Modern Batteries for Vintage Flash Units w/ Bulbs - Specifically Argus

[Fragomeni]

This question has to have been asked and answered time and time again but for the life of me I can't find anything on the subject. I apologize if this has been answered before.

Anyway, is there any resource that describes using modern batteries in vintage flash units that used flash bulbs?

I have an Argus C3 with flash unit thats been sitting in my collection for a while and I did some work getting it back to prime condition and I'd really like to take this out and use it with some flash bulbs in the flash unit. Now I know nothing about batteries or battery equivalents. The battery compartment of the flash unit appears to take 2 batteries the size of modern C batteries. Is the solution so simple that I can just use modern C batteries?? I don't want to damage anything so I've not tried putting modern batteries in the unit yet.

If someone could let me know what batteries I can use and what bulbs I can use in the flash unit it would be very much appreciated. Thanks!

 

[Fragomeni]

I answered my own question. You can se modern C cell batteries in this flash.

 

[2F/2F]

IME, modern alkaline cells work fine in old flashguns, and they also last a very long time, unlike when used for electronic flashes. The ones in my Speed Graphic's flash have been in there doing their job fine for over five years, both for igniting flashbulbs and simply for releasing the shutter - via the solenoid on the lens board - for every shot (mostly without flashbulbs).

 

[Fragomeni]

IME, modern alkaline cells work fine in old flashguns, and they also last a very long time, unlike when used for electronic flashes. The ones in my Speed Graphic's flash have been in there doing their job fine for over five years, both for igniting flashbulbs and simply for releasing the shutter - via the solenoid on the lens board - for every shot (mostly without flashbulbs).

Yea, im excited to play around with this. I've got 2 dozen Sylvania 25b bulbs that Im testing out. Its a lot of fun and really draws some attention hahaha! Unfortunately I put in a bad bulb while looking at it with my face only about 8 inches away from the bulb and reflector and the bulb went off on its own right in my eyes. Singed my hand and really messed with my eyes pretty bad. I think it was so powerful that it actually made me a little physically sick and almost 4 hours later my eyes are still not back to normal Lesson learned! Never look at the bulb especially not that close!

Anyway, Im shooting them off in this Argus C3 and running Tmax 100 through it. Not sure how the ISO lines up but we'll see how they turn out after I develop the negatives and pop out a contact sheet. I was using the recommended f-stops for "Daylight Type Color Film" from the original Argus C3 manual. I noticed the recommendations progressed from ASA 10-16 films to ASA20-32 to ASA 40-46 and then to "Daylight Type Color Film" which I'm assuming was higher ASA then 40-46 and Im hoping it was at least somewhere near ISO 100. Any clue how to figure out the recommended f-stops accurately for ISO 100??

 

[Steve Smith]

IME, modern alkaline cells work fine in old flashguns, and they also last a very long time, unlike when used for electronic flashes.

THe cells in bulb flashes do not have to be able to supply an instantaneous current to fire the flash as there is usually a capaitor in there as well.

When the bulb is inserted the capacitor is charged by the capacitor via a resistor (to limit the current and prevent the bulb from firing early*). When the shutter contacts are closed the capacitor is connected directly to the bulb and fires it.

The cells therefore have quite an easy life.

capacitors have a low internal resistance and can supply a high current peak easily. If it was just a simple circuit with cells and a bulb, the higher internal resistance of the cells could lead to late and/or erratic firing of the bulb.

Unfortunately I put in a bad bulb while looking at it with my face only about 8 inches away from the bulb and reflector and the bulb went off on its own right in my eyes.

* exactly what the resistor should stop it doing!


Steve.

 

[Steve Smith]

Circuit if anyone is interested:



Steve.

 

[Fragomeni]

Any clue how to figure out the recommended f-stops accurately for ISO 100??

Again, I figured this out right after writing that post. I don't know why I can't figure this stuff out before I post questions haha. Anyway, I found my solution on the back of a second Sylvania 25b bulb box (I have two different bulbs from different time periods). Here is how to figure it out if anyone needs it or is interested:

(Pay attention to "Guide Number" which I abbreviate "GN". You'll use this to figure out f-stops)

Film Speed 80-125 ASA (ISO equivalent) @ 1/30 = GN 200, @ 1/125 = GN 95, @ 1/250 = GN 70, @ 1/500 = GN 48, @ 1/1000 = GN 46

For f-stop, divide Guide Number (GN) by distence, in feet, bulb-to-subject. (Ex: If Guide Number is 110, distance 10 feet, 110/10= f11

If anyone wants the full chart with ASA/ISO 10-500 let me know and I'll try to upload the chart so you can have it.

* exactly what the resistor should stop it doing!

You're right! I suppose maybe it wasn't a bad bulb but perhaps the resistor is broken. There is a little rattling in the socket of where the flash unit receives the bulb. I noticed this before putting in the first bulb and was concerned that the unit wouldn't work but it did and I put the rattle out of my mind because I was just happy that the flash unit still worked. I guess that rattling could have something to do with the resistor.

