Tom: I think a lot of it comes down to personal experience. I've never even touched the 105mm Sigma so I couldn't say one way or the other. I do know that it rates pretty good on PhotographyReview.com (see link) with 72 reviews from consumers, it rates a 4.67 out of 5. I've seen a couple guys on DPReview rake the Canon 70-200 f/2.8L over the coals. I've used this lens a half dozen times (I'm renting the IS version again this weekend for an event) and I know this lens is phenomenal. But the copy they had was apparently defective. shrug. Yea, the compatibility bothers me sometimes, but so far Sigma has stood behind their lenses. When the 10D came out and it was found that some older lenses didn't work, Sigma immediately let it be known that if you sent the lens in they would reprogram it and clean it at their cost. That's pretty good. Don't get me wrong. I love the Canon lenses (28-135IS, 28-70L, 70-200L), but in my experience the Sigmas have been very good lenses at an exceptional price point. Smaller pic? What??!! Are you insane!!! Do you know I beat the last person to within an inch of his life with a small, wet napkin when he asked me to do something like that??!!! :) Sorry, I didn't realize how big that photo was. Will delete it. -=>Donald.