I noticed the new Digital Rebel has a penta-mirror instead of the penta-prism that the 10D has. What is this and how will this effect the camera compaired to the 10D? I have also read that all focusing is done automatically such as switching from sports to portrait and back to sports if it thinks the subject has moved. How will this effect the camera?? I am wanting a DSLR and I am trying to decide between the Rebel and the 10D. HELP!!!