Sigma lenses on Olympus 4/3
Only Sigma I own is the 105 macro. I like it pretty well. Not in the same class as the 50 Oly Mac, but it's a good, sharp lens with decent color rendition and contrast. I'd say AF is about what you see on the "Standard" grade Oly's. Only thing I really don't like is the finish. It's kind of a black matte that is prone to collecting dirt. I'm happy with it, and wouldn't sell it. I waited and waited for the rumored Oly f 2.8 macro and finally just gave up and got the Sigma. Glad I did.