Here's one I haven't seen before: Canon Mirror Lens TV-800mm f/3.8
It has mounts for both Canon TV and Canon SLR (R-mount)*. Note the size difference between the front cap (with "Canon" on blue circle) and the rear cap, which is leaning on the front cap, in the first image below.
It's the smallest of a rare trio: TV-800/3.8, TV-2000/11, and TV-5200/14.
Check the size of the SLR stuck on the back of the 5200/14 (second image below). It looks like the cap for a PC sync port.
P.S. The starting bid of 4,863,637 yen (about $49k CA) for the lens in the first photo, is much lower than you might expect, because the lens has fungus and some scratchy bits. You could probably get it cleaned up for $5k, and still be ahead.
* R-mount is the old (1960's) predecessor to the FD mount, not the modern RF-lens R-series digital cameras.
Canon TV-800mm f/3.8, current listing on Yahoo! Japan Auctions, ID q1184931631
Canon TV (and SLR) Mirror Lenses, courtesy Ernst Thiel NL, posted on mir.com.my (Leonard Foo's place)
Those are CAT lenses designed for mid-century orthicon tubes. I would not be expecting high IQ. Imagine being the grunt having to haul and set them up all the time.
