Canon FD 135mm f/3.5 S.C.
Canon F-1 w/ mirror and diaphragm prefire

Vignetting: A- @ f/3.5, A thereafter
Distortion: none

Aperture Center Corner
f/3.5    B      C+
f/5.6    B+     B-
f/8      B+     B
f/11     B      B-
f/16     B      B-
f/22     B      B-

Notes:
moderately low contrast at f/3.5;
moderately high contrast at f/5.6 to f/16;
moderate contrast at f/22.