Pentax Mount Compatibility

I have a Vivitar v3800N SLR with a stated PK mount and would like to know if this is compatible with the standard Pentax K mount. I recently learned the hard way that a Pentax M42 screw mount lens is not fully compatible with any other standard SLR with a T mount and don't want to repeat a similar mistake. Thanks.

There is just one mechanical K mount. All sub variants are about AF or aperture communication. The standard k-mount communicates the aperture ring setting to cameras able to read that. - The "crippled k-mount" AF DSLRs are not able to read that out. Old k-mount has a non linear movement of aperture lever and blades. Cameras attempting to close the aperture to a value set in camera (Chinon) might be 2/3 of an f-stop off. Ricoh bodies used different electric contacts than Pentax ones for aperture information. - Ricoh auto aperture lenses can be a bit tricky to remove from AF bodies.

 

About m42: No that is not T2 (or such) but you can get fairly inexpensive adapters to hold M42 lenses on a lot of SLRs besides Nikons (& IDK which others), which won't focus to infinity.

Thank you Jochen,

The T-mounts are 42mm, but with a different pitch (x0.75, I think) than the original Contax-S 42mm (x1). Attempts to mix them are a way to ruin the mount and the lens.

 

There are unsubstantiated rumors that the Praktica B and the Pentax K were intended to be compatible, but it didn't turn out that way. Close, but no cigar: