The Pentax K mount was introduced in 1975 and has been Pentax’s SLR mount for both film and digital since. The K mount has seen some innovation since it was introduced to enable new features, but all Pentax K lenses will mount and work on your latest Pentax digital SLR camera. A great number of other manufacturers have also produced K-mount lenses and K-mount cameras, and therefore, Pentax K users have access to a wide range of legacy lenses. M42 lenses are also usable on Pentax K mount with an adapter.
Note: Ricoh Pentax K mount lenses have the “Ricoh pin”. The extra pin needs to be removed for safe use on autofocus Pentax cameras, as it can otherwise become locked within the autofocus shaft. Lenses locked to the camera body this way are difficult to remove and may require complete dismantling.
Pentax K mount was made popular by the Pentax K1000 (1976-1997), one of photography's greatest, most popular and longest-lived 35mm SLR cameras. The K1000 is still one of the go to recommendations for photography students and others learning 35mm photography. The ability to use Pentax K mount lenses on newer digital cameras and mirrorless systems has kept the demand up for legacy K mount gear.