-snip
However, the SuperFP flash duration could be as long as 1/25 sec. 1/25
equals 60/1500. So given a curtain speed of 1/60 (or 25/1500 sec) we could
have a SuperFP flash that is up to 60/1500 - 25/1500 = 30/1500 sec (or
3/150). Why would there be a SuperFP flash that lasts 3/150 sec longer than
it needs to? The fact that such a long flash duration is possible with the
F280 in SuperFP mode makes me think that the curtain speed might be slower
than 1/60 second for some shutter speeds. Why this could be the case, I have
no idea. It might be true that even if the curtain speed is never slower
than 1/60 sec, this super-long flash duration might still be needed, but I
can't think of why that could be.
<taking a deep breath>
I bought an F280 recently for fill-in flash on sunny days with hard shadows,
and for a little extra light indoors with slow film. One thing I'll be sure
of is to do a lot of testing before I start shooting with it for real!
Robert Swier
Rochester, NY
Truly awesome analysis. There may be some difference in the shutter
of the OM77 which the F280 was originally designed for. The F280 in
FP mode also has higher guide numbers than for the OM4T which
indicates a different shutter design.
--
Winsor Crosby
Long Beach, California
?
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