I am age 81 and have a number of expensive (in pre-1985 era) lens for the Canon AE-1 and Canon T-70. I have been sticking strictly to cameras like the Canon G6 but have now acquired a Canon Rebel XT. I know that the older lenses will mechanically go on the Rebel XT. I would think that for the zoom lenses I would want something like the Canon 70-300mm F 4.0-5.6 IS USM and Canon EF 28-125mm 3.5-5.6 IS lens to take advantage of autofocsing. But, what are the problems to be encountered in using non-zoom older lens such as the Canon FD 50mm 1.4 or Canon FD 28mm 2.8? I realize I need to "go back to school" and read up on the current camera technology. I realize that the area of the digital sensors is much smaller than the old 35mm film area. But, wouldn't a good 28 mm or 50 mm fixed focus lens from the 1980s give comparable results to a newer Canon 28mm or 50mm lens?