I have a 20cm Q and an AiS. They're both great but I still don't seem to use them very much. The focus throw is pretty long, I don't know how sports photogs did it before AF, but it keeps me from having to track back and forth a lot to find focus. If you have a split prism screen like the F's 'A' screen f/4 is close to the point where one of the split sides will go dark and you have to use the surrounding matte. The old non-Ai lenses look rather funky too. They're classics; light, sharp and cheap enough that almost anyone can pick one up if they want to.