Be aware that a few older Non-Pentax K-mount lenses...
I took some time to reach out to one...
Lens mount adapters for M645 lenses from Fotodiox are...
Flange Focal Distance & What FFD Means for You...
M39, L39, LTM, Visoflex L39, Zenit M39, Canon Screw...
‘Focus-By-Wire’ is a term for a newer focusing technology...