Flash Bulb Question P25 and #5 vs M25 and M5 or later M3

windly9 · Apr 3, 2011

Sorry, i have one question but not related to flash bulb...

What is frame number(on the backing paper of film roll??) ?

What are they for?

Thanks!

Wade D · Apr 3, 2011

Most all of the old medium format cameras had a red window on the back of the camera. After each exposure the film was wound to the next number in the window. This was before the more modern cameras that wound to the next frame and then stopped automatically.

brianmquinn · Apr 16, 2011

I finally found the answer to the question that started this thread in some old printed GE information.
The M5 and M25 were the same size and had the same total light output. Their timing was different. The M25 was 15ms to peak and the M5 was 20ms to peak. The M5 was made to have the same 20ms to peak time that the larger and brighter GE #5 had. The larger GE #5 put out about 25% more light then the M5.
Simple box cameras of the time ( 1950s ) had fixed shutter speeds of about 1/30 sec. That is about 32ms long. They also had what was in effect X sync. There was no delay in opening the shutter on these simple and cheap cameras. They relied on long shutter speeds for flash sync. They also had small fixed F stops of about F16 to get maximum depth of field with their fixed focus lenses. The reason an M25 bulb was recommended for these simple cameras was all of the flashbulb’s light output would be during that 32ms. With a slower M5 bulb the shutter would close before the bulb burned all the way out. This would result in a reduced guide number for the M5 if used in these simple cameras.

windly9 · Apr 19, 2011

flash unit... flash bulb?

Hi, I've just bought an Argus 75. The flash unit comes with it has a reflector measured about 4.5 inches. Is it considered to be a 5 inches reflector? and what kind of bulb will it take?

brianmquinn · Apr 19, 2011

I can't say for sure without seeing your unit but the Argus units I have seen in the past took the bulbs with pins on the side of their base. That would be the #5 or Press 25 or bantam 8. With an adaptor they could take the M2, M3, M5, M25 bulbs.
Look on your unit most flashguns gave a distance to subject to use with a listed bulb. The bulb listed is the one you need.

windly9 · Apr 21, 2011

RE

My camera and flash gun look something like this(photos from internet...)

PS: A few bulbs with unknown bulb size(I didn't know how to differentiate the bulb size) come with the camera and they can fit into the flash unit(those bulbs have two small pins at the side each, and just need to push them into the reflector and they stay in there)

brianmquinn · Apr 21, 2011

The only bulbs with pins I know of are the ones I listed as the first reply to this question about your flash. Any of them should work.

bblhed · Apr 21, 2011

Here is a good way to think about M3 and #5 flash bulbs, I know because I have done it.

With an M3 at about 1/30 sec and F/8 you can illuminate some people IN your back yard at night.

With a #5 at about 1/30 sec and F/8 you can illuminate some people AND your back yard at night.

I have tried this in a Honeywell Tilt-a-Mite, the M3 and #5 may have about the same light output, but the #5 can spread it out a lot better than the M3.

brianmquinn · Apr 21, 2011

Real tests ALWAYS top what the manufacturer says their product does. Test bulbs with your camera and film combo to insure it works for you.

nickrapak · Apr 26, 2011

bblhed said:
I have tried this in a Honeywell Tilt-a-Mite, the M3 and #5 may have about the same light output, but the #5 can spread it out a lot better than the M3.

The M3 and #5 don't have nearly the same light output. They have similar guide numbers, but if you look at the fine print, you'll see that the M3 is for a 3" reflector, and the #5 is for a 5" reflector. Basically, this means that with the tilt-a-mite (5" reflector), the M3s are actually a stop dimmer than their GN says, as evidenced by your test.

bblhed · Apr 26, 2011

nickrapak said:
The M3 and #5 don't have nearly the same light output. They have similar guide numbers, but if you look at the fine print, you'll see that the M3 is for a 3" reflector, and the #5 is for a 5" reflector. Basically, this means that with the tilt-a-mite (5" reflector), the M3s are actually a stop dimmer than their GN says, as evidenced by your test.

