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Re: filmscanners: was:(OT) Pixels per inch vs DPI now: flash synch speeds

I believe most studio flash systems are considerably brighter than 
camera mounted portable flashes, and this might explain the differences. 
  I wasn't aware, since I do not use studio flash, that they could be so 
long.  I suspect if the average hand held/camera mounted electronic 
flash had that long a flash period, with the same guide number, the 
batteries would be gone in no time.


SKID Photography wrote:

> For the record, we use ProFoto studio lights, where we've experienced 
> the 250th of a second cut off of lighting output on our Polaroids.
> Harvey Ferdschneider
> partner, SKID Photography, NYC
> RogerMillerPhoto@aol.com wrote:
>     The Speedotron Black Line 2400 watt-second has a flash duration of
>     1/300th second, and shorter if you dial down the power.  That's
>     typical of studio power packs.  That duration is measured between
>     the 10 percent points.  I'm not sure why you'd care about latency (I
>     have to admit I haven't been following this off-topic discussion
>     closely).  Latency (the time lag it takes for the light out put to
>     reach 10 percent of its peak) should be measured in microseconds
>     rather than milliseconds and should rarely be of concern.
>     In a message dated 10/31/2001 3:56:05 PM Pacific Standard Time,
>     darkroom@ix.netcom.com writes:
>          > I thought the longest flash durations were in the
>         neighborhood of
>          > 1/500th sec.  I don't recall seeing exposure differences at
>         shutter
>          > speeds 1/250 or slower where ambient light isn't a factor.
>         It takes "some" time for the flash to actually fire...and I
>         would also guess
>         different types of flashes have different timing (latency). 
>         Does anyone
>         actually know what a typical flashes latency time is?
>         I can check my Elinchroms to see what they say this time is
>         supposed to
>         be...as I have the service manuals for them, and they are pretty
>         comprehensive...hopefully, they'll have something to say about it.


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