 

[Steve Smith]

It's unlikely that a resistor would go short circuit or lose resistance over time. More likely it would go open circuit and the flash would stop working.

Does the rattle stop if you place a bulb in the socket? The rattle is more likely to be the flash bulb contacts within the plastic (I assume) moulding which are a bit loose untill they are pushed out by the bulb.

I expect your mishap with the first bulb was caused by a bit of residual charge in the capacitor and an accidental shorting of the sync. contacts. Is there a manual fire button on the back?

I used to have an Agfa bulb flash for my Isolette I had when I was ten (35 years ago!). I have an Isolette now and some bulbs so it would be nice to get a flash for it. Mine used a 22.5v battery, the same size as a standard 9v battery but with a contact at each end.


Steve.

 

[2F/2F]

Again, I figured this out right after writing that post. I don't know why I can't figure this stuff out before I post questions haha. Anyway, I found my solution on the back of a second Sylvania 25b bulb box (I have two different bulbs from different time periods). Here is how to figure it out if anyone needs it or is interested:

(Pay attention to "Guide Number" which I abbreviate "GN". You'll use this to figure out f-stops)

Film Speed 80-125 ASA (ISO equivalent) @ 1/30 = GN 200, @ 1/125 = GN 95, @ 1/250 = GN 70, @ 1/500 = GN 48, @ 1/1000 = GN 46

For f-stop, divide Guide Number (GN) by distence, in feet, bulb-to-subject. (Ex: If Guide Number is 110, distance 10 feet, 110/10= f11

If anyone wants the full chart with ASA/ISO 10-500 let me know and I'll try to upload the chart so you can have it.



You're right! I suppose maybe it wasn't a bad bulb but perhaps the resistor is broken. There is a little rattling in the socket of where the flash unit receives the bulb. I noticed this before putting in the first bulb and was concerned that the unit wouldn't work but it did and I put the rattle out of my mind because I was just happy that the flash unit still worked. I guess that rattling could have something to do with the resistor.

It is interesting that they list a GN for '1000, as this speed was only found on FP shutters. I don't think any of my boxes for class M bulbs list a GN for that speed. Are you sure you don't have class F bulbs?

Notice how different it is from '30, in which the film records the entire blast of light, though. You lose over two stops by clipping the duration of the flash.

You also lose a fair amount of light by using the B bulbs instead of the clear ones. I try to only use the B ones for color film, but I am all out of clear #25/G.E. #5 bulbs, and only have #40/G.E. #11 bulbs left in the clear variety.

 

[DWThomas]

THe cells in bulb flashes do not have to be able to supply an instantaneous current to fire the flash as there is usually a capaitor in there as well.

When the bulb is inserted the capacitor is charged by the capacitor via a resistor (to limit the current and prevent the bulb from firing early*). When the shutter contacts are closed the capacitor is connected directly to the bulb and fires it.

The cells therefore have quite an easy life.

capacitors have a low internal resistance and can supply a high current peak easily. If it was just a simple circuit with cells and a bulb, the higher internal resistance of the cells could lead to late and/or erratic firing of the bulb.



* exactly what the resistor should stop it doing!


Steve.

Sorry, but I am forced to question this one. I have a 1958 vintage C3 and I'm pretty sure its two C cell flash gun is purely brute force. It was early sixties when I acquired a flashgun with a fold-up fan reflector (Honeywell "Tilt-a-Mite") that took smaller bulbs, when I saw the capacitor type unit. The one I had took a fifteen volt battery, common for portable electronics at the time. The capacitor in the unit I have slid into the holder next to the battery (to allow easy replacement I guess), each was slightly smaller than a double A cell. I think that was the big deal for the capacitor units, that it allowed a much more compact flash unit. When I originally saw this thread title, I feared the OP was looking for one of those 15 volts battery types which may have gone the way of the dodo by now.

Further possible unhappiness, any 1950s vintage capacitor that hasn't seen occasional use over the intervening years is likely no longer a capacitor (this assumes they were electrolytic types which they'd surely have to be for the required output surge).

 

[Steve Smith]

Sorry, but I am forced to question this one. I have a 1958 vintage C3 and I'm pretty sure its two C cell flash gun is purely brute force.

You may be correct. The only bulb flashes I have had experience of are for smaller bulbs and they all had a capacitor fitted.



Steve.

 

[Mike Wilde]

I was also yearning to run old flash holders, and last year found a place in Los Vegas that sold me a couple of new manufacture zinc carbon 22.5v batteries for a very reasonable price.

For my flash holders that take 15V batteries I pry the old guts out of the carbon zinc battery can, and re-use that can and end contents. I pack in a modern tiny 12V alkaline battery , and fill the empty negative terminal space with a short piece of 1/4" copper tubing or wadded up aluminum foil to link it to the old 15V battery contact.

12V alkalines are used in most NA car makers key fobs to power the remote door unlocking transmitter.

