Focus method for races

[brmill26]

Hey guys, I haven't posted much in this forum yet, but I'm a huge race fan. Coming from P&S, I'm used to pre-focusing and then trying to capture the vehicle at just the right moment.

I'll probably be going to an Autocross event next weekend, which I'd like to use as a little practice, b/c in a couple weeks I'll be at the AMA Supercross in the rather dim Georgia Dome. I'm shooting with an XTi and the 50mm F1.8 II (a non-USM lens), which is, to me, is a much faster-focusing setup than the old POS, but I know it's not exactly a fast sports lens either.

So, the point: is it better to try to pre-focus and then pan with the vehicle to capture it, or is AI servo the way to go - and if so, should I use the center-point focus? The Autocross probably won't be too bad, being outdoors, but for the Supercross, I know the focus will have to be basically perfect to account for the thin DOF at the wider apertures I'll have to use (hand-held only). Should I attempt to use the body's flash for the Supercross? Thanks for your suggestions.


This is the best image I took with the POS - 3x zoom, ISO 400, no flash (it was useless anyway). The "Greatest of All Time," Ricky Carmichael, from 2005.