Are you confusing vignetting with central brightness loss? Gary's tests
say T-stop for the Zuiko is almost f8, which would agree with the Modern
figure of f8.27. I think the 0.8 stop is the falloff in brightness from
center to corner.
Tom Trottier wrote:
Yes, loses .8 stops. Oly has significantly more contrast than any
other mirror, but is not as sharp as the longer Questar or Celestron.
From
( http://brashear.phys.appstate.edu/lhawkins/photo/mp-cat-tests.txt )
500/8.0 Zuiko (8/84 pp. 70-71, 130):
Actual: 498/8.27, Distortion: 1.040incush, Falloff: 0.8 stops at
f/8
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