Flash Bulbs, Gear Info, Images of Gear & Guide Number Data

[Harold_4074]

Flash powder was still important in 1944

That's not the half of it--the Army Air Corps dropped M46 photoflash bombs containing 100 pounds of flash powder, for night aerial photography. (There was also an M120 that was apparently even bigger.) They were apparently among the most dangerous ordnance items in the inventory---an old Ordnance Corps text that I have says that in case of an accident, destroy in place--do not disturb. Flash powder in quantity detonates, like TNT, rather than burning like black powder. Must have been interesting on the ground below...

Aren't we all glad that flashbulbs were invented?

[Tin Can]

An APUG seller sent me a complete camera kit with a 3/4 bottle of 'Smokeless Flash Powder' through USPS. i didn't know it was coming. I expected a knock on the door or SWAT. Nada, but from the book I know a whole lot more about this particular type.

The igniters came with it and resemble 22 cal blanks and are perhaps 'soundless' per book.

I also got one NOS flash pan with ignitor trigger.

The book describes powder amount and effective light power. Now I need a dark wet forest. Not a problem 50 miles from here. Maybe next year or Winter.

I always wear safety goggles and cotton clothes. I am a welder.

[Harold_4074]

Randy, if it is "smokeless", it isn't the traditional metal plus oxidizer style. Part of the charm of flashpowder pictures is that the billowing white smoke (aluminum, magnesium or zirconium oxide aerosol) acts as a reflector and diffuser for the latter part of the burn. What you have may well be a lot safer, but you might want to rethink the cotton clothes for wool or leather...

I like that dark, wet forest idea a lot!

[Tin Can]

Randy, if it is "smokeless", it isn't the traditional metal plus oxidizer style. Part of the charm of flashpowder pictures is that the billowing white smoke (aluminum, magnesium or zirconium oxide aerosol) acts as a reflector and diffuser for the latter part of the burn. What you have may well be a lot safer, but you might want to rethink the cotton clothes for wool or leather...

I like that dark, wet forest idea a lot!

Yes, the quoted book does say it has way less umph. It's what I have. I could make some.

In the dark wet woods I will have leather jacket, good boots and I have yet to burn myself too badly with cotton. Welders set each other on fire as jokes. I do have some bare skin scars from dripping, flaming rubber that fell on my arms. That was exciting, as your first impulse is to wipe it away, which spreads it. I took the rest of the day off. But in the end, just male beautification.

[mjork]

Sorry I'm bringing the discussion back from flashpowder to flashbulbs...

I just got started with using flashbulbs. Based on my initial test shots, the manufacturer's published guide numbers seemed somewhat optimistic. In particular, an outside shot at night was clearly underexposed. So I decided to measure the light output of some bulbs with a light meter. My Sekonic L-558 seems to have no trouble measuring flashbulb output in cordless mode. It automatically detects the flash being fired and measures it.

I put the light meter and the flash on tripods exactly 9 ft apart. The test was done at night with no reflecting surface nearby. Obviously I'm measuring the full output of the flashbulb that one would get with a leaf shutter set at 1/25 exposure time or longer. After measuring a GN this way for ISO 100 for example, I assume I can calculate a correction factor by comparing my number with the published number from the table. Then I would apply that correction factor to all table values to figure out the actual GN for the other, shorter exposure times (and of course other ISO numbers).

I got very consistent results with some clear bulbs I tested. However, the blue #5B bulbs from different manufacturer's and of different vintage were all over the place...

For a GE #11 screw-base bulb in a 7" reflector, I got a GN of 235 at ISO 100. And the equivalent Sylvania P40 bulb measured exactly the same. The number printed on the package was GN 320 for GE and 300 for Sylvania. So my measurement was almost one stop slower than advertised.

This result actually makes sense based on the fine print: I found a GE "Photolamp & Lightning Data" brochure from 1961 on the Butkus Web site that states: "all exposure data is based on the use of G-E Lamps in good reflectors -- indoors in an average living room with medium colored walls and ceiling -- with lamp, camera and subject on a streight line. Outdoors at night, or in large or dark-walled interiors, use one stop opening larger than the guide indicates [...]".

My measurement for GE #5 bulbs in 5" reflector was GN 180. And an equivalent Westinghouse #5 measured exactly the same.

But blue #5B bulbs in 5" reflector were very inconsistent:
- old stock Sylvania (yellow & black package) GN 162
- newer vintage Sylvania (colorful package) GN 180
- Westinghouse GN 126 or GN 120

[Tin Can]

No worries.

We always digress a bit.

You say you had your meter and bulb 9 ft apart. You didn't say if they were aimed at each other. Were you using spot meter mode?

I am not an expert at this, only hobbiest, to establish that.

