So, I recently bought a Nikon F100. I want a telephoto zoom. I'm probably going to save up and get an 80-200 f/2.8 D eventually, but in the meantime, I want to get a cheaper used zoom. I'll use it sometimes with my d70 as well, but probably not often. The top contenders so far are: -Sigma 70-300 f/4-5.6 APO -NIkkor 70-300mm f/4-5.6D ED AF -I've also looked around at the older Nikkor 75-300 f/4.5 AF lens, which it seems a lot of people have good things to say about compared to the newer 70-300, so maybe I should throw that in too. All can be had for around $100-150 depending on its condition Aside from image quality, one thing that I want to know about is focusing speed. I have a Sigma 24mm 1.8 and it's a SLOOOW focusing (on my d70), heavy lens. It is a very crisp lens though and gets the job done nicely when I use it. Also, since i'm going to be using it mostly on a film body, and the Sigma APO seems to be optimized for digital, is there any reason why I shouldn't get the older cheaper version of it? So, any thoughts?