If one is willing to stop down FOUR stops from maximum aperture, the results
of using the Olympus 2X Teleconverter approach that of the prime lens alone.
Here are the comparisons involving the 100mm f/2.8 and the 135mm f/3.5.
Again, focusing is hampered by terrible performance wide open, as well as
darkening of focusing aids in the normally used screens.
***
100mm f/2.8 Zuiko (single-coated) ***no converter***
Vignetting = A
Distortion = None
Aperture Center Corner
f/2.8 D- D-
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+
100mm f/2.8 Zuiko (single-coated) with Olympus 2X Teleconverter
Vignetting = B+
Distortion = slight pincushion
Aperture Center Corner
f/2.8 (5.6) F+ D-
f/4 (8) D D
f/5.6 (11) C- C
f/8 (16) B B-
f/11 (22) B+ B
f/16 (32) B B-
f/22 (44) B- B-
Notes: soft at small apertures.
135mm f/3.5 Zuiko (multi-coated) ***no converter***
Vignetting = A-
Distortion = slight pincushion
Aperture Center Corner
f/3.5 C+ C
f/5.6 C C
f/8 B- B-
f/11 B B
f/16 B+ B+
f/22 B+ B
Notes: contrasty, but moderately low resolution
135mm f/3.5 Zuiko (multi-coated) with Olympus 2X Converter
Vignetting = B+
Distortion = moderate pincushion
Aperture Center Corner
f/3.5 F F
f/5.6 F+ F+
f/8 C+ C
f/11 B- C+
f/16 B B-
f/22 C+ C+
Notes: soft in contrast.
Gary Reese
Las Vegas, NV
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