Canon FD 100mm f/2.8 pre-S.S.C. breech mount
Canon F-1 w/ mirror and diaphragm prefire

Vignetting: A- @ f/2.8, A thereafter
Distortion: moderate pincushion

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

Notes:
provisional SQF grades at f/8 due to overexposure;
moderately high contrast at f/2.8 and f/4;
high contrast at f/5.6, f/22 and provisionally at f/8;
very high contrast at f/11 and f/16.