On Fri, Jul 19, 2002 at 11:18:28AM -0700, William Sommerwerck wrote:
> Someone recently remarked that you won't get an accurate exposure reading
> when a shift lens is off-center.
>
> Hel-lo?
>
> Unless the lens has severe edge fall-off (which shift lenses are designed
> _not_ to have), there is no difference in metering with the lens centered or
> moved all the way over. What matters is _what_ you meter, not the part of
> the field it's in.
Until I had a shift lens I thought this too. When you use a metering system
based on a even reflective surface your opinion is true. This is why I like
ADM when using a shift lens.
But all other metering systems use optical elements (at lest the fresnel
element
in the ground glass), and are designed to guide maximum light on the metering
elements with centered lenses. With a decentered lens a lot of light, wich
should be
metered, is not reaching the metering cells. The metering system is indicating
too long exposure times.
This is why a decentered shift lens is fooling the viewfinder metering systems
of any OM-cameras. Use the lens like described in the manual, and you're fine.
Sure metering with a centered lens, and then light fall-off is fooling you too.
Frieder Faig
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