Old lenses on new cameras.
While i am a specialized Pentax user, I also use other brand lenses with other kind of mounts.
Especially M42 and PK* lenses.
To do this, you need an adapter to convert M42 to K* mount ( * also referred as PK mount )
PK* lenses can be mounted without an adapter, but also with this type of lenses, there are many different kind of mounts -> electrical contacts, an A setting on the lens, a switch for manual/auto, metal latches in the mount and hand controlled apertures
Doing this for a while now, i came across a few problems.
But also if you have another brand of camera, or want to use other type of mount, you’ll need adapters and can come across coupling problems either electrical or mechanical.
For this I wrote a few post’s about this subject, you can find them here :