[cupic]

I found a old near new that I originally bought (for my Pentax ME Super) in 1989 and was wondering if it has a problem mounting on a K20D
Its a Sigma 35-70mm f/2.8-4 Macro , Zoom Master.I have inspected the mount and it doesn't have pins but ball on the mount cap it has stamped on it

For Pentax -K and Ricoh XR-P

cheers

[usn ret]

Sigma lens will fit and work in manual mode, looks like a good piece of glass. I have several pieces of old glass that work just fine on K7 and K2000. Get your owners handbook out and do some homework. Manual focus, manual aperture and shutter. Install and use/play with it and get to know the lens on the K20..Have fun.Cliff

[Douglas_of_Sweden]

Careful now! If it is marked RIcoh P it will have Ricoh's own electronic mount (corresponding to but not compatible with the KA mount). The Ricoh mount has got a ball instead of the KA contacts for communication between camera and lens.
It mounts as a K (not KA) lens without problems on a Manual focus Pentax film SLR. But in autofocus bodies, the Ricoh ball can get stuck in the screw drive auto focus gear of the camera mount, and the lens will sometimes be very hard to remove. Or so I heard. I have no Ricoh P lenses, and have never experienced this myself.

[Designosophy]

I had a Sigma 70-210 manual focus lens that had the ball-type Ricoh contact. The ball-type Ricoh contact doesn't interfere with AF because it does not extend from the mount.

[Douglas_of_Sweden]

I have got the feeling from peoples comments that it is Ricoh's own P lenses that cause most problems, but that often the third party lenses have a simpler design on the ball that does not interfere. But there are reason non the less to be cautious.