And to further mention. The aperture mechanism in the OM system is
quite strong to accommodate many types of lenses, extension tubes and
couplings. For example, the 350/2.8 needs a lot more force compared to
a 50/1.8. Hence, the strong aperture mechanism is a major source of
vibration in the OM system, especially compared to the shutter. Since
the OM-4t self-timer actuates the aperture mechanism before the shutter
is released, a significant amount of vibration is reduced by self-timer
aperture pre-fire. (One of the inherent advantages of rangefinder
cameras and vibration - no aperture mechanism to activate.)
A trick is to pull the self timer lever on the OM-4t just enough to
activate self-timing, then, gently, with the fingernail, shift the self
timer to release the shutter. Saves waiting 10 seconds, but requires
the right touch. I use this many times with macro shots. Anyone
thinking of redoing the OM-4 circuits should add a 2 second self-timer
mode.
Joel once did a test with the OM and 200/4 lens with an attached laser
pointer, and I think photographed the vibration of the projected laser
spot. (I think my memory serves me here, but I have poor memory.)
(Joel?) The 200/4 lens seemed to accentuate the vibration with the
OM's, or resonate particular badly, and was speculated to be the cause
of poor performance attributed to that lens. You'll even notice with
Gary Reese's test data, that lens performance improves a lot with
aperture prefire OM-4t versus the OM-1 data. The resonance effect is
most pronounced in the 1/4-1/30 speed range. If you are near that
range, consider aperture pre-fire for reduced vibration. 1 second
exposures and longer, you may get away without it.
The E-1 system has only electronic coupling. This is a great way to
reduce vibration. I know people wish the E-1 would activate the OM
Zuiko lens aperture mechanism, but I prefer the lower vibration the
electronic coupling provides. A 90/2 on the E-1 will do better than the
OM-4t without aperture pre-fire. Oly does do some things right despite
all our complaining.
Gary Reese says, use sandbags for vibration, they work great.
Wayne
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