(multi-coated)

OM-4T with mirror and aperture prefire and additional monopod support on camera
Vignetting = A- @f/2.8 (with slight underexposure), A thereafter
Distortion = none
Aperture Center Corner
f/2.8    B      B+
f/4      B+     B+
f/5.6    A-     A-
f/8      A-     A-
f/11     A-     A
f/16     B+     B+
f/22     B+     B+
f/32     B      B
Notes: Very easy to focus on a 2-4 screen. Moderately high contrast at f/2.8 and f/11; very high contrast images at f/4 to f/8; moderate
contrast images at f/22 and f/32.

350mm f/2.8 Zuiko with Olympus 1.4x teleconverter (both multi-coated)
OM-4T with mirror and aperture prefire and additional monopod support on camera
Vignetting = B+ @f/2.8 (4), A- @f/4 (5.6), A thereafter
Distortion = slight pincushion
Aperture* Center Corner
f/2.8 (4) B      B
f/4 (5.6) B+     B
f/5.6 (8) B+     B
f/8 (11)  B      B
f/11 (16) B      B+
f/16 (22) B-     B-
f/22 (32) B-     B-
f/32 (44) C+     C+
Notes: *Effective aperture in parenthesis (). Moderately high contrast at f/2.8 (4); high contrast images atf/4 (5.6) andf/5.6 (8); moderate contrast images atf/8 (11) and f/11 (16); moderately low contrast at f/16 (22) to f/32 (44).

350mm f/2.8 Zuiko with Olympus 2X teleconverter (both multi-coated)
OM-4T with mirror and aperture prefire and additional monopod support on camera
Vignetting = B- @f/2.8 (5.6), A- @f/4 (8) andf/5.6 (11), A thereafter
Distortion = very slight waveforming with no tendency
Aperture*   Center Corner
f/2.8 (5.6) C+     C-
f/4 (8)     C+     C
f/5.6 (11)  C+     C
f/8 (16)    C+     C
f/11(22)    B-     B-
f/16 (32)   B-     B-
f/22 (44)   B      B
f/32 (64)   C      C-
Notes: *Effective aperture in parenthesis (). Not an Olympus recommended combination. Moderately high contrast at f/2.8 (5.6),f/4 (8), then f/11 (22) to f/32 (64); high contrast at f/5.6 (11) andf/8 (16).