(multi-coated)

OM-1 with mirror lockup
Vignetting = A
Distortion = none
Aperture Center Corner
f/2      C+     C+
f/2.8    B-     B-
f/4      B      B
f/5.6    B+     B
f/8      A-     A-
f/11     A      A
f/16     A+     A
f/22     A-     A-
Notes: Exceptionally high contrast images with exceptional image detail in low contrast range details; remarkable lack of vignetting wide open.

OM-2000 with mirror and aperture prefire, same lens as above
Aperture Center Corner
f/2      *      *
f/2.8    B-     B
f/4      A      A-
f/5.6    A      A-
f/8      A      A
f/11     A      A
f/16     A-     A-
f/22     B+     B+
Notes: * = not available. Moderately high contrast, except moderate at f/16 & f/22.