While fiddling with my camera about a year ago I found the auto exposure bracketing feature on my Canon Digital Rebel XTi. I've been pretty satisfied with it so far, but I'm a little disappointed that it only does 3 frames. I know that the Nikon D200, for example, does up to 5 or 7 frames.
Does anyone know if it's expandable? If not, then do you know why it's only 3 frames? Is it because the burst mode is only 3fps?