Often, lower-priced LED panels will have a color cast that can be difficult to correct in post, particularly if you're working with mixed lighting. This great video shows both how to detect the issue and how to correct it.
In this video, Tony Reale of Creative Edge walks us through the process. The idea is manually set a camera to the white balance the lights are rated for and shoot them lighting a white wall. From there, we import the photo into Photoshop or Lightroom and crank the saturation, which will make any color bias readily apparent. After that, the solution is simple: we gel the light with the color complementary to its bias.
If the light shows a green bias, we'll need minus green gels; if it shows a magenta bias, we'll need plus green gels. Most lights tend to show a green bias, requiring minus green gels. As Reale suggests, you can keep a list of the bias and compensation for each of your lights, making it easy to quickly and properly gel them on set. It's a great solution for working with cheaper LED panels.
Be sure to check out Reale's website for more.
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I like your non-political posts! Thanks
Yes, gels sometimes can't fix it. I meticulously tried to gel-correct DeSisti LED fresnels. Brand new bulbs in the Arri kit, clean white cyc, camera and monitor (just to have another set of "eyes") setup...
Alas, I could only get CLOSE. In fact, the closest result made the tungsten seem a little green in comparison. I think the final gel stack was a combination of 1/8 CTB, 1/8 minus green, and I think a straw (yes, I know that sounds stupid, CTB and a warm gel). Maaaybe a 1/16 minus green on top of the 1/8 minus green would've worked, but 1/16 minus green doesn't exist.
Just to be pedantic, "minus-green" is magenta. "plus green" ...is just green. Lee is right that what makes LED lights problematic is that their spectrum is uneven. LEDs for lighting are naturally just a single color, blue, that is modified with phosphors to simulate a spectrum to the eye. The quality of the phosphor mix is what makes the difference, but a particular phosphor mix that evidences a red GAP appears to be common from less expensive Chinese LED lights. But filters don't add color they subtract the complement--which means there really is no true fix for a gap the spectrum--that light just wasn't there to begin with. I have LED lights with that red gap, and I crank up the red gain in my Canon cameras to compensate, which works better than filtration, but isn't perfect.