flashbulb question for rolleiflex

[randy6]

So i want to play with some old flashbulbs. I replaced the capacitor and replaced batteries with 2 12v in series so it's working. Any how I'm trying to understand these bulbs. The rollei 2.8b syncs up to 1/500 sec I have an old flash meter say I flash it roughly 12 feet away and I get a f number of 16 Would this be the peak of the bulb and would the peak of the flash. be simultaneous with a shutter speed of 1/500? Or would it be better to stick with the guide number formula on the box?

 

[BrianShaw]

I find it better to use guide number, or one of the dial calculators in an old Kodak PhotoGuide.

 

[BrianShaw]

With faster speeds, don't forget the correction factor.

 

[AgX]

The rollei 2.8b syncs up to 1/500 sec ...

That is true for electronic flashlights. Bulbs have a retarded peak. To get get most effect out of these at fairly short exposure times one needs premature triggering. Alternativey (2nd best) one uses the X-setting and a rather long shutter time.

 

[randy6]

I might have one of those old kodak photo guides. So use the X sync and a long shutter speed I would get the most out of the bulb?

 

[Prof_Pixel]

I might have one of those old kodak photo guides. So use the X sync and a long shutter speed I would get the most out of the bulb?

No. Use the M setting!

 

[BrianShaw]

No. Use the M setting!

Very important... use the M setting!!!

 

[frank]

I might have one of those old kodak photo guides. So use the X sync and a long shutter speed I would get the most out of the bulb?

Actually yes, but I'm not sure how much more exposure you'll get. There will be some accumulation of light during the burn time using a slow shutter speed, but not sure if it would be significant/noticeable. Use a flash meter.

Use of M sync for flashbulbs is important when using shorter speeds as it delays the opening of the shutter until the brightest moment of the burning bulb.

This is how I understand things. Could be wrong.

 

[Ken Nadvornick]

The 'M' setting (instead of 'X') delays the shutter from firing for about 20 milliseconds. This allows the bulb to burn up to near maximum brightness before the exposure occurs.

Best to just use the published Guide Numbers for exposure control with flash bulbs. If you know the Guide Number for the bulb and reflector combination you are using, I can help you quickly create an accurate table of subject distances by aperture for each film you might use, at any aperture resolution you like, if those might be useful.

Ken

 

[randy6]

Okay if I use M setting 20 milliseconds delay and I burned a bulb for a test at my flash meter adjust to the camera F number to my flash meter I should be close for my exposure regardless of shutter speed. But best to use the guide numbers. The reflector is 5 inch. Thanks for all the help.

 

[Prof_Pixel]

If this is a flash meter designed for electronic flash units, I doubt it will give you meaningful information about medium peak flashbulbs.

 

[BrianShaw]

Okay if I use M setting 20 milliseconds delay and I burned a bulb for a test at my flash meter adjust to the camera F number to my flash meter I should be close for my exposure regardless of shutter speed. But best to use the guide numbers. The reflector is 5 inch. Thanks for all the help.

I don't know if the flash meter will correctly meter a bulb or not, but I do know that you need to consider a correction factor based on shutter speed faster than 1/60 or so.

 

[Sirius Glass]

The package of bulbs should give guide numbers for different size reflectors and their surfaces based on the shutter speed.

 

[Ken Nadvornick]

I don't believe standard electronic flash meters would register correctly, as there is no built-in matching 20 millisecond (1/50 sec) delay before measurements are triggered. That means if the meter is set to, say, 1/125 sec, then that measurement interval would begin at the instant the bulb igniter was lit, and would only capture a small portion of the rising intensity as the bulb burned up to its maximum output.

However, if the meter was set to 1/25 sec, then it might measure the full volume of light on both sides of the peak. This would be the equivalent of an unsynchronized open flash scenario, but would still not mimic the 20 millisecond delay used with mid-range shutter speeds faster than 1/25 sec, where the goal is to synchronize the mid-point of the 1/125 sec shutter interval with the mid-point of the intensity curve of the burning bulb.

The analogous photographic situation would be to set the 'X' sync speed, then use flash bulbs. Anyone (including myself) who has ever switched from electronic flash to flash bulbs and forgotten to switch from 'X' to 'M' knows the end result. The shutter (set to mid-range) opens and closes before the bulb can burn to useful intensity, and the resulting negative looks as if no flash was used at all.

My guess is that a standard flash meter would react in exactly the same way.

