Canon FD 35mm f/2 bayonet mount
Canon EF with mirror and aperture prefire

Vignetting = B @ f/2, A- @ f/2.8, A thereafter
Distortion = slight waveforming with slight barrel tendency

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

Notes:
* = tested with a Quantaray UV filter.
Moderate contrast images at f/22;
moderately high contrast images at f/2 (with and without filter) through f/4 and at f/16;
high contrast images at f/5.6 through f/11.