I shoot BMX at skateparks, mountain biking in the woods, and at parties where light is scarce and shots are very tight. I am just getting going with my 450D/XSi and the 18-55 kit lens and am hurting for better light in these situations.
I've decided I need a 430exii or 580exii. The 580 is about $80 more than the 430. I am also considering a nifty-50, but I'd probably do better with something 16-22mm f/1.X-2.X.
My question is about speed and power. The indoor park is very dim, and I want to be able to capture tight panning sequences with the flash (about 3.5 fps as I understand), but I am unsure if either of the new speedlites fire that fast.
Could someone provide me with some advice on where to proceed?



