I have a Baush & Lomb (now Bushnell) 'Discoverer'
15x-60x spotting 'scope. With camera adapter tube and
adapter ring, it becomes a 1000mm-4000mm 'lens'. I put
'lens' in quotes because it is pretty poor as a lens.
1000mm is tolerable if that is all you have. Over that
is garbage. Not to cut up the 'scope, they are just not
engineered for photography. An Astonomical telescope with
camera mount is an entirely different animal. You can try
a 'scope for a lens, somewhat better than nothing. Good luck.
/Clay