After lens coating became universal post WW2, designers were given more freedom in using extra air-to-glass surfaces in correcting lens aberrations, without fear of the ill effects of surface reflections. Zeiss also pioneered glass coating, and before the war coated lenses were offered. In the years before lens coating was generally practiced, this had advantages for contrast and resistance to lens flare. The greatest advantage of the Zeiss lenses was the reduced number of air-to-glass surfaces in Bertele's designs. The young lens designer Ludwig Bertele, formerly of Ernemann, was charged with the responsibility of designing the lenses.

Other main features included focusing drive built into the camera body for use with standard lens, removable back, shutter-speed knob integral with film-wind knob placed at the front of the camera body, and black-enamelled finish. To enhance accuracy, a novel rotating wedge system was employed instead of the common swinging mirror mechanism. One of the key design features was a coupled rangefinder with a very long baseline, with its own eyepiece next to that of the viewfinder. Zeiss also invented the System Camera, with all sorts of near-photo, wide-angle, mirror-house, long-focal-length lenses for specific situations. Replacing these ribbons was difficult but, contrary to modern cameras, made for a 400,000-cycle life. The interlocking slats were aligned by specially woven silk ribbons, which were very strong but subject to wear. The fact the shutter ran across the shorter dimension of the format area was a significant factor for achieving this technical feat. The Contax design allowed a higher maximum shutter speed: the top speed was 1/1000s, then increased to 1/1250s in the Contax II. By contrast, the competitive Leica followed the established design of using rubberized fabric shutter curtains wound around rollers, moving horizontally. This complex shutter became the characteristic of the Contax camera and its Super-Nettel derivative. Using a die-cast alloy body it housed a vertically travelling metal focal-plane shutter reminiscent of the one used in Contessa-Nettel cameras, made out of interlocking blackened brass slats somewhat like a roll-up garage door. Made between 19, the original Contax, known as Contax I after later models were introduced, was markedly different from the corresponding Leica. Heinz Küppenbender was its chief designer. The name Contax was chosen after a poll among Zeiss employees. While the firm of Ernst Leitz of Wetzlar established the 24 mm × 36 mm negative format on perforated 35 mm movie film as a viable photographic system, Zeiss Ikon of Dresden decided to produce a competitor designed to be superior in every way. 6.3 Lenses for Yashica/Kyocera-built SLR models.6.2 Lenses for the Dresden-built SLR models.6.1 Lenses for the original rangefinder models.

Contax serial numbers