Quote Originally Posted by shutterdown View Post
Wouldn't the subject and the optical axis be on nearly the same axis with an extended zoom though?
Yes, so you need to get the flash away from that axis.

Also, as Mark points out, it's more of an issue with longer focal lengths because of the narrower angle of view. I suppose that's what you meant by 'zoom' but telephoto would be the correct term (the 8-15mm fisheye and 16-35mm are zooms, too, but less prone to redeye).