On Thu, 28 Jun 2007, Moose wrote:
> What may not be obvious is that the Auto OTF-TTL metering is full frame
> average, not center weighted. Manual and the in-viewfinder indications
> for Auto are center weighted, but not the actual Auto exposure itself.
I had no idea, but makes sense now that you mention it. Quite interesting!
> I'm not sure it makes much difference with this rather symmetrically lit
> subject, but center weighted metering is not in play here.
I stand corrected, but as you point out, the ratio of the sky and ground
is rather similar in the full frame and the center area.
What I meant to say earlier was, let's say the clouds are at EV17, while
the ground is EV13 on the average. Sounds roughly realistic to me. So, now
that we have a frame with 50% clouds and 50% ground, if we calculate the
average EV naively (the electronics in the OM might not work quite like
that) it should be at EV15.
Now my thinking is that if we expose straight at that value the ground is
placed at -2, which may not be desirable as that seems quite dark, so I
might use exposure compensation to bring it up some. That's what Lukasz
also did initially. However, I speculated that some amount of metering
error of the camera and the response characteristics of the slide film
(which favor underexposure) affected the situation enough so that dialing
in the compensation was not necessary after all.
priit.
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