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  1. #21

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    Well, I have some preliminary, albeit negative, results to report.

    I got hold of a Nissin 4500 GTE flash (a pretty convincing flash: its guide number in feet is 148, and if you fire it at an unsuspecting person, it takes them quite a long time to recover themselves and beat you up) and made an IR filter for it out of Primary Red and Congo Blue theatrical gels. (They're really cheap; I think it cost me US$8 for each 20x24" sheet.)

    Two layers of blue and one of red produces a filter that on paper should start transmitting fairly freely above circa 700 nm, and that to the eye looks indistinguishable from an 89B. The flash at full power, through this filter, is quite noticeable but not disturbing; you'd never overlook it, especially in a dark room, but it doesn't leave an afterimage or create a visible floodlighting effect. Adding a third layer of blue produces something a bit darker to the eye and reduces the flash visibility quite a bit.

    I shot a roll of Efke IR 820 with a mixture of frames assuming guide numbers of 40, 28, and 20 (five feet from the subject, at f/8, f/5.6, f/4, which is the limit of the lens I was using---well, it goes to 3.5, but the difference seemed unlikely to be significant). I had pretty high hopes, but unfortunately the roll developed clear, so I'm going to assume that either the film was too far past date (dated February 2009, but kept refrigerated; its contemporaries have been fine) or the film just isn't sensitive enough even for this rather potent flash.

    I'll try the Rollei IR400 film next. At some point I might try the Efke film again, leaving the shutter open in a dark room and firing the flash multiple times to see if I can get anything to come out at all.

    -NT
    Nathan Tenny
    San Diego, CA, USA

    The lady of the house has to be a pretty swell sort of person to put up with the annoyance of a photographer.
    -The Little Technical Library, _Developing, Printing, And Enlarging_

  2. #22
    bvy
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    Thanks for the follow up. Sorry it didn't go well, but I'm very curious to hear about your results with the Rollei film. Please continue to keep us posted!

  3. #23
    Sjixxxy's Avatar
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    Yes. Use the Rollei film. My results with Efke was just as tragic.
    Gear: Camera, Brain, Light.
    Website - FB

  4. #24

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    Kip, did you work out the approximate effect of the filter on guide number?

    -NT
    Nathan Tenny
    San Diego, CA, USA

    The lady of the house has to be a pretty swell sort of person to put up with the annoyance of a photographer.
    -The Little Technical Library, _Developing, Printing, And Enlarging_

  5. #25
    holmburgers's Avatar
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    Quote Originally Posted by holmburgers View Post
    The mention of IR flashbulbs got me thinking.... by dipping ordinary flash bulbs in some kind of very deep red (infrared) dye...
    Yes, I'm quoting myself.....

    And although no one jumped at my flash-bulb idea, I figured I'd continue the research and include it here just for reference. So incase you guys get the itch, the info will be here.

    Anyways, I discovered this product by Rosco designed specifically for dipping bulbs for scenic applications. http://www.rosco.com/us/scenic/colorine.cfm

    Using the same idea as mixing a red & blue gel, you could mix red & blue 'colorine' and presumably get a visibly opaque coating, that would hopefully have some IR transmittance.

    I've emailed them once, and they pointed me towards some strobist kit... *ahem* ... no thanks I said flash bulbs lady!



    Anyways, I'm hoping she'll be able to give me a tech pub or something with the characteristic curves. But from a design standpoint, you'd want these bulbs to transmit as much IR as possible to cut down on overheating. So there's hope yet.
    If you are the big tree, we are the small axe

  6. #26
    Mike Wilde's Avatar
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    Quote Originally Posted by holmburgers View Post
    Yes, I'm quoting myself.....

    this product by Rosco designed specifically for dipping bulbs for scenic applications. http://www.rosco.com/us/scenic/colorine.cfm

    Using the same idea as mixing a red & blue gel, you could mix red & blue 'colorine' and presumably get a visibly opaque coating, that would hopefully have some IR transmittance.

    I've emailed them once, and they pointed me towards some strobist kit... *ahem* ... no thanks I said flash bulbs lady!
    Heylloyd's web site discusses this idea for making red safelights sucessfully.

    The key is to find a theatrical distributor. I am fortunate Rosco has a dsitribution agent (actually one of their own reps) here in the GTA. Things might be a bit harder to find at your end.

    I wish I had the time to try this out, because I have about 250 M2/M3 bulbs in stock, and a pal looking to unload about 30 rolls of Ilford SFX in 120.
    my real name, imagine that.

  7. #27
    holmburgers's Avatar
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    Mike, thanks for the heads up. I can't seem to find anything about safelights on that website however. Got a link?

    edit: found some stuff via the "googles" ... durrr

    further edit: Ok, Rosco got back to me w/ a bunch of worthlessness and apprently they don't have any transmission data on their colorine product as it's meant for "entertainment". Indeed, this Hey Lloyd guy is a big proponent of making your own safelight bulbs this way. I found a few older forum posts where he talks about it. He claims that transmittance is free past 650nm but I don't know what he's basing this off of.

    Testing is the only option at this point, it appears.
    Last edited by holmburgers; 10-04-2010 at 03:23 PM. Click to view previous post history.
    If you are the big tree, we are the small axe

  8. #28
    holmburgers's Avatar
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    "...At the suggestion of A. Barrett, the Kodak Research Laboratories in England worked out a formula for an infrared-transmitting lacquer which could be applied to flash bulbs for candid photography and for photography in blackouts when regulations forbade the use of visible flashes. The formula was published in 1940 by Morris and Spencer."

    Morris, R B, and Spencer, D A, "Dazzle-Free Photoflash Photography", Brit. J. Photo., 1940, 87, 288-289

    If anyone has easy access to this article, please post it. In the meantime, it's on my library list.

  9. #29

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    Quote Originally Posted by Mike Wilde View Post
    The key is to find a theatrical distributor. I am fortunate Rosco has a dsitribution agent (actually one of their own reps) here in the GTA. Things might be a bit harder to find at your end.
    It looks like mainstage.com, the site I got my gels from, sells colorine. I've only had the one transaction with them but it was unobjectionable, for what that's worth.

    -NT
    Nathan Tenny
    San Diego, CA, USA

    The lady of the house has to be a pretty swell sort of person to put up with the annoyance of a photographer.
    -The Little Technical Library, _Developing, Printing, And Enlarging_

  10. #30
    mhcfires's Avatar
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    Quote Originally Posted by holmburgers View Post


    "...At the suggestion of A. Barrett, the Kodak Research Laboratories in England worked out a formula for an infrared-transmitting lacquer which could be applied to flash bulbs for candid photography and for photography in blackouts when regulations forbade the use of visible flashes. The formula was published in 1940 by Morris and Spencer."

    Morris, R B, and Spencer, D A, "Dazzle-Free Photoflash Photography", Brit. J. Photo., 1940, 87, 288-289

    If anyone has easy access to this article, please post it. In the meantime, it's on my library list.
    My son is a research librarian, I'll ask him if he can locate the book.

    m
    Michael Cienfuegos


    If you don't want to stand behind our troops, please feel free to stand in front of them.

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