Knut, You're right about the 35/2 FA; I had forgotten about this autofocus lens.
I guess I stand corrected about the Sigma 50 macro being sharper than the Pentax 50/2.8 FA. It sharpness is nothing short of phenomenal. Yoshihiko Takinami writes: "This macro is excellent not only for macro work but also for normal use. Better than Sigma EX because the SMC coating is better.... In my experiences, FA50/2.8 macro seems the *sharpest* with great resolving power and contrast. And David Collett of Oxford University: "My top two sharpest primes (from a subjective rather than objective measurement) are the FA50/2.8 macro and my k35/3.5. My A50/1.4 is a pretty close third." In favor of the Sigma, Tanya wrote, "Took the most three-dimensional-looking pictures I've ever seen." And there are also numerous superlatives, as I recall, by users at the various lens rating sites. I think Tanya's comment and others I've read left me with the impression that the Sigma was the macro to beat. Now to the 135mm contest: Pentax 135/1.8 vs. Vivitar Series 1 135/2.3. Somehow, all my collected comments on the Pentax have been erased. The comments I've collected about the Vivitar state that it's sharp at all apertures. The Pentax, as I recall, must be stopped down a bit to become truly sharp. Not surprising, since it's about two-thirds stop faster but only 5mm wider in filter size. I was drawing an inference that it "can't" be sharper than the Vivitar. I also agree with you that the lack of an autodiaphragm can be a big drawback. Paul Franklin Stregevsky - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .