"Toby"
http://www.canonfd.com/mirrorlenses/index.html
This brochure tells about Canon mirror lenses - 800/1:3.8, 2000/1:11,
5200/1:14. Interesting monsters... Made for a special purpose? Never
heard that we're having something like that now.

Apparently not. They were used for the '64 Olympics and could mount either
Canon SLRs or TV cameras. Did you notice that the 5200mm lens weighed 100
kg?

But 100 kg... But 5200*1.5 for digital... But 100 kg... That's wow! All
current lenses can just relax. I guess that mechanically they should be
very primitive, I'm not even taking about "electronically", the number of
lines per unit is rather significantly smaller, but these terrible
numbers... I'm very impressed. Maybe it was not very bad for TV with its
much lower requirements for the picture?

Just D.