There is absolutely zero reason to buy this lens if you can swing a used 70-300/4-5.6 IS/VC from Canon or Tamron. It's a piece of crap that'll frustrate you unless you're outdoors in broad daylight.
I completely disagree! I purchased this same lens last fall and have been very impressed with it's sharp images. I use it mostly on my Canon T2i and it surprises me with much better than expected results. I had the Canon 55-250mm EFS lens and it was fine..but at full length, showed soft outer edges. I could crop a little and it's not a issue, but there are images that I did not want to crop. I then tried the Canon 75-300 EF, not stabilized, and I was getting lots of chromatic aberration (CA) in bright sun. I also found it slow to focus..especially at full focal length.
Enter the Sigma: build quality is very good, auto focus motor seems quieter than both of the Canon's, focus is good at all lengths, and it's sharp IF there is good light. But all of these big lens need good light. Is it perfect? No..I get a little purple fringing in certain sunny situations and very light CA..but it's usually when I'm shooting with more sun facing me. Btw, I have captured some really sharp photos at all lengths handheld..that said, bracing on a solid object or a tripod/monopod will definitely work, especially if windy.
Go here (my favorite lens site) to see actual images captured by the Sigma..pretty darn good for a budget priced lens! Btw, click on the full size image tab to see some really good resolution.
Last edited by jimx200; 02-15-2013 at 10:23 PM..