Note, you may be interested in my review of this lens.
I went out in the park with my Reflex-Nikkor C 500mm f/8 catadioptric lens yesterday which prompted me to write this piece. I’ve been asked a number of times on flickr and forums if this lens is worth buying, and my answer is a resounding yes. It’s slow, and the donut boke is infamous, but it also can be sharp, is small, and so hand holdable all day. And despite what some say, you don’t need a tripod, at least not on a sunny day.
I suppose it’s a matter of taste, but at certain ranges, I think the boke gives a really nice cloudy effect as in these pictures I took yesterday. At thumbnail size, it can be a little busy, but at large sizes it’s quite a nice effect.
This lens is easily found under $200, and as such is the cheapest way I know of to get to 500mm (unless you do something crazy like put 2 TC200s on a cheap 135mm lens).
For twice as much as the reflex, you can use a TC200 2x teleconverter with an MF 300mm f/4 or f/4.5. This buys you more flexibility and gives you a bit more reach and lacks the donut bokeh. With both combinations available to me, I tend to use the 300mm a lot by itself and sometimes with the PN-11 extension tube, and the 500mm reflex as much as the 300+TC.
Finally, an old favorite with the reflex lens.