Canon FD 300mm f/5.6 S.S.C.
Canone AE-1 using self-timer

Vignetting = B @ f/5.6
Distortion = slight pincushion

Aperture Center Corner
f/5.6    B      B-
f/8      B      B-
f/11     A      B
f/16     A-     B
f/22     B+     B-

Notes:
high contrast even wide open, although only moderate at f/22;
difficult to focus.