@smithchild normally I'd say go with the AF lens for sports shots of any kind, even if I'd never used it. But if the light is failing you might need the primes.
The problem with this is to let in as much of the failing light as possible you will need to use them as far open as possible, which means narrow depth of field. You could stick them on a tripod, but that won't really help, as the point of a tripod is longer exposure time, which means the riders will blur. Personally I'd go for prime on tripod, compose frame, get the focus dialled in to a particular point, set the drive mode to burst (3 or whatever pics in a row), press it just before they are in focus, et voila.
@smithchild normally I'd say go with the AF lens for sports shots of any kind, even if I'd never used it. But if the light is failing you might need the primes.
The problem with this is to let in as much of the failing light as possible you will need to use them as far open as possible, which means narrow depth of field. You could stick them on a tripod, but that won't really help, as the point of a tripod is longer exposure time, which means the riders will blur. Personally I'd go for prime on tripod, compose frame, get the focus dialled in to a particular point, set the drive mode to burst (3 or whatever pics in a row), press it just before they are in focus, et voila.
Forget the built in flash, they're crap.