Contrast is close to medium and on axis (till image height 6mm) fine detail is resolved with good visibility and only slightly fuzzy edges, but in the field the contrast drops rapidly and details become quite soft.

 

Figure 133: diagram 26

Stopping down brings some improvements, but gradually and we need to use aperture 1:8 to get a clear definition of the fine detail over most of the picture area, excluding the outer zones that stay soft. In the centre we now very good definition of the very fine details. For best close-up pictures, stopping down is necessary.

Vignetting is 1.5 stops and distortion very well controlled.

 

6.6.4 2.8/35, Summaron, 1958

The first series have been produced in Wetzlar and later series in both here and in Midland. This Summaron is closely related to the previous one in design and adds a half stop. At full aperture we have medium overall contrast, vignetting of almost 2 stops and a more even coverage of fine detail rendition over the picture area. It is a visible improvement over the namesake at its aperture of 3.5, specifically in the field.

At 1:4 the on axis performance improves with visible recording of very fine detail, but in the field we see no improvement. At 5.6 image quality levels off, as field curvature softens the details. Overall at this aperture the new version is better than the older one, but at 1:8 we see comparable quality.

 

Figure 134: diagram 27

Distortion is very small. Close-up performance is very soft at the wider apertures.

 

6.6.5 2.0/35, Summicron (1), 1958

In the same period of the introduction of the Summaron, Leitz Midland produced an 1:2 Summicron, which followed the classical double-Gauss pattern too, but added two lens elements. Sometimes one can read or hear the remark, that a 'true' double- Gauss lens, has to have 6 elements, grouped as two symmetrical halves. In fact any lens should not be analyzed by counting elements, but by analyzing the refractive powers and the path of the rays. The D-G lens is typically set up as follows: A positive (converging) meniscus element is followed by a second meniscus or convex element with lower refractive index and higher Abbe-number, the third element is of similar specification, then we have the stop and the fourth element is a bi-concave element of flint glass, and the fifth and six elements are flints too of biconvex shape.

These rear glasses are of an higher index than the front elements. They are often more expensive and the smaller diameter of the rear elements offsets the price differential. In this case, the two additional inner meniscus lenses do not change the basic pattern.

 

Figure 135: diagram 30

The 8-element design has relatively large front and rear elements, presumably to reduce vignetting. In fact, at full aperture vignetting is 2.5 stops and at aperture 2.8 is 2 stops, about the same as the Summaron. At full aperture overall contrast is low and coarse detail is rendered with soft edges over most of the picture area. Fine detail is visible on axis (image height 6mm), but becomes blurred when extending to the corners. At 1:2.8 contrast improves markedly and now centre quality is better than that of the Summaron. At 1:4, we note a small improvement in the field and at 1:5.6 fine detail is defined crisply till the corners, which stay very soft. On axis very fine detail has good edge sharpness, but the contrast is lower. There is a pronounced tendency to flare at wider apertures over the whole picture area, due to the presence of coma. Close up performance is fair and one needs to stop down for good imagery.

The lens is very compact and the balance between size and image quality is evident.

Distortion is negligible.

 

6.6.6 2.0/35, Summicron, (2), 1969

The six element redesign, from Midland, is a very short lens, and has been produced as a more economical version of the 8-element predecessor. At full aperture overall contrast is medium and higher than that of the previous version. The new design has on axis (image height 5-6 mm) a good definition of fine details, rapidly becoming softer in the field. Here (in the field) the previous one has an advantage. AT 1:2.8 overall contrast improves, which in itself sharpens the recording of fine detail, even if we cannot see more of it. At 1:4 very fine detail is recorded with clean edges, but performance in the field refuses to improve.

 

Figure 136: diagram 31

Stopping down further spreads the circle of good definition to image height 9mm, but the outer zones stay soft with low contrast. At 1:8 image quality inches up another small step, but is still somewhat less in the field than the 8-element version.

At close distances however this lens has a really high performance and could be used for repro-work, when stopped down to 1:11. Flare tendency is high at wider apertures, but only in the field. Flare pattern is different between this lens and the previous one. The light patches in the previous version are larger but the energy is more diffused, where the newer lens has smaller flare spots, but of higher energy concentration. There is a balancing act here again: flare is often generated by coma, but this can be reduced by allowing more vignetting. As so often, the overall character of a lens is more like a personality, than as a simple listing of resolution figures. Vignetting is high with more than 2.5 stops, but the lens is distortion free.

 

6.6.7 2.0/35, Summicron, (3), 1971

A Midland redesign of the six element version, still with the same number of glass elements, brought some improvement in overall contrast. specifically on axis. In the field the performance drops significantly and is somewhat below that of the previous six element design. The optical design uses different glass types and the second group has a very small airlens, where the first version was cemented. Flare tendency is reduced compared to the previous designs.

 

Figure 137: diagram 32

Vignetting is lower with less than 2 stops, but now some distortion is visible.

Generally however, these differences in fingerprint are low and will be visible only in direct comparison. This lens has a few millimetres more length to make the reading of the numbers on the rings easier.

 

6.6.8 2.0/35, Summicron (4), 1979

The fourth Midland version with seven elements delivers a medium contrast image and much improved quality at full aperture, specifically in the field as field curvature is corrected to a higher degree. Overall contrast is higher than in the previous version, but the corners are still very soft. Coma is less visible in the middle of the image area, but the lens shows a tendency to flare in the outer zones, where one can detect coma spots around bright small points of light Fine detail is recorded with soft edges, becoming quite fuzzy in the outer zones. At 1:2.8 rendition of fine detail becomes quite crisp till image height 18mm, abruptly becoming very soft in the corners. At 1:4 very fine detail is detectible over most of the picture area, excepting the corners and at 1:5.6 this level of detail recording is visible. Stopping down further brings more edge sharpness to this level of detail and at 1:11 we have a medium contrast coupled to a good definition of textural structures, which can stand bigger enlargements.

 

Figure 138: diagram 33

Vignetting is high with 2.5 stops and distortion is not visible. This version however is often referred to as a bo-ke champion. (SEE DISCUSSION in chapter 2.1).

Compared to the predecessors it is an excellent design and its compactness has its own advantages. Optically however it is limited by the principles of the DG-design

6.6.9 2.0/35, Summicron ASPH, 1997

The Summicron ASPH belongs to the same design family as the Summilux aspherical and ASPH and shares with these lenses the radical new design. (see the Summilux aspherical report). At full aperture the lens exhibits a high to very high contrast, with crisp definition of very fin e detail over most of the picture area.

Corners are softer, but the image structures are well visible. Stopping down to 1:2.8 extends this quality of definition to the level of the very fine detail. At 1:4 the optimum is reached with very clean outlines and a high fidelity reproduction of small surface textures. After 1:8 contrast drops and edges of fine detail become softer. As with all modern Leica lenses, stopping down too much diminishes the excellent quality visibly. It is better to use slow speed film, than to stop down to 1:11 with higher speed films.

 

Figure 139: diagram 34

Vignetting is lower with 1.8stops and distortion is only visible at the far out zones.

Flare is very well suppressed, but the lens is not immune to it: there are situations where secondary images or a strong flare patch can be noticed. This is an outstanding design and exhibits the lucid overall clarity, that is one of the characteristics of modern Leica lenses.

 

6.6.10 1.4/35, Summilux, 1961 (11870 to 1 meter, 11871 to .65 meter).

In 1961 Leitz Midland computed the Summilux 1:1.4/35mm for the M -system as the world's first 1.4/35mm lens. It stayed in production till 1993, when the (second) aspherical version appeared. At full aperture the overall contrast is very low . Coarse detail is recorded with clean edges, but becomes much softer when going to the corners of the picture. Fine detail is rendered with low contrast and even finer structures are lost in the image noise, as contrast becomes so low as to blur the small details.

 

Figure 140: diagram 37

The flare level is on the high side. Stopping down to 1:2.8, overall contrast quite markedly improves and from that aperture the performance characteristics are identical to the Summicron (3) 1:2/35. Indeed so identical is the performance that one could get the impression that both lenses share the same basic computation. The long production period of the Summilux is a clear indication how difficult it is to improve on a well designed lens when the parameters are really difficult (1,4 and an angle of 64o are heavy obstacles for a designer. (SEE ENERGY FLUX). Vignetting is high with almost 3stops and distortion is not detectible. The Summilux, when compared to the Summicron version of its day showed a much lower contrast at wider apertures, but when stopped down had better performance in the field.

 

6.6.11 1.4/35, Summilux aspherical, 1990

The Double-Gauss design had reached its performance limit when applied to high aperture, wide angle lenses. During the research it became clear that substantial improvement of image quality asked for a new approach. Field curvature, chromatic version of astigmatism and oblique spherical aberration are the limiting optical errors for the DG-type. The employment of aspherical surfaces could reduce the spherical aberration, but not the rest of the errors. So a radical departure had to be found. The DG-type has a symmetrical construction with a converging lens (+)-diverging lens (-) -stop-diverging lens (-)- converging lens (+) sequence. This + - - + sequence has been flanked by two lenses with negative powers (diverging) to become - (+ - - +) -, giving the designer much more power to correct the aberrations. It is simple, but as always with genial ideas, simplicity is the hindsight. The design goal was to significantly enhance the image quality in the field, while keeping the physical volume small. The lens employs two aspherical surfaces of the grinded type and is probably the first lens, where the design is structured around the use of the aspherics. The method of grinding the aspherical surfaces was technically closely related to the procedure used for the Noctilux 1.2/50mm. The production started around 1988, while the lens was introduced in 1990. The Summilux aspherical is generally two stops ahead of the previous Summilux from 1961. At 1:2 it is better than the older one at 1:5.6.

 

Figure 141: diagram 38

 

Figure 142: 2.4.1 A

At full aperture we note a high overall contrast and very fine details are recorded with fidelity and high clarity on axis (image height 10mm). From there the quality is reduced gradually and at the corners the details are fuzzy. At 1:2 contrast improves visibly and the definition of very fine detail is crisp, excepting the outer zones where these details are becoming softer, but still with good visibility. At this aperture it is ahead of the Summicron asph at 1:2. But the Summicron at 2 is ahead of the Summilux at 1.4, which is no surprise as there is a full stop difference. At 1:2.8 the very fine details are very crisply rendered over almost the full image area and at 1:5.6 extremely fine detail and subtle shades of grey and colour hues are reproduced with accuracy. Flare is well suppressed but at the widest aperture there is some internal reflecting that becomes visible as secondary images. Vignetting is lower with about 2 stops and distortion is visible.

 

6.6.12 1.4/35, Summilux ASPH, 1994

This lens uses one aspherical lens surface of the blank-pressed type. Generally this lens performs in an identical way as the 'aspherical'-version. There are a few very subtle differences: the 'asph' version has on axis slightly lower contrast, but a more even performance in the field at apertures 1.4 and 2. From 1:2.8 both are equal in image quality.

 

Figure 143: diagram 39

 

Figure 144 6.6.12

A aspherics Vignetting is slightly higher with 2.5 stops and distortion is visible. The fingerprint differences are really very small, if measurable and I would not be put to the test to identify which lens is used when presented with some pictures.

 

6.6.13 2.8/35, Elmarit-R (1), 1964

The 1964 version has low to medium overall contrast at full aperture, soft rendition of fine detail and a smooth reduction in performance from centre to corner. In the field there is low contrast and image details are outlined with fuzzy edges. Vignetting is 2 stops and distortion is just visible. Stopping down to 1:4 markedly improves the overall quality with a crisp rendering of fine detail that extends into the field until image height of 12mm. Stopping down further does not bring additional performance in the field, with the exception of the edges, that do improve. The lens is sensitive to flare, vignetting is 2 stops and distortion is well visible. Later versions had all metal mounts and a change in the optical cell, where the 2nd and 3rd element are no longer cemented, but have a tiny airspace. Performance does hardly change, so it is a matter of opinion if one would recognize this as a separate version.

Sometimes optical changes are made for reasons of production technique and not necessarily to change and improve the performance. This lens is stopped down very good, but given its modest specifications, one would expect no less.

 

Figure 145: diagram 28

 

6.6.14 2.8/35, Elmarit-R (2), 1973.

The next version, from 1973, has much improved overall contrast at full aperture and fine detail is rendered with good visibility on axis (image height 6mm), becoming progressively softer when reaching the corners. Vignetting is slightly less with 1.7 stops. Stopping down to 4 brings marginal improvements and at 5.6 very fine detail becomes visible on axis, but in the field is quite blurred. At 1:8 performance evens over the whole image area and contrast begins to drop a little. In the field the definition of finer details is soft. Distortion is more visible. This behavior is typical of many older designs. Performance improves only reluctantly and is more governed by the natural effects of a smaller aperture (crispening of finer details as marginal rays are cut-off from the image forming process) than by the inherent correction of the lens.

 

Figure 146: diagram 29

Close up performance is excellent and if this is a required application, the Elmarit should be preferred over the Summicron-R 35mm.

 

6.6.15 2/35,Summicron-R (1), 1972 Wetzlar design and Midland production

The first version of a 1:2/35 lens for the R has the same fingerprint as the Elmarit-R 1:2.8/35mm (second version). At full aperture overall contrast is medium and while on axis (till image height 6mm) we see clear definition of fine detail, in the field the contrast drops sensibly and details are soft., becoming fuzzy in the edges. There is a tendency to flare and ghost images.

 

Figure 147: diagram 35

Vignetting is less than 2 stops. At 1:4 the overall contrast improves and this brings good edge sharpness to the outlines of larger subjects. At 1:5.6 the contrast in the field is enhanced and for the recording of fine detail is now as good as on axis. We need to stop down to 1:8 to record really fine detail over a larger part of the image field. At 1:4 overall performance is somewhat below the Elmarit, but from 5.6 the Summicron offers better imagery in the field, due to an improved correction of field curvature. For good image quality at closer distances, one should close down a few stops, as distortion is visible at wider apertures.

 

6.6.16 2/35 Summicron-R (2), 1977

Midland design and Wetzlar production. Relatively soon, in the Leitz world at least, an improved version has been introduced. It is more compact and also of less weight. At full aperture overall contrast is a bit lower, but the performance on axis extends farther into the field (till image height 12mm). The edges are not as good as with the previous version, which is more visible too as the field performance is better. Vignetting is 2 stops. Secondary reflexes are suppressed to a higher degree. At 1:2.8 contrast improves and brings the usual crispening of edge sharpness. From 1:4 we see comparable performance as with the previous version, which has lower contrast in the field. At 1:5.6 the newer version has a marginal edge and from !;5.6 both lenses perform on the same level.

 

Figure 148: diagram 36

The remarks on close-up pictures for the previous version are valid here too. This lens is specifically better at the wider apertures with higher contrast and less flare and improved rendition of finer details. If we look for family signatures, the Summicron- M 2/35 from 1979 is closest, with the M-version exhibiting more overall contrast and slightly softer detail rendition in the field.

 

6.6.17 1.4/35 Summilux-R, 1984

The design of a very high speed 35mm lens is not easy, as angle of view and aperture conspire together to allow a large amount of light energy to pass through the lens, with a corresponding boost in the level and amount of aberrations to be controlled.

A very high speed lens for the R-system should complement the Summilux 1.4/80 and 1.4/50 from 1970. The first 1.4/35 design for the M was created in 1961 and it took the Leitz designers 20 years to get to grips with the same specifications for the R, with two additional requirements: very close-up performance and retro-focus design. The Summilux -R for the 35mm focal length was a Wetzlar design and a vast array of optical means was required to improve upon the M-version from 1961. The M-version had to be designed within the limits of a compact lens and it may represent what was then possible with conventional means. The R-version could be designed with more liberty concerning the size and so a ten element optical system with a floating element emerged from the drawing board.

 

Figure 149: diagram 40

At full aperture overall contrast is medium: on axis fine detail is rendered with clarity till an image height of 6mm and from there to the edges the definition becomes softer rapidly. Vignetting is less than 2.5 stops. Performance in the extreme corners does often improve because of vignetting, and this lens is no exception, especially if we look at the level of the rendition of very fine detail. At 1:2 overall contrast improves and fine detail in the field is now defined with clean edges. Stopping down further improves the contrast on axis and at 4 and 5.6 really fine detail is accurately reproduced. In the field the improvements are small and very fine detail is just visible with blurred edges. At 1:5.6 centre performance is excellent, with a gradual softening of the small textural subjects. In extreme light conditions the Summilux has good flare suppression and less coma, better than the 1:2/35 companion lens. Close -up performance is significantly enhanced thanks to the employment of a floating element. The extender however should not be used.

 

6.6.18 2.8/40 Elmarit-C, 1973

This lens was initially planned as the standard lens for the Leica CL. A few hundred found their way into the public domain, read the collectors. Its general performance is close to that of the Elmar 12.8/50mm At full aperture overall contrast is low, coarse detail is rendered with low contrast, but acceptable visibility. Finer detail is fuzzy and becomes blurred in the outer zones.

 

Figure 150: diagram 41

Vignetting is 1.5 stops. At 1:4 overall contrast jumps up, improving the definition of fine detail on axis, but in the field there is only a marginal improvement. Stopping down further brings in the clear definition of fine detail in the field. But even at optimum aperture, the performance is really below the standard of the day and it would have been bad for the reputation of Leitz if this lens had become the standard lens for the CL.

 

6.6.19 2/40 Summicron-C, 1973

This 6 element double-Gauss is better in all respects than the 2.8/40mm. A compact 6-element Gauss lens is not easy to design. A 5-element version is compact, but has disturbing chromatic errors in the field and a 7-element would be too long. For the front lens Leitz used a glass with high refractive index to partly address this problem of the aberrations. Some of the glass was created in the Leitz glass lab. (The Minolta version used Minolta glass). At full aperture the overall contrast is medium to high and fine detail is rendered with clean edges on axis only (image height till 3mm), with a fairly rapid drop in the field and edges. Vignetting is 2 stops. Stopping down to 1:4 improves on axis performance significantly till image height of 6mm, after which the contrast drops rapidly to low values and very fine detail is just recordable. At smaller apertures the image quality in the field slowly improves with excellent definition of very fine detail on axis and fairly good in the field. Distortion is detectible, but not disturbingly so.

 

Figure 151: diagram 42

Overall performance is between the Summicron 35 type 3 and type 4. The 6-element Summicron 35 has a slightly better performance at full aperture, but stopped down is a bit less good in the field. The 7-element Summicron 35 is better in the field, but it suffers more form strong zonal errors. So it would be horses for courses? Partly yes.

The differences in fingerprint or character do also show that is very difficult to describe a Leica lens in a superficial manner as every lens has its own specific characteristics. 6.6.20 4/35mm PA-Curtagon-R, 1970 Perspective Control (PC) translated into German becomes 'Perspektivischer Ausgleich', hence the PA in the name. This version has a movement of 7mm in horizontal and vertical direction.

Image quality is good for the intended purpose, but below that of the later PC-28. It is a low contrast lens with limited ability to reproduce fine detail accurately. But as this type of lens needs to be stopped down substantially to use the shift facility, the wide open performance is less interesting. When moving the lens, the ground glass will progressively darken as the exit pupil of the lens and the entrance pupil of the finder are displaced relative to each other.

 

Figure 152: 6.6.20 PA C It has

Figured in the catalogue for almost 25

years.

 

6.7 60 to 80mm

In this range we find two types of lenses: those around 60mm, which are designed for macro and close-up photography and those around 75mm, designated for use in low light situations. The specific focal lengths have been chosen for practical or optical reasons. The 60mm is a bit easier to correct than a 50mm lens. The 75mm lens started life as a 70mm, which fits in more nicely in the focal length table, and the prototypes in the Leica archives all are 70mm and designed in Wetzlar. The production design was reformulated in Midland in the last half of the seventies.

These lenses are probably the last ones which have been designed by the analytical or synthetic method. (see chapter 1). The Summilux 1.4/75 and 1.4/80 for M and R are similar designs and represent the new approach of Leitz to try to design the same lenses for both systems, if possible.

 

6.7.1 3.5/65, Elmar, later Elmar-V, 1960

This is a lens for the Visoflex attachment. It is a low contrast lens with a soft recording of finer details at full aperture. Vignetting is one stop. Stopping down does improve the performance, but it stays a bit fuzzy.

 

Figure 153: diagram 67

The use of the Elmar design as a macro lens may be questioned. Distortion is visible.

