I really love my new Nikon FE2, but desperately want a new lens. The Soligor 24-80 isn't too bad, but the zoom function has trouble holding a constant focal length. So I'm looking into getting some Nikkor primes, but am confused about the Nikon system. I'm a Pentax guy and have gotten used to their K-mount system so never really had to worry about compatibility. Nikon's got me stumped. I wikipediaed the camera and lens, but got lost somewhere in this whole AI or non AI deal. And the Nikonian site lists a bunch of lenses and body combos, but not the FE2. So, in short, can anyone tell me what kind of lens mount/AI/non AI deal I should look for? Oh, and while I'm at it, what's with the little metal 'tab' that sticks up off the aperture ring?