Re: [photo-3d] Multiple flash...

["David W. Kesner" <drdave@xxxxxxxxxx>]

Oliver Dean writes:

> Although not a caver, I have been fascinated by this excellent and
> informative thread.

Flash photography is flash photography whether it is in a 
cave, in your living room, or just outdoors at night. Cavbing 
just adds some interesting "twists" to it *{;-)

> I was just wondering -- in order to maximize depth of field and also
> avoid schlepping flashbulbs in (and out!) of the caves, wouldn't it be
> possible, for a given flash position, to make multiple flashes from that
> position to build up exposure on the big or distant shots?

Yes, you can build up flashes. Although you have to be good at 
formulas to calculate the exposure. If you need f8 for one 
flash it doesn't translate to f11 for two flashes. You also 
have to consider the depth of the scene. Whether you use one 
big flash or lots of little flashes from the same position if 
you expose for the passage 200 feet away and you also have 
passage 50 feet away the close stuff will be greatly 
overexposed. That is why it is better to have multiple flashes 
spaced out over the entire scene.

Of course you can always use flash pans with dozens of bulbs 
to get a really BIG GN. The site I keep mentioning has some 
really nice ones <http://www.flashbulbs.com/index.htm> I have 
seen home made ones where a single bulb is in the center of a 
regular pie pan hooked to a 9 volt battery. The rest of the 
pan is loaded with bulbs and when the main is fired it sets 
off all the rest. That's right - one bulb just being close to 
another is enough to set it off. Many an old time new 
photographer has burned his or her leg when a bulb sets off 
all the others in their pocket!

> I'm assuming you are using the camera on a tripod, of course. 

Yes, you need a tripod for the multiple single flash setup. 
However using multiple flashes and slaves means never having 
to take a tripod in the cave with you. Even a single flash 
fired once doesn't need a tripod as you are shooting in total 
darkness and don't have any ambient light to cause blurs.

That's all for now,

David W. Kesner
Boise, Idaho, USA
drdave@xxxxxxxxxx

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