That wasn't a test, that was just me trying to get some well lit photos. I have to say that if #5 weren't so annoyingly bright I would use them a lot more for outdoor night photography.

wilsonlaidlaw · May 8, 2011

Just going back to bulb flash after 50 years

I am just going back to bulb flash after 50 years or so. My father's US agent sent me a Brownie Starflash in the early fifties which got me started but it was quite difficult to find the required Sylvania bulbs in the north of Scotland. I moved on to occasionally borrowing my father's Bilora to use with my Retina and Reid III cameras. However bulb flash went out the window when I was given a Mecablitz 102 as a Christmas present in about 1959.

I have decided that bulb flash looks nicer with B&W film, as opposed to the Leica 24-D and 58-D flashes I use with my M8 and 9 cameras. I have recently found a near mint Leitz CEYOO to use with my IIF and M4 Leicas and I had hoped to use it with my Rolleiflex 3.5F Planar TLR as well but the PC lead will not fit, as it is the early shallow push on and turn Leica type. I have been lucky enough to locate a Rolleiflash, complete with ring, arm and reflector for just £12. I have a pair of SBC to small base adaptors and I am on the point of buying an SBC to PF adaptor.

For bulbs, I am proposing to start with PF1 and PF5 for the Leica and M3 for the Rollei. I only really take B&W in film now, so not worried about blue bulbs. Any other suggestions as to good bulbs to start with (taking availability into account, remembering I am in Europe).

I am probably going to replace the capacitor in both flashes. Someone has in the past replaced the Leica capacitor but it looks like some time ago and the soldering is of the splatter and hope variety. Amazon have axial wire 470 μf/35v capacitors but not the original 100 μf. Do folks think that the high value capacitor makes any difference other than taking slightly longer to charge after you put the bulb in.

Below pics of the CEYOO and Rolleiflash

Wilson

brianmquinn · May 19, 2011

First off as far as capacitors go they are not as needed as in the past. Decades ago the standard zinc-carbon battery held little total charge and had a short shelf life. So even when not in use they would get weak just sitting in the flash gun or in the unopened box on the store shelf.

Several of the Kodak flash guns from the 50s could use regular AA batteries OR a 14 volt battery in combination with a capacitor. The capacitor just ensured that the flash went off if the battery was weak. Since 14 volt batteries are hard to come by today I just uses the AA batteries. With a fresh (unexpired) set of modern Lithium or Alkaline batteries I have never had a problem. Modern batteries are good for years on the shelf and setting a flash off only takes a very small part of their total charge. They should be good for 1,000 of flashes. With old style zinc-carbon batteries Kodak said to replace the batteries after only 100 flashes.

Now I have a question. I have trouble in the USA finding Philips Style flash bulbs but M3 bulbs are common. In the UK is it easy to find M3 bulbs or are the Philips style bulbs more common?

wilsonlaidlaw · May 19, 2011

Advantages of a capacitor

One of the advantages of a flashgun with a capacitor is accuracy of firing. Now if you are using a camera at 1/30 sec, it is not too important but if you using say a Rolleiflex at 1/125 with a fast rise bulb, the flash needs to fire at exactly the correct time. The bulb gets such a whack of current with the capacitor, that it goes off instantly.

You can find Philips PF1, PF1B and more rarely PF5, PF5B bulbs on UK Fleabay. The F in PF stands for "fast" not focal plane, therefore only useful for leaf shutter cameras, not Leicas or SLR's. PF1 has a guide number of about 40 and PF5 about 65. The blue bulbs about half this. My Leica IIFRD can just about use PF's at 1/30 because it has a unique feature. It has a small dial on top with settings of 1 to 20 which vary the delay between the shutter starting to open and the flash firing.

There does on the face of it, appear to be one supplier in the UK, Marriottworld. However since the death of his wife, Stephanie last year, poor Fred Marriott is in such a state, that he has no idea of what stock he has and where to find it. I did not even get a reply to my last contact. All these second hand camera shops in the UK are closing down rapidly.

I bought a rag bag of mixed bulbs (all BC base) from the nice guys at Pacific Rim Cameras. They probably have PF's if you need them. Bill Cress has them as well.

Wilson

Sirius Glass · May 19, 2011

brianmquinn said:
First off as far as capacitors go they are not as needed as in the past.