 

6.7.2 2.8/60,Macro-Elmarit-R, 1972

At full aperture overall contrast is high and very fine detail is crisply rendered over most of the image field, becoming a shade soft in the corners. Vignetting is low with 1.2 stops and distortion is absent. Stopping down to 4 brings in the definition of extremely fine detail and at 5.6 the optimum is reached with a clear rendition of this level of detail recording. Performance from centre to the extreme corners is even and is in this respect better than the current Summicron-R 50mm.

 

Figure 154: diagram 66

On axis we see the same level of image quality. Close-up performance is as good as that at infinity and if a versatile lens is needed with excellent definition over the whole picture area, this lens might be an interesting alternative to the Summicron-R 50mm.

 

6.7.3 1.9/73, Hektor, 1931

The Hektor 1:1,9/73mm was the first attempt of Berek to design a high speed lens with a moderate angle of field. The triplet design however could not be stretched too much. The Hektor 2.5/50mm and the Hektor 1.9/73mm allow the same amount of energy flow to pass through the lens. The wider aperture of 1.9 (2/3 of a stop more than the 1:2.5) is offset by a 50% smaller angle of field. (34° versus 45°). clearly was aware of the limits of the generic Hektor design. The 1:1.9/73mm short telephoto lens at the wider apertures has that typical softness at the edges of outlines and the very smooth transition of the sharpness plane into the unsharpness blur of fore-and background, that became the defining characteristic of the portrait lens for generations of photographers. At full aperture the overall contrast is very low and while outlines are recorded with soft edges, the finer details are very soft and becoming blurred in the outer zones. Stopped down to 2.8 the higher contrast improves the clarity of outlines and coarse details. Closing down a few more stops, brings in the fine details, that stay soft however. Given the coarse grained films to be used with this lens, the finer details would become immersed in the grain noise and become invisible. On the other hand, the larger blur circles of this lens would force the grains to clump together more.

 

Figure 155: diagram 68

Distortion is not visible. Flare sensitivity however is very high. With a price tag of RM 105 (1938) it was 22% more expensive than an Elmar 50mm and about as expensive as the Hektor 28mm.

 

6.7.4 1.4/75, Summilux-M, 1980 & 1.4/80, Summilux-R, 1980

Comments apply to both lenses and fingerprint differences are noted when appropriate. At full aperture, overall contrast is medium and coarse detail is defined clearly over most of the picture area. Fine detail is recorded with good visibility but softer edges on axis. Performance drops very gradually when going to the corners in the case of the R-version and drops more rapidly with the M-version. Vignetting is 1.5 stops. Flare is well suppressed, but in high contrast light there is a softening of overall contrast. Coma is corrected to a high degree and the typical butterfly images of small light points in the field are relegated to the outer zones. At 1:2 overall contrast markedly improves and very fine detail is recorded with crispness on axis.

Again the R-version has the edge in the outer zones, when one looks at the outlines of subjects. We should realize however that these differences, while measurable, will be probably lost in every day picture taking. At 2.8 the on axis quality (till image height 6mm) improves visibly, and extremely fine detail is now recorded with clean edges. In the field we see no improvements when compared to the 1:2 aperture. At 1:4 the circle of excellent quality extends to 9mm image height. From 1:5.6 the image quality in the field is gradually enhanced and till image height of 15mm we see extremely fine detail crisply recorded.

 

Figure 156: diagram 69 (75)

 

Figure 157: diagram 70 (80)

Distortion is not visible. Comparison with a Summicron 90mm is not easy as there are several versions. The R-80 comparison with the Summicron R-90 shows that at 2 and 2.8 on axis performance of the R-80 is better (specifically the overall contrast) and the R-90 has the edge in the field. At smaller apertures this behavior does not change, but the differences are less visible of course. The M-75 comparison to the Summicron-M (3)-90 from 1980 shows that at 1:2 the M-75 has a very clear edge in overall contrast and the definition of fine detail in the field has somewhat higher micro-contrast. From 1:4 the M-90 inches ahead with a marginally better quality in the field, similarly the R-lenses. In the outer zonal areas the 90mm lenses render the extremely fine details with crisper edges, which will be visible in bigger enlargements.

On the assumption that these lenses will be used at lower speeds in handheld reportage situations, the finer points of difference will vanish for all, but the most critical inspection. The superiority of the 1.4 designs extends to apertures around 1:4.

If you use your lenses mostly at middle apertures, the Summicron's are as good a choice and I would suggest that then the latest or current Elmarit1:2.8/90mm would be the obvious choice. The new Apo-Summicron-Asph 2/90mm at 1:2 provides an image quality that the 75/80/90 lenses offer at 1:4 or smaller. This optical progress is hard to believe or accept, but it does show what we can expect from the design team in Solms. There is a time span of 20 years between the 1.4 designs and the new M- 90mm, and during this period, there has been progress in many areas, which explains in part the difference noted.

 

6.7.5 1:2/75mm Leica Summicron-M ASPH

When Leica indicated that they were about to develop a new lens with a focal length of 75mm, I was a bit surprised. The 75mm seems to hold an uneasy place between the 50mm and the 90mm. There is a certain myth around this focal length, based on the excellent qualities of the Elcan 2.4/75mm, designed by the late Dr. Mandler.

The physical specifications of this lens have been closely copied by the Voigtlander 1:2.5/75mm. Many photographers dismiss the 75mm as the lens seems to be too close to the 50mm focal length. If you make a few steps forward to your subject with a 50mm lens you can emulate the magnification factor of the 75mm, so the argument goes. And for the 90mm it is the reverse argument: just step back a few steps and you have the magnification of the 75mm lens. This type of reasoning ignores the finer points of the laws of perspective, about which I have to say more in this review.

To answer the basic question why the 75mm came into existence, we have to return to the high speed wars in the sixties and seventies. In those days, every respectful manufacturer tried to outdo the competition with ever-faster lens designs. The aperture 0f 1.2became the norm and the number of lenses with the specifications 1.2/50, 1.2/55, 1.2/58, 1.2/85 grew rapidly. Leica could not stay behind and produced the 1.4/80 for the R-series and the 1.4/75 for the M-series. The choice for these parameters was simply dictated by size and weight considerations. A 1.2/90 for R would be too big and heavy and a 1.2/90mm for M would obscure the rangefinder window too much. And the aperture of 1.2 could not be designed on the basis of the Leica equation for image quality.

So the 1.4/75 was a solution that satisfied the competing demands for size, weight and optical performance.

The rangefinder had to be redesigned with an additional frame for the 75mm and this change was partly responsible for the flare issues that have plagued the rangefinder window after the introduction of the M4P, the first body that could accept the 75mm lens. In fact both were introduced at the same time.

The Summilux 1:1.4/75mm has been designed more than a quarter century ago as a derivation of the classical Double-Gauss design. It offers excellent image quality, even according to current state of the art references. Its wide-open performance is quite good, but lacks the punch of lenses with smaller apertures. The effect of the residual aberrations is too strong at this wide aperture and cannot be countered by the means then available. The wide open performance sits between the more painterly drawing of the Noctilux at 1/50mm and the scientific drawing of the Summicron at 2/50mm, but is improved upon the Summilux 1.4/50mm, due to the smaller cone of light it has to transmit to the film plane.

The Summilux-M 1.4/75mm is a true workhorse: you need the lens and then you use it or you do not need it and then you do not buy it. The lens has no glamour or myth attached to it and is not a collector's item. And when you need it, you use it indefinitely and that may be the reason why so few Summilux 75mm lenses are offered on the second hand market.

The new Apo-Summicron-M 1:2/75mm ASPH is a derivation of the recently introduced Summilux-M 1:1.4/50mm. It has the same design characteristics: floating element, aspherical surface, a copious use of exotic glass types, the variety and cost of which explain in part the price. The design uses seven lens elements as analysis showed that element eight did not contribute to the image quality and had no added value.

The philosophy behind this design can be read in my review of the Summilux-M 1.4/50mm ASPH.

In a recent talk about the design considerations behind this lens, the designer drew attention to the main problems when trying to achieve superior performance with high-speed lenses. We are familiar with the main types of image aberrations, like spherical aberration, coma, astigmatism etc. But once these are sufficiently corrected the designer faces serious trouble in the reduction of the Petzval sum and the secondary spectrum (by means of achromatization). These aberrations can only be reduced by the use of the combination of many different glass types. If we are able to reduce the primary aberrations of spherical, coma and astigmatism, we get a perfectly sharp image point, but on a curved surface. The surface is curved because the lens elements have a curved shape. But we need a plane surface at the film gate. In the past, the designers had to introduce controlled amounts of astigmatism to offset the Petzval curvature. Leica lenses, especially the M lenses, used this technique, partly based on the nature of the Leica photography for reportage and documentary purposes, where good definition from centre to corner was not the prime directive.

Most aberrations are corrected by the method of lens bending: changing the radius of curvature. But lens bending cannot influence the Petzval sum and the chromatic aberrations. Only a change in the power of the lens element and the spacing of the lens element can do the trick. Changing the power implies often a different type of glass (different glass index) and the matching of the glass types can hardly be optimized by use of the computer. That may be one of the reasons why in the range from 35 to 90mm, the designs are all based on the Double-Gauss design type.

Leitz did experiment with exotic glass types in the past and even added layers of different glass together in one element to come to terms with these problems. An example of this glass can be found in my book. A theoretical study to break out of the grip of the classical designs was conducted at Leica several years ago and the result was a lens of breathtaking performance (an eight element 50mm design with GRIN lenses), but too expensive to manufacture. The insights gained however, were instrumental in designing the new Summilux 1.4/50mm ASPH. The Summilux is not so fully corrected as the Apo-Summicron-M 1:2/75mm ASPH, which is logical as the field of view and the aperture are both smaller, easing the design problem. But the liberal use of the high index glasses with anomalous dispersion, the use of the floating element (the spacing problem!) and the use of an aspherical element add up to the solution for the reduction of the Petzval sum and the chromatic errors. The aspherics in both the 1.4/50 and the new 2/75 are both the moulded version of the aspherical surfaces, not the grinded versions. One of the arguments to use the aperture of 2 is the size of the aspherical lens, which would be too large if the aperture were to be stretched to 1.4.

The floating element is of a special construction. To get a focusing range from 70cm, wider than the customary 1 meter, the throw of the rangefinder curve had to be widened by 5mm to accommodate the range from 70cm to 100cm, which is mechanically complicated. And the relative movement of both groups is not linear as in most designs.

The Summicron 75mm is a normal long lens construction and not a telephoto version. This supports the performance at close ranges. Still the image quality in the close range is not as good as what is delivered in the range from 1.5m tot infinity.

For really critical work one needs to stop down to improve micro contrast and the overall contrast of the image.

On test

At full aperture the lens delivers a very high contrast image with even performance from centre to the extreme corners. The resolution of 80 linepairs/mm from centre to edge is unsurpassed at this time of writing. Of greater importance is the edge contrast that is sharply delineated without the smallest amount of colour fringing.

The lens is not perfect wide open as we can see a small band of lower contrast (a dip) in the zone from image height 9 to 15mm. Here the contrast of the horizontal line patterns suffers a bit, but the lines can be seen quite clearly, but with some fuzziness.

Coma, often a problem in high-speed lenses is fully corrected, as is astigmatism.

Stopping down to f/2.8 improves contrast and now the dip is gone completely.

Resolving power reaches a value of more than 100 to 125 lp/mm over the whole image area. The image is of exceptional clarity and punch and the definition of extremely fine detail is outstandingly good. Stopping down further increases depth of field, and some crispening of the finest recordable detail, but this will be hardly visible outside the lab situation.

In practical terms we may say that the lens can be used wide open with the utmost confidence and the images can be blown up to whatever size one wishes without fear for blurring the details. Pictures made at f/2 at medium distances around 4 to 6 meters deliver excellent imagery and when studying the level of recorded details, one cannot believe that these are made at an aperture f/2.

The colour rendering is quite neutral and on the rich side as far as saturation is concerned. The particular strong point of this lens is its stunning propensity to show the depth of the subject with a three dimensional quality that is seldom encountered.

Veiling glare is totally absent and the lens produces deep black shadows with clean separation of subtle shadow detail. The internal blackening of the mount and the black paint on the rims of the lens elements effectively reduces secondary reflections and halos around specular highlight spots are not detected. On the other hand, we cannot shoot deliberately against the sun without causing some reflections and the lens is not fee of secondary images under all circumstances. It would be quite unrealistic to assume that a lens is totally immune for flare. The Apo-Summicron 75 is quite good in this discipline.

This lens is a primary choice whenever the realistic rendition of solid objects is required. The definition of the unsharpness blur is quite smooth and lacks the harshess of some very high speed lenses.

I made comparison pictures with the 2/50, 2/75 and 2/90mm Summicron lenses and the same distances and at the same magnification and of course wide open and stopped down. The conclusion of this exercise will not please the bo-ke fans. I did not see any visibly significant differences in the reproduction of the background blur.

The famous words that beauty is in the eye of the beholder may be transposed to the bo-ke discussion. The subjective qualities of the background are often a major element of the composition, but one should not focus too much on this aspect. The quality of the sharpness area is still the defining property of a picture.

The Summicron 75mm operates with the solid smoothness that is the defining property of the current generation of Leica lenses. The lens is heavy for its size, but the weight of the special glass types asks its toll.

High contrast lenses

There is some confusion about the meaning of high contrast in the context of lens testing. One reads very often about the possibility that a high contrast lens should be matched to a low contrast subject and a low contrast lens should be a good choice for a high contrast subject. The match of a high contrast negative to a low contrast printing paper is well known and presumably one assumes that the same kind of match works for the contrast properties of a lens. A high (low) contrast subject or scene is one where the contrast range from deep shadows to specular highlights is wide (narrow). Or in other words the tone reproduction curve is steep or extended.

What works for the tone reproduction cycle in the subject-negative-positive process cannot be migrated to the properties of a lens.

A high contrast lens does reproduce the spatial frequencies with good edge contrast.

The low spatial frequencies (around 10 to 20 lp/mm) define the main outlines of the subject. But we need the high spatial frequencies to get good edge sharpness. See the figure below, which shows a bar line with steep edges. To reproduce these edges we need the high frequencies! In the diagram the rounded smoothed curve represents the reproduction of the bar line when the high spatial frequencies have been filtered.

The resulting bar line has soft edges and will be seen in the picture as an outline with a fuzzy edge.

A high contrast lens will reproduce the details of the subject with good edge contrast, whereas the low contrast lens will reproduce the details with fuzzy edges and the cutoff level where fine detail is totally blurred is reached quick quickly.

Low contrast lenses are not able to reproduce the high spatial frequencies faithfully and quite often have a high amount of residual aberrations, which will be seen in the picture as an elevated level of flare. This may be the cause for the confusion: the flare in the low contrast lens will redistribute some of the light of the highlight parts of the picture to the shadow areas, which will have more density at the expense of the highlights. It seems that the tonal range is extended in the shadows, but that is not the case. The tonal range is identical, and there is not more shadow detail. The shadows seem to be easier to print.

Comparison with other Leica lenses The obvious candidates are the Summicron-M 2/50 and the Apo-Summicron-M 2/90 ASPH.

The MTF diagrams below are indicative of the state of the art. The Summicron 50mm is weaker in the corners and the critical frequency of 40 lp/mm is for a large part below a contrast transfer of 40%. In practice this translates in a slightly less punchy imagery. The Summicron 50 at full aperture draws with somewhat wider brushstrokes than the Summicron 75mm. One may reflect on the additional effort that has to be put into the 75 to get a visibly enhanced imagery compared to the relatively modest outlay of the 50mm design.

The Summicron 90mm is in the same class as the 75mm, but note the more pronounced curvature of field of the 90mm. At the most critical inspection of pictures made at aperture f/2 with the 75mm and the 90mm, one can note that the 75mm has a tighter grain structure, an indication that the residual aberrations are reduced to an even lower level.

The four lenses in the focal range from 50mm to 135mm represent the Olympic platform for the Leica M range: the Summilux-M 1:1.4/50mm ASPH, the Apo- Summicron-M 1:2/75mm ASPH, the Apo-Summicron-M 1:2/90mm ASPH and the Apo-Telyt 1:3.4/135mm are able to extract every possible image detail from today's film emulsions and one feels entitled to question the necessity to improve these lenses further as long as one is working with film.

The Leica M camera system is often designated as predestined for wide-angle photography and while undoubtedly true, the qualities of the standard to medium focal length lenses are such that the joy of photography on the performance edge of the medium has to be experienced to become a true Leica master.

The Color-Heliar 2.5/75mm This Voigtlander design is the obvious candidate for comparison with the new Leica 75mm lens. Overall the C-H has a very good definition of detail in the centre part of the image, but with quite soft rendition of detail in the outer zonal areas of the negative. There is also a visible colour fringing at the edges of the main subject outlines. Stopping down improves the contrast and the performance becomes more evenly distributed over the whole image area.

In numbers: wide open the resolution in the centre is excellent with 125 lp/mm, but this drops to 30 lp/mm at the edges with quite low contrast and fuzzy edges. At f/5.6 the edges are improved to 50 lp/mm with some fuzziness and a faint amount of colour fringing.

The C-H is a very good design with an excellent price-performance relation and one can wonder how it is possible that Cosina can deliver such a performance for the modest price asked for the lens. The image quality of the lens will satisfy many users, it in self a sign that the relentless drive for the ultimate performance has a natural end.

Status of optical design The Summilux-M 1:1.4/50mm ASPH and its sibling, the Apo-Summicron-M 1:2/75mm ASPH do represent the current state of the art in optical design. The combination of aspherical surfaces, floating elements and in particular the break through in glass manufacture with the new glass types may be the turning point in the history of optical design for film based photography. Looking at the MTF graphs one may see still room for improvement, compared the best designs in the R range (the long focal lenses), but for the M range one is inclined to see the current level as a platform. To extract more performance out of the design would imply more complicated designs at a cost that no one will feel prepared to pay. On the other hand the technique required to use this high performance is so demanding that it makes the concept of a dynamic style of M photography obsolete. Mechanically the new lenses are at the bleeding edge of manufacture and quality assurance. These designs could never be made in large quantities and one may be very happy that Leica is not sitting on its laurels and wishes to exploit its niche properties to deliver outstanding quality for the discerning Leica user and aficionado.

The position of the 75mm in the M lens line.

When I first heard of the introduction of the new 75mm lens, I was a bit sceptical and wondered if the lens, however good, would be squeezed between the popular and classical 50m and 90mm focal lengths. I already own the Summilux 1.4/75mm and I am familiar with the fact that the perspective and field of view of the 75mm are often advantageous, compared to the 50mm and 90mm focal lengths. The 50mm angle of field is in many cases just too wide and you have the inclination to reduce the distance between the camera and the subject, but then some subtle distortion will mar the picture, especially when photographing persons. With the 90mm you need more distance than is required for fine focussing or a psychological rapport to your subject. When you change quickly between the 75mm and 90mm, you will be surprised how fast and accurate the focusing becomes with the 75mm, where the 90mm is slower due to its bigger throw and the reduced (visual) accuracy of the finder. The 75-135 pair could replace, or ideally complement, the classical combo of 50mm and 90mm with a wide latitude in picture opportunities.

The magnificent four (to borrow a title from that classical Western movie, the magnificent seven, deliver the best imagery money can buy in the M line. While there is a certain overlap in possibilities, the fingerprint of these four is sufficiently different to justify the existence of them all.

 

6.8 85-90mm

The focal length of 90mm has been one of the first to be added to the Leica lens system. It has been designated as a portrait lens, but it did not originate with such a goal. When films had limited enlargement capacity and quite coarse grain, finer details could not be recorded. The 90mm could be used to magnify details above the threshold of the recording capacity of films and in the original documentation you will find references to this usage. With the 35mm wide angle lens, introduced at the same time, the Leica system comprised of three lenses which have been the classic triumvirate since more than 70 years. The 35, 50 and 90mm focal lengths have been redesigned often, with all kinds of changes in physical dimensions and apertures. The Summicron versions formed the backbone for the best optical quality of the Leica system. For the M-system this still holds. The R-system evolved in a different direction with the high quality zoom lenses. As a historical aside, it may be mentioned that these three focal lengths, developed in the early part of the 20th century, have shaped our view of the world through photographic images. I would not like to label the 90mm (or for that matter the 35mm lens) as the lens for a certain class of objects, nor to state that the 35mm or the 90mm is the prime lens for the Leica M or R system. Lenses are tools, and should be selected based on goal and intention. The 90mm is indeed a fine instrument for portraits, but so is a 180mm or a 50mm and the 90mm may be excellent for reportage and landscapes. The key to successful Leica photography and 35mm photography in general is to fill the small picture area with as much visually attractive content as possible. The old masters were fully right in insisting that the less enlargement, the better. The 90mm is very good for visual concentration, but on the other hand quite demanding on composition. It is easier to find a pleasing composition with a 35mm lens than with a 90mm.

