> I am still not sure about the OM metering off the curtain at speeds just
> above sync speed. What you say makes sense, but still have a vague
> recollection that John said it doesn't quite work that way.
The OM-2S, and I think the OM-40, do things slightly different because
of the program mode which activates the aperture blades at a later
stage than mirror up and is driven by a different type of mechanism
than the usual aperture stop-down mechanism in the other OM bodies.
But the way the OM system operates is that the first curtain has the
reflective pattern which is read by the OTF sensor cells from the
beginning of the exposure itself and will continue to read the
reflected light off the curtain and film surface until sufficient
exposure (with a time offset to correct for mechanical delay) and
triggers the second curtain.
As a result, the metering system ALWAYS begins to read the first
curtain and will continue to read the film surface until sufficient
exposure is attained. This is why the pattern changed in the first
generation OM-2. At higher shutter speeds, the OM-2 was much more
center-weighted than at longer shutter speeds.
--
Ken Norton
ken@xxxxxxxxxxx
http://www.zone-10.com
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