Leitz 28mm f/2.8 Elmarit-R (1980 3-cam)
Leicaflex with mirror and diaphragm prefire
Vignetting = C @ f/2.8, B @ f/4, A- @ f/5.5, A thereafter
Distortion = slight waveforming with no tendency
Aperture Center Corner
f/2.8    B-     C+
f/4      B      B-
f/5.6    B+     A-
f/8      A-     A-
f/11     B+     B+
f/16     B+     B+
f/22     A-     B
Notes: Moderate contrast at f/2.8; moderately high contrast at f/4 and f/22; high contrast at f/5.6, f/11 and f/16; very high contrast at f/8.