 

6.8.1 1.5/85, Summarex, 1943/1948

The Summarex 1:1.5/85mm is first mentioned in a 1943 catalogue as a black version with the inscription 1:1.5/9cm. The earliest reference is 1940, when 6 lenses have been produced, presumably as a Null-series. In 1943 a batch of 500 has been allocated, but is doubtful if these lenses have been all produced and certainly only a precious few would have been available for sales to the general public, at least in 1943. Closer study of the archives shows that the first 100 lenses of the production were all of 1.5/90 designation and went in a lot to Berlin, to the 'Beschaffungsamt'(purchase and distribution department) of the German Army.

The other lenses (with addition of a 'B'(for the 1.5/85 designation, have been sold to the public, but only after the war. The next series is from 1948 and production stopped around 1954. This might be the appropriate place to mention that actual production period and dates of allocation of serial numbers do not coincide. It is reasonable to assume that a batch will be produced in one production run as the workers at the assembly line can get well trained in the assembly of this lens. In this case the last allocation date is early 1954 with a batch of 1000. The true production period might be anywhere in 1954 and sales might extend well into 1960, when the lens is officially put off the catalogue. To be precise, it would be preferable to state the actual production dates and not the period a lens does figure in a catalogue.

 

Figure 158: diagram 71

At full aperture the Summarex has very low contrast, but its performance is even across the whole picture area and astigmatism is very well reduced. Outlines and coarse detail is recorded quite visibly, but with fuzzy edges and finer detail is fully blurred. At 1:2 overall contrast improves and now the on axis performance increases visibly. At 1:2.8 we now detect finer detail in the field and on axis performance has a bit more power. From 4 to 8 the definition of fine detail gradually improves over the whole picture area. Stopped down to 1:8, image quality is very good and at 1:11 the lens reaches its optimum with an overall performance equal to the Elmar 4/90 at 11 Flare and secondary images are quite visible, even in the coated version. Vignetting is low with one stop and distortion hardly visible. This lens might be called a limiting case. Stopped down it is as good as any Leica 90mm of contemporary age, and its wide aperture extends the possibilities of the Leica photographer into uncharted areas, but in itself this wide aperture is a bit daring as the image quality shows. The remarkable improvement at 1:2 is an indication of its true potential.

 

6.8.2 4/90 Elmar, 1930

The Elmar 1:4/90 at full aperture has a low to medium overall contrast and renders finer detail with good clarity over an extended area (image height about 12mm). The corners are weak. Stopping down brings somewhat higher contrast and definition of fine detail on axis improves as stray light is reduced and the peripheral rays are cut off from the imaging forming process. Around 1: 8 the centre has crisp definition of quite fine details and the outer zones now record finer detail with soft edges, but quite visible.

 

Figure 159: diagram 72

The Elmar 90mm lens shows some curvature of field and some focus shift, but can be used with good effect at shorter distances. Compared to the Elmar 1:3.5/50mm we note that overall contrast is on the same level, with the 50mm a shade behind.

Finer detail is recorded with cleaner edges by the 90mm version, and when stopping down, the 90mm improves more than does the 50mm.

 

6.8.3 4/90mm Elmar (rigid and collapsible), 1954

The general optical and mechanical improvements, including coating of lens surfaces, gave the optical performance of this version of the Elmar 90mm a small boost.

Optical layout has not changed, but several new glass types are employed.

 

Figure 160: diagram 73

As noted at several occasions, the lens drawing does not tell the whole story. At full aperture the lens gives a medium contrast image over most of the picture area. On axis the clear definition of subject outlines and of fine detail brings commendable image quality, if one does not enlarge too much. In the field the performance drops considerably, with the exception of the subject outlines, that soften only slightly. As the eye is most sensitive to the contrast at the edges of large subject shapes, the general impression of pictures taken with this lens, is quite good. At the wider apertures the basis aberrations are still degrading the image quality. Stopped down to 1:11 we find a very even performance of a commendable quality over the whole image field.

 

6.8.4 4/90mm, Elmar , 3-element lens, 1964

 

Figure 161: diagram 74

This lens is a Canadian design and with only three single elements, a case-study of optical simplicity. Its full aperture performance is better than that of the predecessor with the classical 3 group/4 element construction. Overall contrast is a bit higher, the definition of fine detail has improved edge contrast and especially the performance in the field is much better. Vignetting is .7 stops. At 1:4 the contrast gets visibly higher and now very fine detail is recorded over the whole image area with good clarity. The Elmarit 1:2.8/90mm at 1: 4 cannot equal the 3-element Elmar here. Stopping down further brings in finer detail and at 1:11 we find image quality of a thoroughly modern level. This lens has been introduced at the same time as the Tele-Elmarit 1:2.8/90mm, which replaced the Elmarit 1:2.8/90mm. As the Tele-Elmarit could not be used with the bellows attachment and had not the best performance at closer distances, Leitz offered the Elmar as a lens for these applications. Close up performance is quite good. Distortion is negligible. It does show the intriguing strategy of fine tuning the lens performance for a specified set of tasks. It was not possible in those days to create one general purpose lens and so Leitz optimised the designs in different directions. A luxury that could not be extended indefinitely as it was a costly strategy. With modern glasses, this lens would deliver a very interesting performance.

 

6.8.5 4/90, Elmar-C,1973

The eagerly awaited Leica CL (the 'Baby-Leica') was accompanied by its own set of lenses, the Summicron-C 1:2/40mm and the Elmar-C 1:4/90mm . This 90mm lens delivers already at full aperture excellent quality with a high contrast image over most of the picture area. It equals the Elmarit-R 1:2.8/90mm of its day (from 1964), and is better than all Leitz lenses in this focal length and aperture 2.8 and 4, at least the ones available in the early seventies. Very fine detail is clearly recorded, be it with soft edges, which might become visible, at bigger enlargements, as a fuzziness when of small textural details. Stopping down to 1:5.6 and 1:8 enhances contrast and on axis the image quality is quite high now, gradually becoming worse when one wishes to capture really fine detail in the outer zones. Generally the zones do not improve that much with this lens: an indication that the residual errors are still quite active.

 

Figure 162: diagram 75

Close up performance is excellent too and distortion is non-existent, making the lens suitable for reproduction work. Vignetting is 1 stop. In the lens diagram we note as a remarkable feature, the negative meniscus lens as the fourth element. The Minolta Rokkor-C is identical and has been built in Wetzlar too. The mount and rangefinder coupling of the Elmar-C are different from the regular M-lenses. The Elmar has a very steep curve, as its turns only 120o. A small movement of the focusing ring translates into a substantial movement of the optical cell, which makes it difficult to use for accurate focusing and measurements. C-Lenses couple accurately to the Mbody as the bayonet is the same, but focusing errors might occur.

 

6.8.6 1:4/90mm Macro-Elmar-M

Every advantage has its negative counterpart. We may assume that there is nothing free in the universe. Gain here, loose there. The Leica rangefinder system is a beautiful construction, which adds great clarity to an accuracy that is good enough for a surveying instrument. The system however is built around a complex mechanical-optical design that has some limitations. The principle is quite simple.

The rotating movement of the distance ring on the lens is translated into an axial movement of the lens unit. The back of the lens unit, the thread, is shaped like a curve with a certain steepness. This curve acts as a wedge that displaces a roller arm, which in turn moves a rangefinder prism that projects an image of the object on a second prism. This second prism also receives an image of the object through the finder and because of the beamsplitting design of the prism, the eye now sees two superimposed images. Moving the distance ring allows both images to coincide. The maximum distance of movement for the roller cam is about 5 mm and the maximum axial distance for a 50mm lens from infinity to 0.7 meter is 5mm too. This is a 1:1 reduction of the lens movement and the cam movement. But the accuracy is not linearly distributed over the gradient of the cam. If we change the distance setting from 5 meter to 2 meter (a difference of 3 meters) the axial displacement of the lens is 1mm. The cam movement then is also 1 mm. In order to translate this movement to the tiny change in the angular movement of the prism, the steepness of the cam must be considerable. If we If we now change the distance setting from 1 meter to 0.7 meter (a difference from 30 cm), we can observe that the axial movement is 1.5mm and the movement of the roller cam is also 1.5mm. We understand that the relative steepness of the curve, the reduction mechanism and the axial movement of the lens have a limited scope. If we wish to focus more closely to the object, we need a longer curve (the total length of the wedge must increase), which is impossible as the diameter of the bayonet mount is fixed. Or we need to change the shape of the curve and so reduce the accuracy of the measurement. We should not forget that Barnack designed this construction 70 years ago and that it is still the best we have.

The longer the focal length, the more the limitations of this mechanical transfer will be approached and the shortest distance that can be rangefinder coupled is restricted.

The second limitation of the rangefinder mechanism is the parallax, but I do assume the reader is familiar with this one. The upshot is a limit on the range for the near focus distances that can be photographed with the M-camera. This is a pity, because there are many photogenic opportunities in the range between 50cm and 1 meter.

 

Macro solutions

Leitz knew this too and in the past several solutions have been proposed. These are Leitz-typical jewels of mechanical engineering. In many instances we see an extension tube with an optical attachment to correct the parallax and can be used for a limited distance range. Collectors know the names by heart, like SOOKY and SOMKY and OMIFO. The handling was also Leitz typical and not the most elegant or efficient to use.

 

Optical evolution

The evolution of the optical design at Leica has been focused, since 1980, when the new focal length of 75mm lens was announced, on the optical improvements of the existing range of lenses. And with great success. Several of the current Leica lenses for the M-system belong to the world’s best lenses and all are part of the top three of the best lens systems of the world. But the photographic opportunities have not been expanded. A 35mm wide angle lens, now and then delivers the same style of pictures, even if the new aspherical version has improved imagery. This changed when the new 24mm was introduced in 1996 and especially with the new Tri-Elmar- M from 1998. Now the M-user could with an easy switch change between three focal lengths from 28 to 50mm. The dynamical style of reportage photography could be enhanced with a new perspective.

The close range however was not the strong point of the M-system. Standard and wide angle lenses could be focused till 70cm, but the low magnification ratio did not allow the subjects to be reproduced large enough on the negative.

 

Macro-Elmar-M 1:4/90mm and Macro-Adapter-M

Now Leica has filled the gap wit a new lens: the Macro-Elmar-M 1:4/90mm. With the use of the Adapter the lens will focus till 50cm, and reach a magnification ratio of 1:3 and that is quite nice. The lens itself is a four element collapsible design, focusing till 77cm. Collapsed it is a very compact unit and with the Elmar-M 1:2.8/50mm will present a very handy travel set. In combination with the Tri-Elmar you have a range of focal lengths from 28-90 and a distance coverage from infinity to 50cm. This is quite versatile.

The danger is that the new 90mm lens will be seen only as a macro lens. In fact it is a very compact, extremely high performance lens that can be used for reportage style photography, where its high class definition can add a new sense of gritty reality to the pictures. (see below) Some people will always put a question mark on the longevity of a collapsible construction. I am one of them. But my heavily used Elmar-M 2.8/50 is still impeccable and is being monitored on the optical bench for any loss of performance.

There is none! The lens hood is most effective and can be put on the lens as a protection. The lens hood will never win a design price and personally I had hoped for a more pleasing design.

With the Macro-Adapter attached to the body and lens the useable range extends from 77 to 50cm. The lens has two focusing scales for both ranges. The Adapter is in fact a thick extension tube with two M-bayonet mounts and an optical attachment with three eyes to put in front of the three eyes of the camera. This one is crystal clear and does not distort the image in the finder. Previous Leitz constructions were not that good. There is additional parallax compensation and this means that two topics must be addressed. The normal frame lines in the finder of the M-camera are too generous in the near focusing range: there is less on the negative than you see in the masks of the finder. Normally this reduction is about 5%, which is not very important. But in close up photography you may miss important edges. The problem of parallax is the second topic. Both these effects make it difficult to get an accurate framing. You must make test pictures to get a good feeling what is being recorded when you frame with the lines in the finder. I used a page from the Donald Duck and you can see quite clearly what is being captured. You might even tape thin strips on the focus attachment to guide you.

In the macro-position the lens works very efficiently. The rangefinder patch is quite enlarged and the alignment of the images is slow: the distance to cover in order to super impose the finder and rangefinder images is quite large. But is very accurate: the thickness of a Eurocent makes a big difference in the rangefinder images.

Depth of field is very thin: at f/4 and magnification of 1:3 it is 3mm. At f/11 it has been extended to 9mm. You need some are when selecting objects to photograph at this magnification.

 

Optical performance

A 90mm lens with aperture 1:4 was already available in 1930 and a collapsible version could be bought since 1954. These specifications for a most modern design do not seem ‘sexy’, but the optical designer has a different view. The demand to create a compact and lightweight lens, that performs excellently at all distances, including the macro range, is not an easy one to fulfil. That is why Leitz had in the past always two versions of the 90mm lens, one optimized for the normal (infinity use) and one for the more close-up use. The evolution of the 1:4/90mm lenses is quite interesting. The 1930 version had the classical Elmar/tessar design with three elements, the last being a cemented doublet. The contrast was quite low and the definition of fine detail was just acceptable. The big problem with a 90mm lens with only a few elements is the wish to combine high contrast and high resolution in a lens that inherently has a large secondary spectrum and a high amount of curvature (high Petzval sum). In 1968 Leitz surprised the world with a new 4/90mm lens with only three lenses and two different glass types. It had an astonishingly good performance. It was only a few years on the market and now is a collectible item, a pity. In 1973 The Elmar-C was introduced for the CL body. This lens had four separate elements with four different glass types. The performance was much higher than before and now we have a high contrast image, good resolution from centre to mid zones and only the cornets were lacking in brilliance. A similar design was used in the latest Elmarit-M/R 2.8/90 lenses.

It would have been easy for the design team to adopt this solution. But then the macro quality is lacking. So a new calculation and optimization was done and the result is an outstanding lens. Again with four separate elements, but now the diameter of all lenses is almost the same. This helps to ease the rays through the surfaces with a small deflecction of the ray at the surface.

If you look at the classical triplet design, you see that the middle lens is much smaller in diameter. Here the rays from the bigger front element are steeply deflected and this causes more aberrations.

At full aperture the M-E-M-90 delivers a high contrast image and a very high resolving power (definition) over the whole frame from centre to extreme corner.

Curvature and astigmatism are absent and decentring as a measure for quality control during manufacture and assembly is not noticeable. The resolving power in the centre is above 150 lp/mm and even in the extreme corners is still around 100 lp/mm. Many lenses would be happy to have 50 lp/mm in the corner with this contrast.

At 1:5.6 contrast increases a bit due to the reduction of internal reflections. At 1;8 the optimum is reached and this performance holds till 1:16. Only at 1;22 there is a noticeable drop in micro (edge) contrast. This is one of the few lenses that perform equally well at all smaller apertures.

The most interesting resolution can be found between the 10 lp/mm and 20 lp/mm and at these frequencies the edge contrast is very high and we do not detect any colour fringing. In fact one wonders why the lens has not been given the APO designation. The Leica designers are very strict and they did not give the coveted star to the M-E-M In the near range from 50cm to 1 meter the performance is exemplary good. In the range from 50cm to 80cm, the overall contrast is a bit lower and the definition of fine details less crisp, but you will not notice this aspect, as the magnification ratio compensates visually the slight reduction in contrast. Due to the slim depth of field you will most often stop down anyway.

Vignetting is 1,8 stops and can be detected as is the distortion of 1%, that will be noticed at very high magnifications.

To answer this question: no, the macro-adapter cannot be used with other 90mm lenses, as the cam of the M-E-M is specifically designed for the macro adapter.

 

The other lenses

The R-system has the redoubtable APO-Macro-Elmarit-R 1:2.8/100mm, a most versatile lens. A real comparison is not possible as we have one the one hand a six element design with special macro lens components and a physically large lens. On the other hand a four element design with slender dimensions. Still it is of some academic interest to see what the performance differences are. The M-E-M delivers at full aperture a fraction more of performance at medium distances than the A-ME- R. The edges of the lower frequencies are somewhat tighter defined and the M-EM gives a crisper presentation of the facts. Presumably the lower number of lens elements and the careful choice of the glass types are the cause of this behaviour. At 1:5.6 the tables are turned and now the A-M-E-R has a slight advantage, which holds till 1:8. It might be the inherently higher level of correction that is at its optimum at the medium apertures that is responsible.

The Apo-Summicron-M 1:2/90mm ASPH delivers outstanding quality at the wider apertures, but it is logical to assume that at 1:2 the A-S-M-A is not as good as the ME- M at 1:4. Again it is the higher overall contrast and the very good edge contrast that make the day for the M-E-M. This comparison is not really fair as the Summicron has a two stops advantage at maximum aperture. When we compare both lenses at 1:4 at medium distances , we may note that the Elmar reproduces the fine detail with a crisper edge. The Summicron at 1:4 is somewhat softer. The large front lens of the Summicron collects some non-imaging forming light from the surroundings (especially in back-lit situations), that softens the overall contrast somewhat. I would hesitate to call it veiling glare as this is not the case. In comparison the images of the Apo-Summicron seem a fraction overexposed in relation to the Macro-Elmar.

At smaller apertures, the Apo-Summicron is as good if not better than the Macro- Elmar.

These three lenses deliver high quality imagery of a very high order. Many people will not note any difference at all. Pushed to the limits or using the lenses at their designated optimum role, you will be able to see the subtle and important differences.

With the Apo-Summicron and the Macro-Elmar, Leica has given the user a difficult choice.

As a related remark, I would comment on the often heard statement that an 1:4 lens is not good for reportage work and thus has no place in the M-System. Such an opinion is not based on real insight. Most pictures of Cartier-Bresson were made at aperture 1:8 and no one will deny that his work is reportage style pur sang. It is true that at 1:4 we have a limit when using the lens in situations where the ambient light level is low, but it not the case that the photographic reportage is restricted to the socalled ‘available-light’- photography. And in many cases a slight fill-in flash does the trick when the speed of the lens is too low. We should not forget that in many situations the depth of field will dictate the use of a smaller aperture. The simple yes/no discussion should be replaced with a more mature when/if discussion.

The other contender is the Voigtlander Apo-Lanthar 1:3.5/90mm. This is a Double- Gauss lens with six elements. At aperture 1:4 this lens is a bit behind the M-E-M, specifically in the corner performance where the Lanthar records 70 p/mm against the Leica lens with 100 lp/mm. Edge contrast is also lower, as we see more colour fringing with the Lanthar than with the Elmar.

 

Conclusion

With the exception of the Elmar-M 1:2.8/50mm, the Macro-Elmar must be the smallest optical package in the M-system. And with the exception of the Apo- Summicron 90mm and the Apo-Telyt 135mm it is one of the best overall performers. Its image quality in the near focusing range is unequalled in the M-range and this brings the added value to the lens. It does not replace one of the existing lenses, but brings new pictorial possibilities into the reach of the M-photographer.

To identify this lens as a pure macrolens would be too restrictive. It is a very fine general purpose lens, that will deliver stunning images with today' s black and white and slide material.

 

6.8.7 2.8/90,Elmarit,1959

In 1959 the Elmarit 1:2.8/90mm closed the gap between the Elmar 1:4/90 and Summicron 1:2/90 designs. It was a triplet derivative with 3 groups of elements, of with the last two were doublets. There are two versions, which differ optically slightly. The first smaller batch has different glass types than the second version, which might be called the normal version. Performance wise it was better at full aperture than the Elmar at 1:4, but at 1:2.8 not as good as the contemporary Summicron 90mm at 2.8.

 

Figure 163: diagram 76

At full aperture overall contrast is medium, coarse details are clearly rendered with good edge contrast. Only the corners lag a bit behind. On axis, the definition of finer detail is crisp, with a gradual degradation when going to the edges. Stopping down to 4 enhances the overall contrast and the edges of the outlines now are sharply delineated. At 1:5.6 the recording of very fine detail comes within visible range and at 1:8 we find a clear and crisp recording of textural details over the whole image field.

