The (Zeiss Nettax Ikon 513/16) is a 6×6cm folding camera introduced in 1954 and made by Zeiss Ikon from 1955 to 1957. It is essentially a Nettar with a built-in uncoupled selenium exposure meter with a cover that is closed manually when not in use and has a release button on the hinge. The camera has a Novar-Anastigmat f/4.5 75mm lens in a Pronto manual loaded shutter. The shutter speeds range from B to 200 and the apertures settings go from 4.5 to 22. This camera also has double exposure protection and it accomplishes this by locking the shutter button. A red lens can be seen in the viewfinder when a film frame is used and it remains till you advance the film which also unlocks the shutter button. You can load the shutter at any time in this sequence.
In 1954 Zeiss added an uncoupled selenium exposure meter to their 6 x 6cm Nettar folding camera and the Nettax was born. It was yet another re-use of an old name by Zeiss, and was not to be the last. There is some confusion about the Zeiss catalog number for these; apparently it was officially 513/16, but a few Nettax cameras have 534/16 on the back, which is the catalog number of the Super Ikonta IV. I doubt that even Zeiss Ikon knows how many or what happened to these few oddly marked. It is important that this camera should not be confused with the earlier Nettax, a 35mm model.