I had previously tested a single coated example of a 100mm f/2.8, and one
which has seen lots of use and abuse. The following are the results from a
100mm f/2.8 multi-coated in much better condition. The most striking
improvement is at larger apertures, which are much better in this multi-coated
version. Stopped down to f/5.6 and beyond, the differences are insignificant.
Likewise, the contrast differences between a single- and a multi-coated
example are undetectable to my eye. Since there was no design change between
the coating versions, I'd have to attribute the poorer results in the single-
coated example to decentering of the elements due to impacts (even though it
was serviced after the last mishap). I'll be testing another single-coated
version to see if that is a reasonable conclusion.
100mm f/2.8 Zuiko (multi-coated)
Vignetting = A-
Distortion = None
Aperture Center Corner
f/2.8 B- B-
f/4 B B
f/5.6 B+ B+
f/8 A- B+
f/11 A- A-
f/16 B+ B
f/22 B+ B
Notes: Contrast loss at f/16 and f/22. No apparent contrast difference versus
single-coated version, but sharper overall (however, see note for single
coated version).
I'll have my WWW site updated with these results in a few days. I'll also be
testing a 100mm f/2 Zuiko next week. Thanks to those OM List subscribers who
provided the lenses for this round of testing!
Gary Reese
Las Vegas, NV
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