Absolutely WRONG!!!! The capacitors are part of the resistor-capacitor circuit which counts on the RC time constant to guarantee the proper timing and shape of the flash. This is basic electrical engineering. Please do not promulgate violations of the laws of physics!

Steve

brianmquinn · May 19, 2011

Concerned;
I agree that a capacitor is very useful in with high speed bulbs or when flashbulbs are shot at high shutter speeds. My post was in reference to the cameras and flashes I use most often. I own over a 100 cameras. Most (but not all) of the ones I use flashbulbs with are old simple cameras from the 1940s, 50s and 60s. Theses cameras have slow shutter speeds of 1/60th of a second or less.

Also to be clear to future readers of APUG. I have flash guns that can be used with OR WITHOUT a capacitor. Do not think you can cut a capacitor out of your flash gun and it will work unless you know what you are doing.

As far as Marriottworld is concerned, I have know of Stephanie untimely passing for a year or so. She had a passion that her husband can not be expected to continue.

I have over a 1,000 M3 and M3B flashbulbs in stock right now. If anyone on APUG would like to trade M3 (or other bulbs) for Phillips style bulbs PM me. That way we can do a trade and cut the ePRAY and PayPal (where is the pal ?) out of the equation.

brianmquinn · May 19, 2011

Sirius Glass, you are smart and I have learned a lot from your posts in the past. We are both smart people. We just need to speak and we will respect each other. Let us not do this on a public forum trying to prove who is better. Neither of us is better. We are trying to post useful information. If you feel I am wrong let us not argue but come up with a proper post. Let us inform, NOT fight. PM me if you would like to talk and we could come up with a proper post that would be useful and informative to APUG.

wilsonlaidlaw · May 20, 2011

For those who might not be sure how a capacitor flash gun circuit works, I post below the circuit diagram of my Leica CEYOO. When you plug in a flash bulb, it completes the outer circuit and a small current, limited by the 10K resistor to just 0.00225 amp (V=IR and assuming the resistance of the bulb is effectively nil compared to the 10K resistor), so the bulb does not fire. This current charges up the capacitor. So how long do you need to leave the bulb in for the capacitor to charge? If my maths is correct and I have remembered my electricity from physics 50 years ago, at 0.00225 amps, a 100 μf capacitor would require just 0.04 seconds to charge up. When the flash contact switch is closed, the battery is effectively out of circuit and it is the capacitor only which discharges rapidly through the flash bulb. The current rise rate of the capacitor would be much faster than a battery, particularly an old fashioned zinc carbon multi cell small battery, which was all that was available in the 1950's. If you have a leaky capacitor and leave a bulb in the flash, the battery will run down quite quickly, which is why it is always a good idea, if you are leaving a bulb in a flash for display purposes, take out the battery.

I have now found a source for 100 μf axial wire capacitors and should have 2 waiting for me, when I get back to the UK next week.

Wilson

wilsonlaidlaw · May 20, 2011

A little bit more physics if you can bear with me. I have a Chinese made 22.5V zinc carbon battery (which I am putting nowhere near my precious Leica and Rollei flashes). I have just been playing with my multimeter and 490 Ω resistor and as far as I can work out, the internal resistance of the battery is in round numbers 20 Ω. A #26FP flashbulb has a resistance of 5 Ω. Therefore if you were to fire with battery rather than capacitor, the flash current would in theory be 0.9 amps (22.5v / 25 Ω) but due to the limiting current of these very small cells, probably around half of this number but let's be generous and say it's 0.6 amp. The capacitor has effectively no internal resistance and the current would be 4.5 amps (22.5v / 5 Ω) i.e. nearly 7 times the amount via the battery. This is the attraction of using a capacitor fired flash.

Wilson

brianmquinn · May 29, 2011

I have a PDF file of the GE Flashbulb data booklet up at:

http://www.butkus.org/chinon/flashes_meters.htm
It is under the title
GE Flashbulb Data 1961

I don't get any money for this. But do donate to Mike if you use his site. He as 1,000s of photo related instruction manuals and you can see how much time he has dedicated to his site.

Randy Moe · Apr 26, 2015

Best info I have found yet.

Thanks!

Flash Bulb Question P25 and #5 vs M25 and M5 or later M3

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