A lens that gives good sharpness within the 300-dollar price range. The problems are: you need to stopped down to at least to f8 in order to gain good sharpness and it's soft beyond 200mm, the filter thread turns when focusing (which means you'd better switch to MF when adding filter or hood otherwise you might damage the AF motor), there's no zoom lock and the zoom does creep, and finally I don't like the Sigma color at all. So basically it's a lens for sunny days. The contrast of this lens is noticeable lower than my Nikon lenses and it does flare, so watch out for it. AF is very slow. One of my friends used to have another copy and he told me that the paint with shiny spot does come off. Anyway, it's still a good performer in its price range when I bought it (otherwise I'd have bought something else); now I suppose the new Nikon 55-200mm DX is not too bad but lacks the 300mm end. This lens weighs 550g.