That was a very good explanation.....THANKS!
Before I lose track of this thread.
Here's a link I found today while looking around for tips on taking racing pictures. I like to see what other people are doing. 90% of the time I say, why didn't I think of that? :thumbup:
http://www.automotophoto.com/images_awheeler06.html
If you shoot wide open, you are going to have better shutter speeds, but pay the price with shallow depth of field.
If you give up a little of that light speed, you will have a deeper margin of error for the focus.
Always the same problem. You can't get both all the time.
Higher ISO you can have more choices, but then you might have a little bit more noise.
Here's some more, not absolute. It's up to you. I try to get the Sun over my shoulder if possible. Not always, but it's a nice start. Better lighting. When you shoot in the morning or afternoon, the Sun will be at a lower angle. This will means less harsh shadows.
As usual, for what you get, you have some other issues. Color shift early and late in the day.
Just the opposite can be nice too for backlighting the shot.
Back to that AI or not. Do some of each. Fast panning, you will get more shots if you pick a spot and pre-focus. If you are at the exit of a corner, the cars/bikes aren't moving as fast, the AF will have a better chance to find the subject.
Coming straight at you, AF often can't pick up on the object, so manual is usually better.
Higher contrast composition, the AF will focus better and faster. Cloudy or less contrast in the foreground and background, and the AF will have problems.
What I'm getting at is there isn't any set rule. AF works, so does manual focusing.
At least with Tv you know the camera isn't going to drop down to 1/30th and try to do the impossible. You might lose a shot because the lens can't open wide enough or because there isn't enough depth of field. But you won't get a huge blob, against a huge blur.
I can't believe I left this out.
Never turn your back on the track! If you are changing a lens, duck behind a barrier. Always be extra aware of what's going on. If you are going for low angle, you might be able to get away with one knee... never even try two knees or anything lower. At 90 miles an hour, the car/bike is traveling 132 feet per second.