So I'm shopping around on eBay and just doing all kinds of research (I have 15 tabs open in firefox with different information) and I'm trying to see just how well AF lenses work that were for SLRs and not DSLRs. Quick answer? Don't need a huge explanation unless, of course, there are exceptions and sometimes SLR lenses won't work with DSLRs. I have a d80 and I don't know what lenses I can buy. I know for sure SLR lenses are MUCH cheaper but I don't know if I can get away with buying them. I'm actually looking for my next lens to be a 1.2-1.8 lens for shooting sports with better light without compromising the ISO speed and making it horrible. I've been reading that a 1.4 shoots well with f/2 and higher (or is it lower?) f/2-f/22 etc is what I'm trying to say. Anyway, I went ADD on you all. Just need the quick simple answer to the question: Will older film lenses work (and auto focus) with my D80? Came up with a new question: Is there a formula to figure out what mm is equivalent in feet or something? or even an "x" zoom. Say 200mm is equivalent to 4x (just a guess) what is the way to figure this out?