I just got a 70-200 f/2.8L IS. I just don't think it's up to par. Maybe a bad lens, maybe I expect too much; but it's not near as sharp as my f/4.0 was. I'm considering returning it but I need some advise. Should I go back to my f/4.0 of try the f/2.8 without IS.
Do you really need IS with the high shutter speeds used for sports photography?

