I'm thinking about replacing the kit lens that I got with my Pentax K200D. Unfortunately the shop mixed up the lenses and gave me a 18-50 instead of the 18-50 II lens. Not really sure if there is all that much difference but it is a bit annoying. They went bust so I can't really do anything about it anymore. Anyway, I've been looking around and I like the look of the Sigma 18-50 f/2.8 lens. I've even seen a comparison between this lens and the Pentax 16-50 f/2.8 which costs almost twice as much as the Sigma, and the reviewer thought the Sigma outperformed the Pentax lens, despite the price difference. Does anyone have this lens. Any comments on it. Most reviews seem to be to hung up on lab tests without actually taking it out for real world tests.