For best close-up performance one should stop down a few stops. Vignetting is very low with only half a stop and the picture area can be considered as even illuminated till the very corners. There is some flare at the wider apertures.

 

6.8.8 2.8/90, Tele-Elmarit-M, 1964

The Tele-Elmarit 1:2.8/90mm, introduced at the same time was of a very short physical length. It is again a Canadian design. In fact it was a modern replacement of the collapsible Elmar 1:4/90mm which could be used with the standard every-ready case. It has slightly higher contrast at full aperture on axis than its ELW predecessor, but also shows some curvature of field where the Elmarit is quite flat. Generally the full aperture performance of the Tele-version is slightly behind the Elmarit.

 

Figure 164: diagram 77

Stopping down to 4 brings visible improvement and at 5.6 both lenses perform on equal footing. It is more flare prone than the Elmarit-version. The Elmarit-R 1:2.8/90mm (first version), introduced in the same year, offers the best image quality.

As noted the R lenses could be built with a larger size and that helped improve the performance. The classical dilemma for M lenses is illustrated here anew: small size and compact designs are more difficult to correct to a very high order.

 

6.8.9 2.8/90,Elmarit-R,1964

This first Canadian design for a 90mm lens for the R-system is an excellent performer and shares by the way most characteristics with the Colourplan 2.5/90, which is almost identical. A medium to high overall contrast is coupled to a very even edge to edge definition of very fine detail, that is recorded crisply.

 

Figure 165: diagram 79

Stopping down slowly improves on this quality and at 1:5.6 a very high contrast is reached with a clean recording of very small textural details over a large part of the centre, falling off quite a bit in the outer zones. For best close-up performance one should stop down two stops at least.

 

6.8.10 2.8/90, Tele-Elmarit-M, 1974

This lens has about the same performance as the Elmar-C and sports a wider aperture of one stop. It is however not as good as the Elmarit-R of 1964 and it is of some interest to find out why this version has been introduced. Leitz wanted to offer the M-user a very compact telelens for use with the ever-ready case. And that demanded a very short optical cell, which was very difficult to create with good performance. This lens is quite remarkable in the Leica evolution. It is evident that in the mid-seventies, the Leitz company had too many lenses in the program. A reduction was necessary and one of the first lenses to go was the 135mm focal length for the M. Still a 135mm lens could not be lacking in the system and so the tiny Tele- Elmarit 2.8/90mm was specifically designed with an 1.5x extender in mind to provide a compact 135mm lens. The idea was very nice, but the performance drop that occurred with the extender, killed the project.

 

Figure 166: diagram 78

Physically it is more compact than the predecessor and follows the design characteristics of the Elmar-C. The new lens is an optically slightly improved version of the Elmar-C and with 4 elements equals the previous Tele-Elmarit 1:2.8/90mm with 5 elements. Only when high contrast motives are photographed the 4-element version shows a somewhat higher flare level at full aperture. Stopped down some differences are observable, as the Tele-Elmarit has some higher edge contrast of fine detail in the field. Vignetting is with _ of a stop a bit less and distortion a bit more than with the Elmar-C. At full aperture the lens delivers a medium overall contrast and clear definition of quite small details on axis, gradually becoming softer and less distinct in the corners. Stopping down edges up the contrast and the image quality in the corners. At 1:5.6 and 1:8 the overall quality reaches a high level and very fine detail is defined with clean edges and clarity of small textural gradations. Close up performance is excellent too. This high quality has been accomplished with only four elements, still retaining the short length. To improve on this level and sticking to the length would have demanded a new design with one or two more lens elements, making it a complicated and expensive lens for its specifications. Leica wisely choose the Elmarit-R from 1980 as the successor, which is 10 millimetre longer, but still 12 millimetre shorter than the previous Elmarit.

 

6.8.11 2.8/90, Elmarit-M, 1990 & 2.8/90, Elmarit-R, 1980

In 1980 the Wetzlar designers recomputed the 2.8/90 for the R again and created the best 2.8/90mm ever in the Leica history (R and M). The first series of the R-version have been built in Portugal. The M-version arrived on the market in 1990, and is, even today, one of the best lenses in the Leica M stable. We seem to have reached a temporary platform here and while the new Apo-Summicron-M Asph indicates the future direction as far as design methodology is concerned, an upgrade would not be very cheap.

 

Figure 167: diagram 80

At full aperture, overall contrast is high and very fine detail is crisply rendered with only a faint trace of colour fringing and astigmatism over the whole picture area. The previous R-version has lower contrast and softer edge definition and needs to be stopped down to 4 to get comparable performance. At 1:4 the contrast improves visibly and at 1:5.6 we reach outstanding image quality with extremely fine detail recorded with high edge sharpness and good clarity over most of the image field. The edges are slightly softer, but this will be visible only when one needs exacting coverage of small details in the corners at bigger enlargements. After this aperture contrast and edge definition drop due to diffraction. Close-up performance is as good as at infinity. Vignetting is low with half a stop, and distortion just visible. Flare suppression is excellent as coma (among others) is well controlled. As the 4 element lens has no cemented surfaces, Absorban can not be used to control colour transmission and it has to be accomplished with several types of coating layers.

 

6.8.12 2/90, Summicron (1), from 1953 and 1957

The first 90mm lens with an aperture of 1:2 has been produced around 1953. It was a six-element design that differed from the second version This was the version with the detachable (and large) lens hood. Most seem to have produced from 1957 to 1959. This design was created in Wetzlar and production occurred in Canada and Germany. The series from 1953 belongs to the mysteries of the Leitz company. In the serial-number documentation, these lenses are clearly defined and allocated.

 

Figure 168: diagram 82

What happened to these lenses, (200 were allocated) is not fully known. The designers allowed the computation to grow to whatever physical dimension was necessary and this lens performed admirably well, when stopped down. At full aperture it has a clear advantage to the Summarex, stopped down to 1:2. Overall contrast is medium now and outlines and coarse detail is recorded with good edge sharpness on axis. Stopping down to 2.8 brings the definition of fine detail in the field above the visibility threshold. At 1:4 the finer details are still a bit fuzzy at the edges and at 1:5.6 very fine detail is captured with clarity on axis and a bit fuzzier in the field. In high contrast situations, this lens shows flare around specular highlights and veiling glare reduces the overall contrast, making the pictures a bit flat, a characteristic that will be often noted with older lenses. Close-up performance at the wider apertures is not so good and stopping down is advisable. This remark is valid for many wide aperture short telelenses. Vignetting is low with one stop and distortion is hardly visible.

 

6.8.13 2/90, Summicron (2), 1963

From 1963 the second version (again a six-element lens, but with different glass types) has been produced. Its design is different from the first version, as can been seen from the diagrams. This one is a Midland design. At full aperture the overall contrast is medium too. The clear definition of coarse detail enhances the overall visual performance, compared to the predecessor. The lens is still sensitive, but less so, to flare. Finer detail is rendered with fuzzy edges, and gives the overall image a softer look. Stopping down to 1:2.8 brings some improvements in detail rendition and at 1:4 we have excellent quality over most of the picture area, the corners excepted. This lens can be used with confidence at the wider apertures and at distances from 2 to 3 meters to infinity.

 

Figure 169: diagram 83

It does exhibit the somewhat turbid recording of finer detail that is the fingerprint the 90mm Summicrons before the Apo-version. Vignetting is low with one stop and distortion is hardly visible. The family trait of the wide aperture 90mm lenses is he relatively large gap between the performance at full aperture and stopped down, mainly attributable to the lower overall contrast, which also lessens the ability to reproduce the very fine and textural details with good clarity or at all. We often do not realize the amount of light energy that flows through a lens with a diameter of almost 50mm. And how forceful the aberrations are acting to degrade the potential image quality. It is relatively easy to note the differences in performance, but much more difficult to appreciate the efforts of the designers to control these aberrations.

 

6.8.14 2/90, Summicron-R, from 1970

This lens for the R-system arrived in 1970 on the market and has not been changed during its long production life of more than 25 years. It is closely related to, but not identical to the Summicron-M, third version, introduced for the M-line in 1980. It is a 5 element design from Midland origin, and at full aperture not as good as the Mversion from 1963. At full aperture contrast is low to medium, with coarser detail recorded with fuzzy edges. Performance is quite even from centre to the outer zones,, dropping in the far corners. Flare is somewhat less well suppressed. Stopped down to 2.8, image quality improves markedly and from aperture 4 there is a gradual improvement till 5.6, where an excellent quality is attained, comparable to that of the M-version. Vignetting is more pronounced with one and a half stop and distortion too is more visible than with the M-design. We see here the careful adjustments and compromises when designing lenses for several camera systems. The R-lens had better performance at the closer distance range, on the assumption that the R-system would be more frequently used in that range.

 

Figure 170: diagram 86

The slight softness of the Summicron at full aperture would support the romantic portraiture of women, and the lower contrast would help taking reportage style pictures in high contrast lightning situations. These notions are still en vogue today and the full aperture characteristics of the Summicron 90mm lenses is mostly described in this context. I have always felt some hesitance to use these notions. The 1970 version is an excellent lens at apertures from 1:2.8 and even more so around 1:5.6, we should also acknowledge the fact that its full aperture performance is not state of the art.

 

6.8.15 2/90, Summicron-M (3), from 1980

This 3rd redesign of the Summicron 90mm, follows the design principles of the Rversion, but there are slight differences, as the diagram indicates. Now we have a 5 element lens of less weight. The lens is also shorter (more Tele-type) and more compact. The computation of this version had been completed several years earlier and the long gestation period shows how labourious the process was to bring a lens from blueprint into production. This also is an example of the effort of Leica to ensure that the originally computed image quality will be available in every assembled lens.

 

Figure 171: diagram 84

The 1980 version shows another type of design compromise. The M line of lenses is a quite demanding one for an optical designer, as the two pillars of M design: optical performance and physical compactness are not easy to accommodate. It is like the squaring of the circle. If you prefer compact lenses, the optical quality must suffer.

And if you need superior image quality then the lenses have to be bigger. So the headache for M-lens designers is to do the impossible: get high quality and keep dimensions small. The fingerprint of the M-version shows a higher overall contrast, and due to a better correction of the field curvature, an enhanced performance in the field. Stopped down to 2.8, the contrast improves and so does the definition of fine detail. Still smaller objects are recorded with fuzzy edges. At 1:4 the definition of very fine detail crispens significantly and at 1:5.6 the overall image quality is of a really high order, comparable to the Elmarit 2.8/90mm,) which has more sparkle and points to the new era as its imagery demonstrates. Vignetting is more pronounced with one and a half stop and distortion too is more visible. Two lens surfaces are plane and while this may help to lower production costs, it also derives the designer of additional correctional possibilities. At full aperture the 1980 version is still a shade soft and its overall contrast may be described as medium. Flare in the field gives fine detail fuzzy edges and in extreme cases even will blur the reproduction of detail. This softness at the image plane has the advantage that the transition to the unsharp zones of the image before and after the plane of good sharpness is quite smooth. This behavior has been described as 'smooth sharpness' which in fact is a 'contradiction in terms'.

 

6.8.16 2/90, Apo-Summicron-M ASPH(4),1998

To achieve really state of the art imagery at full aperture is not easy and we mostly underestimate the effects on performance when we open up one stop. Aberrations grow nine-fold in magnitude, especially in the field. Optical corrections are possible, but now the demands on tolerances and mounting are sky-high. We may not look at it this way, but when we buy Leica lenses we pay for the wide aperture performance.

As the demands on lens accuracy and mounting and quality control become more drastic, production costs rise proportionally. The current Apo-Summicron-M 1:2/90 Asph is a clear example of this trend. Let us first look at the performance.

 

Figure 172: diagram 85

At full aperture (2.0) we find a high contrast image with extremely fine detail rendered with good clarity and high edge-sharpness over the whole picture area, including the outer corners. A faint trace of colour can be detected. At 1:2,8 the contrast improves a bit and the whole image crispens somewhat, lifting the exceedingly fine details above the threshold of visibility. Stopping down after 2,8 only improves depth of field. This superb behavior holds till 1:11. At 1:4 we find an enhanced capacity for recording very subtle textural details with crystal clear clarity and excellent microcontrast. Perfect centering, only the faintest trace of astigmatism and no curvature of field added by meticulous engineering are further characteristics of this lens. To give you another more intuitive performance measure. At full aperture this lens records more than 100 linepairs/mm from centre to corner with excellent edge contrast.

The apochromatic correction. In practical picture taking you will note that edges of fine detail and also coarse detail (outlines of major subjects) are much cleaner if the adjacent colours are opposed in the colour spectrum. If you see a blue and a red colour next to each other, (or a blue and a white colour patch) the colour fringing and fuzziness of the borderline is quite substantial in the case of the 2/90 and practically nonexistent with the apo90. That gives outlines and fine details a crispness and clarity that greatly surpasses the 2/90. Also the smaller point-spread function of the apo90 gives it a big advantage in recording fine grey values, which can be seen when doing b&w picturing with 100ISO and smaller. The apo90 is one of the best corrected lens in the M-line at this moment. It employs special glass and uses an aspherical surface, presumably to correct part of the spherical aberration that plagues the predecessor. The apochromatic correction enhances overall and microcontrast.

Leica employs a new type of mechanism to engage the roller cam of the rangefinder. This allows a wider throat diameter at the back and reduces vignetting.

These optical and mechanical measures show the amount of study in order to improve a lens nowadays. As the apo90 is on the same price level with much improved performance as the predecessor, we see here a clear example of Leica's future direction in optical design: a blend of optical mastery, mechanical engineering and cost reduction (better maybe cost containment!) will give us, Leica users, optical systems with enhanced imaging capabilities that stretch our own limits of technical mastery and of the films we use.

Vignetting is low with one stop and distortion hardly visible. We do often assume that the optical progress is levelling off and that improvements in performance are evolutionary rather than revolutionary. In some cases, such a view can be supported.

This new 2/90mm lens incorporates the latest insights in lens design, in aspherical technology and glass selection for apochromatic correction and in mechanical sophistication. Its full aperture performance is superb. At 1:2 this lens outperforms the previous 2/90 at 1:3.5, the current Elmarit-M 2.8/90 at 1:4, the previous versions of the (Tele)-Elmarit at 1:5.6 and the older 4/90 versions at 8 and 11. The collapsible Elmar 4/90mm, as example needs to be stopped down to at least 1:11 to reach a level that the Apo-Summicron asph delivers at 1:2. A time-span of almost 50 years separates both designs and the performance difference does prove the limited validity of the statement that older lenses are as good as current ones or that all lenses stopped down to 1:5.6 will perform on the same level. Of course, lenses will be closer in image quality when stopped down. But often performance does not improve that much. After analysis of comparison pictures, still most pictures show a higher level of image quality. What happens is that stopping down increases the depth of field. The eye is more sensitive to sharper details than to blurred ones and tries to avoid looking at them So if the image has more sharp detail. It looks as if the image quality has improved. In fact the same level of quality has been extended over a larger area.

 

6.8.17 2/90, Apo-Summicron-R ASPH (2)

This lens is optically identical to the M version of this design. The main difference is the shortest distance that can be focused: the R-lens focuses to 50cm.

 

6.8.18 2.2/90,Thambar,1935

The Thambar 1:2.2/90mm is a so-called soft-focus lens that allowed the photographer to make portraits with the soft effects that were very popular in those days. The extent of softness can be regulated by the iris diaphragm and a special opaque disc, that can be placed in front of the lens and cuts off the central rays. As now only the outer rays will be available for image formation, we see a strong degradation of quality as these outer rays are generally less well corrected than he central rays, that are blocked now. Given the special character of the lens, an evaluation of performance is not relevant.

 

Figure 173: diagram 81

 

6.9 100 to 125mm

 

6.9.1 4/100, Macro-Elmar,1968, and Macro-Elmar-R, 1978

Optically all versions of this lens are identical and for the report I used the R-version which can be used as a normal interchangeable lens. Aperture and angle of field are modest and with this specification it will be no surprise that vignetting at full aperture and distortion generally are reduced to zero.

 

Figure 174: diagram 87

At full aperture overall contrast is low to medium, and subject delineations and coarse detail are rendered quite crisp as astigmatism and field curvature are very well corrected. As with many older designs, the small textural details are defined with low contrast, making them difficult to detect. With this lens, they are just visible, partly because of the clean edges, which separates them clearly. Stopping down to 1:8 improves the quality significantly with high overall contrast and a clear definition of extremely fine detail over a larger part of the picture area. Stopping down further just extends the depth of field and improves the corners a bit. Contrast as usual drops as diffraction scatters the concentration of rays from its intended point location.

 

6.9.2 2.8/100, Apo-Macro-Elmarit-R,1987

The first lens to bring apochromatic correction in a medium tele-lens, that can be used at infinity as well as close-up, it was a revelation at its introduction and quickly became the informal yardstick for image quality. It is still an excellent lens, but is gradually being overtaken by newer designs. Who said, that lens performance has levelled off and has reached a plateau? It is a six element design with an additional group for close up performance. While this group enhances the quality at closer distances, it also limits the feasible optical quality at longer distances. At full aperture a high overall contrast image is being generated, with an even performance of very fine detail from centre to corner. Extremely fine detail is rendered with crisp edges and clarity of colours and subtly graded shades of tones. Vignetting is low with 0.7 stop and at 5.6 the picture area is very even illuminated.

 

Figure 175: diagram 88

Stopping down brings marginal enhancements in contrast and a crispening of the minute object structures. At 5.6 we not a slight focus shift. In the field exceedingly fine detail is rendered with high contrast and great clarity, becoming of slightly lower contrast on axis. Overall its performance stopped down compares well with newer designs, without however reaches their level. Distortion is zero.

 

Figure 176 6.9.2 main lens

With the Extender-2, performance at 1:5.6 equals that of the prime lens at 1:2.8, with overall a drop in contrast that is most visible with the rendition of very small details.

Stopping down to 1:8 improves performance visibly. 6.9.3 6.3/105,Elmar,1932 The so-called Berg-Elmar 1:6.3/105mm is a compact and very light-weight lens of only 240grams. This lens shows the concern of the Leitz company to produce lenses that are compact and light-weight. These characteristics match the Leica body as the camera for dynamic photography and the camera as travel companion. The lens shares with the first Elmar 4.5/135 the characteristic that the original designs were computed for large format camera's (6x9cm). It started its life as a 1:4.5/105mm.

 

Figure 177: from HOVE

Often this fact is referred to as an indication of very good image quality. In reality it is not, as lenses for larger format negatives invariably are computed with lesser demands on the recording capacity, due to a smaller enlargement factor. It is a low contrast lens with a modest definition of coarse to fine detail, that crispens visibly after stopping down. 6.9.4 2.5/125, Hektor, 1954 This lens can only be used with the Visoflex attachment and is a bit contradictory in its specifications. It is evidently positioned between the Summarex 1:1.5/85 and the Hektor 1:4.5/135 as a higher speed lens for candid portrait and reportage applications. But the Visoflex, while an admirable piece of equipment, is not very user-friendly for these assignments. There is however an adapter which allows this lens to be used directly at the camera. One may marvel at the ingenuity of Leitz to offer all these flexible options. At full aperture overall contrast is low to very low and coarse detail is rendered with good visibility till image height of 12mm, after which the definition becomes rather soft. Vignetting is a mere 1/3 stop.

 

Figure 178 diagram 90

At 1:2.5 this lens may be described as a 'Weichzeichner' (a soft-focus lens).

Stopping down enhances contrast significantly and the on axis performance brings in fine detail with clear edges. Outlines now are crisply rendered over most of the image area, but finer details are soft and becoming very soft when we try to capture small structures. At 1:5.6 the circle of very good quality extends to image height 9, and to 12mm when stopping down to 1:8. Distortion is not visible. Its true focal length is 120mm

6.10 135mm

The 135mm focal length belongs to the classical group of 35, 50, 90 and 135mm lenses, that defined and represented the rangefinder photography since 1930. The importance of this group becomes quite clear if we reflect on the fact that Leica introduced almost 70 versions of these lenses, which is about 50% of all lensversions in the history of the company till now. For the M-line, the 135mm is the longest focal length that the rangefinder can accommodate, in accuracy and magnification and framing. With the M3, the M6J and M6 .85, the user has an instrument that is very well suited to the employment of this focal length. Leitz was well aware of the limits and designed the 2.8/135mm with viewfinder attachment that used the 90mm frame lines to define the 135mm selection. This lens is heavy and so the advantage of the higher speed is nullified by the weight, which forced the user the select a higher shutter speed. Once very popular, the 135mm lens was taken off the M-lens program, more than once, and has re-emerged recently with the Apoversion, which is one of the best lenses for the M-system ever. Many users assume that the 135mm lens does not identify or support the style of photography with the M-body, but as is the case with most sweeping generalizations, it is hard to substantiate. For all kinds of photography (candid and formal portraits, situational figure studies, landscapes, urban scenes, city and farm animals, etc) the 135mm offers a very seductive perspective. With a relative enlargement of 2.7 (compared to the 50mm standard lens), perspective and selective framing is more important than sheer magnification, which is restricted when the distance is larger than let us say 5 meter.

