(multi-coated)

@ 100mm setting

OM-1 with mirror lockup, sample 1
Vignetting = B at f/5, A thereafter
Distortion = none
Aperture Center Corner
f/5      C+     B-
f/8      B+     B
f/11     A-     B
f/16     B+     B
f/22     B-     B-
f/32     B-     C+
Notes: Moderately low contrast at f/5, moderate contrast elsewise.

OM-4T with mirror and diaphragm prefire, sample 3
Vignetting = None
Distortion = slight barrel (None?)
Aperture Center Corner
f/5      C+     B-
f/8      B      B
f/11     B+     B
f/16     A-     B+
f/22     B      B
f/32     B-     B
Notes: Low contrast at f/32, moderately low contrast at f/5, moderate contrast at f/8-22.

@ 150mm setting

OM-1 with mirror lockup, sample 1
Vignetting = none
Distortion = pincushion
Aperture Center Corner
f/5      B-     B-
f/8      B      B-
f/11     B      B-
f/16     B+     B-
f/22     B      C+
f/32     C+     C-
Notes: Very low contrast at f/5, low at f/8, moderate contrast elsewise.

OM-4T with mirror and diaphragm prefire, average of samples 2 and 3
Vignetting: A- @ f/5, A to A- at f/5.6, A thereafter
Distortion: slight pincushion (none?)
Aperture Center Corner Contrast
f/5      A-     B/B+   mod. high to high
f/8      A-     B+/A-  mod. high to high
f/11     B/B+   B/B+   high
f/16     B+     B/B+   mod. high
f/22     B+     B      mod. high
f/32     B/B-   B      moderate

@ 200mm setting

OM-1 with mirror lockup, sample 1
Vignetting = B at f/5, A thereafter
Distortion = slight pincushion
Aperture Center Corner
f/5      D      D+
f/8      D+     C-
f/11     B-     C+
f/16     C      C+
f/22     B      B-
f/32     B-     C
Notes: Image probably degraded by internal camera body vibrations from shutter and automatic diaphragm mechanism.

OM-4T with mirror and diaphragm prefire, sample 3
Vignetting = A- at f/5, A thereafter
Distortion = slight pincushion
Aperture Center Corner
f/5      B+     B-
f/8      B+     B-
f/11     A-     B-
f/16     B+     B-
f/22     B      B-
f/32     C+     C+
Notes: Low contrast at f/32; moderate contrast at f/22; moderately high contrast at f/5, f/8 and f/16; high contrast at f/11.

100-200mm f/5 S Zuiko (multi-coated) with Olympus 2X Converter
OM-1 with mirror lockup

@ 100mm setting (effective 200mm)
[not tested - useless combination]

@ 150mm setting (effective 300mm)
Vignetting = A-
Distortion = slight waveform
Aperture  Center Corner
f/5 (10)  F+     F+
f/8 (16)  D      D
f/11 (22) D+     D+
f/16 (32) C      C
f/22 (44) C      C
f/32 (64) D+     D+
Notes: Moderately low contrast at f/5

@ 200mm setting (effective 400mm)
Vignetting = A-
Distortion = slight pincushion
Aperture  Center Corner
f/5 (10)  C+     C+
f/8 (16)  B-     C+
f/11 (22) B      C+
f/16 (32) B-     C+
f/22 (44) C      D
f/32 (64) D-     D-
Notes: Very unstable and ungainly combination. Nearly impossible to focus even with a Varimagnifinder and a 1-8 screen. I used a second tripod to support the front of the lens, which probably accounts for superior SQF values over the 200mm setting without 2X Converter or support. The 1/8th to 4 sec. exposures may have caused harmonic vibrations within the OM-1 body, despite mirror lockup, a heavy tripod and use of a cable release.