In your comparison, the size of an object relative to the background (perspective) remains the same in the two formats because the two photographs were taken at the same distance. (You have to change distance to change perspective.) The image from the EOS Digital Rebel, however, will show the object taking up a greater proportion of its frame, because its frame is smaller. If this were mere "cropping," you would expect that the resolution of the Rebel image would roughly equal the cropped center portion of the image from the EOS 5D—and this would indeed be the case if this were done on film. But in fact, because of the greater pixel density of the D-Rebel, its resolution of the object's image will be greater than that of the 5D—6.3MP versus about 4.87MP for the 5D. The difference would be even starker with a 12.2MP EOS Rebel XSi, which would produce more than 50 percent greater resolution than the 5D in the same scenario. That ain't just cropping.