This low magnification power at larger distances may be one of the reasons of the demise of this focal length in the R-system. The 180mm has taken over as the premium focal length for candid and reportage photography and the vario-lens of medium range do incorporate the 135mm position as with the 70-180mm and 105- 280mm and 80-200mm.

 

6.10.1 4.5/135, Elmar, 1931

The Elmar 1:4.5/135mm, as the 6.3/105mm version started life as a larger format lens. At full aperture it is of low contrast and shows strong chromatic errors, blurring the finer details in the field. On stopping down improvements are very gradually and this lens needs to be stopped down to 1:8 and smaller for a acceptable image quality.

Leitz replaced this lens with the better Hektor 1:4.5/135mm, which was still not as good as the Sonnar version of Zeiss of those days.

 

Figure 179 from HOVE

As 135mm lenses were primarily used to magnify objects structures, in order to capture small details on the negatives, that could not stand bigger enlargements, the relatively weak performance would not be noticed too clearly.

 

6.10.2 4.5/135, Hektor,1933

Of Wetzlar origin, this lens improves upon the predecessor, and shows no vignetting at full aperture and no distortion overall. Overall contrast is low and coarse detail is clearly rendered with soft edges on axis till image height of 9mm, rapidly becoming quite blurred in the outer zones and corners. At 1:5.6 there is a marginal improvement, but we need to stop down to 1:8 to see the area of good definition spread to image height 15mm. Contrast stays low and fine detail is now visibly recorded, but with low micro-contrast. At 1:11, detail definition improves and the outlines of major subject outlines have clean edges that make them stand out from the background. Smaller subject details have fuzzy edges, that make them more difficult to discern in the lower image noise of flare and the film emulsion.

 

Figure 180; diagram 92

 

6.10.3 4.0/135, Elmar,1960

We often assume that lenses with modest specifications evolve slowly. In this case the almost 30 years that lay between both versions bring significant advantages. The new Elmar at full aperture is better than the Hektor at aperture 1:11! Wide open the lens has a medium overall contrast, Vignetting is low with 0.7 stops and distortion is barely visible overall.

 

Figure 181 diagram 93

At full aperture we have a medium contrast image, that brings in the crisp definition of coarse detail and lifts the definition of fine detail above the threshold of good visibility. This lens hardly improves on stopping down. Of course there is some enhancement of overall contrast and better visibility of finer details. But basically this lens at full aperture already is at its optimum. At 1:11 overall contrast drops. Closeup performance of the Elmar is not as good as that of the Hektor.

 

6.10.4 4.0/135, Tele-Elmar, 1965

With this lens Leitz equalled and in some areas surpassed the Zeiss Sonnar 1:4/135mm , which had set the Olympian record for a lens of this specification. At full aperture overall contrast is improved compared to the Elmar, but vignetting is a bit higher (0.9 stops). Very fine detail is crisply resolved over most of the picture area (till image height 12mm) and becomes gradually softer when approaching the corners. At 1:5.6 the edges of the smaller textural details are cleaned up even more and the overall image has a high level of clarity and fidelity of reproduction of the object structures. Stopping down does not change the performance till 1:11. Close up performance is equal to that at infinity and flare and secondary images are very well suppressed.

 

Figure 182 diagram 94

Distortion is visible, and as with the vignetting do show the compromises when one changes to a telelens design. This lens is often qualified as to be of apo-quality. It is undoubtedly a front rank design, but for true apochromatic correction we have to look at the next stage.

 

6.10.5 3.4/135, Apo-Telyt, 1998

This design is very compact to fit into the livery of the M-lenses and here we can see the optical progress in vito. At almost identical physical dimensions, we have a half stop more brightness and an improved imagery, that at 1:3.4 is better than that of the Tele-Elmar at 1:5.6. The apochromatic correction has reduced the secondary spectrum to a very low level, but a faint trace of the tertiary spectrum is visible as very narrow colour bands along black or white borderlines. At full aperture we have a high overall contrast, with extremely fine detail accurately recorded over the whole picture area. Vignetting is low with 0.7 stops. At 1:4, there is a visual improvement in the overall quality, which enhances specifically the definition of the tiny textural details. At 1:5.6 the highest level of high fidelity recording has been reached, but some softness at the edges of tiny details is visible in the outer zones of the field at big enlargements. Overall distortion is just visible in the outer zones.

 

Figure 183 diagram 95

This design is a masterpiece of the art of optical designer and the mechanical engineer. It delivers imagery of a level that will challenge the technical capabilities of many users. The sparkling luminosity of fine colour patches and specular highlights, the clarity of outlines of fine detail and the reduced level of image noise, compared to the Tele-Elmar, sets a new standard in this focal length and aperture. This lens shares its fingerprint with many recent designs in that the change from the sharpness plane to the unsharpness areas is quite abrupt.

 

6.10.6 2.8/135, Elmarit(1) 1963, Elmarit(2) and Elmarit-R(1) 1964, Elmarit-M (3)(1973) and Elmarit-R (2),1968 The first version of this lens appeared in 1963 for the M-system. A year later the version for the R-system was put on the market. This version had almost the same lens prescription as the first version: only the two separate front lenses had less thickness and different glasses were used.

Performance-wise there is hardly a difference. This second design has been used for both the M- and the R-systems, but is not exactly clear when the merger took place.

The same story does repeat itself with the last redesign, which first was introduced for the R-version and later incorporated into the M-system. Wider aperture versions have been researched for the R-system with good performance, but the days of the 135mm lens were assumed to be history.

 

Figure 184 diagram 96 M 1

 

Figure 185 diagram 97 M 2 + R 1

 

Figure 186 diagram 98 M3+R2

The Elmarit -M (2)/Elmarit-R (1) at full aperture exhibit low contrast, and the definition of fine detail is rendered with softer edges. Performance is very even over the picture area, and vignetting is low with half a stop. The low contrast in the field, due partly to coma, however, does degrade the overall image quality. Stopping down to 1:4 does enhance contrast and brings the image quality almost to the level of the Tele-Elmar 1:4/135mm at 1:4. Stopping down further improves quality very reluctantly and very fine detail is crisply rendered at 1:8, but the outer zones stay a bit soft. Outlines and coarse detail are recorded quite crisp, but slightly below the quality of the Tele-Elmar.

Distortion is very slight. The next version has improved contrast at full aperture, giving the rendition of coarse and fine details an edge in clarity. From 1:4 the newer version is comparable to the older version, with one exception: the newer version is a bit softer in the outer zones. Close-up quality of the newer design is improved and delivers excellent rendition of fine detail. Vignetting and distortion are comparable.

 

6.11 180 to 280mm

The use of the long focal lenses for the M with its cumbersome but very accurate Visoflex housing had its limits and the quick dominance of the SLR type of body owes much to its easy suitability for longer focal lengths. The R-system expanded quite quickly in this area. There is an interesting shift in use from the 135mm to the 180mm for the reflex system. The more powerful magnification gives this focal length a clear advantage in general use and even for portraits (often the motive of choice for the 135mm) the 180mm delivers imagery with a significantly different view. Artistically the 180mm is a very fine focal length to use, but there is a optical quagmire to deal with. With increased magnification, the residual chromatic aberrations are scaled up too. A lens with a longer focal length has a smaller angle of view, and several of the aberrations that plague wide aperture, wide angled lenses, like coma, astigmatism and field curvature are mostly absent. The image blur, resulting from chromatic errors is magnified and this proves to be more of a problem. The apochromatic correction, in whatever guise, finds its prime application in the longer focal lengths. The evolution of the 180 to 200mm lenses will demonstrate the advantages. The first Telyt 1:4.5/200mm lens for the Leica rangefinder delivers very low image quality, and the recent Apo-Summicron-R 1:2/180mm is more than a light year ahead.

 

6.11.1 2.8/180,Tele-Elmarit,1965

The short lived Tele-Elmarit 1:2.8/180mm (1965) is a Scheider design. Schneider not only provided the wide angles, but also produced parts of the Elmarit 90mm lenses.

What exactly was the intention for this lens is unclear. The design, with its characteristic construction of a cemented group of three elements in the middle, is a close derivative of the Zeiss Sonnar 1:2.8/180mm, of Olympics 1936 fame. This resemblance and the lower quality of this lens (an appraisal based in this case on the constructional details) might be responsible for the vanishing act. In the Leitz archives there is mention of a Midland design of interesting specifications for the Mbody: a 1:3.4/180mm with attached goggles like the Elmarit 2.8/135mm, which might be the successor of the Schneider lens. Anyway, this is just a historical footnote of minor importance. Picture 6.11.1 A: lens diagram: NOTE: not in my file, but it is in Rogliatti's Book, so should be on file at Hove.

 

6.11.2 4/180, Elmar-R, 1976

A 2.8/180mm lens needs at least a front diameter of almost 70mm, which automatically requires a certain physical volume. A lens, more compact, can have a smaller aperture. The 4/180mm is indeed a small and short lens. At full aperture overall contrast is medium, with coarse detail rendered with good clarity over the whole picture area. Vignetting is below half a stop. At 1:5.6 contrast improves marginally, which brings more edge sharpness to the delineation of the medium detail outlines. Very fine detail is now defined with soft edges over most of the field.

The fingerprint of this lens is remarkable because of the low contrast of the definition of very fine detail, which is markedly below that of the 2.8/180 at 1:5.6.

Stopping down further lowers contrast marginally, and image quality stays on the same level. This typical behavior of many longer focal lenses, that performance does not improve that much at smaller apertures is the result of the residual aberrations and not necessarily, as is often assumed, a signature of optical excellence. Distortion is quite visible in the outer zonal areas when straight lines are reproduced. For best close up performance one should stop down a few stops.

 

Figure 187 diagram 99

 

6.11.3 2.8/180, Elmarit-R,1968

This 5-element design delivers medium contrast at full aperture and a very even performance over the whole image area. Vignetting is only a half stop. Delineations of subject outlines have soft edges and fine detail is clearly defined. There is some field curvature, that reduces the contrast of very fine details in the field. At 1:4 overall contrast improves visibly and brings in the crisp definition of fine detail. Very fine detail is recorded with some blur in the field. Stopping down further does not improve the performance, but reduces the contrast in the field and corners, a sure sign that the secondary spectrum is still alive. Distortion is just visible. The previous Telyt version (4/200) is at middle apertures not as good as this one at full aperture.

 

Figure 188 diagram 102

 

6.11.4 2.8/180, Elmarit-R,1980

The earlier version of this lens was a heavy-weight with 1300 grams. This redesign is reduced in weight through the use of newer glass of anomalous dispersion and other measures for weight reduction. At full aperture the lens delivers medium contrast and coarse detail is rendered with clean edges over the whole image area, with the corners being even better than the centre. Overall the performance is equal to that of the replacement lens. Vignetting is slightly higher at 1 stop. Stopping down to 1:4 improves the contrast, but brings only marginal better definition of fine detail. From 1:4, image quality does improve very slowly, with an improved definition of very fine detail on axis and a reduction of contrast in the field. Here one sees the effect of the residual chromatic aberrations. Distortion is visible in the outer zones. This lens has also improved performance at closer distances. The improvement in image quality has been made possible by a reduction of lateral chromatic errors and the chromatic version of astigmatism, which points already in the direction of the apochromat. Not well-known is the thermic problem. Bigger glass elements, which are cemented or tightly contained in a mount, will expand substantially when heated. The earlier prototypes had some trouble here, as the glass has a tendency to crack due to different thermal expansion coefficients. A careful selection of glass types is needed to tackle this problem, which has relevance for all large lenses, which are cemented.

Picture 6.11.4 A: lens diagram

 

Figure 189 diagram 103

 

6.11.5 3.4/180, APO-Telyt-R, 1975.

This lens has gained a mythical status. It started life as a special purpose lens for reconnaissance purposes, but it soon was incorporated into the normal R-system with 6000 units planned for production. The apochromatic correction with synthetically grown fluorite crystals had the problem of the sensitive surfaces of this material and Leitz preferred the use of glass with specific properties. At full aperture we have high overall contrast with a crisp definition of very fine detail over most of the image area, becoming much softer in the outer zones. Vignetting is one stop.

Outlines are reproduced with very clean edges, that really stand out from the background with brittle sharpness, and this is even true when the background is of much higher luminance as in contre-jour picture taking and in high light contrasts.

We should be realistic here. This image quality is really first class. But the Elmarit 2.8/180 from 1980 has comparable performance, stopped down to 1:4. Where the Apo-Telyt scores is the image quality when stopping down to 1:5.6. On axis till an image height of 10mm, the definition of extremely fine detail is brought to a new level with very clean edges and excellent clarity of textural details. In the outer zones the performance drops visibly with a much lower contrast. Distortion is visible in the outer zones too. There is some tendency to flare, but internal contrast stays high. Let us have no illusions here. Any lens can and will under adverse conditions generate secondary images or flare patches. This lens, especially around 1:5.6, defined the state of the art of 180mm lenses in the eighties. The next 'apo'- designated lens in the 180mm class is the Apo-Summicron-R 1:2/180mm, which at 1:2 has improved image quality, that surpasses the performance that the Apo-Telyt 3/4/180mm delivers at 1:3.4. This is a stunning leap forwards and indicates the progress made by the Leica designers in the last 20 years.

 

Figure 190 diagram 100

 

6.11.6 2.8/180, Apo-Elmarit-R,1998

At full aperture we see an very high overall contrast with a crisp definition of extremely fine details over most of the picture area. Exceedingly fine detail is defined with crystal clarity and excellent edge contrast. In the outer zones the micro-contrast of tiny image structures drops somewhat. Vignetting is low with 0.7 stop. At 1:4 this level of detail recording softens slightly and at 1:5.6 we see a faint drop in overall contrast. At this aperture, the lens can be compared favourably with the 3.4/180mm, which has the advantage on axis over a small central area, while the 2.8/180 has much improved imagery in the field. There is some distortion visible in the outer zones. The new Apo-Elmarit has a most interesting behavior. At full aperture it is already at its zenith, with a superb performance, that is constant over the aperture range, with only a drop in contrast when stopping down. The previous Apo-Telyt 180mm has excellent performance at full aperture and improves on stopping down, an indication that chromatic errors are not so well corrected as in the case of the Apo-Elmarit. Both lenses meet each other around 5.6, where the Elmarit is already lower in quality and the Apo-Telyt is at its best.

 

Figure 191 diagram 104

Part of the magic of these lenses is the internal focusing, that improves imagery significantly and also gives very smooth focusing. This lens is handholdable, but best performance will be extracted when the lens is supported. The perspective of the 180mm in combination with the distinctive background blur are excellent for portraiture, full figure and fashion/glamour photography. The rendition of the finest detail in the subject sets a new standard and the overall contrast brings in detail and a new level of penetrating power for long distance shots. Both the Apo-Summicron 2/180 and this 2.8 focus past the infinity mark. The additional distance is more than 5 millimetres. The amount of glass and metal in these lenses is such that thermal expansion becomes an issue. The free space beyond the infinity mark has thoughtfully be provided so that whatever the temperature the true infinity focus can be used. The apochromatic correction delivers true apo quality over the whole image field to the corners (no colour fringes whatsoever). Close up performance ( about 2 meters) is absolutely equal to the infinity setting. There is some pincushion distortion, however. The overall imagery is even a fraction better than at infinity.

This is a most remarkable behavior and can be explained by the mechanism of internal focusing. Only one lens element inside the lens moves when you focus and the designer has very skilfully used this shift to correct the close up performance.

Not a real floating element, but sort-of, so to speak. The 2.8/180 does not exhibit any stray light, blacks are deep dark and light sources are very tightly delineated.

Specular highlights show finely graded shades of white and secondary reflections are only observable under very unfavourable and not often encountered circumstances.

This lens delivers optical quality of a very high order indeed and is in an absolute sense better than the Apo-Elmarit 1:2,8/100 (R) and the Apo-Summicron-M 2/90 (M).

 

6.11.7 2/180,Apo-Summicron-R,1994

At full aperture performance is better than that of the Apo-Telyt 3.4/180mm at its 3.4 aperture, and only slightly below that of the Apo-Elmarit 2.8/180mm, which shows progress indeed. Very high overall contrast, vignetting of 1 stop and a very crisp rendition of extremely fine detail till image height of 10mm and a gradually softening of the fine object structures, characterize the lens. At 2.8 the quality equals that of the Apo-Elmarit, with the exception of the corners, that stay a bit soft. From there is absolute equality in character and performance between both lenses.

Stopping down after 1:8 is to be avoided if absolute quality is required. Distortion is very small.

 

Figure 192 diagram 105

The depth of field of the 180mm at f/2 and 2.5 meter is about 1 cm (10 mm). That's pretty narrow. It is by the way a new experience to use such a lens with DoF even less than that provided by the Noctilux. The Leica documentation mentions that the 2/180 can be used hand held and used on a monopod. This you need to interpret liberally. A slight movement will generate unsharpness at full aperture. So this a lens for stationary use, landscape, portrait, nature, wild life, the fashion cat walk. The extremely high quality of this lens is not degraded by the permanently attached protective filter in front of the lens. Of extremely high contrast, the 2/180 also exhibits a rarely seen definition of fine detail and a very distinctive unsharpness/sharpness gradient. The 70-180 Vario lens has an excellent 180 position. But both the Apo-180mm lenses (2 and 2.8) are better and if you need the ultimate in performance one of both is the choice. The 2/180 has obviously more weight (2.5 Kilo versus less than a kilogram) and a much larger diameter. The full stop advantage may be crucial and so the choice should be made very carefully The Summicron 2/180 at full aperture is almost on the same level as the Elmarit at 2.8.

The overall contrast is exceptionally high and over an image height of 5 to 6 mm (image circle of 10 to 12mm) exceedingly fine detail is defined with excellent clarity and exceptionally high edge contrast. In the outer zones the contrast drops visibly, when one looks the definition of the very fine detail. Outlines of subjects are defined very crisply. The far corners are quite soft and fine detail, while clearly visible is soft with fuzzy edges. Stopping down to 2.8 improves micro contrast in the outer zones and now the performance is almost identical to that of the 2.8/180. Further stopping down improves the micro contrast of the outer zones, but now the on axis performance drops a fraction. Close up performance is identical to infinity performance and can be explained by the same mechanism as in the Elmarit 180.

The outstanding property of this lens at full aperture is its definition of the smallest possible detail with a very high micro contrast and overall contrast. On location photography in twilight and semi-dark level of exposure (50 ISO at 1/4 to 4 seconds) shows an excellent power of penetration of distance: fine detail at a distance of 50 meter in very low contrast light is defined with outstanding edge contrast and subtle shades of colours are recorded with high fidelity. Colours itself are clean and transparent. Shots of models at about 5 to 10 meters in the twilight record details not visible with the naked eye. Portraits close up produce pictures with a very pleasing perspective and a recording level (even at full aperture) that would be a challenge for any medium format lens to equal.

 

Figure 193 6.11.7 internal focusing

The 2/180 is obviously a tripod only lens and performs superbly in its intended application: location and studio photography in a stationary situation. The catwalk is an obvious deployment as is model (glamour?) photography, where the low light capabilities of this lens extend the limits of twilight photography. Nature, and animal photography are also suitable areas. The 2.8/180 is a bit more versatile as it can be used handheld. Both lenses have an extremely shallow depth of field (the Summicron at 2 to 3 meters operates at about 1 to 3 cm!). The accuracy of the R8 is fully capable to handle this and you can be assured that the plane you wish to focus on, is indeed recorded with the best image quality. The 2/180 again does not have any stray light and for such a lens it is amazingly well behaved here. Halos are also very well suppressed although a shade less than the 2.8/180. Secondary images can be seen when shooting straight into the sun or another strong light source. When the light source is just outside the image area, and very oblique, then we may see in certain but not all situations, a veiling glare that can be distractive. The excellent suppression of stray light shows in the details that hold contrast and gradation.

