It's short for "Focal Plane SHUTTER." As opposed to in-lens shutters.
Like the F280, there used to be flash bulbs that ignited to produce a long,
even flash that lasted while the FP shutter traversed the focal plane.
So with FP bulbs, you could use 1/1000 sec. exposures with the FP bulbs whose
flash lasted the ~1/60 sec time for the shutter to go across the entire frame.
They had some ramp-up time, so the FP setting set it off ~40 ms ahead of the
opening of the shutter. For in-lens shutters, the setting was "M" (anyone know
why?) and the delay was ~20 ms, I recall. "M" bulbs weren't as even as FP
bulbs, since there was no pesky little slot being dragged across the frame.
Tom
> Date: Wed, 5 May 1999 16:18:31 +1000
> From: "Higgins, Michael (Ex AS01)" <MHiggins@xxxxxxxxxxxxxxxx>
> Subject: RE: [OM] X/FP?
>
> I know I'm getting way off on a tangent here, but why FP "Focal Plane"
> flash bulbs? What has putting the flash on the focal plane got to do with
> anything? Surely they would work just as good off the Focal Plane? (I
> love knowing the origins of the markings on my OM-2... and I had assumed
> that FP stood for Flash Bulb, but in another language! in fact I'm sure
> I've told people this! oops.)
>
> Mike
>
------------------
From: Tom Trottier, President, ACT Productions Inc.
infoanim@xxxxxx http://www.act.ca
+1 613 594-4829 fax +1 613 594-8944
199 Holmwood Ave, Ottawa, Ontario, Canada K1S 2P3
"Make it as simple as possible, but no simpler" - Einstein
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