Thanks to all.
Date: Fri, 17 Jan 2003 18:38:19 -0800
From: Moose <olymoose@xxxxxxxxxxxxx>
Subject: Re: Subject: Re: [OM] advice needed: SPOT meter reading
differs from AUTO ongray > card??
No matter where you set the f-stop ring, the metering you are viewing=20
actually takes place with the lens wide open and any vignetting effects=20
will be those of the wide open lens. The lens does not stop down until=20
the shutter release is pressed and just before the first curtain is=20
released. With spot metering, you have set the shutter speed that will=20
be used after the lens is stopped down. With average metering, you are=20
only looking at an estimate of a shutter speed which will actually be=20
based on the light coming through the stopped down lens under TTL=20
exposure control.
Of course you are right. I did not think of it.
Because of these differences, the only way to accurately carry out a=20
test between the two modes would be to expose film and test the results=20
with a densitometer. Slight differences should be expected between=20
different lenses and cameras of the same models due to tolerances in the=20
coupling mechanisms that tell the camera the f-stop that is set on the=20
lens and stop the lens down for exposure.
Moose
Right too. I will do a test film and will see whether it matters.
Good advice. Thanks.
Cheers, Thomas
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