SMC Pentax-K 35mm f/3.5
With Pentax digital cameras sticking to a 1.5 crop format APS-C sensor, it makes the 35mm focal length desirable as a standard lens, which conveniently was a very popular wide angle for 135 format (35mm) film. So which of these old manual focus lenses is the best?
Pentax has had 3 series of manual focus primes with a K mount. These are the K, M, and A series lenses. The K are lenses not otherwise marked M or A. The M series was the replacement to the K series, mainly making them smaller and cheaper to construct, and the A series added electrical contacts for the program cameras.
So how does this 35mm f/3.5 perform given that it is 35 years old? Not too bad. The center is strong enough at all apertures, and the partway region is good (this is most of the frame). Only the extreme corners suffer wide open, but resolving power is still acceptable and improves when stopping down. This lens would be best on one of the 10 MP or less cameras, the K-5 starts to press the center resolution.
Thanks to Lloyd Shell for providing this sample of the SMCP-K 35mm f/3.5 to test. He invites you to a gallery of images taken with the lens. Resolution charts follow on the next page (see link below gallery).
Gallery of images I took. These are untouched. Note that the contrast is a bit low and is helped a lot by post processing. There is a bit of purple fringing in high contrast situations (note the star bursts on the water and the overexposed tree shot), and some flare is visible in rare circumstances (see the train).