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How to minimize the green spike in flourescent light?

Joel Arvidsson

Joel Arvidsson

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Does anybody have a good trick to minimize the green spike in flourescent light in camera?
 
Take a look at a color wheel.

Offset green by using the opposite color in the spectrum. Try offseting with Magenta.

David
 
Can you do that in camera? Sorry have not had so much time learning all menus just yet. Just found the tint menu on the manual. Thanks.
 
You can manually set the tint in the color temperature menu tab to make the monitor output read less green but this will not change the green tinge in the RAW file and it will not limit its effect to just the "spike" which can lead to odd secondary color shifts.

Strongly suggest you put minus green gels on the lights. IF that's impractical for your situation then be prepared to tackle the issue in grading where more precise control can be used to offset the green spike without as much collateral damage.

Cheers - #19
 
Joel Arvidsson said:
Can you do that in camera? Sorry have not had so much time learning all menus just yet. Just found the tint menu on the manual. Thanks.
Click to expand...

you would typically gel the fluorescent lights with minus green gels or replace the tubes with kino tubes in either 5600 or 3200 depending on the needs. You can set the tint in camera to offset this but if you are using other color temperature lights on set this could start to look funky and shift your other colors.
 
Just to piggy-back on what others have already said, essentially, this is an issue for shooting, not for in post. Your options are: (1) use minus-green gels on the fluorescent lights, (2) use plus-green gels on all you other lighting fixtures, so you can remove the green equally in post, or (3) buy fluorescent bulbs with your preferred color temp and swap the the green-tinted ones for those.
 
1) I suggest replacing tubes as a best option. Skin tones will be best this way

2) Add plus green to your cine lights and use a CC10M or CC20M filter in front of lens. It's best to take the green out BEFORE it hits the sensor at least part way.

3) Add minus green to flourescents.

#2 and 3 will usually suffice but result in poorer skin tones. Many will argue that skin tones can be graded back to normal but there is always a difference to my eye and you cannot manipulate them as subtly as you might like because you are doing a major correction to get them back to normal. This is all assuming you don't want warm green or cyan skin tones.
 
Eric's suggestions are great, and practical, but only "1" is a pure fix - because color rendition is already poor on household fluorescents, and if after that you are gelling you are bringing down CRI to very difficult to deal with low values. Try color correcting a RAW photo of someone under sodium vapor streetlights for a good illustration of the pitfalls of low CRI - or try grading out the effect of a strong party gel. This will be much less extreme than that, but it's the same idea. Plus, a spike is not a shift, if you fix the spike, then other areas will look more magenta than they should. A spike is a bit like a bump in a color curve, not like the whole curve staying straight but being shifted over.
 
Mixed lighting is always an issue, especially if you combine tungsten, florescents, and daylight contamination from windows. I know some cinematographers go for mixed lighting just to create a jazzy look, but it's not appropriate for all scenes, and it's a nightmare to deal with in post when the white reference and skin tones go to hell. This will add lots of time to your color-correction session, plus (to me, anyway) it never looks as good as it would if the florescents were properly gelled or replaced.
 
Fluorescent light that is not constructed for cinematography (like KinoFlo) is hell to grade. This is because it's not continuous, but a spectrum with quite a few spikes. Household fluorescent lights have a mix of spikes that looks (kind of) white to our eyes, but a camera sees them completely differently. Swap them out wherever you can!
 
Minus green comes in many flavors because so do household fluorescents - as they age they get greener.
 
Eric Haase said:
1) I suggest replacing tubes as a best option. Skin tones will be best this way

2) Add plus green to your cine lights and use a CC10M or CC20M filter in front of lens. It's best to take the green out BEFORE it hits the sensor at least part way.

3) Add minus green to flourescents.

#2 and 3 will usually suffice but result in poorer skin tones. Many will argue that skin tones can be graded back to normal but there is always a difference to my eye and you cannot manipulate them as subtly as you might like because you are doing a major correction to get them back to normal. This is all assuming you don't want warm green or cyan skin tones.
Click to expand...

I agree with Eric here completely.

I want to add that you want prefer these changes in the ORDER he wrote them in. As Rob wrote, the only real fix is #1, everything else is a compromise because of how crappy household fluorescents are. You just can't drive the CRI up another way.

If budgeting for KinoFlo tubes is an issue, there are commercial fluorescents that are much better than the typical household units, and much cheaper than KinoFlo. I think they are GE "full spectrum" tubes. I used them once, and they suck compared to KinoFlo, but they kicked ass compared to the installed practicals. First off they were new, second, while they still spiked they had a lot more of the other colors in their white output, so correcting with minus green was much more effective/pleasant.
 
Rob Ruffo said:
Try color correcting a RAW photo of someone under sodium vapor streetlights for a good illustration of the pitfalls of low CRI - or try grading out the effect of a strong party gel. This will be much less extreme than that, but it's the same idea. Plus, a spike is not a shift, if you fix the spike, then other areas will look more magenta than they should. A spike is a bit like a bump in a color curve, not like the whole curve staying straight but being shifted over.
Click to expand...

I generally agree with Rob, but felt like I had to add a detail.

You can use the curves tools in many color correction suites to just pull down a spike. With some experimentation you can really pick out just the spiked green tones and really balance the image back out.

The real problem is the very low CRI of the sources. They just don't have other colors in them ... which means no other color reaches your sensor. Sodium vapor is the worst example so far, but the absolute worst is laser light. Cherry pick the color of laser light and there is no other color left.
 
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