"After all, the flash amount doesn't vary or stop during the exposure."
Ah, but it does, that is what the Super FP mode is all about -- instead of a
single flash of (determined by the camera) length, as in the case of TTL OTF
flash with the T series flashes on OM cameras with that capability. Super FP
provides a burst of flashes whose duration is controlled by the camera. Put
another way, with T series, the camera can tell the flash to "stop now" if
the flash has not already stopped. With Super FP, the camera can tell the
flash when to start, and to keep on going until told to stop.
That is not true, Tom. It shuts down after the shutter closes to conserve
the batteries. It has variable duration which you can check on the specs on
the Esif site.
This subject has been discussed ad nauseum. The quoted statement is
correct -- the flash does not vary or stop during exposure. Flash duration
in Super FP mode is fixed at a value set by the time it takes for the
shutter curtains to open and close at the _highest_ "normal" (non-Super FP)
flash-sync speed. This duration varies _only_ between camera models, due to
differences in curtain speed and movement (horizontal versus vertical).
If you're close to the subject and the F280's output is the principal light
source, exposure is controlled by releasing the second shutter curtain --
light from the F280 looks like any other continuous light source. The flash
is not quenched -- its output must continue at least until the second
curtain completes its journey.
Summing it up... In Super FP mode the F280's output appears to be
"continuous." Its intensity and duration are fixed, not quenched -- exposure
is controlled solely by shutter speed.
From the specifications published in the instruction booklet for the F280:
"Flash duration: Super FP Flash emission: 1/50 - 1/25 sec.
(OM-4-Ti/OM-4-T), 1/70 - 1/30 sec. (OM-707/OM-77AF)."
Don't you just love ringing certainty based on misinformation?
--
Winsor Crosby
Long Beach, California
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