Del goes "full frame." Canon 5D MK "original"
500mm is not all that "long" depending. I have a 500 and 600 lightweight "mirror" lenses, these work like a parabolic reflector
The two outer ones are 600mm which I converted to M42 screw mount on one, and Canon EF on the other. The middle one is a Tamron 500mm
Below a couple of shots of my power weatherhead. I was standing below it I guess it's ?? 10-12 ft above my head? Top one is a full size crop out of the bottom photo