I was just outside popping my Nikon SB 28 with a L-758 to check it against concrete walls and gravel piles, using spot metering.

Just a preliminary test, then use SB 28 with film and correlate to flash bulbs. I also use D750 as Polaroid to attempt correlation, which is tough as new DSLR have very forgiving DR.

I have a thread here somewhere, threads are hard to locate, but I compared P C Buff Einstein at full power with 7" reflector to one Press 25 in 6" reflector as almost equal when observed on film. No Densometer available to me.

All baloney so far.

But

What I want and it seems you also want, is to create data for guiding us in practical usage, by empirical testing. Then we need to publish our results here.

Where do you want to go?

Which bulbs do you have the most of?

I have dozens of P5 and P25.

I have 100's of M2 & M3, which I want to burn up first. Then my M5's.

I think flash bulbs progressed with similar power output with ever smaller size. Except for screw base, which can be all over GN grid. I have those for later, they are not cheap.

AG1 bulbs have near the power of M5 amf P25. 3 physical sizes. 3 burn times.

Your thoughts?

and welcome to the forum

[Jac@stafford.net]

You say you had your meter and bulb 9 ft apart. You didn't say if they were aimed at each other. Were you using spot meter mode?

I wrote of metering using cord mode for flashbulbs long ago, but it is good to repeat that it works well. Everyone else who responded to whether it was possible to use a flash meter with bulbs said it was not possible. I only double-up on this point to possibly encourage others to use bulbs especially where portability and lots of light is necessary.

Shooting at night with no reflective walls, metering as incident with the proper reflector is perfect when establishing a real GN.

Thanks to mjork for the good article.

[LabRat]

Careful with that flashpowder in that dark, wet, forest, Randy... There's a chapter in "Cyanide and Spirits" by Bill Jay about flashpowder explosions in the 19th century... Seems that when the stuff gets damp, it explodes...

Another no/no for flashbulbs was a practical joke someone set up in the copy camera room at a lab where I worked... Someone removed all the photofloods from the trough light reflectors, (I think 8) and replaced them with #5's while the operator went to the bathroom... Operator comes back and turned on the "lights", WOOOSH, and comes out of the room mad as hell, (and blinded) freaks out on who he thinks did it, and has a heart attack during the melee... Off to ER, but survived... (Don't try this at home, kids!!!!)

Steve K

[mjork]

No worries.

We always digress a bit.

You say you had your meter and bulb 9 ft apart. You didn't say if they were aimed at each other. Were you using spot meter mode?

I am not an expert at this, only hobbiest, to establish that.

I was just outside popping my Nikon SB 28 with a L-758 to check it against concrete walls and gravel piles, using spot metering.

Just a preliminary test, then use SB 28 with film and correlate to flash bulbs. I also use D750 as Polaroid to attempt correlation, which is tough as new DSLR have very forgiving DR.

I have a thread here somewhere, threads are hard to locate, but I compared P C Buff Einstein at full power with 7" reflector to one Press 25 in 6" reflector as almost equal when observed on film. No Densometer available to me.

All baloney so far.

But

What I want and it seems you also want, is to create data for guiding us in practical usage, by empirical testing. Then we need to publish our results here.

Where do you want to go?

Which bulbs do you have the most of?

I have dozens of P5 and P25.

I have 100's of M2 & M3, which I want to burn up first. Then my M5's.

I think flash bulbs progressed with similar power output with ever smaller size. Except for screw base, which can be all over GN grid. I have those for later, they are not cheap.

AG1 bulbs have near the power of M5 amf P25. 3 physical sizes. 3 burn times.

Your thoughts?

and welcome to the forum

I pointed the flash directly at the white dome of the meter for an incident flash reading.

The bulbs I'm interested in and own is anything that I can use with the M sync of my leaf shutter lenses. I want to be able to use fast shutter speeds. So far I thought that comes down to only 4 general choices (plus the blue version of all these), in order of light output:

1. PowerMite M5 with adapter in 5" reflector
2. GE #5 or Sylvania Press 25
3. GE #11 or Sylvania Press 40
4. GE #22 or Sylvania type 2

The M2 you mention would only be useful with X sync and slow shutter speeds. I don't have any specs on M3.
I never considered AG1. But looking at it now, it might actually be usable even though it has a 15ms time to peak (which is shorter than the 20ms M sync time). The GE brochure does have a GN table for AG1 M sync and includes fast shutter speeds. But using these in a 5" reflector is probably not a good idea? I think that's why I didn't consider them.

[Jac@stafford.net]

But using these in a 5" reflector is probably not a good idea?

The big bulbs work better with the 7" stepped reflector.
Something like item # 261978558706 on the big auction site.