These lenses approach the ideal of a lens, that gives optimum performance at full aperture, do not degrade when stopping down and perform as well at close distance and at infinity and give equal image quality over the whole image area (2.8) or a big portion of it (2.0).

 

6.11.8 4.5/200,Telyt,1935

A Visoflex-only lens, that is free form any distortion and brings at full aperture a low to medium overall contrast with coarse detail rendered clearly on axis and becoming very soft when approaching the corners.

 

Figure 194 diagram 107

Vignetting is low with .8 stops. Stopping down improves performance only reluctantly, an indication that the residual aberrations are strong. At 1:8 contrast is medium and fine detail is accurately recorded with slightly soft edges. This lens exhibits the typical dullness that is the fingerprint of several older designs, when one looks at the definition of finer details and the overall impression of sharpness. At smaller apertures it has comparable image quality as the Hektor 4.5/135mm. The small angle of view makes life easier for the designer and he did not have to ponder the possibility of an apochromatic correction, as the glass types needed were not available and any way the computational and mechanical complexities ruled out this solution.

 

6.11.9 4/200,Telyt,1959

This four-element Visoflex-only lens is a visible improvement over the previous version. It has reduced the monochromatic aberrations to a lower level, which gives a more consistent quality in the field. Overall contrast is slightly improved, but the cleaner reproduction of finer detail in the field, gives a higher clarity image.

Vignetting is a mere half stop.

 

Figure 195 diagram 106

Stopping down at first enhances contrast in the centre, and from 1:8 the field also improves. At 1:11 image quality is at the level of the Hektor at the same aperture, but the Telyt draws visibly softer. Distortion can be neglected. Close up performance is very good.

 

6.11.10 4/250 (1), Telyt-R,1970

This Midland lens expanded the range of the Leicaflex lenses with a new dedicated design and at full aperture it shows medium overall contrast with vignetting of a half stop. Performance is very even over the whole picture area. Coarse detail is crisply rendered, but finer detail is of low contrast, and stopping down to 1:5.6 enhances the definition of fine detail and does capture very fine detail with medium contrast and softer edges, especially in the field. Further stopping does not improve the image quality, but makes the chromatic errors (the curse of longer focal lengths) more visible with a rather soft recording of fine details in the outer zones.

 

Figure 196 diagram 108

There is some distortion in the outer zones. Close up performance is not so good as with the long focus lenses (Telyt 4/200 and Telyt 4.8/280), because of the telelens construction. .

 

6.11.11 4/250 (2),Telyt-R,1980

This redesign adds one lens element, and loses a bit of overall contrast at full aperture. Vignetting is slightly above a half stop and coarse detail is rendered on the soft side in the field. Stopping down to 1:5.6 enhances the contrast and now very fine detail is within the visibility range, but with fuzzy edges.

 

Figure 197 diagram 109

At 1:8 the micro contrast of fine detail increases, but the blurred edges stay. At smaller apertures there is no improvement and here we have a medium contrast image with clearly delineated subject outlines, becoming progressively softer when we approach the corners and the finer object structures. Distortion is on the same level as the previous version. For best performance at closer distances one should use the smaller apertures.

 

6.11.12 4.8/280,Telyt,1961

This Midland designed Visoflex only lens offers medium overall contrast at full aperture with .3 stops vignetting. Coarse detail and outlines are cleanly recorded with a lower contrast over the whole image area. Finer detail is clearly visible, but is of very low contrast. Stopping down to 1:8 does crispen the definition of fine detail, with a marginal improvement of the overall contrast. Stopping down to smaller apertures does not improve the recording capability of fine detail and in fact softens the edges visibly. Here we see the fact that the natural improvements of stopping down are offset by the residual aberrations.

 

Figure 198 diagram 112

Given the modest aperture of 4.8, stopping down would be helpful only to a small extent. It has very low distortion and close-up performance is improved too. From # 2340944 a newer design with higher contrast and better definition of fine detail has been produced. Close up performance is very good.

 

6.11.13 4/280, Apo-Telyt-R,1993

The really spectacular advance made in lens design and image quality is best appreciated when one compares this lens with the Telyt-R 1:4/250 (2) of 1980. This Apo-Telyt-R is one of the really few lenses in the Leica lens family that is truly (almost) diffraction limited. If you need to be convinced that resolution figures can only be interpreted and understood in context, just reflect on the fact that this lens has a resolution limit of a breath-taking 500 lp/mm (1000 lines per mm!) at full aperture. It is impossible to even come close to using this level of resolution, but it does show the diffraction limit. Let us quickly return to photographic reality. At full aperture the Apo-Telyt-R has an even performance from centre to corner and will record outlines and extremely fine detail alike with exceptional clarity and very crisp edges. Overall contrast is very high. Vignetting is low with 0.7 stops.

 

Figure 199 diagram 110

Exceedingly fine detail of a smallness that will challenge the current film emulsions to the bone, is defined with clean borderlines and a fidelity of reproduction that is almost mirror like. In the field you can notice a faint softening of edge detail.

Distortion can be neglected. The construction philosophy of current Leica designers is evident if we consider the following comparison. The Apo-Telyt-R has only seven lens elements for its stunning accomplishment and the Canon EF 1:2.8/300mm IS USM, which is close to but not equal in image quality , needs 17 (!) elements.

 

6.11.14 2.8/280, Apo-Telyt-R, 1984

Add one kilogram to the weight of the Apo-Telyt-R 4/280 and one lens element and you get the 2.8/280mm. It is still not possible to enlarge the aperture without adding weight. At full aperture overall contrast is high and very fine detail is crisply rendered with very good clarity. There is a slight softening of edge sharpness when going to the corners, at this level of detail capture. Extremely fine detail is clearly recorded with a detectible colour fringe at the edges of tiny structures, that soften the edges and the micro contrast.

 

Figure 200 diagram 111

Stopping down to 1:5.6 improves the performance on axis, but the residual chromatic errors start to blur the definition of tiny details in the field. With these type of lenses we are in the stratosphere of optical performance and the cutting edge is redefined regularly: the Canon lens referred to in the 4/280 report will have the edge, in the outer zones, but it is a photo-finish. Added advantage for the Leica lens is the mechanical stability and the precision of the mount, as we will see in the Module report.

 

6.12 350 to 500mm

With these focal lengths, we enter the domain of the specialist. The lenses in this range are often quite exotic and have a narrow field of deployment.

 

6.12.1 4.8/350,Telyt-R,1980

Closely related to the 4/250 (2), this lens exhibits essentially the same character, but with a generally lower contrast. At full aperture contrast is low to medium, with a vignetting of one stop. Outlines of the larger object structures can be detected clearly, but with softer edges.

 

Figure 201 diagram 113

Performance gradually decreases in the field. Finer detail is defined with fuzzy edges and really fine detail is blurred when bigger enlargements are made. The residual chromatic errors do soften the edges of fine detail as there is a fair amount of colour fringing at small spots. Distortion is just visible in the field.

 

6.12.2 5/400,Telyt,1937

The narrow angle of field and moderate aperture allow for a distortionless image with no-vignetting at all. At full aperture overall contrast is low and only coarse detail is defined with clarity and clean edges over most of the picture area, with a slight drop in the corners. Fine detail is defined with very low contrast, adding a kind of image noise over the picture. The lens marginally improves in contrast of the finer details and interestingly has slightly better image quality in the outer zones than on axis.

 

Figure 202 diagram 115

The static behavior, when stopping down, blows away another time-honored rule: that all lenses improve in quality when stopping down. A fair amount of the lenses, presented in these reports, do not improve optically and only extend the depth of field at smaller apertures, which may be misinterpreted as enhanced image quality.

 

6.12.3 5/400, Telyt, 1956

This Visoflex-only lens has a slightly higher distortion level than the predecessor. At full aperture it has very low overall contrast and a marginally higher vignetting of one third of a stop.

 

Figure 203 diagram 112

Overall behavior is close to the earlier Telyt-version.

 

6.12.4 2.8/400, Apo-Telyt-R, 1992

The 2.8/400mm is a markedly improved design, when compared to the telescope lenses. At its full aperture (1:2.8) it is already better than the 5.6/400 at 1:5.6.

Compared to the 1984 version of the Telyt-R 2.8/280 we note a slightly softer rendition of very fine detail in the field. The focal length of 400mm does enlarge the residual chromatic errors a bit more and that is visible. Overall the performance of the 2.8/280 and the 2.8/400 are quite close. And in absolute terms, the 2.8/2400 is an excellent lens. At full aperture overall contrast is high (a necessary condition for a long focus lens), vignetting is about 1 stop. Very fine detail is crisply rendered over the whole picture field , with a faint softening when approaching the outer zones.

Extremely fine detail is clearly captured with some fuzziness around the edges, but it is a light year ahead of the older designs.

 

Figure 204 diagram 118

 

Figure 205 6.12.4 internal focusing

Stopping down to 1:5.6 brings in exceedingly fine detail that is rendered with good clarity, if a bit soft in the field and becoming really blurred in the edges. Generally we may note that the newer long focus lenses exhibit a level of image quality that is in itself extremely high and surpasses that of the wider angle/wider aperture lenses with ease. We should remember however that these long focus lenses 'cheat' a bit as they have a larger magnification that brings in more detail to the unaided eye of the observer, who will assume that the lens does capture more detail, which is not true.

Still, the 180 to 400mm lenses for the R-system are a revelation in image fidelity.

 

6.12.5 8/500, MR-Telyt-R, 1980.

The mirror system or catadioptric system, has some distinct advantages a few very grave problems. As the mirror is a perfect imaging system, an optical system, using mirrors for imaging purposes is free from chromatic aberrations and the monochromatic errors are of much smaller magnitude. It is also possible to build such a lens with smaller physical dimensions and weight.

 

Figure 206 6.12.5 A diagram

The drawback is the fact that the image is located in the beam of incoming light and has to be beamed out of it with the help of a secondary mirror. (see illustration). This construction lowers the amount of available light and most importantly reduces overall contrast significantly. An image of low contrast and low illumination, is very difficult to focus and its optical performance is weak. A true mirror system has no additional refracting elements (like ordinary lens elements), but to correct some of the problems of the mirror system, you can introduce lens elements into the design.

This is called a catadioptric system, and the MR is such a system. The addition of the normal lens elements introduces new aberrations and corrects some other defects.

The end does not deliver excellent image quality. Leitz offered in the early seventies a Minolta lens 8/800 with R-bayonet. The principal drawback is the difficulty of focusing and the low contrast of the lower spatial frequencies.

 

6.13 Telescope lenses: 400 to 800mm

From 1 966 Leitz introduced a series of telescope lenses, also designated as Telyt-lenses, but with a totally different construction and design. The former Telyts were telelens or long focus designs, consisting of four or five elements The new ones are telescope lenses, consisting of a single doublet (two cemented elements) or a three-element cemented group (800mm lens). If we disregard the many versions of the mount of these lenses for the M- and R system (Televit, Visoflex, Novoflex etc) the optical cells can be classified in three groups: 5.6/400 and 560 (1966), 6.8/400 and 560 (1970) and 6.3/800mm (1972). What is the rationale behind these lenses? We noted that chromatic aberrations are destroying the image quality of the longer focal length lenses. Without recourse to true apochromatic correction, one solution is the telescope, which by nature is free from distortion, coma, lateral colour and spherical aberration. Astigmatism however is large and so these designs provide only good quality on axis. Given a smart design, one can correct additionally for the residual chromatic errors, if the glass choice (high index glass) is done very cleverly. With the three-element design, we have extra tools for correction and an even smaller secondary spectrum can be reached.

 

6.13.1 5.6/400 Telyt 1966, 6.8/400 Telyt 1970, 5.6/560 Telyt 1966, 6.8/560 Telyt 1971

The 6.8 lenses are in fact identical to the 5.6 lenses with a smaller aperture. This report is based on the 6.8 versions.

 

Figure 207 diagram 120-121

400: At full aperture overall contrast is medium, vignetting is below half a stop and as the theory has it on axis performance is much better than in the field. From image height of 6mm contrast drops rapidly and only quite coarse detail is rendered with good clarity. On axis fine detail is recorded crisply, but only till image height of 3mm.

Stopping down from 1:8 to 1:16, improves overall contrast, extends the circle of good definition to 12mm and increases the micro-contrast of fine detail. Generally we have good quality only in the centre part of the picture. The absence of larger colour fringing gives this lens good clarity. 560: with almost identical fingerprint, we note a somewhat lower overall contrast, but the circle of good definition is a bit wider.

 

6.13.2 6.3/800 Telyt-S, 1972

This lens has higher overall contrast, and at full aperture we have a crisp and clear rendition of fine detail till an image height of 9mm. Beyond that the performance rapidly drops. Stopping down to 5.6 improves contrast and at smaller apertures we see the usual contrast drop.

 

Figure 208 diagram 122

This lens and the other two Telyts demand much user attention and specific experience is needed to use these lenses. Atmospheric conditions will alter the colour rendition. The cement used for these glasses is very soft and over time performance may be degraded by asymmetry effects. If you intend to take pictures that cover the whole image area, the low image quality in the outer zones asks for a careful selection of objects in space.

 

6.14 The Apo-Telyt-R module system, 1996

The module system has been specifically designed for the photographer who needs several long lenses for his assignments. And when one is considering focal lengths above around and above 280mm, there is a great chance that flexibility and ease of lens changes are of importance. The system consists of three focus modules with enlargement factors of 1, 1.4 and 2 and two lens heads with can be combined to get 6 different systems.

Σ 2.8/400

Σ 4/400

Σ 4/560

Σ 5.6/560

Σ 5.6/800

The several units are very sturdily built, and can be focused very smoothly with an internal focusing mechanism. Being primarily designed as a system, its advantages are found where a system of lenses is needed. There are many smart design elements, like close distance focus, short overall length, rotatable tripod thread, carrying handle, fine thread focusing Optically the lenses perform as a family and can be described as group, noting differences when needed. From module 4/400 overall contrast is very high at full apertures and performance is even over the whole image area. Fine detail is very crisply rendered with a trace of colour fringing at the edges in the field. Stopping down improves overall and micro-contrast and the rendition of extremely fine detail is outstanding. Again a faint trace of chromatic aberrations in the outer zones may be detectible as a slight blurring at the outlines of minute details.

The 2.8/280 and 2.8/400 exhibit a high contrast at their maximum aperture, again over the whole image area. Extremely fine detail is recorded with very good fidelity with the 280 version. The 400 version has a somewhat softer look, but you should see this in perspective. Its image quality is equal to that of the previous Apo-Telyt-R 2.8/400, but is does not reach the level of the non-module Apo-Telyt-R 4/280.

Stopping down to middle apertures the capture of extremely fine detail is beyond the capabilities of most film-emulsions. Some residual chromatic aberrations are detectible in the field. It is evident that the performance of these lenses can only be exploited with a photographic technique of a very high order. The slightest vibration and defocusing will degrade the inherent quality. These lenses are capable, optically and mechanically, to deliver a very level of imagery. The module system is truly a challenge for the photographer and the material. The quality of the results justifies the efforts.

 

Figure 209: 123 to 128!!

 

Figure 210: 6.14 A system overview

 

Figure 211: 6.14.B internal focusing

 

6.15 Vario lenses

The development of the vario systems and the technique has been detailed in previous parts. Suffice it to note here that the concept of the vario lens has added significantly to the ease of use of 35mm cameras .

6.15.1 1:3.5-4/21-35mm Vario-Elmar-R ASPH

 

General considerations

The zoomlens may be considered as the standard type of lens construction since a decade or two.

Photographers and cinematographers have always wanted to change focal lengths quickly and easily. The step from the thread mount to the bayonet mount was the first method in this direction. The turret with two or three different focal lengths was the next step and this was even offered for the Leica M camera. But a smooth change of focal lengths became only a possibility with the zoomlens. This type of lens is now the norm.

The lens line up of one of the best known names in 35mm camera production consists for over 50% of zoom lens designs. The Leica R lens catalogue shows that about 20% of the current lenses are of zoom lens design.

In cinematography and video cameras the zoomlens with large focal length ratio is ubiquitous. And the current crop of digital cameras is almost invariably equipped with a zoomlens with a ratio above 1:10.

The optical performance of the first zoomlenses in the late fifties and early sixties of the previous century was quite mediocre. For a long time it was widely assumed that this design could never challenge the image quality of the prime lenses with fixed focal length. When you study the current lens designs, you may indeed wonder how it is possible that a single lens with 9 elements can cover the range of focal lengths between 21 and 35mm, where the prime lenses need from 6 to 9 elements to cover one single focal length.

The answer is not so difficult to provide: better knowledge of the design problems, new glasses with special properties and/or with high refractive indices and the insight into the possibilities of aspherical surfaces allow the designer to create zoomlenses with great performance. The major factor for the good quality of the zoomlens is of course the relatively low speed of the lens. Doubling the speed of a lens implies a hefty increase in the impact of the optical aberrations. And any lens designer will tell you that it is not possible to reduce all these aberrations to a level that they are inconsequential in normal photography. You may comment that the new generation of digital cameras have zoomlenses that combine high speed and a large zoomratio. That is true, but to paraphrase a famous remark by Bill Clinton: it is the format, stupid! When the image area is small(16mm movie film, APS format, 6x8mm sensors), a high speed lens is less difficult to create, compared to the relatively large 35mm picture size.

Designing really high quality zoomlenses for the 35mm format is not easy and when you add the requirement for high speed, it becomes quite a daunting challenge. Not only optically, but also mechanically. Increase the speed and the zoom range simultaneously and you are stuck with a very big lens that is not convenient to handle.

When you look at the lens diagrams of modern zoomlenses, you may feel impressed: many lenses have a very high number of lens elements, from 15 to over 20. And if you care to glance into other areas, the zoomlenses for videocameras may have more than 30 elements.

The basic zoomlens however can be designed with only two elements. The focal length is changed by increasing or decreasing the variable air space between the elements. Then you shift the whole system to keep it in focus. That is not convenient and a second moveable element was added. One element moves to provide the shift in magnification (focal length) and the second element moves to hold the focus. The relative movement of both elements is very non-linear and that causes he elaborate mechanical linkage of the moving elements. This is the basic principle of he mechanically compensated zoomlens. In a real lens, you do want not only to change the focal length and hold the focus, but also to correct the aberrations. The basic layout consists of a primary lens group that corrects the aberrations and a zoom group that is responsible for the other actions. The zoomgroup is often designed in the classical plus-minus-plus configuration. The original Cooke triplet is indeed a seminal design. The front lens element is used for focusing, the middle element for changing the focal length and the third element is the mechanically linked compensator for the focus position during the zooming action. This layout can be seen very clearly in the Apo-Elmarit-R 1:2.8/70-180mm. But in the more recent designs the construction is more elaborate and the relative movements of the lens groups are more interlinked. Here we see a natural evolution of knowledge and experience.

It is not too difficult to create a lens with the current optical design programs. The optimization algorithms are very powerful and the manufacture of lenses is often highly automated. But the number of lens elements does increase often beyond necessity. The prime directive of the current generation of Leica designers is simplicity of design, based on a true understanding of the problems involved in a lens design. It is the basic principle of Lothar Kölsch, the former head of the optical department, that it does not make sense to try to optimize a lens, without a very good grasp of the inherent problem areas of a design. Pencil and paper are still the starting tools of the Leica designers as is creative understanding of the optical configurations.

The quest for a design with minimal elements also supports that other goal of the Solms designs: every lens element must be mounted without any deviation from the intended location. The drive to assemble a lens without the slightest amount of decentring may be seen sometimes as obsessive, but it is this seamless integration of optical perfection and mechanical excellence that provide the fingerprint of current Leica lenses.

The other side of the coin is a lens, which offers less features than can be found with the competition.

