Canon FD 50mm f/1.8 bayonet mount

Canon AE-1 with self-timer only, first sample

Distortion: slight barrel
Vignetting: C+ @ f/1.8, B+ @ f/2.8, A- @ f/4

Aperture Center Corner
f/1.8    C-     D+
f/2.8    B+     C+
f/4      A-     B
f/5.6    A      A
f/8      B+     B+
f/11     B      B
f/16     B      B-

Note:
moderately low contrast @ f/1.8,
moderate contrast at f/16,
moderately high contrast at f/2.8 to f/11.

Canon EF with mirror and diaphragm prefire, 2nd sample

Distortion: barrel
Vignetting: B @ f/1.8, B+ @ f/2.8, A thereafter

Aperture Center Corner
f/1.8    B      B-
f/2.8    B+     B
f/4      A-     B+
f/5.6    B+     B+
f/8      A-     B+
f/11     B      B+
f/16     B      B+
f/22     B      B

Note:
different lens sample than above AE-1 test.
Moderately low contrast @ f/1.8,
moderate contrast at f/2.8 and f/22,
moderately high contrast at f/4 to f/16.