Canon FD 35mm f/2 breech mount, S.S.C. convex front element version
Canon EF with mirror and diaphragm prefire

Vignetting = B- @ f/2, B+ @ f/2.8, A- @ f/4, A thereafter
Distortion = barrel

Aperture Center Corner
f/2      B+     B
f/2.8    A-     B+
f/4      A-     A-
f/5.6    A-     A-
f/8      B+     B+
f/11     B      B
f/16     B      B
f/22     B-     B

Note:
high contrast at f/5.6 and f/8;
moderately high at f/2 to f/4, f/11;
moderate contrast at f/16 to f/22.