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RE: [OM] Flash sync question

Subject: RE: [OM] Flash sync question
From: "John A. Lind" <jlind@xxxxxxxxxxx>
Date: Mon, 28 Aug 2000 21:00:52 +0000
I don't think this will work, unless you can get the flash duration to at
least 1/45 second and fire it just before the opening curtain is released.

The reason is the curtains travel at a constant speed across the frame
regardless of shutter speed, and that takes less than 1/60 (hence the
X-sync at that speed), but longer than 1/125 (??), otherwise you could
X-sync at 1/125th.  One of the tricks for designing a faster X-sync besides
increasing curtain speed is to change the design to vertical curtains.
Vertically they only have to travel only 2/3 the distance as horizontal
ones.  With all the OM bodies except the OM-2000 (with a vertical shutter
and faster X-sync), a slit travels across the flim plane at all speeds
faster than 1/60th.

BTW, the guide number drops dramatically as shutter speed increases using
"FP" whether it's the old long duration bulbs or an "FP" capable unit like
the F280.

-- John

At 01:05 8/29/00 , you wrote:
>Lex,
>I think this might be somewhat "doable" by using a powerful , hence, longer
>output strobe.  Say a 1800 watt/second unit set to full power. The longer
>duration might help a little, but you're still talking less than 1/60
>second, probably ~1/250/sec..  All flashes decrease output by shortening the
>length of the flash.
>
>The problem is going to be that most flashes you and I use are short
>duration devices (1/1000 and less).  Smaller flash units, or flash set for
>low power get down to 1/40,000/sec.
>Brian P. Huber
>
>Troy, OH
>bphuber@xxxxxxxxxx
>
>Does anyone make a flash (clip-on or studio) that allows synchronization
>beyond the usual limit for a camera?  As I understand it, this is a factor
>of flash duration.  If a flash duration is long enough, one can in effect
>extend synchronization beyond that designed for a particular focal plane
>shutter mechanism.  Any thoughts?
>
>Lex
>===
>
>
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