I own the canon 70-300 IS lens on a 40D and found it difficult to photograph my son's baseball games at dusk even when cranking up the ISO (too slow a shutter speed). I was considering the 70-200 2.8 IS. I thought it would help and would be a good lens for any indoor sports/school activities. I would consider myself an amateur and am having a tough time "pulling the trigger" on this expensive lens. I probably should have bought that lens in the beginning instead of the 70-300.