Contax/Yashica lenses

Yashica and Contax manual-focus lenses with a common bayonet mount were introduced in 1975 simultaneously on the Contax RTS and on the Yashica FX-1. The Yashica range of lenses included a premium range of lenses for the more serious photographer (termed 'ML' or 'MC' for multi-coating), while consumer SLR cameras were usually equipped with 'DSB' lenses, which had single-coated optics. The top of the line was the renowned Zeiss AE series of lenses, intended for the Contax SLR cameras, each of which displayed a T* for Zeiss' proprietary multi-coating. Some Carl Zeiss lenses were made in Germany and the rest in Japan under Zeiss license. But all of these lenses were interchangeable with any Yashica or Contax camera equipped with the C/Y bayonet lens mount.

In 1983, Kyocera acquired Yashica, and continued to manufacture Yashica ML and Carl Zeiss AE/MM lenses under license.

The C/Y mount was modified in 1985 with new Zeiss 'MM' design lenses, which permitted the use of program and shutter-priority on the Contax 159MM and subsequent bodies. The new MM lenses are distinguished visually by the color of the f-stop markers: the highest f-stop on the MM lenses is marked in green. On the older lenses, also called AE lenses, it is marked in white. The lenses are physically compatible but with the older lenses you cannot use the exposure meter of the newer bodies to its full potential. Unfortunately, the program mode of later manual focus Yashica (Kyocera) bodies (FX-103, 107/108/109MP) do not have full MM compatibility.

One of the more interesting adaption of the Zeiss AE/MM lenses is to the Contax AX camera, built by Kyocera. This camera allows autofocus of the manual-focus Zeiss lenses, by actually moving the film plane (rather than the lens) back and forth. The AX can also be used with other lens mounts, via adapters.

Later Contax SLR lenses for the auto-focus Contax N series built by Kyocera use a different mount, aptly called "N mount."

While every brand has its adherents, optical testing has generally shown that Zeiss AE/MM lenses were among the sharpest ever made for a production 35mm SLR. Adapters to use Zeiss T* AE/MM lenses on other cameras, most notably Canon EOS, have proved popular.

Yashica ML and MC multi-coated lenses for the C/Y bayonet mount, while not to the standard of Zeiss, have also earned a reputation for high quality. Yashica already had a reputation for fine optics dating from the early 1960s with its optics supplier (later subsidiary), Tomioka Optical, and is also believed to have benefited from its licensing and manufacturing relationship with Carl Zeiss.