Is this true? I just looked at the shutter curtains of a 2n, 4, 4Ti and
PC(40) and the patterns all look the same. If there is any center
weighting in the pattern, it must be very subtle. Take a look at the
comparison pictures of old vs. new (1978) OM-2 curtains at R. Lee
Hawkins' site
<http://brashear.phys.appstate.edu/lhawkins/photo/om2-curtains.shtml> .
The (vertical) center weighting is clear in the old pattern, but the new
looks quite even.
The only hypothesis that reasonably fits Oly's specs that say center
weighted and the curtain patterns is that center weighting in these
cameras takes place elsewhere in the metering system, possibly in the
(sensitivity by) angle of view of the metering cells (a very easy
change). If this is the case, there would be no variation in center
weighting with shutter speed. This problem could even be why the design
was changed early in the production of the pre 'n' OM-2 cameras, as a
result of field experience of the effects of loss of center weighting at
slow shutter speeds.
The OM-10 and G(20) patterns are heavily (horizontal) center weighted
and dark at the center, indicating a completely different metering
system with a polarity reversal somewhere in the circuit. The change to
metering based on the 'single-digit' type exposure system in the OM-PC
was likely needed to add TTL T series flash control.
The curtain pattern on the OM-1 is completely even, all black, and I
don't have (or want) any of the other models.
Moose
Tom@xxxxxxxxxxxxx wrote:
I've been wondering about this. I understand that the
first shutter curtain has a black and white checker
pattern which is used to center weight the meter's
sensitivity. The OM-2 had two different versions of
this, one more emphasized then the other. However,
what happens when the exposure is significantly longer
then 1/60? The checker pattern will have very little
effect on the meters. Are longer exposures less
center weighted because of this?
Yes.
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