From:
http://photography.about.com/library/weekly/aa040201d.htm?iam=dpile&terms=FP
+X+sync+flash+photo
"Since the flash operates almost immediately the switch is closed, the
synchonisation of this with the camera shutter has to be different to that
used for the relatively slow burning flash bulb. The contact firing the
flash must only be made once the shutter is open - usually a few
milliseconds after the release is pressed.. Some cameras have two flash
contacts, one marked X - for flash - and the other usually marked M, for
bulb flash. Since focal plane shutters only fully uncover the film at their
slower speeds, they could not be synchronised at high speeds with electronic
flash. With those medium format cameras using focal plane shutters, the
normal solution was to provide special lenses - usually for portraits - with
built in shutter to allow higher speed flash sync."
And from a similar about.com article:
"Flash synchronisation obviously made flash photography much easier to do.
There were slight problems as bulb flash does not ignite immediately, but
requires quite a few milliseconds to begin to burn and even longer to reach
the peak output. To use the same release to fire both flash and shutter
requires a slight delay to be built in to the shutter opening. The actual
length of this delay was different for different bulbs, but typical values
were soon determined for the 'M' setting as a mean value and flash
synchronisation was soon the latest feature of new cameras. Focal plane
shutters also presented a problem at their faster speeds, as the blind
closing the shutter follows the opening blind across the film which is never
all open to light at the same time. Special FP bulbs with longer burn times
allowed focal plane shutters to synchronise at higher speeds, using a
special FP setting on the synchroniser."
on 1/23/02 1:48 PM, M. Royer at royer007@xxxxxxxxx wrote:
> I know this sounds really dumb, but what IS the
> difference between all these different syncs. What
> exactly is FP sync? How is it any diffrent from X and
> what makes X so special. Pardon my ignorance. I've
> only ever used T-flashes
>
> Mark Lloyd
> < Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
>
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