Ken

 

[frank]

A flash light meter, set to a slower speed, registers both the flash light and the ambient light, so I think it would be capable of providing an accurate reading for flash bulbs, when set to slower speeds that would encompass the entire burn time of the flashbulb.

 

[MattKing]

Some flash meters work in purely incident mode, and do not even give you the opportunity to factor in either shutter speed or flash duration.

Use "M" and a relatively long shutter speed, and a flash meter that works that way.

 

[bsdunek]

Yes, you're overthinking it. I used flash bulbs for years with Compur shutter cameras. Use the M setting and the flash guide. I usually used 1/100th or so, but it will sync at any speed. Even 1/500th sees most of the flash.

 

[randy6]

Another question. Mid century photographers with the graflex cameras using there flashes in outdoor(fill)/indoor light. What do you think there secret was I mean did they tell the subject stand here a while I measure the distance to you and look up the guide numbers so I can find the f stop?

 

[BrianShaw]

They knew the basics and had experience. It was intuitive rather than an academic thought process

Some cameras had built- in flash calculators, like the super graphic. If unsure it took just a glance after focusing. Many would tape a list of distances and aperture settings for the film the use. It's a short list since with most film the setting just needs to be "close enough".

The correction for shutter speed is more important when you want to be more exact or when your film dictates. E-6 and Ektar100 are situations where I find exactness to be useful.

 

[Arklatexian]

So i want to play with some old flashbulbs. I replaced the capacitor and replaced batteries with 2 12v in series so it's working. Any how I'm trying to understand these bulbs. The rollei 2.8b syncs up to 1/500 sec I have an old flash meter say I flash it roughly 12 feet away and I get a f number of 16 Would this be the peak of the bulb and would the peak of the flash. be simultaneous with a shutter speed of 1/500? Or would it be better to stick with the guide number formula on the box?

There should be a switch on the front of your camera marked: M and X. The "M" is for flashbulbs that have magnesium wire inside. I think that is the type of bulb that you have. The most common was GE #5 and Sylvania #25. Both were about the same. When your camera is set on "M", the shutter closes the flash contacts 20 milliseconds before the flash reaches its peak. This will synch at any shutter speed with those bulbs. The "X", on the other hand, closes the contacts when the shutter is wide open and is intended for electronic flash (strobe, etc) and also synchs at all speeds, but and I repeat only with electronis flash. I would set my camera on "M" and use the guide numbers on the packages. Divide the your distance to the subject into that guide number and the answer will be your f stop. I hope this helps.......Regards!

 

[Arklatexian]

So i want to play with some old flashbulbs. I replaced the capacitor and replaced batteries with 2 12v in series so it's working. Any how I'm trying to understand these bulbs. The rollei 2.8b syncs up to 1/500 sec I have an old flash meter say I flash it roughly 12 feet away and I get a f number of 16 Would this be the peak of the bulb and would the peak of the flash. be simultaneous with a shutter speed of 1/500? Or would it be better to stick with the guide number formula on the box?

I should add to my advice posted above, If the camera does not synch on "M" with bulbs, the camera may have had that feature removed during a CLA or overhaul. Also be sure to set the switch on X (and leave it there) if you normally use electronic flash.......Regards!

 

[Sirius Glass]

There should be a switch on the front of your camera marked: M and X. The "M" is for flashbulbs that have magnesium wire inside. I think that is the type of bulb that you have. The most common was GE #5 and Sylvania #25. Both were about the same. When your camera is set on "M", the shutter closes the flash contacts 20 milliseconds before the flash reaches its peak. This will synch at any shutter speed with those bulbs. The "X", on the other hand, closes the contacts when the shutter is wide open and is intended for electronic flash (strobe, etc) and also synchs at all speeds, but and I repeat only with electronis flash. I would set my camera on "M" and use the guide numbers on the packages. Divide the your distance to the subject into that guide number and the answer will be your f stop. I hope this helps.......Regards!

No, M is the type of synchronization and is not related to magnesium.

 

[Prof_Pixel]

If I remember correctly, the 'M' stands for medium peak. There were also gas filed bulbs that were type 'F' for fast peak that were used with the 'X' flash setting.

 

[BrianShaw]

Some shutters, Ilex for example, had non-X setting for F bulbs. Graphex shutter has 2 M settings (black and red) but I'd need to do homework to recall the difference.

 

[Sirius Glass]

That sounds correct.