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Thread: Continuous Lighting question?

  1. #1
    stradibarrius stradibarrius's Avatar
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    Continuous Lighting question?

    I received some gift certificates for X-mas and am thinking about continuous lights for my little studio.
    I have looked at several CFL cool lights that say the are "daylight balanced" 5500k. If they truely are 5500k does that mean that I can shoot color film with out having to use my 80B blue filter?
    They product description says a lot about digital cameras but nothing about film.

  2. #2

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    Re: Continuous Lighting question?

    Film? Is that the stuff kodak made?
    yes, 5500k is 5500k, on paper. There may be a color cast (likely) they aren't mentioning. Led's are the way to go.

  3. #3
    Jim Jones's Avatar
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    Re: Continuous Lighting question?

    Vinny is right about CFLs. Some are advertised for photography, and may be better than others. A standard for determining this is the C.R.I. (Color Rendition Index). The higher the better. Some of the flourescent lamps that B&H sells have a C.R.I. of 82. Most of theirs don't list the C.R.I.. Even a high C.R.I. might not yield accurate color photographs, since flourescent lamps emit strongly in some colors and very little in others. The right balance of these spikes of color might give a high C.R.I. but poor color in photos or vice versa. I have a somewhat large and heavy Panasonic flourescent bulb with a C.R.I. of 84 and a color temperature of 2800K. It emits pleasant light, but I haven't tried photography with it yet. In contrast, an LED with a C.R.I. of 73 and 4100K color temperature looks unpleasantly blue. Both measure close to the rated color temperature with my old Gossen Sixticolor. I suggest trying photography with any CFL or LED before you buy in quantity. Some with a high C.R.I. are expensive.

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    Re: Continuous Lighting question?

    It's not just a question of color temperature—with their spiky light spectra, fluorescents and LEDs can have the effect of shifting certain colors unpredictably. Claims of "full spectrum" are flatly wrong, if not fraudulent.

    With that said, I think they would be fine for general stuff. Someone's blue sweater might unexpectedly render as deep purple or something, but unless you're doing product photography, it's probably not the end of the world.

  5. #5

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    Re: Continuous Lighting question?

    Quote Originally Posted by stradibarrius View Post
    I received some gift certificates for X-mas and am thinking about continuous lights for my little studio.
    I have looked at several CFL cool lights that say the are "daylight balanced" 5500k. If they truely are 5500k does that mean that I can shoot color film with out having to use my 80B blue filter?
    They product description says a lot about digital cameras but nothing about film.
    Take a look at the LED continuous light systems. Kirk Tuck has written a new book covering their use.

  6. #6

    Re: Continuous Lighting question?

    CRI (color rendering index) is helpful but it definitely does not tell the whole story. 5500K "Daylight" lamps (or any lamps) can vary widely in the wavelengths they emit. You can find this information in Spectral Power Distribution charts that should be available for the better lamps.

    So look for Spectral Power Distribution information on the lamp you consider using. The more closely the distribution of the output of the lamp imitates that of daylight, particularly in the sensitivity range of the film or sensor, the better for color accuracy.

    Once you get close, a small amount of correction via a CC filter gel will help you fine tune your set up, usually a tiny bit of magenta.

  7. #7

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    Re: Continuous Lighting question?

    What subject will you be shooting with these lights?
    If people, electronic flash is probably best with color film and you could use hot lights with B&W. If you are shooting still life in color or B&W then you could go with hot lights and use your 80A filter to correct for color shift. The 80A is more important with transparency film than color negative.

    I shoot still life with tungsten lights and stocked up and froze quite a bit of Fuji NPL before they discontinued it. When I run out of NPL I will shoot daylight color neg with an 80A.

    I had always thought that the CFL lights were better used with digital as any color temp problem could be corrected with a custom color balance with the digital camera.

  8. #8

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    Re: Continuous Lighting question?

    It's not possible to color correct for lightsources with spiky spectra. Even if you correct the color temperature and get a grayscale rendering 100% perfectly, the spikes can cause a loss of differentiation between hues, or give colors an inaccurately pronounced component (red, blue, green). Since there's no way for software to differentiate between "purple" and "purple that should be blue," they will both stay purple.

    The extreme example of this is the orange streetlight that most cities use. They're quite spiky by design, presumably so astronomers can filter them out. But try shooting a Macbeth by streetlight. You can remove the orange/yellow cast with optical filtration or white balance adjustment, but you'll be left with an almost monochromatic image.

    Obviously the CFL/LED lights marketed to photographers have more even spectra, but there are still spikes and rough patches. They also tend to be pretty expensive. Unless you're shooting video, why not just use strobes? That way you don't have to worry about shutter speeds and motion blur.

  9. #9

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    Re: Continuous Lighting question?

    I don't want to be needlessly contrarian, but I have never seen good light come out of an LED. If you want continuous light, use what the cinema guys use: KINOs or HMIs. Both are expensive, but give perfect daylight.
    Please email me - my inbox is always full.. (press ALT and click on my name, then select "Send email to Uri A"). Thanks!

  10. #10
    Drew Wiley
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    Re: Continuous Lighting question?

    Hooray, Ben - finally something we 100% agree about !

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