I thought I would chime in with my dos pesos.... I know it is not popular to say anything nice about Sigma lenses, but mine has been a fine lens. Just after purchasing my first Pentax, a PZ-70, I needed an AF lens with a bit more reach. B&H had a sale going on and they had a Sigma 1:3.8-5.6 28-200mm zoom AF in Pentax mount, so I bought it. This was in the mid-90's and to this day has performed flawlessly and has made many excellent images, up to 11x14. I have used it on the 70, a PZ-20, and in manual focus on a Chinon They later had an improved version with APO glass. Because of its range it has become my walking around lens.... no mechanical or other problems, including 3 trips to Ireland, so I can recommend it without reservation. Only gripe, does not focus particularely close.
Jerry in Houston
