I have a Promaster 500mm cat lens that I bought new back in the mid-90s. It has come in handy a couple times for shots for which a 28-200 isn't long enough. My main issue with these is that they are tricky for ME to focus, because I don't see as well as I used to, and the DOF of a 500mm lens at f/8 is quite thin. When properly focused, they can do a decent job. When it's the difference between getting the shot or not getting the shot, this lens is adequate for the job.