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RGB or Hue/saturation Lee gel equivalent?


Jonathan O'Neill
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Hi, I'm new to RGB lights. I'm testing a Falconeyes F7 fold.

How do I create the colour of a Lee Steel green gel on a tungsten lamp, using an RGB light?

The controls the RGB light has are :

R: 0-255 , G:0-255 , B:0-255

H: 0-360° , S: 0: 100 , I: 0-100%

I feel the HSI option would be best? as using RGB once you find the colour, brightness changes would need more calculations?

Does the info attached from the Lee filter website help at all? Does the 'X' or 'Y' correlate to anything?

 

Thanks in advance

 

Screen Shot 2021-03-20 at 10.05.13.jpg

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Either will work fine provided you have a master intensity control(im pretty sure the falcon eyes does). There is a couple apps that  give you rough RGB values for different gels.

RGB and Hue/Saturation values given on the GUI of a light are rarely calibrated to any kind of standardized colour space, so are fairly inaccurate and wildly differ between different models of lamps. You will just have to fine tune by eye.

The x and y values are useful if you have a meter to read them, but there is often more than one way to vector a light with multiple emitters to a specific x-y coordinate(especially if there are wide band emitters like a white or amber). So it can still be quite tough to manually get an X-Y ‘match’ that renders accurately on less saturated colours.

 

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Yes, x and y do correlate to something, but you'd need a light that had the option to enter a CIE xy colour coordinate. If you did that it ought to (roughly) match, but many don't.

Yes, HSI should be more convenient as you can vary the output independent of the colour.

Unfortunately there is no standard for how HSI (or RGB) colour controls work and the only way is to eyeball it. Make sure you eyeball it looking at a monitor not with your eye.

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2 hours ago, Jonathan O'Neill said:

Hi thanks for the replies guys. Back to gels then I think! 😅

Careful, though; gels can behave unpredictably on LEDs. The spectrum of a tungsten-halogen light or daylight, against which gels are developed, are not the same as LEDs. Test carefully, including all the LEDs you want to use, because they don't all work in the same way.

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Posted (edited)

With a Falconeyes F7 Fold I want to get the equivalent of a Steel Green on a tungsten light , with camera at 3200k .

HSL mode you can get the hue in a ball park, then if you desaturate the LED it will ultimately go to about 5600k at 0% saturation....

RGB would just be ages of flicking through RGB combinations and thats if you have no plan to have a brightness option...

CCT mode is a separate set of LED emitters , with no option for + or – green.

Can someone recommend a different brand of RGB lighting , where you can set your base kelvin, e.g desaturate to 3200k? And accurate LEE filter options? and a CCT mode with + or - green? cheers

Edited by Jonathan O'Neill
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On 3/24/2021 at 2:21 AM, Jonathan O'Neill said:

With a Falconeyes F7 Fold I want to get the equivalent of a Steel Green on a tungsten light , with camera at 3200k .

HSL mode you can get the hue in a ball park, then if you desaturate the LED it will ultimately go to about 5600k at 0% saturation....

RGB would just be ages of flicking through RGB combinations and thats if you have no plan to have a brightness option...

CCT mode is a separate set of LED emitters , with no option for + or – green.

Can someone recommend a different brand of RGB lighting , where you can set your base kelvin, e.g desaturate to 3200k? And accurate LEE filter options? and a CCT mode with + or - green? cheers

I've had relative luck and have faith in the Kino Freestyle line. However, you're asking a lot from any fixture. 

Most, if not all LED's can't resolve every LEE/Rosco/whatever filter colour, for every camera. Even if you accurately input information due to the discontinuous spectrum of all RGB LED fixtures it's likely the frequency bands emitted while being perceived as accurate from our photopic vision or even one camera system it may not be on another (due to different camera spectral response curves). 

Even if you measured with a colorimeter or such to match the two. You're matching them both to one constant when in reality the 'detector' - to put it crudely, is also a variable. 

 

Edited by Gabriel Devereux
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  • 4 months later...
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On 3/20/2021 at 3:35 AM, Matthew Parnell said:

There is a couple apps that  give you rough RGB values for different gels. 

 

Which apps? 

I would love something to help me unify skypanels, spectrums, and titan/Helios colors/gels through blackout with regular geld hmis and tungsten. 

 

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I suspect any such thing would be extremely rough. Bear in mind that most modern colour mixing LEDs of any quality aren't purely RGB devices anyway, so RGB is just another way of expressing a colour - just like CIE xy numbers. The difference is that xy numbers have at least the intent of being consistent, light to light and manufacturer to manufacturer, whereas RGB doesn't.

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