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Thread: using flashmeter for bulbs

  1. #1

    using flashmeter for bulbs

    Though flash bulbs are expensive, I have decided it is still affordable compared to flash equipment. At least for an occasional portrait. I was told flashmeters do not work well with bulbs. Curious your responses to that. My thought is the meter would respond to initial output and would register before the bulb is at max intensity?

    I was also told that the PF300 bulbs would be brutal on the model. Not the intensity but the duration. It was suggested a 22 euro would be a better pick. I want to use the 8 x 10 but I am not sure the 22 euro will be enough light. So I may have to use a 4 x5.

    I'd appreciate any advice!

  2. #2
    Moderator Ralph Barker's Avatar
    Join Date
    Sep 1998
    Rio Rancho, NM

    using flashmeter for bulbs

    I've never tried metering flash bulbs, so take my thoughts with a pinch of flash powder, Phil. I'd think, however, that a flash meter might miss the bulb's output altogether due to the difference in sync delay.

    The format itself won't affect the results, of course - just the potential limitations of the aperture range available on your 8x10 lenses, along with DOF considerations.

    The larger issue, I'd think, would be the quality of light produced by the bulb, and options available to modify that. Even with long-duration bulbs, the flash would be more kind to the subject than hot lights that would allow the same aperture.

  3. #3

    Join Date
    Mar 2002
    now in Tucson, AZ

    using flashmeter for bulbs

    I once took a flashbulb (one with a household lamp base) and put it in a ceiling fixture. Triggered the flashmeter and hit the light switch. POP- f/16 on the meter. I never tried taking a photo with that lighting- perhaps the longer duration of the flashbulb might give more light than was metered. A test with film would answer that. But I'd be as concerned with the quality of light produced, or at least how to preview it. O.Winston Link used to hard-wire his huge sets for photographing steam locomotives at night.. miles of lamp cord... and would test the setup with ordinary lightbulbs. Whe continuity was assured, they would then replace all the lightbulbs with flashlamps. Perhaps you could predict your lighting the same way?

  4. #4

    Join Date
    Jun 2004
    Melbourne, Australia

    using flashmeter for bulbs

    Phil, you're right that a flash meter won't work properly with bulbs. Because the bulbs take time to reach full power and then more time to drop back to zero power again the behaviour is quite different to a strobe. A strobe is faster than a shutter, so no matter what speed you use you get the same amount of light from the strobe reaching the film. A bulb can be slow enough that the faster shutter speeds allow less light to reach the film.

    I've been using a variety of bulbs with my Speed Graphic set-up and have found the little tables on the back of most flash bulb packets to be quite accurate. The size of the bulb is not necessarily a good indicator of its power as improving technology allowed them to shrink quite rapidly in size. The bulbs I'm using are anywhere from 20 to 40 years old and dud bulbs have been very rare.

    One thing to be aware of is the size of the reflector. A smaller reflector concentrates the light, so is brighter but gives less coverage. With a 5" reflector and the standard 135mm lens the edges of the negs are usually dark, so I really should be using a 7" reflector for full coverage.

    I can't imagine why you would use the meggaflash bulbs, the are so expensive compared to secondhand. I normally buy from eBay and flea-markets and try to pay no more than 50 cents each for small bulbs. There are still an awful lot of bulbs out there if eBay is anything to go by.

    Check out Bill Cress at as he has a lot of information there and has all the various bits and pieces you might need. His prices reflect the fact that he is running a business rather than just off-loading stuff found in the attic, but the service you get is much higher too. I certainly haven't regretted any purchases made from him.

  5. #5

    using flashmeter for bulbs

    Exactly, the meter would not record the entire flash from the flash bulb because it has such a long burn time.

    This is way lenses have X and M settings. X for the instant burst of the strobe. M to delay the opening of the shutter so it is open when the flash bulb is at its maximum brightness.

  6. #6

    using flashmeter for bulbs

    Thanks for the info. I have not bought the PF300s yet but have purchased some older ones a little cheaper.

    I can fire the bulb from my meter. If I select a sync time greater than the duration of the lamp burn time wouldn't that be a good measurement?

  7. #7

    using flashmeter for bulbs

    Consider running a simple test to equate the f/stop required with flashbulbs @ 1/30th sec with tungsten modeling lamps. Set up a pan reflector with lamp socket (Smith Victor or similar tungsten lamp) on a light stand, and using the published GN as a reference, do one or more test exposures using flash (plug the lamp cord into a circuit with batteries and the sync cord). Replace the flashbulbs with a tungsten lamp and AC power, and take an incident meter reading. Adjust the meter's EI setting and choose the shutter speed which gives the f/stop determined by flash tests.

    For use, set up one or more tungsten lights anywhere (reflectors, diffusion panels, bounce cards, etc.), meter with the settings determined by the previous test, set f/stop, swap tungsten bulbs for flashbulbs and plug cords into battery adapter, and shoot. Meter again if the modeling lights/flashbulbs are moved. Of course, the tungsten lamps may be used for still life or portraits with slow shutter speeds. Also, a bare bulb flash held a foot or two from a white ceiling can light a room.

    If you do this often, you might want to opt for a used studio flashpack. Although the initial cost is more than bulbs, the used resale value is considerably higher, and it's more convenient. I tend to reserve flashbulbs for outdoor use to stop motion and overpower daylight.


  8. #8

    Join Date
    Dec 2010
    Santa Barbara

    Re: using flashmeter for bulbs

    wow..I was thinking of posting just this and searched and here it is

    with re: to the meter missing the flash - my minolta flashmeter III can be triggered by cord...or 'non cord' - so I can hit the button, then manually flash the flash and it'll read it

    I imagine if one uses the 'non-cord' option..the meter would read the entire output of the bulb

    I should give this a try

    also..I bet I can use a bulb flash holder with an umbrella

  9. #9

    Join Date
    Aug 2000

    Re: using flashmeter for bulbs

    The meter willl not help. Use the guide number that should be on the bulb package. We used these for decades prior to the advent of electronic flash.

  10. #10

    Join Date
    Aug 2013
    Atlanta, Georgia USA

    Re: using flashmeter for bulbs

    Quote Originally Posted by Walt Calahan View Post
    This is why lenses have X and M settings.
    May I point out that shutters have X / M settings, not lenses.

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