The down side to getting all the old flash holders to work is that it gives you a reason to buy up flash bulbs. I am presently holding between 400-500, mostly in ag2, ag3, and ag-1, both B and uncoated sorts. The 48 M25's I had I traded to someone with a functional Graphic holder.

 

[Fragomeni]

It is interesting that they list a GN for '1000, as this speed was only found on FP shutters. I don't think any of my boxes for class M bulbs list a GN for that speed. Are you sure you don't have class F bulbs?

Notice how different it is from '30, in which the film records the entire blast of light, though. You lose over two stops by clipping the duration of the flash.

You also lose a fair amount of light by using the B bulbs instead of the clear ones. I try to only use the B ones for color film, but I am all out of clear #25/G.E. #5 bulbs, and only have #40/G.E. #11 bulbs left in the clear variety.

Excellent point on whether or not the chart I was looking at was for M or F bulbs, I didnt think of that. However, now Im completely confused. The box that had the chart was a Sylvania 25b box with a woman holding a camera on the front, looks like probably from the late 60's or possibly 70's and it doesn't say M or F anywhere on the box. I pulled out my other boxes which are all the older Sylvania yellow and black boxes, they are Class M and are Press 25 and Press 25b bulbs. The yellow and back boxes provide guide numbers on the sides but the blue bulb guide numbers are different from the clear bulb numbers (as would be expected). Also, the boxes don't use ASA but use "Daylight Exposure Index" instead. Can someone please explain the difference? The Press 25b boxes list Daylight Exposure Index from 8-32 and shutter speeds up to 1/200 where the Press 25 boxes (clear bulbs) list Daylight Exposure Index from 8-160 and shutter speeds up to 1/400.

I plan on running several sheets of Tmax 100 4x5 through a Speed Graphic and 1 or two rolls of Tmax 100 35mm through the Argus C3 to test the exposures. Can anyone shed any light (no pun intended) on the best guide numbers to use when using Press 25 and Press 25b bulbs with modern Tmax 100 film? This would be extremely helpful! Also, how do the Cress Photo charts compare to the charts on the original Sylvania boxes and which would be preferable to use?

My Speed Graphic is shooting through a Carl Zeiss Jena 135mm Tessar that has a maximum shutter speed of 1/200. Any help finding the best guide numbers using both 25 and 25b bulbs running Tmax 100 4x5 through this would be a big help. Also, Im running out of 25b but there seems to be no shortage of 25 so I'm probably more inclined to run several tests using the 25's.

Thanks for all of your help everyone! I anxiously awaiting your input!

 

[Fragomeni]

Cress Charts:
http://www.flashbulbs.com/ClearBulbs.htm
http://www.flashbulbs.com/BlueBulbs.htm

 

[Fragomeni]

Ok, I just placed a call to a friend who has more experience going back decades then anyone else that I know and he provided me with the following solution that you can apply to any bulbs that you come across:

Guide numbers are figured by measuring light at a specific distance relative to the ISO (ASA previously) using a light meter and then multiplying the f-stop reading by ten.

Process (for ISO 100):
Have an assistant hold a tested and trusted light meter with hemispherical (domed) attachment (I use a Sekonic) 10 feet away from you. Use a tape measure to be as accurate as possible. Make sure that you are in a room that allows you to control your ambient light. Don't do this outside or in a room with bright open windows or anything that will cause any excess ambient light to throw off the reading. Have your assistant, at a 10 feet distance from the flash bulb, point the meter at the center of the bulb. Have the meter set to flash (not ambient or flash w/ cord). Have the assistant trigger the meter and immediately after you know they've triggered the meter ignite the flash bulb. Keep in mind that the longer you wait to ignite the flash the more skewed the reading will be because the meter will be recording ambient light from the moment it is triggered so ignite the flash bulb immediately. Now take the f-stop reading from the meter and multiply it by 10. This is your guide number for that particular flash bulb type. Use this guide number to figure the f-stops for any distance that you may be shooting just as you have before i.e. Guide Number divided by distance in feet (lamp-to-subject) equals f-stop.

 

[Fragomeni]

Back to the Sylvania bulbs. Can anyone confirm that all Sylvania 25 and 25b bulbs are class M? I have some of the later white boxes with the woman holding a camera but I cant find any class makings on the box. The yellow and black boxes say Class M right on them.

Thanks!

 

[mopar_guy]

Francesco,
Sylvania Press 25 and Press 25B ARE Class M (Medium peak bulb).

Press 25 (ISO100):
up to 1/30 sec = guide number 280
1/60 sec = guide number 260
1/125 sec = guide number 220
1/250 sec = guide number 180
1/500 sec = guide number 130

Press 25B (ISO 100)
up to 1/30 sec = guide number 190
1/60 sec = guide number 180
1/125 sec = guide number 150
1/250 sec = guide number 120
1/500 sec = guide number 90

I always try to err on the side of over exposure. All of these guide numbers assume a scene of average brightness. If the scene has a lot of dark colors, open up the aperture. If the scene has a lot of white, close the aperture more.