I got my old FD 500mm f8 Cat lens out for some playtime. Of course the birds were not cooperative. So what else, shoot their house!
Catadioptic reflex telephoto mirror lenses don’t autofocus. Plus, their smaller apertures (f/8 for my 500mm) make accurate manual focusing difficult. Secondly, there are no such lenses with image stabilization. They can produce doughnut shaped out of focus highlights, mistakenly called Newton's Rings sometimes. They vignette more than refractor lenses do typically.
No lens correction in LR, darn!
Used on my 1D Mk IV with an Ed Mika glassless converter.
The young lady stopped by for a bite. Finally. They must be thinking about the long flight ahead of them.
FD 500mm f8 Cat lens on a 1D Mk IV. 500mm, f8, SS 1/1000 at ISO 800. No IS. No lens correction in LR. No AE or AF, no nothing. Hand held. I love it! They way it is supposed to be. 
