Rene, I have a Rikenon XR 50/1.4 P lens. It is a much better lens than my Pentax SMC-M 50/1.4 in fit and finish, smooth focus, and feel of the aperture setting ring. I find the optical quality excellent. The Rikenon does not appear to be made by Pentax. The mechanical build is different. The "P" means it has the option of aperture adjustment by auto exposure as do the Pentax A lenses. The Rikenon takes a 52mm filter and is heavier than the Pentax M lens. The Ricoh seriol number is 104123. How does that compare with your lens?
Bill Lawlor
