FP as a flash sync timing circuit goes WAY back for use with flash bulbs.
Sync switch closes as mirror hits the top, before first curtain starts to
move, by the time the bulb ignites (maybe 1/30th second?), the shutter is
open.
Creating a flash to work with FP, is this reverse engineering?
John
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----- Original Message -----
From: John A. Lind <jlind@xxxxxxxxxxx>
To: <olympus@xxxxxxxxxxxxxxx>
Sent: Monday, January 24, 2000 8:44 AM
Subject: Re: [OM] flash sync
> At 15:37 1/24/00 , Doris Fang wrote:
> >for short-DOF portraits in strong light. Did OM invent FP ? I thought
> >they did not.
>
> Depends on what invention specifically: the electronic strobe for it, or
> first practical application of the concept?
>
> I don't know about the electronic strobe version; Oly seemed to have one
> around with the F280 before I heard about the others.
>
> The concept is ancient! My circa 1954 Contax IIIa CD has "FP" sync for
> 1/100th to 1/1250th and I know it predates that! However, it was designed
> to be used with flash bulbs such as the #26, a second cousin to the
> blindingly high GN #25 or famous "Press 25."
>
> Works much the same way. The sync triggers the flash about 15-20 msec
> before the opening curtain is released. The #26 and others flash bulbs
> like it are called "long duration" FP bulbs. They have a flat peak output
> longer than normal ones that would keep a relatively constant light level
> during opening and closing curtain travel. The GN on them plummeted with
> increased shutter speed just like the electronic FP strobes.
>
> Don't know *who* invented (developed?) "FP sync" or first put it on a
> camera, but it's been around for at least 50 years. It was only a matter
> of time before someone put enough electronics in a strobe to do the same
> thing as long duration FP bulbs did.
>
> -- John
>
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