I realize I likely won't be able to get a good specific answer to this question here, but any general advice would be appreciated. I recently purchased a new Canon Rebel XTi, and I like it quite a bit. I also have a high-end (at the time) Canon film camera from roughly 10-15 years ago (before digital cameras existed). The film camera has a really nice zoom lens that's much better than the one that came with the XTi. Since the XTi was a fairly large drain on my disposable income, I'm not willing to buy a new lens at the moment. Fortunately, however, my old lens from the film camera appears to work with the XTi (or, at least, auto-focus does). My question, then: is there any reason you can think of to NOT use the older lens instead of the lens that came with the XTi? For example, could it negatively impact the pictures? For the record, the old lens is a Ultrasonic 28-105mm Vivitar lens (To find that, I simply wrote down everything written on the circumference, so I don't know what order it should be in). The film camera is a Eos A2e. Thanks.