I used to be a little into photography, but now my brother just bought a Canon Rebel XSi and my parents want to get him a fisheye lens for a graduation present. He wants a fisheye because he wants to start shooting skating/snowboarding I guess. He is pretty creative so I think this shouldn't be a problem for him. Anyway, can someone recommend a good lens to go with around the $600 (online from a reputable retailer) range? I've taken a look at some lenses, and right now I'm leaning towards the Sigma 15mm F2.8 EX. But, then I also saw they have a 10-20mm and was wondering if that might be a better lens to have if he only has one fisheye (although I saw that it seems to have less superior optics than the fixed lens). Thanks for the help.