Re: [photo-3d] capacitor grenades

[David H Quackenbush <dhq@xxxxxxxx>]

On Sun, 31 Dec 2000 09:44:28 -0800 ers <ers@xxxxxxxxxxxx> writes:
. The reason is that I would like to up the 
>output of a 
>ring flash, as opposed to constructing a multiple flash array. Looks 
>like I'll 
>have to try it myself? The fact that a single capacitor can generate 
>multiple 
>values for a flash is proven by the Vivitar 283 Varipower module, 
>which seems 
>to limit the amount of charge. By backing off the setting, you can get 
>a 283 
>down to about 1/20,000 of a second-- at the cost of light, of course.
=================================================
Hi, 
 Let me offer a little primer on strobes for others who would like to try
this route. And since Elliott is aware of the hazards I suggest this: Get
another photoflash cap equal to whatever is in the one that you want to
-overdrive- and just parallel it to the existing cap or caps, you don't
even have to solder it in to find out if it will work, ( watch the
polarity!) If it works the way you expect it to, then add an outboard box
for the cap and solder the connections 
If it doesn't work you'll only lose a couple bucks.  

 A strobe, just like a flashbulb has only one -volume- of light. Once
fired they do their thing all at once. With the invention of the variable
or automatic strobe photographers were given a very useful tool for
adjusting exposure. To control the amount of light from a strobe it is
necessary to adjust the time that the tube is "on". The first auto
strobes did this by switching the current from the caps to a "quench"
tube to use up the remaining current. This was wastefull because it used
up the charge on the caps, recharge time was the same regardless of the
aperture or distance. Modern circuits limit the time that current flows
to the tube, so that when a lot of light is not called for the caps will
not dischare completely, hence multiple flashes before the ready light
goes out. So if you shoot in auto mode it won't make any difference how 
much power you add to the strobe, the circuit will shut the tube off when
enough light hits the photosensor.

Regards,  David Quackenbush

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