Cyclocross is a wonderful sport to photograph. No sidelines, no referees getting in your shot, it is truly a spectator's sport. You can get right next to the riders whizzing past you. You can cross over the course to get to where the action is because the course is only a bunch of caution tape strung between stakes. You get plenty of opportunities for a great shot because you know the riders will be coming back around. A cyclocross race is a great place to experiment. I raced the Orchard Cross race near Portsmouth, New Hampshire as a Cat 4 two weeks ago. Afterwards I went out with my gear and spent a short time playing around with my speedlites and high speed sync. This is my firt time trying this kind of lighting. I was using two 430EXII's as my main lights and a 580EXII on camera as my master and on camera fill. This setup was pretty nice because it was light weight and easy to set up. However, I quickly found the need to keep everything in view of my on camera flash quite limiting. It forced me to re-adjust lights almost everytime I moved my camera's postion, and prevented me from putting my lights behind me. I also didn't like the extra weight of the strobe on top of my camera.
The flashes were kept on ETTL to automatically compensate for the different lines the riders were taking. Here and there I would change the flash exposure compensation on the individual strobes to have them act more as key and fill lights when I wanted to. Pocket Wizard FlexTT5's would have been nice to have especially with their new ST4 adapter to control Elinchrom RX systems remotely.
Another issue I ran into was focusing. I was generally shooting at ISO 200-400 and f/3.2 on my 70-200mm lens to keep the strobes from working too hard. So I couldn't just blast off four frames each time a rider would go by because the strobes couldn't recycle fast enough. I had to prefocus and then hope I tripped the shutter at the right moment. With the shallow depth of field brought by the large apertures I was using I got a lot of out of focus photos. Some external power packs would have been welcome to speed up recycle times but the rechargable NIMH batteries that I use are actually quite good and I can't see the value in external packs at this point.
The first place I photographed was in the shade underneath a bunch of apple trees. I was able to underexpose the ambient light quite a bit here. The other I also went right out into the middle of a field where the sunlight was quite bright and shot some photos. It was here that I kept the ambient only slightly underexposed and helped shape the light with my strobes. I think I had my most successful photos from this setup.