(multi-coated)

OM-2S with mirror and diaphragm prefire

Vignetting: B @ f/2.8, A- at f/4, A thereafter
Distortion: NA
Aperture Center Corner
f/2.8    B+     B
f/4      B+     B
f/5.6    B      B
f/8      B+     B
f/11     B+     B
f/16     B+     B+
f/22     B-     B-
Notes: Moderate contrast at f/16 and f/22; moderately high contrast at f/11; very high contrast at f/2.8; extrememly high contrast at f/4 to f/8.

Test subject modification: map was hung in a 180 degree arc with the lens on a plane with the two ends of the map.