Spent Saturday with a friend at Mid-Ohio raceway, watching the motorcycles zoom around the twisty, hilly course. The weather was mostly to partly cloudy (great for shooting). I did this to add to my stock library, and to practice shooting rapidly moving targets. You can see the results here
This ain't easy. You need a fast autofocus system, a very long lens (as fast as possible), and quick reaction time. If your lens isn't particularly fast, you're going to need to shoot at high ISO and hope you don't get too much noise.
Here's what's going on. Imagine you're located at a fixed point. You can spin around, but you can't move away from your spot. Now, imagine a motorcycle located, say, 1/2 mile from you traveling along the edge of a perfect circle. Imagine also that there's a long rope connecting you, so that as the motorcycle travels along, you pivot to keep it in the view finder. Finding the subject, framing it, focusing, and pressing the shutter can take four or five seconds, which is all the time in the world.
Now imagine that same motorcycle is 250 feet from you, coming towards you, and at 100 feet or so suddenly veers away. Oh, yes, and it's doing 180 miles an hour. Not so easy now. First, your autofocus is going to fight to keep this target in focus because the distance to the camera is changing really fast. Second, you now have about 1/2 second to compose, lock, and shoot.
I was shooting mostly at 1/1250 of a second, ISO 1400, f5.6 with a 70-300 mm lens. You'd think that 1/1250 would freeze the action solid .... but it doesn't. In shots where the motorcycle was closest to me and traveling in a straight line at, say, 130 miles an hour, I'd see motion blur. That's because the motorcycle is traveling about 6 inches during your shutter click. Even if you're perfectly tracking it (pivoting very rapidly and hoping you don't fall over your own feet or bump someone next to you), you're going to have some motion blur. The closer to you the cyclist is running, the more blur you're going to get.
Depth of field is another issue. If the bikes are in a line, and you're shooting wide-open to get the shutter speed up, you're going to have relatively shallow depth of field. The cure for this is to get high up and shoot at a downward angle.
If this sounds like I'm whining, I'm not. Learning how to anticipate (listen for the engines changing pitch), how to keep the panning motion smooth (follow through; don't stop when you think you've got the shot), how to get the best results.... for me, that was fun.
Enjoy the pictures! You'll get similar training from shooting volleyball, diving, and parachute landings. Hope you have as much fun as I did.