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  1. #21
    wilsonneal's Avatar
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    When I was a kid, in one of the Photo Books I borrowed from the library, there was a terrific black and white portrait of Louis Armstrong, holding his horn, and the quality of light was very clean, diffuse and broad. I immediately liked the way it rendered the skintones. There were additional photos that showed how this portrait was made. It was in a studio with a giant homemade bank of fluorescents. At the time, my pre-teenage lighting skills were limited to on-camera flash, so this was a revelation to me.

    Others on this thread know more about the science of it all...color temps, etc...but I saw that image more than 30 years ago and it still is fresh in my mind. I would think that for black and white fluorescents could be a good source and worth experimentation.

    Neal

  2. #22
    keithwms's Avatar
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    Neal, with colour film, I have yet to see a shot that had the skin tones that I like.
    Of course, everything is worthy of experimentation, but at the end of the day, films are optimized for more natural spectral power distributions so one cannot expect them to behave optimally if that is not the case.

    Last edited by keithwms; 12-05-2006 at 03:27 PM. Click to view previous post history. Reason: added image link
    "Only dead fish follow the stream"

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  3. #23
    Helen B's Avatar
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    Here are two comparisons of sources of equivalent CCT using specific, rather than generic, tubes: the Kino-Flo tubes.

    Best,
    Helen


  4. #24
    keithwms's Avatar
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    That's helpful, Helen. I would have thought that the kinos wouldn't use mercury vapour, which is the source of the spikes. But there are the spikes, plain as day in the cinema tubes. It's basically the same thing you get for any fluorescent that involves mercury vapour (i.e. all "energy efficient" bulbs).

    [Glancing at the kino site, I got the quick impression that if one uses chromakey or similar backgrounds with colours similar to the spike maxima then one might achieve better separation. I can imagine adding emission lines to a bulb to make the chromakey pop.]

    Anyway, while we're on the topic of spectra, here is the one for a solux fluorescent, which has has a smooth spectrum:



    For reference, the spikey data is for a standard fluorescent containing mercury vapour. So basically, it looks like the solux bulbs are simply mercury-free.
    "Only dead fish follow the stream"

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  5. #25
    Helen B's Avatar
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    Keith,

    Solux lamps are incandescent, not fluorescent.

    The Kino-Flo tubes are likely to be mercury discharge because there isn't much of an alternative. Any discharge lamp, including HMI, will produce a spiky spectrum by its very nature.

    Best,
    Helen

  6. #26
    keithwms's Avatar
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    I see. Well then I guess the only way to deal with the spikes is filtration.

    Or avoid fluorescent lighting.
    "Only dead fish follow the stream"

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  7. #27
    JBrunner's Avatar
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    Quote Originally Posted by keithwms View Post
    I see. Well then I guess the only way to deal with the spikes is filtration.

    Or avoid fluorescent lighting.
    Or use post color corection.

    Often, on commercial shoots it is impractical to turn off all flo sources- a supermarket for instance. It is not practical to turn out the lights and replace all of the available illumination with your own. The lights available to suplement do not match the available illumination- say HMI's that happen to have a predominantly magenta spike. The supermarket flo's in this instance turn out to have a prominent green spike. So you can't filter at the camera, or color correct for one source without really screwing up the other.

    So what do you do? In this case I usually add plus green to the HMI's to bring their spectrum as close as I can to the flo's. Now I am dealing with a uniform problem, instead of an uncorrectable mixed bag of spikes. Also, the overall greenish light (or magenta, depending on the varibles of a given scenerio) freaks out the necktie people, so you have that to watch, which is always amusing, and makes it worth doing, for that reason alone.

    The resultantly uniform green can now be corrected with a camera filter, or by color timing. I personally usually opt for color timing, because it keeps the suits freaked out, and maintains the illusion that you are a master of dark alchemical arts, and also because I usually don't want to sacrifice my stop to yet another filter.

    So that's an example of one particular scenerio I deal with, and how I personally go about managing it. YMMV.

    [Pro driver on closed course- do not attempt- ]
    Last edited by JBrunner; 12-05-2006 at 06:57 PM. Click to view previous post history.

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