I bought this lens for indoor and nighttime sports. So far I've used it for basketball, gymnastics, concert photography, and night alpine racing. I find the lens to be sharp even wide open, which is good, because that's what it's useful for. The lens is well built and feels more substantial than I expected (I thought it would be more like the EF 50mm f/1.8 II). Of course, as per Canon's policy with respect to consumer grade lenses, it comes without a lens hood. However, the lens is inexpensive (I got mine for $370 online) and the hood is a $24 item, so it's difficult to complain. I've found the lens to be great for basketball on the 30D. The autofocus and reach are much more useful than with the EF 50 f/1.8II, my previous basketball lens. The hit rate is lower than I would like (25-50% for basketball), but since I shoot primarily at f/2 - f/2.2 on a 30D, I think that's to be expected, given the narrow depth of field. This is a particular problem when I'm under the backboard and a player is driving toward the basket. The depth of field is extremely thin under these circumstances and perhaps this is a little too much to expect from a prosumer body. I think a pro body (1D MkII-IV), 7D, or even a 40D/50D/60D would fare better. The images that are in focus look great, however. Chromatic aberration is noticeable in high contrast situations. I notice this some on white, home jerseys around the dark numbers (see sample image). It's only apparent some of the time and it isn't severe. Given the size and cost of the lens, I consider it to be acceptable. I recently used this lens for a Todd Rundgren concert with great results. Highly recommended.