Plays, basketball games, hockey: f/4, not fast enough really. It will be a struggle to stop motion. f/2.8 is better though still not best, f/2 or faster would be better which means a prime (85 f/1.8, 100 f/2, 135 f/2). But the zoom is versatile in other ways of course but expect to use 3200 ISO if you have it or 1600 at the very least to try and get a decent shutter speed at f/2.8.
Nooooo, not 40D vs 50D again!!! 


