I don't inderstand the talk about the extra reach of 1.6 crop cameras versus full frame. It seems to me that whatever reach means, a 100 mm lens has the same reach on both cameras. The issue is whether you want to crop on the camera or later in Photoshop. At a more technical level the issue is what the sensors give you back. The sensor density per square centimeter of the 8.2 megapixels in the 30D is somewhat higher than the 12.8 megapixels in the 5D and that would imply higher resolution in highly enlarged pics, but I don't know how that plays out in practice. Maybe someone else knows. What I do know is that the 5D I now have produces a lot less noise than the 10D I previously had and that is a really useful feature. With most subjects, I have no hesitancy to shoot at ISO 1600 when necessary. And the wider full frame angle gives more freedom in framing the subject. My wife shoots with the 10D and does well with it, but I would never go back.