These considerations may be read as background information when discussing in general the philosophy of the Leica R zoomlenses. Compared to other well-known manufacturers and certainly when compared to the independent makers of zoomlenses, the specifications of the Leica zoomlenses seem quite modest. A lens however is the result of a series of conflicting demands: specifically a small size is very difficult to combine with excellent optical performance. And a compromise is then unavoidable. Leica will never soften their focus on optical excellence, even if this implies that a lens may have specifications that are not up to what the competition does offer. And the Leica users will have to accept this fact. One of the very charming consequences of this approach is the fact that every lens will perform in identical fashion (with the exception of course of the notorious Monday morning lens, that is always possible, even with the very quality conscious environment of the Leica manufacture)

Optical considerations

The Leica Vario-Elmar-R 1:3.4-4/21-35mm ASPH is a good example of this philosophy. The lens has nine elements in eight groups and has two aspherical surfaces, both located before the aperture stop. The Leica Elmarit-R 1:2.8/24mm has nine elements too, but is much less versatile and does not offer more image quality.

The design goal of the Vario-Elmar-R 21-35 was to provide a very compact lens with excellent performance over the whole focal range. One of the most pressing problems in a zoomlens is the distortion, which cannot be eliminated, but only distributed over the whole system. Here we have a part of the argument why Leica did not extend the zoomrange to 17 or 18mm on the wide angle side. If we look at the distortion figures, we see that at 21mm the distortion is -3.5%, which is quite visible in architectural work and when there are straight lines at the outer zones and the horizontal edges of the picture. The distortion diminishes when changing the focal length to 35mm, where it is -1% (at 28mm it is -2%).

Vignetting varies from two stops at 21mm to about one stop at the 35mm position.

Many persons are a bit amazed that the values for vignetting should be so high. In fact they are not. We may study current and older lens designs form Leica and note that in most cases the wide angle lenses have vignetting form around one to two stops at the wider apertures. This is not a typical defect in Leica lenses, but is the consequence of the cosine-to-the-fourth law. Total vignetting is the sum of artificial (mechanical) vignetting and natural (physical) vignetting. The mechanical vignetting can be reduced by using large lens diameters, but the natural vignetting is based on a physical law. It can be explained as follows. When we have a pocket torch and point it directly (with a straight angle) to a wall, we see a circular patch of light that uniformly illuminates that part of the wall. When we point at the wall from the same position, but with an oblique angle, the illuminated area is much bigger, but the illumination itself is less, because the distance has increased. Vignetting with wide angle lenses is a fact of life. It is at times very annoying and can spoil your picture, but you cannot eliminate the effect, only take care of the consequences.

The relatively low number of nine glass elements is one of the reasons for the excellent clarity of the pictures at full aperture. Careful treatment of the glass surfaces and very effective coating techniques are other reasons for a picture quality that surpasses the comparable fixed focal length lenses. Of course you cannot compare directly a 4/35mm lens with a 1.4/35mm. The design parameters are too different.

But at comparable apertures the zoomlens has definitely the edge, especially in the outer zones of the picture. This is a general characteristic of the Vario-Elmar-R 21- 35mm in comparison with the fixed focal lengths: the improved quality in the outer zones of the image. When you study the MTF graphs, you may notice two characteristics of the newer zoomlens: the tangential and sagittal curves are close together and the drop in quality at the edges is quite limited. Astigmatism and curvature of field are very well controlled and this should please most users, as they can use the full picture area without expecting a loss of quality. The Leica users who like smooth unsharpness gradients and picturesque background shapes (the bo-ke effects) may be slightly disappointed: the new Vario-Elmar-R 21-35mm does not produce harsh and brittle shapes in the unsharpness zones, but is does produce somewhat rough shapes.

Colour fidelity is very good and colours are reproduced with natural hues. Even when using slide films with a warm balance, the colours are very pleasing.

Flare and secondary reflections are hardly visible, as is coma. With this lens, you can stop worrying about unpleasant surprises when shooting in demanding conditions and the choice of aperture and focal length is purely a matter of artistic consideration.

The high level of optical correction has pushed the residual errors to the margin as can be seen from the behaviour of the MTF graphs. There is a tendency in the internet user groups to diminish the information value of the MTF curves as being irrelevant to real picture taking, drawing a parallel to the resolution figures as a yardstick for image quality.

It would be a pity if this approach to MTF graphs would become wide spread.

Studying these curves is very informative: it will tell you at once that at all focal lengths, stopping down the lens has hardly any effect on the quality of the image. As example one may care to analyse the graphs of the 31mm position.

There is a high contrast image at full aperture, as can be seen in the closeness of the graphs for the 5, 10 and 20 lp/mm and the fact that all three graphs are above 9% contrast transfer. Micro contrast is excellent too as can be seen from the shape and location of the graph for the 40 lp/mm. At 5.6 very fine detail in the outer zones becomes quite crisp and edge contrast is very good too. There is no colour fringing at the edge of black-white borders. At 8.0 we note a slight reduction in overall contrast and some residual colour errors.

The best performance can be found at the focal positions from 28 to 31mm. The 21mm focal length is slightly softer overall and should be stopped down to 5.6 for best quality. This is especially true when making pictures in the near focus range.

A comparison of the MTF graphs at the various focal lengths and at full aperture indicate the evenness of image quality. The Leica brochure has a value of 1:3.5 attached to the full aperture at every focal length: in reality there is a progression from 21mm (1:3.5) to 28mm (1:3.7) and to 31 and 35mm (1:4). The half stop difference is however not a problem in normal situations.

Resolution figures, for whom it may concern, do vary from 70 lp/mm to 150 lp/mm, with the exception of the far corners, where we find values around 20 to 40 lp/mm.

 

Handling considerations

A compact lens with very smooth handling characteristics and relatively low weight, can not be constructed without the use of thin aluminium tubes for the focusing mount. A thick metal wall would increase the lens diameter and make the focusing less smooth. Compare the ease of handling of this 21-35mm with the 70-180mm vario lens. Sometimes you may hear a complaint that the focusing mount can be distorted when putting a strong pressure on it, as when you lift the lens out of the camera bag with a strong grip on the front part of the lens. The mount cannot be distorted, it is too strong for that, but you can change the smooth movement by pressing hard on the mount and so increasing the friction. Some see this behaviour as a lowering of the manufacturing quality of the Solms products when compared with the rock solid mounts of the older Leica lenses with fixed focal length. This conclusion would be wrong: it is not a question of manufacturing quality, but of ergonomics and a more complicated combination of demands. The focusing movement of a zoomlens is very different from that of a fixed focal length lens. And the handling requirements of a zoomlens must be taken into consideration.

This said, we might notice that the Vario-Elmar-R 1:3.5-4/21-35mm ASPH is a delightful lens to use, with the solid smoothness of movement and positive clickstops we expect from Leica, but do not always get.

When using the lens at the 21mm position during street photography and group photography, you should try to avoid having persons at the edge of the filed, as they will be stretched horizontally to inelegant proportions. This is not the effect of the distortion mentioned above, but the result of the wide angle characteristics as explained in the chapters on the 15mm and 19m lenses.

The comments made in the earlier chapters from 19 to 35mm about the artistic considerations (perspective, relative size, and depth of field) apply for this lens too and should not be rehearsed here.

 

Conclusion

The Vario-Elmar-R 1:3.5/-421-35mm ASPH has an optical performance that equals and in many cases surpasses the comparable fixed focal lengths and delivers very punchy images.

The 19mm and the 28mm fixed focal lengths have an aperture of 2.8 and somewhat better performance and indicate that there is room for dedicated lenses. The Summilux-R 1:1.4/35mm is obviously the champion in low ambient light, but in other areas shows its age, as does the Summicron-R 1:2/35mm. The older 21 design is of significantly lower contrast and the 24mm design can only compete on axis with the performance of the 21 position of the Vario-Elmar-rR The range of 1:1.7 seems a bit on the low side and looks more limited than it is in daily use. The range from 21mm to 35mm covers a very interesting range and should be able to help you create very potent pictures in the wider angle range from 90 degrees to 63 degrees. Especially if you are looking for close contact pictures with a sense of tightness and immediacy, this lens is very versatile and useful. You need to adjust to the lens characteristics in real photography and do not judge solely from first experiences or from paper specs.

The maximum aperture of 1:3.5 does seem to limit the deployment possibilities a bit, especially when using slow speed slide film. I am not so impressed with this type of argumentation. If you choose a film and a lens carefully, you do so with a specific goal in mind. And then the speed limitations are obvious, but can be countered by flash and/or a tripod. Only when scrolling around on the search for a suitable subject, you may find yourself in a position where the speed of the lens and the speed of the film are at a mismatch. But then the human quality of improvising may be honed.

My only problem with the aperture of 1:3.5 is the brightness of the focusing screen, tat makes accurate focusing sometimes difficult. In this respect Leica has to reconsider their technique of the focusing screens.

It is customary to designate this lens for landscape or reportage photography as the preferred areas, but this is too limited a view. Situational portraits, human interest scenes in close and tight quarters and everything that can be imagined by the photographer to benefit from a wider perspective at close distances can be captured with this lens. It is the photographer not the lens that defines the subject.

The Vario-Elmar-R 1:3.5-4/21-35m ASPH is very pleasant to use, compares favourably to companion lenses of fixed focal length, has excellent to outstanding overall performance and gives the user a new range of creative possibilities. It is one the few lenses that has no weak points in performance or handling.

 

6.15.2 3.5-4.5/28-70,Vario-Elmar-R,1990 & 1997

This is a Sigma design. Both of these lenses can be described together. The first version has a weaker performance at the 28mm position. In the second version this has been improved. At all other settings the image quality is the same. At the 28 position overall contrast is high at full aperture (3.5), outlines are crisply rendered over most of the picture area., excepting the corners and finer detail is recorded with slight fuzziness in the field. Vignetting is 1.5 stops. Stopping down improves contrast and improves the rendition in the corners. Barrel distortion is very high and would make this setting not really useable for exacting work.

 

Figure 212 diagram 133-134

At the 50 position overall contrast is high at full aperture (4), with vignetting that can be neglected. Fine detail is rendered clearly over most of the picture area and very fine detail is defined with good visibility on axis, with a gradual drop in quality to the corners. Stopping down brings in a somewhat higher micro-contrast in the field and with the definition of very fine detail. Pincushion distortion is clearly visible. At the 70 position we see at full aperture (4.5) a high contrast image with crisp rendition of fine detail with good coverage over the picture area. Vignetting can be neglected.

Stopping down does not bring improvements. Pincushion distortion is high. The lens is a definite improvement on the earlier Minolta design, but no match for the current Vario-Elmar-R 4/35-70. Stretching the focal length to 28mm may be a bridge too far for this type of design. With 11 elements, compared to 8 for the Solms designed lens we can grasp the significance of the remark that less is more.

 

6.15.3 2.8-4.5/28-90mm Vario-Elmarit-R ASPH

 

Introduction

This is a new zoomlens, designed and manufactured by Leica, Solms, that has a remarkably long list of innovations. First: this is the first zoomlens with a range of more than 1:3, to be exact: 1:3.214, close to the magical number pi (3.14....). Second there is a new method of mechanical movement to ensure an almost frictionless smoothness of focal range selection and distance setting. Thirdly there is a new method of assembly that minimizes tolerances to a narrow range. The zoomrange covers 90% of the most frequently used focal lenths,as a study by Canon, some years ago indicated. The analysis of thousands of pictures indicated that the statistical mean was a shutter speed of 1/125 and an aperture of 1:8 at a focal length range from 28 to 90mm, with the 135mm as a quite often used lens, but now almost extinct. The aperture starts at 1:2.8 and ends with 1:4.5, which is very good, considering that one of the closest competitors, the Zeiss Vario-Sonnar-T* f/3,5- 4,5/24-85mm starts at 1:3.5 (and 24mm). The Leica literature now uses the Zeiss designation with f/2.8 and not the classical Leica designation with 1:2.8. What is in a name, mused Shakesperare.

The Leica designers have to wrestle with the following problem. If you study a modern handbook about production technology, you will find that for small production batches (typically 500 to 1000 pieces) CNC machines have to be used. It is not cost effective to do dedicated machine tooling to produce the required parts.

Economy of scale is not possible. CNC tools are very flexible, but quite expensive and there are technical limits to the designs that you can manufacture with this technology.

Given the small batches of production, one can only use the time honored method of hand assembly. There is no use employing robots ar other automatic methods of assembly. One of the arguments to use as low a number of lens elements (besides the optical ones) is the additional effort during hand assembly: every additional element implies an additional cause of errors and an additional step in the quality assurance chain.

These facts of life can be seen as advantages too: Lens design and assembly methods can be integrated already at the initial stages of the optical design. The normal way of operating is to divide the total task in two unrelated subtasks: the best possible optical design and the best possible method of assembly. The connection between the two is a statistical analysis of the error distribution of the manufacturing tolerances and the assembly process. The idea is to find the widest range of tolerances before the required image quality drops below a precisely defined limit.

Assume that you specify an MTF value of 60% at a certain location in the image field. Your tolerance range is ± 10% (assumed average) : you will accept every lens that will perform within a 54 to 66% range. If the tolerance analysis indicates that a certain lens element can be decentred by x%, before it will effect the final result to a level below 54%, this decentring may be accepted and the quality assurance can be adapted to this knowledge.

The Leica designers nowadays approach the problem from the other perspective.

They know the possible accuracy of the CNC tools and they know the precision with which human beings can assemble parts and they know the precision of the equipment to adjust the assembled parts. They can design a lens in such a way (calculating an aspherical surface as example) that they know for sure that this shape can be manufactured within a very narrow tolerance in order to avoid adjustments and compensations during assembly. The optical design is already taking into account the limits of manufacture and assembly and the construction can already be prepared for tolerance compensation to stay within narrow limits.

 

The optical specs and the mechanical construction

The designer of a zoomlens has in fact a luxury problem: he has a larger number of lens elements to correct lens aberrations than are available with a fixed focal length.

That is the reason why the best zoomlenses can deliver quality above that of fixed focal lengths. With the exception of the maximum aperture: here the fixed focal lengths are still unsurpassed. Fixed focal length lenses are totally stationary: the lens elements are fixed and there is only a helicoil movement to change the total lens group (with the exception of 'floating elements'). In a zoomlens we have several lens groups that move in raltion to each other in a complicated way and they have to move with a very high precision. One needs a different mount: one in which the cylindrical mount has a number of slots (curved lines) in which the guiding rollers slide to govern the movements of the separate lens groups. When you have a two group zoom (as is usual with the Leica lenses) this mount can be made with the required structural stability. The new lens has a three group zoom design and in this case the number of slots in the mount would be destabilizing the cylindrical mount.

Leica has employed a new method (as far as I know unique in this area) and has designed a mount where the slots are milled into the inner surface of the aluminium mount with the help of CNC machinery, designed by Weller, a previous Leitz Wetzlar subsidiary. There are numerouys chisels that work at the same time to cut into the inner walls of the mount to get the rquired shape and precision. The challenge here is not only to operate at an accuracy of 0.01 to 0.005mm, but also to ensure that the surface roughness is also below these tolerances to ensure a smooth movement.

The usual requirement at Leica is a mechanical tolerance of 0.01mm. But in this case there are additional requirements. The surfaces of the lens elements are manufactured to a tolerance in the nanometer range. (aspherical shapea and surface treatment to allow the new methods of coating). These lenses must be fitted into the mounts and assembled without the slighest stress or strain. This could deform the shape of the surface and generate a drop in performance. This is not easy with normal mechanical methods and hand assembly. Leica now uses a method of integrated mechanical compensators. This is a mechanical device that is already integrated in the original lens design and mechanism to make very small adjustments during assembly to minimize the tolerance bandwidth.

During the subassembly and testing of the lens with high magnifcation MTF equipment, any deviation from the norm can be adjusted without re-assembly or adding shims or negative/positive lens elements.

The lens consists of 40 main parts (without lens elements and electronics and aperture mechanism) and it takes an average of two hours to assemble the parts.

The lens consists of 11 elements in 8 groups and has two aspherical surfaces, one in front and one at the back (like the old Noctilux).

The minimum focus ovr the whole range is 0.6 meter. A macro facility is not available, but at 90mm one still has that 0.6 meter near focus and that is acceptably close in many situations.

 

Performance

The Vario-Elmarit-R f/2.8-4.5/28-90 mm ASPH is an excellent performer at all apertures and focal lengths/ A fixed focal length can be optimized for one distance (or magnification) and this is usually the infinity position. A zoomlens can be corected for one focal length, usually the one in the middle and both extremes suffer.

With this lens, we see a gradual improvement from the 28 position to the 90mm.

Generally we may note that the performance over the whole image area is very high, where the fixed focal lengths often have a very high quaility in the center portiona nd a gradual dropping towards the corners.

and full aperture (2.8) we have a high contrast image that can record above 150 Lp/mm in the centre of the image and more than 80 lp/mm in the outer zones.

Only the corners are weak with a soft recording of fine detail. Stopping down to 5.6 the performance of the centre now extends over an image circle of 12mm diameter.

There is no trace of astigmatism and a slight field curvature. Some colour fringing is visible at very high magnifications. Distortion is visible with -3% (barrel distortion) and so is vignetting at 2.5 stops. Compared to the Elmarit-R 1:2.8/28mm, the overal contrast is a bit lower and so is performance at the corners.

At 35mm and full aperture (2.8) there is a small improvement in the outer zones where the lens now records 100 lp/mm with good micro-contrast. Distortion now is about -1%. At 5.6 we have optimum performance with a crisp rendition of very fine detail over most of the image area. Vignetting is practically gone. Compared to the Summicron-R 1:2/35mm the vario version has an improved definition in the outer zones and a crisper rendition of small details.

At 50mm and full aperture (3.4) we see a very high contrast and an exceptionally high resolving power of more than 150 lp/mm over a large section of the negative. There is still some faint colour fringing, but in practice one would be very hard pressed to note it. At 5.6 we have impeccable performance that easily surpasses the quality of the Summicron 50mm lens, especially in the outer zones of the field. At this aperture the Summicron has less definition of the very fine details. Most people have never noticed this drop of performance in the Summicron, and this is an indication of the every high quaility of the new zoomlens At 70mm and full aperture (4) the image quality becomes superb and we have an extremely high contrast and a very crisp definition of the finest details. Stopping down to 5.6 does improve edge contrast and now the corners are quite good too.

Distortion is 1% (pincushion) and vignetting is negligible.

At 90mm and full aperture (4.5) the best performance is reached and compared to the 70mm position the outer zones and corners are now as good as the centre of the image. Vignetting is gone and distortion is very low with 1%. The low distortion at the tele side of the zoomrange is quite remarkable. A comparison with the Apo- Summicron-R 1:2/90mm ASPH shows that this lens has the same performance at 1:2 as the Vario lens at 1:4.5. Still the vario lens has a slightly higher impact, because of lower internal reflections and a smoother unsharpness gradient.

Flare properties I made a special study of the flare properties of the lens, as this is the one area where lenses have to go 'a bout de souffle';. Veiling glare is hardly visible at all focal lengths, implying there is no loss of contrast when the background is much brighter than the subject itself. When the sun is obliquely shining into the lens, and is behind the subject, one can see some secondary reflections of small extent in the picture, but the well-known diaphragm blade reflections are not visible. With the sun flooding the image, there is of course a bleaching out of the picture details, but in such a situation one would change the position slightly to evade this direct confrontation with the sun.

In general I would say that for veiling glare the lens is better than the average Leica lens, and for secondary reflections it is slightly better.

 

Conclusion

This is a lens with amazing characteristics. It offers outstanding quality and can be compared very favourably to the fixed focal lengths. A detailed comparison with the equivalent fixed focal lengths is now possible based on the published graphs in earlier chapters and in the lens data sheets, available separately on the leica website.The reader can do this him/herself. In general the fixed focal lengths will be more compact and offer a higher speed per focal length. Stopped down there is no longer a big difference and compared to older lens generations, the zoomlens often has better imagery in the outer zones of the image.

The images made with the Vario-Elmarit-R f/2.8-4.5/28-90mm ASPH have a very good colour fidelity, a very fine pictorial depth and documentary realism. This is a lens for slide film and if you have not yet tried slide film, the acquisition of this lens might be a good incentive to try these films.

The wide zoomrange from 28 to 90mm highlights another property of the reflex system: the normal finder screen of the R8/9 is a bit too dark at the 90mm position and it is difficult to focus accurately at the 28mm position. Focusing at the wide angle range is often not very critical as depth of field will cover slight errors. If accurate focus is required, it is best to focus at 70mm and zoom to 28mm (or 90mm and zoom to 35mm).In this range, focus constancy is abolutely spot on.

