* Button for Focus

I am curious when I might use the 4 different settings for the * button

I mainly shoot sports and was wondering on my camera the * button on my XTi its under CFn. 4 and I have options 0-3 listed below.

which one is best for sports and what might I use the others for?

0 = AF/AE lock
1 = AE lock/AF
2 = AF/AF lock, no AE lock
3 = AE/AF, no AE lock

Ready for a long read??
All your answers are here
https://photography-on-the.net/forum/showthre​ad.php?t=46965

First of all, you should understand that everyting before the slash / refers to shutter button, everything after the slash refers to * button.

is the default, the ‘regular’ setting.
Half pressing the shutter button will lock focus; full press will actuate the shutter.
Exposure is locked with the press of the * button.

1 is the opposite of 0.
Half pressed shutter button locks the exposure, pressing the * button executes auto focusing.
This is convenient when you want to meter off one part of the frame, lock the exposure, recompose, focus on the other part of the frame and shoot.

2 auto focuses with half pressed shutter button; stops and starts again auto focusing with * button.
Exposure is not locked until shutter is fully pressed, just before the shot is fired.

3 is very convenient for sports and wildlife, when subject moves through different lighting.
Auto focusing is started or stopped with the * button, exposure is locked just before the shot is fired.

Good link.
0 & 1: I never use Cf4 for that. First set the f-stop & shutter speed you need. Then adjust the ISO. Need an exposure crutch?

How the subject affects the exposure & why manual keeps me worry free: Post #47