The Ricoh program lenses are P mount the KAR is an aftermarket mt that allows the lens to be used in program mode on Ricoh and pentax manual focus program bodies. My camera is working with the aftermarket lenses but not the original Rikoh Rikenon P lenses. The only difference between the two that I can see, is the Rikenon lenses have a small "shield" beside the accuating lever. since the shutter doesn't open I can't see what is going on from inside the camera and since it works fine when the lens is removed, I can't see what is happening from outside the camera. Right now I'm using it with the 50mm f1.7 on the 2X multiplier in KAR mt and it works fine.