First off, I'm very new to the SLR scene. I found a Nikkormat FTn on CL for $20 and it came with the standard 50mm f/2 f-mount lens. I was told it was a good deal (not by the seller, but by some other friends online), and probably a much better camera than my Minolta X-700. Needless to say, I got the thing. I'm looking for a few lenses for it, but I don't understand lens mounting systems and how to look for lenses on the internet or in shops. I know it is a Nikon F-mount, but that's pretty much the extent of my knowledge on this subject. Can someone help me out and explain lens mounting systems? I'm totally in the dark.