K mount lenses

The K mount was introduced by Pentax in 1975 with their line of [series bodies]. The K mount was initially a joint development betwee Pentax and Zeiss, that never materialized and in order to maintain compatibility, it was decided to retain the same flange/film distance as the M42 screw mount lens mount (46.42mm). K-Mount was introduced as open standard, meaning that a handful camera makers soon offered SLR bodies and lenses with K-mount, for example Cosina, Chinon and Zenit. The mount standard has been revised and extended several times (e.g. to add autofocus) and remains in use on Pentax's