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Re: [OM] Flash sync question

Subject: Re: [OM] Flash sync question
From: "Gregg" <giverson@xxxxxxxxxxxxx>
Date: Tue, 29 Aug 2000 20:12:03 -0400
Lex,

How about some flash powder.  That would have the long duration you
need.  I would certainly keep it outdoors though.

I believe the  difference between the FP bulbs and the M bulbs is how
fast they light and how long they stay lit.  The Ms are for a leaf
shutter.

Gregg


----- Original Message -----
From: "Lex Jenkins" <lexjenkins@xxxxxxxxxxx>
To: <olympus@xxxxxxxxxxxxxxx>
Sent: Monday, August 28, 2000 11:56 PM
Subject: Re: [OM] Flash sync question


| Thanks, John.  I've been around *just* long enough to have used FP
flash
| bulbs (not cubes, etc.) for a couple of years as a kid when they were
still
| available and not considered collectibles.  And I understand how sync
| differs; besides FP and X I seem to recall an "M".  But I wasn't sure
how
| units like the F280 operated, having never seen one.  I didn't know
whether
| this flash emits a long, continuous flash or a series of relatively
lower
| intensity strobe bursts.
|
| Purely out of ignorance and speculation I'm wondering whether a
conventional
| electronic flash unit can be modified to emit a single burst of long
| duration, or whether this simply isn't feasible.  I can imagine this
would
| wear out the unit and batteries pretty quickly, but for certain photo
uses
| it'd be worthwhile.
|
| Lex
| ===
|
| >From: "John A. Lind" <jlind@xxxxxxxxxxx>
| >Subject: Re: [OM] Flash sync question
| >Date: Mon, 28 Aug 2000 20:20:27 +0000
| >
| >This is defined as "FP" flash sync.  It was originally done with
special
| >long duration flash bulbs such as the the 26, the long duration
cousin of
| >the famous press 25.  To sync correctly the camera had to have an
"FP" sync
| >position which would prefire the flash bulb about 20ms before
releasing the
| >leading curtain so that the bulb would be up to full output before
anything
| >opened.  The duration had to be long enough for the trailing curtain
to
| >completely close; standard flash bulbs were not long enough in
duration.
| >
| >In today's world of electronic strobes, the long duration is
accomplished
| >by a very rapid series of light bursts consuming the entire output.
As
| >with flash bulbs, an electronic FP sync must prefire the flash just
before
| >the leading curtain opens and its duration of very rapid bursts must
| >continue until the trailing curtain closes.  This is how the F280
with an
| >OM-3ti or OM-4ti works in "FP" mode.  The trick would not so much be
| >getting an extended duration; electronics could be added to a flash
unit to
| >do that.  The trick would be prefiring prior to the leading curtain
| >release.  On any but the OM-1[n] with the "FP" position (set up for
flash
| >bulbs, not electronic), you would have to somehow modify the sync to
| >prefire the flash unit.  Perhaps an OM-3ti or OM-4ti could be
adapted; I'm
| >totally unsure of that.
| >
| >That would be the daunting task.  The X-sync works by firing the
flash
| >after the leading curtain has fully traveled.  It presumes you will
be set
| >to the X-sync shutter speed which has the opening curtain fully open
for a
| >short time before the trailing curtain is released to close the
shutter.
| >It means you would have to monkey with the sync timing considerably
and fix
| >things so that the flash sync fires the flash just *before* the
opening
| >curtain is released.
| >
|
|
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