Left digits shows camera model, and the right ones shows the negative size.
The last digit of the left number was usually incremented by one if for new or improved model.
This table should help you to find out the camera size:
Number | Metric Size | Focal Length |
4.5x6cm | 75mm | |
22x31mm | 45,50mm | |
1 | 45x107mm | twin65mm |
2 | 6x9cm | 105mm |
3 | 6.5x9cm | 105mm |
4 | 6x13cm | twin 75mm |
5 | 8.5x11.5cm | 135mm |
6 | 8x14cm | 150mm |
7 | 9x12cm | 135mm |
8 | 9x14cm(ICA) | |
9 | 10x15cm | 165mm |
10 | 9x18cm(ICA) | |
11 | 13x18cm | 210mm |
12 | 4x6.5cm | 75mm |
13 | 13x18cm(ICA) | |
14 | 5x7.5cm | 90mm |
15 | 6.5x11cm | 120mm |
16 | 6x6cm | 80mm |
17 | 8x10.5cm | 190mm |
18 | 3x4cm | 50mm |
20 | 18x24cm | |
21 | 24x30cm | |
24 | 24x36mm | 50mm |
27 | 24x24mm | 40mm |
Table compilation by McKeowns Price Guide.