So after much internal and external debate, I ponied up the dough for a used 17-35mm f/2.8L and I'm pretty excited. However, I've heard that the lens hood might not provide the necessary coverage on a cropped sensor body (I've got a 30D). Is this true? I know the lens is the equivilant of 28-55 (or so) on my camera, but I didn't realize the crop factor would impact usefulness of the lens hood. I hear that the 17-55mm hood works on this lens as well as the 16-35, and 17-40. So I'll get one if it will work better, but I'd just never heard of this before.