EF 135mm f/2


This is a SEXY lens that takes amazing pictures! I dont' think you'll need the extra reach at all for indoor basketball. In fact, you might be too close on a 1.6x cropped body like the T1i. And, if you're not too close, then you should be just right, or if you need the "reach" - just crop. You've got 15MP to work with there. You really want f/2 or lower for indoor sports. f/2.8 is pushing it, unless the place is VERY well lit. Your 50mm f/1.4 might work if you're able to get real close, but otherwise I'd stick with the 135. Sean said it right that the 85mm f/1.8 would be great. I have no experience with that lens, but hear it's very nice. Focal length sounds good. I have used the 85mm f/1.2 (very expensive) and it's a bit slow for sports but great in low light. The EF 135 f/2 should run you right about a grand. Go for it! again.... SEXY! :P