How did flash pans work?

AshleyC

AshleyC

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Just thinking about this the other day. How did they manage to time the flash with the shutter? Was it just waiting till the gunpowder started to fizz before hitting the trigger or something more scientific? I was just thinking of ways of setting up a modern off camera flash trigger thing for my LF.
 
Shutter? Remove lens cap or hat placed over lens - fire flash pan - replace hat or lens cap.
 
As above. This was in the days of extremely slow ortho plates, there was very little risk of light contamination from ambient light.

From memory (what I was taught as a student, not personal memory):) the flash powder was a mixture of magnesium and black powder. When it didn't injure people or set fire to the place it did a very good job of providing high volumes of light.
 
I thought the powder was a mixture of aluminium and magnesium.


Steve.
 
My other hobby is as an amateur magician, and you can get flash powder, paper and wool from many magic suppliers. Not sure what they are made of, but they whoosh and provide a very fast flash that can be triggered by a spark or battery.
 
Interesting, thanks :) was just curious how they synced the two, all down to the slow shutter speeds. Is there any sort of bolt on you could get to drive a flash off a shutter trigger?
 
Wouldn't they use a very long shutter speed, of the order of seconds? Take hat off lens, ignite gun powder, put had back over lens. No "sync" required not any more than a fleshy photographer. The "flash" cuts the other wise enormous exposure time down a little.
 
If the lens on your large fomat camera has a PC socket then you could use wireless flash (with a cord) or a PC cord to attach to the flash gun and fire them.

Being a leaf shutter it should sync at all speeds.

I think thats right?
 
Knikki said:
If the lens on your large fomat camera has a PC socket then you could use wireless flash (with a cord) or a PC cord to attach to the flash gun and fire them.

Being a leaf shutter it should sync at all speeds.

I think thats right?
Click to expand...

At the time when flash powder was used, LF lenses didn't have shutters.

If you triggered flash powder with a shutter (no need for a wireless link) you would still have to use a long shutter speed as it takes a bit of time for the flash to start. At most shutter speeds the shutter would be closed again by the time the flash started.


Steve.
 
thanks peeps :) i wasnt thinking of trying to blow myself up though, just work out a way of getting a flash to work out of curiosity.
 
Steve Smith said:
I thought the powder was a mixture of aluminium and magnesium.


Steve.
Click to expand...
I don't believe so.
Magnesium burns very bright and very hot, but needs a lot of heat to get it going. Black powder (AKA gunpowder) provides that heat and ignites easily, I can't be certain but I don't think that the flash powder could ignite without it.
 
I believe some "flavours" used magnesium, probably the more powerful ones though.
 
like an atom bomb, it needs a smaller bomb to get it going :) Just watch the eyebrows.
 
Steve Smith said:
There is definitely aluminium powder in it.

I might have imagined the magnesium.

EDIT: Here it is. Potassium perchlorate and aluminum powder: http://www.wikihow.com/Make-Flash-Powder

EDIT AGAIN: Although this page suggests magnesium powder and perchlorate - http://notesonphotographs.org/index.php?title=Flash_Photography


Steve.
Click to expand...
I think you'll find that that isn't the flash powder we're talking about, it's powder that flashes, as in pyrotechnics, e.g. fireworks.
 
The second link is the one which suggests magnesium and that is specifically about photography.


Steve.
 
Steve Smith said:
The second link is the one which suggests magnesium and that is specifically about photography.


Steve.
Click to expand...
Magnesium will have been the primary ingredient, there's no doubt about that.

But, as I said earlier, magnesium doesn't light easily so it would need to be mixed with a propellant such as black powder. Technically, black powder is a low level explosive (not a propellant) but when mixed with something like magnesium it would deflagrate (burn at subsonic speed) so black powder would fit the bill. Deflagration propagates through heat.

This is Garry the firearms enthusiast here, not Garry the photographer:)

BTW, in case anyone really fancies making some, although the ingredients for black powder are readily available, once mixed together is is illegal to possess it without holding an explosives certificate. I could make some, but I have more sense...
 
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