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Re: [OM] OM4Ti OTC metering

Subject: Re: [OM] OM4Ti OTC metering
From: "Peter A. Klein" <pklein@xxxxxxxxxx>
Date: Wed, 17 Feb 1999 23:47:11 -0800
At 05:07 PM 02/17/1999 EST, Gary Reese wrote:

>I posted lots of data here on the variation in film surface reflectance for a
>variety of popular films.  And I'm heartened to see Buddy (who also tested
his
>favorite films) has taken that variation into account with his exposure
>practices.  I wasn't sure that anyone cared that OTF metering no longer met
>the original design assumption of having the film within 1/3 stop of 18%
>reflectance.  Given the variation that Buddy and I found, it leads to OTF
>exposures that are outside tolerance limits for the metering system!

Can you remember the subject line--so we can easily find it in the archives?

Doesn't this also mean that when using a film that isn't 18% reflectance,
normal picture-taking speeds (which mostly use the shutter curtain pattern)
will meter accurately with available light, but long exposures (which are
more dominated by film reflectance) will have to be adjusted with the
exposure compensation dial?  At what shutter speed does this start to
become significant?

OTF flash would at least be consistent, since measurements are taken with
the shutter curtain wide open, completely off the film.
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