Originally posted by atomic Another question if I see a pentax older lens on ebay and the seller described it as having a k mount. Will I need an adaptor to put on my k-r? What if it is a old sears pentax lens or seller said it will work on a pentax camera and describe as having a k mount? Are sears lens any good?
As the posters above said, all K-mount lenses will fit on your Kr and our other dSLRs. The exceptions: some few lenses marked Vivitar that have an oversize aperture guard. And some few lenses with the Ricoh pin. Both can be removed as described.
The K-mount has a number of variations:
- KM or PKM: On K-series lenses (which only say Pentax SMC) and M-series lenses (like M50/1.7), is only a mechanical aperture link. Use these in M(anual) mode.
- KA or PKA: On A-series lenses (like A50/1.4) there are also electrical contacts on the lens base, allowing the aperture to be controlled from the camera.
- KR or K/R (but not KAR, which is Konica): On Ricoh-compatible lenses is also the bothersome Ricoh pin or the harmless Ricoh button. More on this below.
- Autofocus (full-frame): On F- and FA- and FAJ-series lenses (like F35-70) is also a hole for the AF drive screw. This hole is what a Ricoh pin can get caught in.
- Autofocus (APS-C): On DA- and DAL- and DFA-series lenses (like the DA18-55) are all the above, but without an aperture ring. Can only be used on APS-C dSLRs.
- K-zero: These have no aperture linkage at all, just the K-mount bayonets. This mount is mostly seen on adapters, macro tubes and bellows, and some mirror lenses.
Like Vivitar, Sears contracted with various lensmakers. Many different models of some lenses exist; I know of at least 6 versions of a Sears Auto 135/2.8.
Some Sears lenses are extremely good. I have never encountered a bad Sears lens, and I now own 8 and have sold another 10. Focal (K-Mart) contracted with many of the same lensmakers. The Focal-brand lenses I've encountered are about as good as Sears, but with a more limited selection. I own 4. All the Sears and Focal A-type lenses I've seen are KR-mount, with the safe Ricoh button.
KR lenses can also be distinguished by the markings on the aperture ring. A Pentax A-type lens has an A (for AutoAperture) next to the 22 mark. A Rikenon (Ricoh) lens has a P there (they call the mode Program, not AutoAperture) and may have the bothersome pin. The Sears and Focal KR lenses I've seen have an A(P) marking there, and only have the safe Ricoh button.
All the KA and KR and F and FA and DA lenses have electrical contacts on the lens base, to transmit aperture information and control, making flash use easy, and storing the aperture information in a picture's EXIF data. These lenses are easy to use. For the other K-mount types, see the USING MANUAL LENSES link provided above. Have fun!