Good info on using flash bulbs.

StepheKoontz

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Got a fan type BC flash with a tower rangefinder and some P25 bulbs. Got a battery and a new capacitor on the way and trying to find a source of info on guide numbers etc to play around with this. TIA
 

BAC1967

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I assume you don’t have the box, it’s usually in a table on the back of the box. I can check if I have it on one of my boxes.
 
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StepheKoontz

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BAC1967 said:
I assume you don’t have the box, it’s usually in a table on the back of the box. I can check if I have it on one of my boxes.
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The instructions I have just list films like "kodachrome, anscochrome, ektachrome, kodacolor" etc. I wasn't sure if there was a website I was missing that talks about using flash bulbs I wasn't finding. This looks like it could be fun!
 

BAC1967

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StepheKoontz said:
Thanks!!! And from these guide numbers, that's an insane amount of light!
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They do put out a lot of light, if you're taking pictures of people they will complain about loosing their vision but it's usually only temporary. I have done some bracketing tests by placing markers at different distances with the distance and f-stop marked on them. I also included a test patters with a range of colors. That allowed me to make a cheat sheet that I taped to the flash. I did this for my View-Master camera since it has a dedicated flash and there's only one shutter speed that works with the flash. I just guess the distance and set the aperture, works great.
 

MattKing

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Be careful when using old flashbulb data that references ASA or old films.
The ASA standard was revised in 1960 - essentially doubling the number for most films.
As Kodachrome II came out in 1961, you are probably safe using the film speeds on that first box.
And yes, they give out a lot of light. That is why you can find lots of flash pictures on ASA 10 Kodachrome!
 

voceumana

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FYI, clear flash bulbs are for black and white and tungsten color films; blue flash bulbs are for daylight color films and can be used for black and white. Tungsten color films are not around much today (if any) as electronic flash is color balanced for daylight films.

As to the amount of light, it is quite intense. Probably one reason that in the 1960's the AG1 bulb (the size of a lima bean) became popular--its the size bulb used in the first flash cubes.
 
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StepheKoontz

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MattKing said:
Be careful when using old flashbulb data that references ASA or old films.
The ASA standard was revised in 1960 - essentially doubling the number for most films.
Click to expand...

Good info. Sounds like there might be some trial and error testing in order. I also want to see if the "quality" of light is different. I'm thinking with this flash unit I have with a fairly flat reflector that the light will be more omni directional than a strobe?
 

Kodachromeguy

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Another hint: if you are indoors in a room with white ceiling and reasonably neutral walls, try using bulbs without the reflector. You will get a lot of reflection from the ceiling and walls, and the light will not look as directional (unless you specifically want that look).
 

GRHazelton

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I well remember the bulb days! In the late 50's I shot for my high school newspaper, using IIRC M 3 bulbs in a flash gun by Kodak that held 5 or 6 bulbs in a plastic circular "magazine" which fit into a battery capacitor gun on a bracket attached to the camera's tripod socket. This let me shoot pretty fast with my leafshutter 35mm rangefinder. Shooting football I'd try to anticipate the action, prefocus, and wait. Same sort of thing with basketball. Four or five keepers per football game was a good eening! The power of the flash let me use smallish apertures on Plus X rated to about ASA 300, souped in Beutler. When automatic electronic flashes arrived at an affordable price it was wonderful!
 

Sirius Glass

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With ISO numbers.
 

AndyH

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If you plan to shoot with bulbs, I can't give a better recommendation than the Kodak Master Photoguide. Calculators, tables, and a whole lot more. You can find one cheap on the 'Bay or at major online dealers.

Andy
 

mgb74

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I'm curious - wouldn't the size and shape of the reflector have an impact on GN? And, with older equipment, the condition?
 

BrianShaw

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Some GN tables have different values for different reflector types.
 

Dirb9

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Size, shape, and even finish of the reflector will have an effect on the GN; the 1977 kodak guide has guide numbers for "polished bowl", "intermediate" and "shallow cylindrical" reflectors. Bill Cress' site lists different GN tables for different style reflectors as well: https://web.archive.org/web/20180519103715/http://www.flashbulbs.com/ClearBulbs.htm . An old Westinghouse #11 bulb box I have states "increase exposure 1/2 stop for satin-finish type reflector"
 

BrianShaw

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... and as long as we’re discussing the myriad considerations that are important to consider when using flashbulbs, don’t forget the effect of shutter speed on GN. It can be significant!

see in posts 3 and 6, and the right side table in post #14.
 
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StepheKoontz

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Thanks for the link. Here is a shot of the flash unit I am rebuilding for this project. I found the correct battery and am going to replace the capacitor, should work great It works with both P25 and M3 type bulbs.

 
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