Ellis Vener , Jul 05, 2007; 02:52 p.m.
Number 1 is I'd switch to digital -- specifically the EOS 1D mark 3. I've shot ALMS at a bigger track the one near Monterey with an EOS 1D mark 2. Even if you have to rent it, do it. You need to shoot a lot to get even a few keepers, and film and processign will eat you up
Forget the teleconverter: anything that slows down focusing is bad. Using a 400mm f/4L DO lens with no converter on with the car coming towards me on a straight section, I'd be tracking focus on a cars nose and consistently the tail would just be what came out sharp --and that was at 8fps. So then I tried prefocusing and the results were consistently no better, tho' if you do this a lot no doubt you'll develop better senses and reflexes.
Scout the location and pick your spot(s). When doing this pay a lot of attention to what the background is and how that works as a part of the composition. Also think about what the light is doign and where it will be coming from later in the day. Once you got a background you're happy with then you can pay attention to the cars.
Practice panning, and here a tripod with a good head really helps. if for no other reason than your arms and back don't get tired holding up the camera and lens. The 80-200mm f/4 yielded excellent results for me.
Lens choice: variety of views is good: it what you want to get is a matter of intent and no one else knows your mind.
Do more watching than shooting during the first laps, you'll get a sense of the race's flow.
Take plenty of water with you.