Vivitar Series 1 90mm f/2.5 Macro
OM-1 with mirror lockup
Vignetting = A-
Distortion = none
Aperture Center Corner
f/2.5    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     B      B
Notes: High contrast image.