Last one for now . . .
My previous, duplicated tests with a 200mm f/4 multi-coated were rather
disappointing. So I borrowed a 200mm f/4 single coated to see if my lens was
bad. It doesn't appear that there is anything wrong with my lens. Rather its
the possible combination of a low mass camera body coupled with a telephoto's
magnification AND shutter speeds in the 1/60 to 1/2 sec. range which give
critical camera vibrations even with the mirror locked up.
Note the 2nd chart which shows an optimum aperture (f/11) at which there is no
apparent loss in image rendering detail using a 2X teleconverter over that of
a 200mm f/4 alone! But the combo is again hard to focus due to degradation of
the image at full aperture, along with the darkened viewfinder. And the image
quality stopped down is marginal.
200mm f/4 Zuiko (single-coated)
Vignetting = A-?
Distortion = None to very slight pincushion
Aperture Center Corner
f/4 D+ D
f/5.6 D+ C-
f/8 C C
f/11 B- C
f/16 B B-
f/22 B C+
f/32 B C+
Note: Slightly longer shutter speeds at a given aperture versus the 200mm f/4
multicoated test. Low contrast images.
200mm f/4 Zuiko (single-coated) with Olympus 2X Teleconverter
Vignetting = B+?
Distortion = pincushion
Aperture Center Corner
f/4 (8) D+ D-
f/5.6 (11) C C-
f/8 C+ C-
f/11 B- C
f/16 B- C+
f/22 C+ C
f/32 C C-
Note: Slightly longer shutter speeds used at a given aperture versus the
200mm f/4 multicoated test; thus the effects of camera shake lessened. Low
contrast images. No performance degradation at f/11 over the 200mm f/4
without teleconverter.
Gary Reese
Las Vegas, NV
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