I am looking to buy a 50-150 f2.8 sigma. (I think this is my only choice for a fast compact medium zoom?) Would the newest verson be any better than the old one to use in a dim arena shooting hocky (on a canon 40d)? I have heard that buying Sigma lenses can be hit and miss util you get a good copy. With this in mind I am thinking that I would likely be better off buying new at a local store with a good return policy incase I get a dud - or unless I find someone very trustworthy with a good used one. Any thoughts?
Also - I am very new to all this and am wondering if I'll be able to tell if my lens is as sharp as it should be. What is a good way to judge?
Thanks very much for all your help. I have gotten great advice on this forum.