In a message dated 10/30/2000 12:00:12 PM Eastern Standard Time,
jhs8956@xxxxxxxxxxx writes:
> Here with another question. According to R. Lee Hawkin's Olympus OM SLR
> FAQs [see below] there were 2 versions of the dot pattern in the OM 2.
Would
>
> the change in patterns have any effect on the photograph.[quality,edge to
> center, etc.] I figured they changed for some good reason or
> complaint.Thanks in advance for your input.
My understanding is that the original OM-2s used a center-weighted pattern on
the curtain to achieve center-weighted metering from the SBC cells. The
problem with this was that as exposures get longer more and more of the
metering is being done off of the film instead of off of the curtain, so the
metering pattern becomes less and less center weighted as exposure times
become longer than about 1/60 or so. Later OM-2s (and, I presume, all
subsequent OMs with OTC/OTF metering) have an overall averaging pattern on
the curtain, and the center weighting is achieved electronically (or perhaps
through a mask over the SBC cells?). I'm pretty sure the OM-40/OM-PC,
OM-2S(P) and the OM-4(T(i)) achieve center weighting through the two segment
SBC cell in the bottom of the mirror box.
I would expect a later OM-2, with the averaged curtain pattern, would give
more predictable results at slower shutter speeds. At faster speeds there
probably isn't much of a difference.
Paul Schings
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