 

6.15.4 3.5/35-70,Vario,Vario-Elmar-R, from #3171001, 1983, and from # 3418891, 1986/88

The optical cell of this lens has not been changed from version 1 to 2, only the mechanics have been re-engineered to align them with the production standards of Leica, Solms. It is a Minolta design and the lens has been manufactured in several locations. There is a still a tendency within the Leica community to want to know specifically where a certain lens has been manufactured. From an optical perspective and for evaluation purposes the origin of a lens is of less importance than its image quality. The Minolta design was not the best on the market and in its original Minolta version showed some manufacturing defects. The Leitz quality control ensured that only the lenses within Leitz tolerances were accepted. At the 35mm position at full aperture we have a high overall contrast and light fall off of 1.3 stops. Performance is quite even over the picture area, with a strong drop in the corners. Fine to very fine detail is defined with soft edges, becoming blurred in the outer zones. Stopping down to 5.6 and 1:8 brings slight improvements, as the definition of very fine detail crispens on axis, but in the field there is a visible blurring of this detail level.

 

Figure 213 diagram 131

Barrel distortion is quite pronounced. At the 70 position at full aperture the image quality is slightly below that of the 35 position, due to somewhat lower contrast.

Vignetting is a half stop lower. Stopping down to 5.6, there is a marked improvement in the field and the centre now lags a bit behind. At 1:8 there is no more improvement. Distortion is less pronounced and as usual of pincushion shape.

 

Figure 214 6.15.2 movements

 

6.15.5 2.8/35-70,Vario-Elmar-R,1997

The step from a f/4 lens to a f/2,8 is a major design problem and the step from f/2,8 to f/2 even more so. The argument for this state of the art view is explained in chapter 1.2. The luminous energy flowing through a lens of aperture f/2,8 is twice the amount of a lens with an aperture of f/4 and the effort to control and manage this energy flow is very demanding. It is not well recognized how difficult it is for a designer to control aberrations when stepping up one stop. The Vario-Elmar-R 1:4/35-70, introduced in 1997, is designed in Solms and built in Japan, has 8 lenses, of which one surface is aspherical. The newer 2.8/35-70 has 11 lenses, many of which are of exotic specification, proving the effort to go up just one stop. With this lens Leica introduces an interesting strategy and that is building a low aperture lens to very high optical standards of performance. With a weight of 500 grams it is half the weight of the 2.8/35-70 and equal the weight of the new Apo-Summicron-M 2/90 ASPH.

 

Figure 215 diagram 129 A B C The performance at 35mm.

At full aperture (4) a high contrast image is produced, slight pincushion distortion is visible and a trace of vignetting in the far corner. On axis (till image height 6mm) outlines of objects are very crisply rendered. Very fine detail can be clearly detected with a trace of softness caused by a very narrow band of colour fringing at the edges.

Extremely fine details are recorded with softer edges and exceedingly fine detail is just perceivable. In the field this performance holds with a slight softening of the details at various levels of detail rendition. The reproduction of extremely fine detail shows a certain softness. In the far corners the very fine detail is still visible, but very soft by now, producing fuzzy details. This level of performance holds till 1 meter and in the macro position, where the distortion is a bit more pronounced. At f/5.6 the overall image gets a visibly higher sparkle and in the field the rendition of extremely fine detail becomes quite crisp, showing that high contrast and very high resolution go hand in hand. Corners stay behind. At f/8 the optimum is reached in the field, where the outlines in the centre already show a slight setback. This performance is identical in the f/11 position, and the f/16 shows the usual fallback of quality. The performance at 50mm. At full aperture the overall contrast is a bit lower than in the 35 position, no vignetting or distortion. In the centre (on axis) the outlines of objects are quite crisp as are the fine and very fine details. Extremely fine detail has fuzzy edges, but still a high contrast. In the field fine detail is crisply rendered and very fine detail has slightly soft edges, becoming quite fuzzy when the extremely fine details are recorded. In the far corners very fine details are just visible. At f/5,6 the image markedly crispens up and at f/8 the extremely fine details possess the sparkle and clarity of the best modern Leica lenses. This performance holds till f/16 and in the close-up range. The performance at 70mm. At full aperture the overall contrast is a bit less than with the 50 position. In the centre the outlines have tightly drawn contours, necessary for the sharpness impression. Very fine detail is clearly rendered with a bit soft edges and extremely fine details are a bit fuzzy and start to overlap each other. In the field fine detail is quite crisply rendered and extremely fine detail is just detectable. The corners show a drop in micro contrast and produce fuzzy detail.

Slight distortion and a bit vignetting can be noted. At f/5.6 the usual crispening over the whole image field is noticeable with a faint improvement of the rendition of very fine details. At f/8 again more contrast and ever finer detail is recorded, now extending into the far corners. At f/16 the performance drops a bit. Performance holds up to and including the macro position, but when flat objects are recorded it is advisable to stop down a few stops. . Centering is perfect. Veiling glare and secondary ghost images are in most picture taking situations non-existent and hardly to just detectible in adverse conditions Compared to the Summicron-R 2/35 and the Summilux 1,4/80 (the 90 would be too long) at their f/4 aperture we see a lower overall performance. A wide aperture lens has an inherently much higher aberration content than a f/4 design and since the current crop of designers masters the intricacies of zoom lenses quite well, we might expect that the fixed focal length lenses are challenged. As they are indeed. Side by side comparison shows that the Summicron and Summilux have a bit less clarity and sparkle of very fine detail than the Vario-Elmar-R , especially in the field. Some study clarifies this behavior.

Looking at the rendition of extremely fine detail we note that this level of detail recording is beyond the capabilities of the Summicron-R and Summilux-R and just within recording level of the Vario-Elmar-R. The Vario-Elmar-R has a lower amount of residual aberrations and a better balance of them. This will show especially in the overall sharpness impression. It is also understandable that the better performance in the field of the Vario-Elmar-R will show in the centre too and the somewhat lesser performance in the field of the 'cron and 'lux will also have its effects on the centre and overall performance. While it is convenient for a test to divide a lens in zones to describe its performance, in practical photography all zones and residual aberrations contribute to the overall imagery of that lens. You have to sum all optical performance aspects to get one overall quality impression. That is what counts for the viewer and the user. Optical analysis can try to explain why a certain lens has this behavior or this image character, but the eye is holistic. It captures the image as a whole.

 

6.15.6 2.8/35-70,Vario-Elmarit-R Asph,1998

This lens has about twice the volume of the Vario-Elmar-R 4/35-70, which makes sense. It is double the aperture. The 35 mm position at full aperture produces a high contrast image with extremely fine detail already crisply rendered. The edges of the larger outlines are a shade of soft and there is a faint trace of astigmatism and miniscule colour fringes along edges. Outlines and very fine texture details are recorded with great fidelity over the whole image field. Only the far edges are soft and here the finest details are lost in fuzziness. There is some slight barrel distortion, some light fall off and absolutely no decentring and curvature of field. The 2.8 performance is better than the 2.8/35 and the 2/35 at 2.8. Not so much in the centre but especially in the field. At 4 the trace of softness disappears, and the corners improve. Now exceedingly fine detail starts to be recorded. At 5.6 the overall image is a bit below the f/4 performance and from now it well useable till f/22, but at these apertures the highest image quality can not be expected.

 

Figure 216 diagram 132 A B C

Close-up performance at full aperture is excellent, but slightly below the infinity setting. One should stop down one stop to get the best performance. The 50 position at full aperture is as good as the 35 position at 4. Extremely fine detail is recorded with clearly defined edges over the whole image field, including the edges.

No distortion or decentring or astigmatism. Stopping down to 4 brings in a shade more crispness and clarity and now the optimum is reached. This lens is better in the field than the Summicron-R 2/50 at 2.8. The performance gain is not very large, but quite visible. Close-up performance has the same pattern as the 35 position. Stopping down a bit for max performance is advised. At 70mm we reach the overall best position of this lens. At 2.8 it approaches very closely the wide open performance of the Apo 2.8/100 . The finest possible details, just at or even over the border of the recording capacity of the best current films, are defined with high clarity and edge contrast. Overall outlines are edged into the grain with a razor-sharp line and this performance extends over the whole image field. Close-up performance is identical.

No need to stop down here. Stopping down to 4 improves contrast a bit and the minuscule details are rendered with slightly better edge contrast. After 5.6 the image softens a faintly and a bit more so after f8. The macro position gives a 1:2.8 reduction which is quite useful, but the shallow depth of field necessitates a small aperture, even if the full aperture performance is very good. The sharpness/unsharpness gradient is intriguing. Leica lenses are supposed to have mythical qualities in this respect. This V-E has a quite steep gradient from sharp to unsharp. The first zone of unsharpness exhibits shape preservation, that is the larger objects keep their geometrically correct form, but loose detail information and in the second zone shapes loose their characteristic form and become amorphous colour blotches of various patterns. The very large object forms have somewhat harsh outlines. On the borderline of sharp/unsharp the outlines of details are a bit rough and have the character of a Van Gogh brush. Atmospheric perspective is enhanced and the sharpness plane is pressed into view quite forcefully. The etchingly sharp outlines of the grosser details are preserved over a large zone in the sharpness/unsharpness border. This effect is most visible in the 70 position. The 35 position naturally has these effects to a smaller degree and with a smoother gradient.

Modern Leica lenses have these characteristics as a family trait: quick change from sharp to unsharpness with shape preservation and a progressive loss of fine detail information. Night pictures are quite demanding as specular highlights, deep shadows and large bright light sources generate secondary reflections and veiling glare and halo effects . The Vario-Elmarit-R is outstanding here. No coma at all: in the critical zone in the negative (2/3 from the axis that is the zone of 12 to 18mm from centre), light sources are cleanly delineated, hold their shape and are without any halo rings. Light sources very close together at far distances are separated clearly and without fuzzy rings and have a brilliantly clear luminance. Dark shadows are clean black and the darker colours have fine colour hues. Often you see here a bit sooty blacks and colours and light sources look as it photographed in a misty atmosphere. Veiling glare and back-lit pictures. It is always possible to take photographs with secondary reflections and veiling glare. No lens I know of is immune to forced glaring effects. More important is the performance in more 'natural' circumstances. When taking pictures with the object against a strong light source (sun or whatever) the Vario-Elmarit-R holds clear edges, dark areas and very fine detail in the non-lit areas. The highlights are very clean, with subtle shades of white light illuminance. the shadow colours are clean and well saturated.

Microcontrast is very high and no loss of overall contrast. When strong veiling glare illuminates parts of the picture you will notice a haze of lightness, but within these areas and just outside the veiled areas, fine subject detail is preserved with good contrast, but the colours are of course more pastel-like. The Vario-Elmarit-R can be used without any reservation in strong backlit situations and in oblique lighting when the sources are just outside the lens elements. When forced you will notice an occasional strongly coloured secondary reflection in the image. Efficient coating on the almost twenty free lens surfaces is evident. Optically this lens brings the vario performance a few steps higher. The 70 position is the best and has Apo qualities.

 

6.15.7 2.8/70-180, Vario-Apo-Elmarit-R, 1995.

At full aperture this lens has very high overall contrast and outstanding edge contrast of subject outlines. In the past (and sometimes even today) excessive attention has been given to resolution figures, but in fact it is the crispness of subject contours that define the sharpness impression. Leica is one of the very few manufacturers to use the 5 lp/mm criterion in their MTF graphs. This value is very important for image quality. Not well known is the fact that good edge contrast implies high micro contrast. The Apo-Elmarit at full aperture renders exceedingly fine detail with good clarity over the whole image field from 70 to 120mm focal length.

 

Figure 217 diagram 138 A B C

Optimum performance will be found at the focal range from 80 till 110 mm where high edge contrast and exceedingly fine detail will be rendered from centre to the far corners. In this span of focal length the performance of the Vario-Apo-Macro- Elmarit-R 1:2,8/100 is equalled if not surpassed. At 70mm the on axis performance is on the same level, but now the far out area loses a bit in the crisp rendition of extremely fine detail. The 135mm position has excellent on axis imagery, but now the outer zones will render very fine detail with good contrast. The 180 position renders very fine detail on axis with excellent clarity. The outer zones and the far corners will show fine detail with good contrast. In comparison the new Apo-Telyt-M 3.4/135 and the new Apo-Elmarit-R 1:2,8/180 are better than Apo-Elmarit-R 1:2,8/70-180 at the corresponding focal. The older generations of the 135 (2,8) and the 180 however are not on the same level as the Vario-Apo-Elmarit-R 1:2,8/70-180, as are the 1.4/80 and the 2.8/90. Vignetting is practically absent at all positions, but distortion at the outer positions (70 and >150) is not. It depends on your deployment if it is acceptable. It is visible though. Stopping down of course improves the imagery a bit, especially at the extreme positions. To preserve optimum quality you should not stop down after 1:5,6 or 1:8.0.

The handling of this lens demands strong shoulders. At almost 2 kg this lens is weighty evidence that optical performance does not come easy. The superb image quality is easily confirmed on the bench or on a tripod (make it heavy and secure!!).

Practical tests in the field with 100 ISO material (and lower) show that many pictures taken at a speed below 1/500 exhibit a slight fuzziness due to movement. At 1/250 or below you are in the chance area. At 1/1000 or above the true image potential may be reaped. Colour rendition is of the modern Leica signature: accurate colours, just on the verge of full saturation, with great clarity and transparency . Flare is suppressed very effectively as can be seen in shots where specular highlights are part of the scene. The Leica hallmark of very smooth and subtle gradation of highlights is fully proven. Images get a sparkle and a high light tonality that must be projected on a large screen to be believed. Mechanical construction and smoothness of all parts is beyond reproach. The distance ring however has a long throw to go from 1,7 m to infinity. A bit prefocussing will help. Turning the ring the whole distance will not improve the much needed stability when handholding and focusing at the same time.

This lens provides outstanding performance in all picture taking circumstances when used expertly. This will be discussed in the next part.

The Vario-Apo-Elmarit-R 1:2,8/70-180 is a very good example of the optical progress of the last ten years and living proof of the capabilities of the optical team in Solms. Some time ago Leica stated with some bravado that zoom lenses would never reach the high level of their prime lenses. At the same time Zeiss was producing zoom lenses with excellent imagery. In the photographic world men dominate as well as in the industrial companies, It is fine twist in history that the VAE is indeed better than most prime lenses which focal length it covers and has been designed by a female optical designer. (the Summicron-ASPH 2/35 is also designed by her). At 70mm, 90m and 110mm the lens reaches its optimum at f/4,0, while at f/8.0 the performance already starts to drop a bit. At 135 and 180 the pattern of improvement of performance must be looked at from two angles. At these focal lengths the performance in the field (outer areas) at full aperture was lower than on axis and in comparison to the wider field angles (70 to 110). Stopping down to f/4,0 improves the image to its on axis optimum. That is over a circular image area with a radius of 15mm. If there is a need to get impeccable quality till the far out corners one should stop down to 5,6 and 8.0. The overall performance (crispness of outline delineations and very fine textural details) will drop slightly. Vignetting at full aperture is very slight and only visible in the extreme corners. (Quite often when masking a transparency it might be covered by the mask). There is some flare at the longer focal lengths in the outer zones when strong light sources are present in the vicinity of the edge of the picture area. Presumably the built-in filter is partly responsible for this phenomenon. When shooting directly into the sun or into the sun partially covered behind a tree or roof of a building the internal reflections are very well suppressed and the black parts just adjacent to the sun spilling over the border are still black and the details are preserved with good contrast.

 

6.15.8 4/70-210, Vario-Elmar-R,1984

This lens is a Minolta design and generally has the same character as the 3.5/35- 70mm lens. At position 70 overall contrast is medium with a clear definition of fine detail over most of the picture frame, softening slightly and dropping in contrast when we reach the outer zones. Very fine detail is resolved with good visibility on axis (till image height 6mm). Vignetting is 1.5 stop. Stopping down to 5.6 brings a high overall contrast and a crisp rendition of very fine detail with some fuzziness at the edges. Barrel distortion is quite strong. At 1:8 performance does not change.

 

Figure 218 diagram 135

At position 150 overall contrast is high and very fine detail is crisply and evenly rendered over the whole picture area, with a slight drop in the corners. Vignetting is 1.5 stops. Stopping down to 5.6 and 1:8 brings a very high quality image with excellent edge sharpness and a crisp and clear definition of very fine detail.

Distortion is visible and of pincushion shape. At position 210 the performance is very close to the one found at 150. Distortion is more pronounced and when stopping down the fine details are defined more soft and with lower contrast in the field than in the 150 position. . The overall performance of the lens does not justify the well-known statements from contemporary Leica students that the variable focal lens will never surpass the well designed fixed focal length lens. Its philosophy of correction is clearly a high performance at the longer focal lengths, as good as if not better than the lenses of focal length above 135mm. This is a sensible strategy. The Vario-Apo-Elmarit-R 1:2.8/70-180, a decade later, not only is a vastly better lens than this one, but also does surpass many of the fixed focal length lenses.

 

6.15.9 4/80-200,Vario-Elmar-R,1996

This lens is close relative of the Vario-Apo-Elmarit 1:2.8/70-180mm as the lens diagrams do indicate. And it has the same relation to this lens as has the Vario-Elmar 4/35-70 to the Vario-Elmarit asph 1:2.8/35-70mm. Overall it delivers improved imagery when compared to the predecessor (3.5/70-210) and is a bit below the 2.8/80-170. Specifically the clarity of definition of the extremely fine detail is duller and more soft. But is has not the apo-designation to be sure. Stopped down is a as good a performer as the apo-relative.

 

Figure 219 diagram 139

In the 80 position at full aperture we have a high overall contrast with crisp definition of fine detail over most of the picture area. Outlines have very clean edges, enhancing the sharpness impression. Very fine detail is clearly visible with some softness in the field of the image. Vignetting is about one stop. Barrel distortion is visible. At 5.6 and 1:8 image quality is visibly enhanced and now is on a par with the 2.8/70-180. In the 140 position overall contrast is higher and on axis (image height 9mm) the rendition of extremely fine detail is very crisp and clean. In the corners there is a drop. Vignetting is again 1 stop. At smaller apertures we see the same level of performance with a faint improvement in the field. Distortion is low and pincushion in shape. In the 200 position there is a general drop in performance, especially over most of the field. At full aperture there is a high overall contrast, but the definition of fine details is a bit fuzzy and very fine detail is blurred in the outer zones. Vignetting is about one stop. At smaller apertures there is no visually detectible gain in image quality. Distortion is more pronounced (and pincushion). As with the 70-180, the longer end of the zoom range is a bit below the quality at shorter end and middle range.

 

6.15.10 4.2/105-280,Vario-Elmar-R,1996

This lens is also closely related to the 4/80-200. In this case the performance balance is shifted to the medium and longer end of the zoom-range.

 

Figure 220 diagram 140

At the 105 position we have medium contrast with clearly defined outlines of subject shapes and a clean rendition of fine detail, progressively softening when reaching the corners. Very fine detail is detectible, but a bit fuzzy. Vignetting is hardly visible.

Stopping down improves the overall contrast visibly. Overall performance stays the same. Distortion is of barrel type and visible. At the 200 position image quality is clearly better, with high overall contrast and a crisp definition of extremely fine detail over the whole picture area. Vignetting and distortion can be neglected. Stopping down deliver the same image quality. At the 280 position overall contrast is medium to high and very fine detail is clearly defined on axis (image height 8mm), gradually becoming softer in the field. Vignetting is very low. Stopping down to 1:5.6 brings a marked improvement on axis and a slight improvement in the field. Pincushion distortion is just visible.

 

6.16 Early zoom lenses.

There are a number of very early zoom lenses, provided by Angenieux, Schneider and Minolta, like the 2.8/45-90, Angenieux-Zoom,1969 and Minolta's 4.5/80-200, Vario-Elmar-R, 1974 and 4.5/75-200, Vario-Elmar-R,1978 and 2.8/45-100, Schneider Variogon and Tele-Variogon 4/80-240.

 

Figure 221 6.16 several pictures

I have no direct or hands-on experience with these lenses. They are listed just for completeness. The product literature of Leitz from these days uses quite evasive descriptions to characterize the performance, which may be a clue. It is interesting to reflect on the fact that most vario-lenses from the beginning had good contrast and a clean rendition of subject outlines. The many lens elements used in the designs needed a very effective reduction of unwanted reflections and the application of efficient coating did enhance the general impression of sharpness at the subject outlines.

© Erwin Puts
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