Ok, I've read a bunch of threads on the various 500mm mirrors... My eyes are starting to hurt!
It would seem that there really isn't a verdict one way or another. Most of the people who actually use them say they aren't that bad for what you are buying. The nay sayers seem to be comparing them to regular zoom or telephoto lenses and most haven't actually used one. But they aren't comparable lens types either.
A mirror lens has no electronics in it, has a fixed aperture (most seem to be f8 but there is one at f6.3 for a few bucks more) and they are entirely manual. This is all by design. Very similar to a reflector telescope. The big difference being they are much more compact in size and weight.
Having said all that, does anyone have any shots they can post? I don't care if it's a wildlife/birding shot, a sporting event or deep sky shot. I would just like to see what kind of results people are getting from them.
Jon.