On Jul 30, 2004, at 2:25 AM, Jinx wrote:

>> Most cheap xenon camera flashes are MUCH longer than a
>> microsecond. IIRC, most are around a millisecond
>
> Presumably you mean the $5 U-type from hobby stores

No, it's more the flash electronics than the tube itself.  Remember
that 1/1000 of a second is pretty short as far as typical camera
exposures go; old 35mm cameras would need to operate the shutter at
1/60 s or so just to make sure that the whole piece of film was "open"
during the "very brief" flash.  As far as I know, MOST xenon flash
attachements for cameras have their maximum output with a duration of
about 1ms; many cut the flash pulse shorter for "automatic exposure",
but they are optimized for light output, after all.

Short flashes (containing the same energy) are more difficult,
requiring higher voltages, more expensive components, and more
attention paid to the circuit design.  The effort you need to go to to
get get those sub-microsecond flashes for photographing bullets is
pretty extreme, and other factors enter into your picosecond laser
pulses.

One way to get interesting photographic effects is to take a bunch of
those cheap disposable cameras and rig up a PIC (heh! on topic) to
trigger them in succession, rather than trying to fire the same tube at
a higher rate...  It's a project on my to-do list...

BillW

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