On Wednesday, May 31, 2006 at 14:40,
Chuck Norcutt <olympus@xxxxxxxxxx> wrote:
...
> So far I've only analyzed the results for 28mm but here's what I've
> seen so far. The first startling observation is that every single
> autofocus shot on the Tokina looks better than the corresponding
> manual focus shots on the same lens. Not by a great deal but enough
> so that you'd readily pick one over the other. That was a bit of a
> shock. I don't know if it's my eyes or the screen but it's a fact.
I'd get the screen or camera checked, or the adjustment of any dioptre adapter.
> The next shock was that I rated the performance of the Kiron 28-70/4
> as "unacceptable" at center from f/4 thru f/8 and "poor" at the
> edges through f/8. It didn't produce what I'd call a decent image
> until f/11 and was still performing better at the edges than center.
...
That does sound like a focus error since the "plane of focus" is often a sphere
or parabola.
Does the 5D have a display and magnify function for the rear screen during
manual focus? - an
electronic VariMagni? You could try bracketing focus slightly, then magnify the
results.
tOM
--
tOM Trottier, Ottawa, Canada
758 Albert St, Ottawa ON Canada K1R 7V8
+1 613 231-6115 N45.412 W75.714
http://groups.yahoo.com/group/ottawa-photo-clubs
"The moment one gives close attention to anything,
even a blade of grass, it becomes a mysterious,
awesome, indescribably magnificent world in itself "
-- Henry Miller, 1891-1980
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