6 replies to this topic

[hrun]

I've been having a bit of a debate about this photo: http://commons.wikim...,_1901-1902.JPG

The consensus was that it's a staged publicity shot for a real act, but the debate shifted into whether it would have been possible to take the shot for real in 1903.

I've suggested that the photo could have been taken using an open shutter, illuminated by confined charges of flash powder to speed up the burn, triggered simultaneously using the old fulminate caps and electric blasting machine more commonly used for dynamite.

I've been completely unable to find any references to people using confined flash for high-speed photography. How bright and how short a flash can you get out of flash powder, especially if you drive it with a detonator?

Edited by hrun, 29 April 2010 - 04:40 AM.

[Arthur Brown]

Open flash seems likely and the flash comps of those days were horrid! But shutter speeds of 1/250th second were available in those days so it's likely that the flashpowder was fired then the picture was taken (before the smoke filled the air!).

[hrun]

I'm convinced that the bikes are actually stationary with hidden supports in the photograph in question. You can see the individual spokes, and I'm pretty sure that 1/250 wouldn't be fast enough to freeze them in motion, especially with the depth of field.

But that's not really what I'm asking! What I want to know is, could you use an open shutter and generate a very short flash using pyro? Specifically, the pyro of the early 20th century?

Edited by hrun, 29 April 2010 - 11:04 AM.

[Mortartube]

I don't think this was taken using flash powder. I think it probably used electric carbon arc lighting. Extremely high light outputs were available electrically by this time.

Most probably a Yablochkov candle was used. This was two parallell square carbon rods separated by plaster of Paris, this kept the arc at a constant distance. They had a piece of conductive chemically impregnated paper, or wire wrapped around the top which caught fire and initiated the arc, this burnt away very quickly.

http://en.wikipedia....blochkov_candle


The carbon candle is on the right of this picture.

http://www.oldbookil...hkov-candle.jpg

[BrightStar]

Given that the faster magnesium flash bulbs of later decades gave light durations or around 1/50s (I happily remember playing with them and the zirconium foil Magicubes as a child), I think it's unlikely that a loose pile of photoflash could possibly be any faster. 1/5s is more realistic as a burn time.

Confined flash with, say 1/1000s burn time would essentially be a maroon - very unpleasant indeed for the photographic subject!

That said, photo flash compositions can easily produce millions of candle power, so in combination with a fast mechanical shutter, something might be possible if rather impractical.

Edited by BrightStar, 29 April 2010 - 11:45 AM.

[Arthur Brown]

I'm still going with a very bright light (that could be pyrotechnic or not) and a short shutter time.

[Potassium chlorate]

I've been having a bit of a debate about this photo: http://commons.wikim...,_1901-1902.JPG

The consensus was that it's a staged publicity shot for a real act, but the debate shifted into whether it would have been possible to take the shot for real in 1903.

I've suggested that the photo could have been taken using an open shutter, illuminated by confined charges of flash powder to speed up the burn, triggered simultaneously using the old fulminate caps and electric blasting machine more commonly used for dynamite.

I've been completely unable to find any references to people using confined flash for high-speed photography. How bright and how short a flash can you get out of flash powder, especially if you drive it with a detonator?

Theoretically you could speed up flash tremendously, even old stuff. Shimizu managed to detonate flash at 1587 meters/s with a blasting cap.