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Forum: Pentax SLR Lens Discussion
07-08-2008, 11:51 PM
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Short question: A K-mount lens should work on a Ka-mount body in aperture priority or manual exposure mode, right?
Longer question: I was home to see my parents this weekend, and I found a stash of old SLRs that haven't been used for over 20 years: a Sears KSX with a K-mount 50mm f/2 and a K-mount 135mm f/2.8, and a Pentax Super Program with a Ka-mount 28mm f/2.8 and a Ka-mount 50mm f/1.7. All nearly mint condition, all apparently never used because almost no one took the time to learn how they worked. The Sears camera (which is built like a tank) was in a diaper bag.
I took the Pentax body, the 28mm, the 50mm f/1.7, and the 135mm f/2.8 body back with me. The camera and the Ka-mount lenses work just fine, and I'm looking forward to shooting with a decent film camera. However, the 135mm doesn't seem to work correctly on the Pentax. The meter massively underexposes (at least 5-6 stops), and it doesn't seem to reflect any changes I make on the aperture dial. Nothing changes when I manually stop the lens down with the depth of field preview lever.
Am I wrong that K-mount lenses should work on the Super Program body, or is it some weird issue with a third-party lens? For reference, it's a Sears 135mm f/2.8, 52mm filter size, built-in lens hood, stops down to f/22, 6-bladed aperture, looks to be multi-coated. I've not had a chance to check the optical quality, but it just sort of feels like a good lens, and I'd like to be able to use it.
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