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Do my LED lights have a green spike?

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chris pike
Do my LED lights have a green spike?
on Dec 31, 2017 at 8:36:59 pm

Hello, I have been in video production for a year now. I have picked up a collection of nine LED panels, new and used. I have two different brands in this collection. I have new panels and panels that are three years old. As a result, I am mixing different light spectrums, which obviously wasn't a smart way to go. I read that LEDs have a problem with a green spike (although my untrained eye can't see it). Some people say that you can correct for this green spike with a minus green gel. However, in my situation, each light would need a different amount of gel. My question is, can I measure the green spike of each light individually, and choose the gel for individual lights? I'd like to salvage the lights I have now, and make them match as much as possible.

One possible approach to salvage these lights would be to aim my newer (and probably better) lights on a model's face, and use the older lights to lite the background. Is that an intelligent way to go?

Thanks, Chris


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Rick Wise
Re: Do my LED lights have a green spike?
on Dec 31, 2017 at 10:54:14 pm

You'd need a color meter to measure each light. Expensive. But with video and a decent monitor you should be able to do some trial and error to determine the correction needed for each of your LEDs. I'd get a few sheets of 1/8 minus green. Keep doubling the amount of magenta until you model looks "normal." Then go to the next light. Be sure to mark on each light what correction you need.

And yes, using the same lights on the foreground and the others on the background could be a way to go.

Rick Wise
Cinematographer
MFA/BFA Lighting and Camera Instructor Academy of Art University
San Francisco Bay Area
http://www.RickWiseDP.com


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chris pike
Re: Do my LED lights have a green spike?
on Dec 31, 2017 at 11:34:04 pm

Yes, I guess a light meter that can see the spectrum is in the $2000. What qualifies as a "decent monitor"? I have an atamos Ninja recorder, which has a five inch screen, but I guess that isn't what you are referring to?


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Rick Wise
Re: Do my LED lights have a green spike?
on Dec 31, 2017 at 11:51:01 pm

A monitor you can trust to be color accurate.

Rick Wise
Cinematographer
MFA/BFA Lighting and Camera Instructor Academy of Art University
San Francisco Bay Area
http://www.RickWiseDP.com


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Mark Whitney
Re: Do my LED lights have a green spike?
on Jan 14, 2018 at 7:10:23 pm

[chris pike] "One possible approach to salvage these lights would be to aim my newer (and probably better) lights on a model's face, and use the older lights to lite the background. Is that an intelligent way to go?"

In short, yes. Matching to your subject is always the best way to go.

That being said, and assuming that the rest of your workflow from aquisition through editing is all digital, you've a LOT more control that simply wasn't possible with silver-halide technology. You CAN selectively adjust a color curve w/o affecting the others.

Also, with digital technology & HDR range these days, your eye IS your best meter. No need to get hung up & distracted by the minutia. Refer to your God monitor if you have one. If it looks good then it is & any minor tweeks can still be done in post.


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