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[OM] Re: [OT] A brief Tokina 28-80 test note

Subject: [OM] Re: [OT] A brief Tokina 28-80 test note
From: "tOM Trottier" <tOM@xxxxxxxxxxxxx>
Date: Wed, 31 May 2006 19:25:41 -0400
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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