Your best cheap telephoto that's actually worth owning is likely whatever used Pentax 300 f/4 lens you can turn up for the least money, matched to a Pentax 2x converter. I owned a cheap 500mm mirror lens once. You'd get sharper photos by shooting with a 50 on fine grain film and enlarging.
Don't forget, whichever way you go, to allocate a substantial amount of money for a rock-solid tripod. Shooting at 500mm and up is a real adventure in camera shake. -- Bob Keefer Keefer Photography www.bkpix.com
