Setting for using GE #5 flash bulbs

campy51 · Dec 12, 2022

I have a Crown Graphic and I am using HP5 film and I don't quite understand what the f stop and shutter should be used. I thought I would set it a f11 and 1/100th or should I use f16? The distance will be 10-15 feet at most.

Donald Qualls · Dec 12, 2022

Your flash holder should have a Guide Number label (in feet or in meters, don't cross them up). You read off the Guide Number for the bulb and reflector you're using and the film speed, and divide by the distance (in the correct units) to get an f/stop. More information here.

BrianShaw · Dec 12, 2022

GN is exactly how you should determine the aperture to use. Shutter speed is a bit more flexible but if using faster shutter speeds you’ll see a reduction in exposure due to shutter efficacy.

GN will also be on the box that the bulbs came in. Or the data sheets are easily found on the internet.

One of the best tools for using flash bulbs is the calculator dial in older Kodak Master Photoguides. I think the 1981 edition may have been the last to include bulbs. And it only includes blue bulbs so to use a plain bulb a 1-stop compensation must be used.

BrianShaw · Dec 12, 2022

And let me add… a flash bulb at that close of a distance will likely blind your subject and leave then with a suntan. Better get your shot the first time because it might be your only opportunity!

campy51 · Dec 12, 2022

So what would the settings be for 400 speed at 10-15 feet?

Sirius Glass · Dec 12, 2022

campy51 said:
So what would the settings be for 400 speed at 10-15 feet?

What is the diameter of your reflector and what kind of surface does it have? See post #3.

rcphoto · Dec 12, 2022

campy51 said:
So what would the settings be for 400 speed at 10-15 feet?

If your holder or reflector doesn't have the chart you can reference the box the bulb came in. It should give you a breakdown based on the diameter of the reflector.

BrianShaw · Dec 12, 2022

Assuming that you are using a plain (not blue) bulb and a Graflite 4-inch reflector… read the black part of this calculator (flash to subject distance) to get an idea of an appropriate aperture. This is not compensated for faster shutter speed so use 1/50 or slower.

BrianShaw · Dec 12, 2022

My profound advice to you given that situation… shoot slower film. At such small aperture you’ll be experiencing the same kind of shutter efficiency “error” as if you were using fast shutter speeds.

campy51 · Dec 12, 2022

The reflector is a shiny 5 inch and the bulbs are old with no information except for b&w 7-25 feet.

BrianShaw · Dec 12, 2022

5-inch… yes… I typed the wrong number in earlier post.

The settings shown in post 8 should get you started. But at f/16 or f/22 you might be an underexposed due to the shutter efficiency, especially if you use a fast shutter speed.

mshchem · Dec 12, 2022

Just go for it! Be careful, those old clear bulbs had a history of occasionally exploding. Blue bulbs are important for panchromatic films. But just do it!

BrianShaw · Dec 12, 2022

Blue bulbs are for COLOR DAYLIGHT film, not panchromatic.

rcphoto · Dec 12, 2022

mshchem said:
Just go for it! Be careful, those old clear bulbs had a history of occasionally exploding. Blue bulbs are important for panchromatic films. But just do it!

They did make clear bulbs with the safety film to keep them from exploding on people.

campy51 · Dec 12, 2022

I took 3 shots, one at f11,16 and f22 from about 5-6 ft away. I'll see how they come out.

BrianShaw · Dec 12, 2022

Good luck! What film; what shutter speed?

mshchem · Dec 12, 2022

rcphoto said:
They did make clear bulbs with the safety film to keep them from exploding on people.

I associate the smell and crackle of 25B flashbulbs with Christmas morning. The smell of that blue plastic coating and the sound. Some of my fondess memories.

mshchem · Dec 12, 2022

campy51 said:
I took 3 shots, one at f11,16 and f22 from about 5-6 ft away. I'll see how they come out.

What shutterspeed? Oh and the flash sync on the shutter, M covers most flashbulbs, M ignites the flashbulb before the shutter opens to give the metal filaments in the bulb time to get blazing. Get an old Kodak master photoguide as pictured by @BrianShaw . I have sold off most of my flashbulbs, I had a 5 gallon pail, full. I would store it in a gardening shed for fear of a fire.

