Mirror lenses

[ericB&W]

I have also a huge russian MTO 1000 f10 mirror, is not bad but very difficult
to keep steady.
I was considering the Tamron 500 mm to fill the focal gap between my zooms and the
quite unuseful 1000 mm.

 

[Mainecoonmaniac]

This Maine Coon Maniac likes them because they're called "Cat" lenses. AKA Catadioptric lenses.