I was interested to come, by chance, across this review article by gun guys who use spotting scopes to check targets at great distances.
What was interesting to me is that many things we see discussed in our forums are present here too: color correction, aperture, stability of mount, eyepieces, even seeing conditions!
It's an interesting read.
The major difference is they have some control over the *distance* of their viewing objects. The central problem of how to detect a black hole in a black bull's eye is what we would call a low contrast issue. And to get that low contrast, color corrected image they are reaching for names familiar to all of us...Zeiss, Pentax, etc.