Focus method for races

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.

On-body flash, while better than your old P&S, still probably won't be enough to make a difference.
Though if you're close enough to use the 50mm, then you might get benefit from the flash.

If you're using AF, definitely stick with the centre focus point.
It works the fastest, and is best in low light.

The 50mm just won't focus fast enough for fast moving objects even on a 1D series camera, put it on an XT series and the speed drops considerably. Prefocus and you'd be OK. A flash would get rid of the shadows but you'd need at least a 580EX flash to get the range youd need for these types of shots. A 70-200 and a flash would work well here. The built in flash is pretty much worthless though.

JS

I know this is not the ideal setup, but it's all I've got to work with at the moment. I'm very much still learning anyway, so I'll see what I can get. The Auto-x shouldn't be that big of a problem. The Supercross, I'm thinking during practice I'll be able to get within 30 feet or so, so hopefully with a little cropping I'll get some decent web-usable images; getting the focus spot-on and the right panning speed will be the challenge.

Thanks for the quick response and great tips! I'll share if I get anything decent.

Check out the recent racing thread, I posted a good link there on panning, it should give you more ideas to work with. Smooth panning is a trick, practice helps. One thing that you need to do is make sure your not moving the camera as you push the shutter button. This happens a lot, especially with lighter cameras. Also lwith the lighter cameras people tend to pan too quickly.

JS