Leitz 50mm f/2 Summicron-M (4th generation 1978 "Mandler" design, multi-coated)
Leica M2 with self-timer
Distortion = none
Vignetting = B @ f/2, A- @ f/2.8, A @ f/4
Aperture Center Corner
f/2      B-     B+
f/2.8    B      A-
f/4      B+     A-
f/5.6    A      A+
f/8      A-     A-
f/11     B+     B+
f/16     B+     B+
Notes: Moderately high contrast at f/2.8 to f/5.6, and f/16; high contrast at f/8 to f/11.