>I am looking at buying a 1000mm for important but occasional use. The >Nikon 1000mm catadioptric is a bit expensive and the 1 review I have >found rates it as optically so-so. There are two Russian 1000mm cats I can't comment on the Russian lenses or the Celestron C5, but I can tell you that my 1000mm Nikkor is clearly sharper than the Celestron C90 that I tried. Of course, my experience is limited to one of each, so YMMV etc. Also, from looking in the pages of Shutterbug and going to trade shows, I believe that with some patience, a used 1000mm Nikkor in clean condition can be obtained for about US $ 1,000. That's quite a bit less than the new mail order price!
