Test of two telescopes and Canon 'L' telephoto lens
Yesterday I tested two telescopes and a 300mm Canon lens for their sharpness and color errors in prime focus.
Even a short (f/6.3) achro renders quite good images.
Small refractors make decent telephoto lenses. This shot was taken through a Megrez 72 and a Canon 7D using a Skywatcher field flattener. It's tack sharp but lacks the depth of field you get with a good camera lens.