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    How to use plus green filters in a fluorescent lit location?
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    I'm shooting in a factory with fluorescent lights on the ceiling. The space is too large and the ceiling is too low to light the whole space. Can you share some knowledge about how I can shoot this using tungsten and daylit LED lights? I have 1/2 plus green and 1/4 plus green gel filters. Which plus green matches with which light? What temperature should I dial my camera to? Thanks.


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    The space it green. Every introduced light must have green added to it too or if it is RGB be dialled green. Simple.

    You will then..

    If shooting 'baked' white balance off a grey card.

    If shooting 'log' shoot a grey card and WB off it in post.

    You could add a mild magenta filter to the camera but still any lights you add need to be green.

    If you have an RGB light meter, use it to balance your introduced lights. If you have a DSLR use the RGB histogram to balance it all.
    Worst case is to use your monitor. But of course have a look on the monitor befoe you shoot!


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    Thanks Sam.

    I will not have a RGB light meter but can look off the RGB histogram.
    I could not find any information online. Regarding the 1/4 plus green and 1/2 plus green, which one goes over the tungsten light and which one goes on the daylight temp light?


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    Unless there is some shift in terminology a green filter (physically green - not a magenta filter that cuts green) will cut R and B making a fixture have a green spike (like the flouros) a green filter would not affect the R+B channels so it is equally relevant to a daylight fixture or a tungsten fixture.

    If you wanted to throw tungsten fixtures into the party they should have CTB (physically blue filter) to reduce the red from the tungsten.. and then a green (physically green) filter to add the green spike.

    --

    I keep saying 'phyiscally green' because technically a Magenta coloured filter, which removes green, is a green filter.
    Last edited by morgan_moore; 07-17-2019 at 01:57 AM.


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    To use a DSLR you should..

    .. no introduced lights.. shoot a grey card

    add your filter to the introduced light.. shoot a grey card.

    compare the RGB on the two greycard shots.

    Fiddle with the filter on the introduced light until that RGB matches the RGB of the ambient.

    On really knackered old tubes (in the building) you may have to add both yellow and green (coloured) gels to your daylight lights.


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    Yes, these are physical green gels to add a green spike to tungsten or daylight lights. I did think about adding CTB and one of the plus green filters to the tungsten light, but wasn't sure. At the Lee Filter site, it doesn't say whether the plus greens should be used on tungsten or daylight balanced lights (actually says used on both). A reviewer at a B&H said he added 1/4 plus green to his tungsten and it did the job. Not really sure if there is a standard with using these different plus green gels with different temperature lights.

    Thanks for the tip about balancing with a grey card.


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    ct-green.jpgCT gel is for colour matching other sources. CT green will convert the tungsten reddish tint to closer, but not the same exactly as the flu lights.

    For info the quarter plus converts tungsten to fluorescent colour and half plus does the same thing but is a deeper tint for tubes with a sharper spike.

    typically I'd use the deeper colour on brand new flus, and the less green one on older, softer tubes. the tungstens look better but not perfect.


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    So Paul do you recommend using the plus green on the tungsten without any other gel? And with the daylight temp. light use a CTO and then one of the plus greens?

    Here is some useful information on reducing flickering when shooting in a fluorescent environment if anyone else is interested.
    https://untamedscience.com/filmmakin...escent-lights/


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    The trouble is that matching continuous spectrum lighting to flu tubes is never perfect. fluorescents, being discharge have spikes in the spectrum corresponding to the gas content, so trying to trick a tungsten is kind of a part-lost battle. If you have 3000k and 3200K tungsten/tungsten halogen, the plus green works pretty well. Daylight, as in LED daylight is less good. If you use CTO, then go back to green, the thing will be like a glow worm. you also need to remember gels are subtractive. If you use a red gel and it removes the red and blue, you cannot convert this extreme example back to blue, because you took all the blue out!

    If you put the CT green on then as the lamp is already bluer, you get a greeney blue which isn't right, but probably OK unless you try to mix it with the other converted source which the camera will spot. Better than doing without.


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    Does your camera tell you the measured Kelvin color temperature when you set a custom white balance? It can give you a helpful base line if your camera does, my A6300 has that feature, but my D7000 doesn't. You might need a 1/4 or 1/2 CTO (color temperature orange) gel on your LED, in addition to the green gel.
    Last edited by Imamacuser; 07-17-2019 at 08:34 PM.


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