Flash bulbs - duration?

M Carter · May 27, 2013

Anyone ever test the actual duration of old school flash bulbs and cubes?

There are times I could use a very slow duration (to fill an entire frame of video or movie film, for instance, at 24 fps... a modern strobe just leaves a white band depending on the scanning rate of the sensor).

Yeah, I know, this is "A"Pug - but I doubt anyone knows this on the digital side!

railwayman3 · May 27, 2013

The duration of light from a flashbulb/cube will be significantly longer than electronic flash. IIRC, there were even "long peak" flashbulbs at one time, for use with focal plane shutters which otherwise could give a similar problem to what you're getting.
I don't have detailed info to hand at this moment, but I'm sure a few minutes with Google will track down exactly what you need.

Sirius Glass · May 27, 2013

The flashbulb manufacturers published booklets with that information including plots and graphs of their products. I cannot find my copies at this time.

removed-user-1 · May 27, 2013

Some of the technical information you're looking for, including a few time graphs, can be found at Cress Photo's website (no affiliation).

M Carter · May 27, 2013

Ian C sent me a link to a pretty massive database - I had searched but never found something so complete. I see some models with close to a second duration, just at a glance.

I'm guessing these could be a good lightning-through-the-window effect when there's no budget for the hollywood-style generators (for video or film motion shoots). You can do that in post, but nothing looks as real as reality. Now I can at least cross reference what's available for sale. Wondering if slightly lowering the trigger voltage might prolong the burst as well.

BrianShaw · May 27, 2013

M Carter said:
Ian C sent me a link to a pretty massive database - I had searched but never found something so complete.

Would you mind sharing that with others, like me, who are also interested?

Ian C · May 27, 2013

Bulb data and time/intensity graphs

http://www.flashbulbs.com/Philips.htm

BrianShaw · May 27, 2013

Thanks, Ian!

Sirius Glass · May 27, 2013

Ian C said:
Bulb data and time/intensity graphs

http://www.flashbulbs.com/Philips.htm

It you have something like that, that kind of thing is what I was referring to. Do you have anything like that?

AgX · May 27, 2013

M Carter said:
Wondering if slightly lowering the trigger voltage might prolong the burst as well.

Trigger voltage is not related to to flash duration. No incandescant flash from a light with electrical contacts is triggerd by that electrical impulse anyway, but by an explosive that is triggered by electrical heating. That heating though has a retardent effect on triggering.

Keep in mind that there are different times to talk about.

With the development of types the trigger voltages and all times involved had been reduced with those common consumer models of bulbs.

brianmquinn · Jun 2, 2013

Sirius Glass said:
The flashbulb manufacturers published booklets with that information including plots and graphs of their products. I cannot find my copies at this time.

See Post #25 here
(there was a url link here which no longer exists)

Sounds like you need a focal plane bulb like the No. 6 or 6B.

They can be found on ebay or I have several bulbs in my basement, PM me if you want to buy a few to try out.

Jim Jones · Jun 2, 2013

Somewhere I have a device that used photoflood lamps at reduced power for modeling lights, and a surge of power from capacitors could be dumped into the photofloods for exposure. The exposure intensity would be fairly long, but with slow build-up and decay.

Flash bulbs - duration?

removed-user-1

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