Canon FD 50mm f/2 (bayonet mount, S.C.) Canon AE-1 with self-timer only Vignetting = C @ f/2, A- @ f/2.8, A @ f/4 Distortion = none Aperture Center Corner f/2 B- B- f/2.8 B+ B f/4 A- B+ f/5.6 A- B+ f/8 A- B f/11 B B f/16 B+ B- Note: moderate contrast, except moderately low at f/2 and f/16.