Donald Qualls · Dec 13, 2022

BrianShaw said:
But at f/16 or f/22 you might be an underexposed due to the shutter efficiency,

I would expect small aperture to reduce the effect of a fast shutter -- the opening blades will fully open the aperture for a larger fraction of the nominal shutter time as compared to "wide open" or nearly so. Still, not a bad idea to keep the shutter at 1/50-1/60 or slower -- or 1/25-1/30 if you only have X sync.

FWIW, an M3 bulb in a pretty small reflector is good for f/11 at ten feet on ISO 100, so your f/11, f/16, f/22 bracket at 5 feet should have, um, plenty of exposure with a #5 in a 5 inch bowl. The f/22 will probably be close to "normal" exposure.

Those big old bulbs were created in the days when ASA 100 was fast film (and before the ASA film speed shift of 1960); many photographers used old ASA 25 (= modern ISO 50) when shooting flash and saved the "fast" film for when flash wasn't an option.

BrianShaw · Dec 13, 2022

This data sheet illustrates the effect of shutter speed and quantifies GN based on shutter efficiency.

GE #5 Flash Bulbs

I suspect, like you Donald, that there will be a counteracting effect of shutter speed and small aperture, especially if a fast shutter speed was used. How much or how the two factors interacted is a bit of an unknown, quantitatively speaking... which might not matter if the images are successful and there is little interest in replicating those results.

One of the potential challenges that @campy51 faces, as you know, is that there are several unknowns in this application as it was described. That was certainly choosing very challenging, if not "extreme", conditions to learn how to use flash bulbs. For that application I'd definitely be oriented toward a thyristor strobe rather than flash bulbs.

I'm looking forward to @campy51's report on the resulting images and the flash bulb experience!

Donald Qualls · Dec 13, 2022

BrianShaw said:
For that application I'd definitely be oriented toward a thyristor strobe rather than flash bulbs.

Or at least an adapter and a smaller bulb. Bayonet to M-based adapters seem fairly common, and M to AG aren't unheard of. I've got a screw based to bayonet adapter, too, so if I hadn't left batteries in the flash (corroded beyond repair) I could shoot an AG-1 on my Six-20 Flash...

campy51 · Dec 13, 2022

Here are the results. Quick edits which I am not that great at. Shot at f11,16 and 22. I believe the first one is at f11. All shot about 5 feet at 1/100th.

BrianShaw · Dec 13, 2022

Well I'm surprised. Those are pretty good. I was expecting them to be exceedingly overexposed.

Cute children!

Donald Qualls · Dec 13, 2022

HP5 can take a lot of extra exposure. Those would probably take a while to print under the enlarger, but they're still on the straight-line part of the curve, it seems.

Helge · Dec 13, 2022

Using other than slow speeds with bulbs, when electro flash is so cheap and plentiful for the last many decades is just plain wasteful and amoral.

Bulbs quality is exactly in the total luminous flux over time.
And, in the quality of the light and the ability to blend with both daylight and artificial light at those slow speeds.

Never use above 1/60th and preferably at or under 1/30th of a second.

The situation is a bit different with the flat peak bulbs that are meant for use with focal plane shutters. But those are IMO still best used with slower speeds like 1/100 to pick up the most light from the bulb.

Chose a slower film and/or remove the reflector or point it away for bounce flash.
This will give much better results.
Unless you are after a Weegee look.

Setting for using GE #5 flash bulbs

campy51

Donald Qualls

BrianShaw

Attachments

BrianShaw

campy51

Sirius Glass

rcphoto

BrianShaw

Attachments

BrianShaw

campy51

BrianShaw

mshchem

BrianShaw

rcphoto

campy51

BrianShaw

mshchem

mshchem

Donald Qualls

BrianShaw

Donald Qualls

campy51

Attachments

BrianShaw

Donald Qualls

Helge

Setting for using GE #5 flash bulbs

Attachments

Attachments

Attachments

Privacy & Transparency

Privacy & Transparency