What does a more expensive digital camera do for you? The 8MP Canon 30d is a couple hundred more than the 10mp rebel xti, so I'm guessing that camera must have something going for it besides the megapixels. Moving beyond that, why spend 2k on a camera? What's it doing for you? The websites like to throw around marketing terms like "CMOS Sensor" but I don't know what that is or how that makes better pics. I guess along the same lines, what does a very expensive film camera do for you? It was my assumption that with film it was mostly the lens, film, and shooter, what does a 1-2k camera do that the lower end models can't? Thanks.