Olympus 65-200mm f/4 Zuiko (multi-coated) 

(multi-coated)

@ 65mm setting
OM-1 with mirror lockup, pre-overhaul
Vignetting = B-
Distortion = slight barrel
Aperture Center Corner
f/4      C      C+
f/5.6    B      B
f/8      B      B
f/11     B+     B+
f/16     B+     B+
f/22     B      B
f/32     B      B
Notes: Very high contrast.

@ 90mm setting
Vignetting = B
Distortion = slight pincushion

OM-1 with mirror lockup, post-overhaul (shop disassembly & reassembly)
Aperture Center Corner
f/4      B      B-
f/5.6    B+     B
f/8      B+     B
f/11     A-     B+
f/16     A-     B+
f/22     B+     B+
f/32     B+     B
Notes: Moderately high contrast at expense of resolution.

OM-4 with mirror and auto diaphram prefire, plus Bogen Telephoto Lens Support; post-overhaul (disassembly and reassembly)
Aperture Center Corner
f/4      B+     B-
f/5.6    A-     A-
f/8      A-     A-
f/11     A-     B
f/16     B+     B
f/22     B+     B
f/32     B+     B
Notes: Very high contrast. Not evaluated in side by side comparisons with the 90mm focal length test above, so differences significant at full grades only.

@ 135mm setting

OM-1 with mirror lockup, pre-overhaul
Vignetting = B
Distortion = moderate pincushion
Aperture Center Corner
f/4      C      C+
f/5.6    B-     B
f/8      B      B
f/11     B      B+
f/16     B      B
f/22     B+     B
f/32     B+     B

@ 200mm setting

OM-1 with mirror lockup, pre lens overhaul
Vignetting = B
Distortion = moderate pincushion
Aperture Center Corner
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-
f/32     B      B-
Notes: Differences with the OM-4 below are significant at full letter grades only.

OM-4 with mirror and automatic diaphram prefire, plus Bogen Telephoto Lens Support; post lens overhaul
Aperture Center Corner
f/4      B      B-
f/5.6    A-     B-
f/8      B+     B
f/11     A      B
f/16     A-     B
f/22     B+     B
f/32     B      B-
Notes: Differences with the OM-1 test above are significant at full letter grades only. Moderately high contrast at f/5.6 to f/11. Significantly reduced contrast at f/22 to f/32.