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Cold light?

Discussion in 'Lighting and Electrics' started by moderately_clueless, Oct 2, 2006.

  1. moderately_clueless

    moderately_clueless Member

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    Hey, a bit of a silly question, but how could I get a beam from a source four to look less yellow and more cold? I'm new at color and design, so I'm just beginning to experiment. I'm going for the look of flourescent light, a sterile white look. I was thinking I could use some very pale blue or purple but I haven't yet had a chance to see how it looks. Any suggestions?
     
  2. JSFox

    JSFox Active Member

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    A very pale green (can't remember the numbers) works well.
     
  3. fosstech

    fosstech Active Member

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    R87 is a good one, or you could go with a color correction gel like R3315 through R3317 depending on how much green you want. R3315 is almost identical to R87.
     
  4. ship

    ship Senior Team Emeritus Premium Member

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    Might go with the green in combination with a 1/4 CTB blue. Yep, that ought to about do it.

    Interesting the comment that the light out of a S-4 fixture is yellow. It at full intensity should be a fairly about 3,300K color temperature at 120v for a 115v high output lamp.

    Two other things you should look into - the dimmer levels and the lamps. First if yellow/amber in output one might expect that this is the look of the light after dimming thus the yellow/amber out of the light you see is due to amber shift. Try say if now you are using a 575w lamp at 60%, installing a 375w lamp and using it at full. This way you will have the same overall luminous output only at full intensity and that blue/white color temperature again.

    Next is the type of lamp used. A 120v lamp much less the long life verses high output lamp will play a large role in what look you get from the lamps. 120v lamps I have limited use for other than in architectural situations. They under voltage drop and dimming conditions are in no way sufficient in getting what's normal for a more modern 115v lamp in higher color temperature, in fact, you would never see the rated color temperature at the norm of 118v thus the lamp not heating up enough to get to that color temperature of about 3,250K or better. A 115v lamp will get higher in color temperature at 118v thus it seeming much more bright.

    The long life lamp in many ways similar to that of the 120v lamp won't get high enough in color temperature either to be blue/white light in output. It on the other hand as a 115v extended life lamp is a often better and more cost effective choice than that of a 120v long life lamp by way of balancing lamp life with output. The amount of color temperature loss on a long life 115v lamp is much less drastic than that of a 120v high output lamp in at least my testing. Consider as opposed to blue/white for the high output 115v high output lamp, a white light out of the extended life version of this.

    Worst would be to be using a 120v long life lamp, yep there is an amber lamp for you which would last a good long time but is not of much use for shows.

    Combine dimming with the various types of lamp and you get lots of amber/dim problems to deal with which won't make it much fluorescent in output look or even crispness. Swap out lamps for what's going to be blue/white, go for the wattage that at full intensity provides the intended output on stage so you don't have to dim as much, than go for the gel or combination of gels. Fluorescent lamps don't provide the full spectrum of light thus the green in limitating much of it and it being harsh in color output. Than so as to boost the color temperature to what a cool white fluorescent produces you need color correction so as to make something around 3K become something about 4K.

    Double gel and proper lamps for the need would be my starting point. Lots of variation on what might be needed to achieve some minds eye vision on stage of a fluorescent lighting effect. First state the goals as it were in achieving this design concept. As a general concept, it might be expressed as something like a 4,100K color temperature with lots of the visible spectrum of light not adiquately represented in the output of the light. Might also note that fluorescent lamps are excellent wash lights in not being directional. A Leko is a very directional lighting fixture and might not in image convey the shadowless light out of a fluorescent even if you achieve the look.

    If already at about 100% in output and color temperature still looks sort of yellow, it could be the lamps to correct for in color correction gel given they are not high output so say a 1/8 CTB blue will be sufficient. If around 60% in output and they look yellow, a more drastic say 1/4CTB will be needed in bringing them up to 4,100K in color temperature. This given lamps are not changed for say lower wattage or high outupt.

    The color boosting gel gets you in the range of the cool white color temperature and reduces what's in the red spectrum to some extent. Dependant upon the lamp and intensity you adjust for this. Could do this by math or a photometer or just experimentation.

    The green gel than added to this would further reduce the blue and red range of output by subtractive color mixing in reducing the full spectrum of light out of the lamp so as to simulate better fluorescent output and color rendering index by way of how much spectrum of light is outputed. Could even almost do the green as a donut gel - hole cut out of it's center so as to get more light towards the center and less towards the edges.

    Beyond this could if doing Lekos, also frost the heck out of them beyond the purposes of the above gel. This would better soften and distribute the light. Granted that much gel would greatly reduce output. Time to do some play testing in keying in what is most best for look. This in addition to adjusting and focusing the fixtures to the best places for the wash of light effect. Still some scoops, boarder lights, PAR cans in wide flood and Fresnels would possibly with the same concepts in gel provide a better shadowless wash of light simulation.
     
    Last edited: Oct 3, 2006

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