Versions of this innovation were adopted by practically all subsequent users of the M42 mount (with the exception of preset or T mount lenses), though early adaptations varied slightly by manufacturer. In 1956 the Contax F introduced an internal aperture stop-down pin located at 6 o'clock inside the lens mount. It was also used by the Russians on Zenits from the second production run of the Zenit E onwards.
In the 1960s several other Japanese manufacturers also adopted the mount for their new 35mm system cameras. Later (1957) it was adopted by Asahi for the Asahi Pentax family of SLRs which sparked the Japanese camera industry. In the early 1950s the mount was also used by the West German firm Wirgin on their Edixa Reflex range of cameras.
It was also adopted by the East German firm KW on their Praktica range of cameras, introduced around the same time as the Contax S. The 42mm screw mount was introduced in 1949 with the Contax S 35mm SLR made by the East German firm VEB Zeiss Ikon. This page is NOT about the T mount thread measuring 42×0.75mm which screws into adapters ('T-rings') which fit many other types of SLR lens mount, first developed by Tamron. This page is about the 42×1.0mm thread M42 screw mount used to attach lenses to SLR cameras, most popular in the 1960s.