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Thread: Open Bulb Flash technique questions

  1. #11
    Tin Can's Avatar
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    Re: Open Bulb Flash technique questions

    Back to business.

    Some won't like this but the best definition of WS and Lumens is found on Paul C Buff. He clears up a few things for me. If you disagree, please tell us why. http://www.paulcbuff.com/sfe-unitsofmeasure.php

    He rates his Einsteins at 28,000 lumen seconds, which I believe is close to the 25,000 Lumens of a Press 25. Which may mean with a same type and size reflector they produce the same amount of flash light power , but with different color temp and duration. http://www.paulcbuff.com/e640.php

    This gives me something to test, I can pop a strobe and a single P25 and expose both DSLR and film at similar ISO and see what I get.

    Soon this will happen.
    2022

  2. #12
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    Re: Open Bulb Flash technique questions

    My research has been tested. i just got C batteries.

    I used DSLR at ISO 100 Full Dark studio, 5 sec @f16. First image is Einstein full power. Second image is P5 flashbulb.

    I had guessed they were close and I think they are. Both were dull aluminum cone reflectors 9" and 11" respectively. They were fired about the same height and distance, 3' apart.

    A lot of light in one egg sized flashbulb and very portable.

    As an afterthought I have added a 3rd image shot with ISO 100, 1/5 sec @f16 2K Mole Fresnel.

    Click image for larger version. 

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  3. #13
    Jac@stafford.net's Avatar
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    Re: Open Bulb Flash technique questions

    Quote Originally Posted by Randy Moe View Post
    My research has been tested. i just got C batteries.

    I used DSLR at ISO 100 Full Dark studio, 5 sec @f16. First image is Einstein full power. Second image is P5 flashbulb.

    I had guessed they were close and I think they are. Both were dull aluminum cone reflectors 9" and 11" respectively. They were fired about the same height and distance, 3' apart.
    The lights appear to be at different angles, but yes, pretty darned good for testing considering that you don't have a lot of bulbs to spare. Ain't it amazing how much light there is in a 25 bulb? (BTW, for the others because you know, the 25 bulb refers to its ~1" diameter in mm.)

  4. #14
    Tin Can's Avatar
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    Re: Open Bulb Flash technique questions

    Quote Originally Posted by Jac@stafford.net View Post
    The lights appear to be at different angles, but yes, pretty darned good for testing considering that you don't have a lot of bulbs to spare. Ain't it amazing how much light there is in a 25 bulb? (BTW, for the others because you know, the 25 bulb refers to its ~1" diameter in mm.)
    Yes, it was different angles, 3 ft apart. I didn't want to move everything as there is no room in here.

    The P5 bulb preceded the P25 bulb, I yet they are interchangeable I believe. They are the same diameter. Are you sure it's a metric assignation? Seems kinda odd for something made in the 30's and 40's

    I have plenty of bulbs for this summer. 1000+ M2, M3: 500 P5, P25: 300 AG1 and 100 #5. Assorted medium base of varying power.

    And all the gear to pop them anywhere.

    They call me the Flash. No they don't...
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  5. #15
    Tin Can's Avatar
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    Re: Open Bulb Flash technique questions

    Adding 1 more bulb type in the same 11" reflector. It is becoming my favorite.

    A M2B flashbulb which I calculated as 3 stops slower than P5. This is a blue coated Color film bulb the size of a grape. A dozen fit in a back pocket in the OE box.

    Shot ISO 100 f5.6 open bulb. I am only going to figure out B&W as I use digital for all color at this time. The camera is set to B&W.

    I am finding Lumens and GN to correlate different bulbs useful. But all these bulbs in their different era boxes have different ways of 'helping' the shooter.

    Even the 50's fancy BC flash holders use a variety of 'tips'. No real standards I guess. They say the same of modern strobes.

    I need to make cheat sheets, 'as my head is like a sieve', if you know that song...I'm not using a meter, preferring to find the basics.

    After the DSLR tests, do them all over on HP5 and X-Ray. Then I start shooting 8x10 in the dark. If I can find a dark spot in Chicago...

    Click image for larger version. 

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  6. #16

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    Re: Open Bulb Flash technique questions

    So speaking of cheat sheets, I use 2: Kodak Photoguide calculators (most of the time) and a LawrenceWalsh FlashRule. Have you compared any of your tests against them?

  7. #17
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    Re: Open Bulb Flash technique questions

    Quote Originally Posted by BrianShaw View Post
    So speaking of cheat sheets, I use 2: Kodak Photoguide calculators (most of the time) and a LawrenceWalsh FlashRule. Have you compared any of your tests against them?
    I am using a NOS Lawrence Walsh Flash Rule, a cool wood slide rule but I don't have the Kodak one. I am checking 'guides' against each other. Some of these bulbs are not marked.

    This is a big help found on APUG. Click image for larger version. 

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  8. #18

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    Re: Open Bulb Flash technique questions

    Can't wait to hear results of your analysis. The old Kodak calculator is my favorite because it reminds me of the efficiency correction based on shutter speed. I have a couple of the slide rules but haven't used them much because I keep getting a gut feeling that the sliderule answer is different from the photoguide answer... and photoguide has worked well for me even with E-6 so it must be right on. But I'm either too busy or too lazy to compare the two.

    I have a random assortment of those bulb manufacturer guides but that one doesn't look familiar. Thanks. The GNs those guides provided seem quite right-on to me in my experience.

  9. #19
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    Re: Open Bulb Flash technique questions

    Another tip from the flashbulb era: When you want to add light, wedge another bulb behind the socketed one. The socketed bulb will set off the other one, and create a longer duration. Oh, and the fun factor - it's dangerous, too!

    Speaking of calculating flash. I have a very old flashbulb 'meter'. It is a rangefinder with a slide-rule type wheel attached.

  10. #20
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    Re: Open Bulb Flash technique questions

    Yes, Jac, I have read that one bulb will fire another (secondary ignition) and a whole bag, pocket or box can make some excitement and danger.

    I am not one of those 'static' people who spark on everything.

    I will try my best to not hurt myself or others. Notice the shields and I just bought the shield a member was selling here today.

    Here's my flash gear I will be using in a variety of ways.

    I will soon test with 35 mm film of the same type I will use for LF and ULF.

    I know most here know this, but the light needed for tiny format is the same as ULF, given all other factors are the same, such as shutter speed, aperture, filter, distance, ISO.

    The tiny Honeywell Tilt A Lite has a unique bulb socket that mounts AG1, M2, M3, M5 and Press 25 bulbs by just pushing them in. The entire Tilt a Lite folds up and goes in a small shirt pocket.

    Even cooler is the tiny AG1 has the same power as the Press 25B bulb the size of an egg.

    Testing with Nikon F5 soon.

    First I am going to DSLR video at 60 fps to look at flash duration. I can't shoot video any faster, 60 fps may be too slow. Need a high speed camera...

    After looking at my video, I am going to choose a shutter speed, probable 1/25 as that is the speed of a Packard and most of my lenses I will be using don't have the old time 'M' setting which as Jac pointed out, fires the flash before the shutter to match them up.

    Click image for larger version. 

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