The M42 mount, also known as the Pentax screw mount or Universal screw mount, is a lens mount standard that was widely used in the mid-20th century. It was initially developed by Carl Zeiss in the 1930s and became popular due to its widespread adoption by various camera manufacturers. Here's some information on the history and manufacturers associated with the M42 mount:
Origins and Development:
The M42 mount was introduced by Carl Zeiss in 1938 for their Contax cameras.
It became an open standard, and many camera manufacturers adopted it, leading to its popularity.
Camera Manufacturers:
Pentax: Pentax (formerly Asahi Optical Co., Ltd.) adopted the M42 mount for their Pentax Spotmatic series, which became very popular in the 1960s and 1970s.
Praktica: The East German camera manufacturer Pentacon (formerly VEB Kamera- und Kinowerke Dresden) used the M42 mount for their Praktica series of cameras.
Zenit: Russian camera manufacturer KMZ used the M42 mount for their Zenit series of cameras.
Yashica: Yashica produced cameras that used the M42 mount, such as the Yashica J and Yashica TL series.
Cosina: Cosina, a Japanese manufacturer, also produced cameras and lenses that used the M42 mount.
Other Manufacturers: Many other camera makers, including Fujica, Chinon, Voigtländer, and countless others, also utilized the M42 mount.