C100: Big Problem with Color Rendition of LED Signage with C100

nedcam

nedcam

Well-known member
I am filming a sales video for a small LED sign start up this weekend. I visited the client for a location scout with two cameras to make sure I can avoid any flicker through shutter and clear scan settings and something very strange happened: The C100 sees their red light sign as yellow! Not so with my Panasonic HPX300. This occurred no matter what kelvin I set the camera to. Pure yellow on monitors although to the eye it's blood red!

Any ideas? This is the type of small sign you might see in a convenience store window stating what the lottery maximum is this weekend. The characters may be static or scroll horizontally.

Also, when they move horizontally right to left, no matter what my shutter is they smear a bit. I can't slow down the scroll speed. Any ideas?

Thanks in advance.
 
Is automatic flicker reduction on?

Also (and this is a shot in the dark), I wonder if the yellow is happening because the highlights are blowing out and they are such fine pinpoints of light. Maybe they are blowing out yellow instead of white. What happens when you bump your exposure down? Still yellow?
 
It's very common among many cameras that saturated red highlights turn yellow, try a different picture style, or just fix it in post or underexpose in camera. If it happens in CLog you may not be able to fix it in camera.
 
I know my C100 can not render the color turquoise, it always 100% of the time makes it look blue, I have no idea why. Not sure if the issue is related.
 
The inventor took it to a dark corner, so in available light I opened up and yes, the red blows out and maybe that's why it becomes yellow? I can't handle it in post because an actor will be swinging it around.

I always have flicker reduction on.

Here is a screen grab from the AVCHD file in QT Player from my laptop desktop. If I stop down to expose the light properly the person will go way dark. Hmmmm........
 

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Did you consider that both your Panasonic HPX300 and your eyes may be incorrectly interpreting the sign as red? I'd think twice before questioning a Canon camera.
 
Eric Coughlin said:
Did you consider that both your Panasonic HPX300 and your eyes may be incorrectly interpreting the sign as red? I'd think twice before questioning a Canon camera.
Click to expand...

A canon is not better than the eyes - the eyes are the delivery medium.

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I think this job could be hard to do well.

Solid yelow is clip of R and G channels - see it in the WFM in your NLE

You need to do some testing that may be (as above) ND on the sign.
Significant boost in ambient light levels - maybe with uncorrected tungsten light to swing the entire scene yellow
Change of camera
Change of camera mode (log?)
Using an RGB WFM to understand what is occurring
And.. a maybe crazy solution.. deep blue (removes green and red) filter on the lens and wild colour balance setting in camera.
Another crazy solution could be to put CTB (blue gel) on the sign to calm the RG channels.

Having shot some bright LED screens I can say lifting ambient light was our (only available) solution (which of course needs care to not get reflections on the item!)

S
 
You could also put a really light mist or contrast filter on the lens. The diffusion will spread the color enough around the edges to see it without clipping. Of course, it will probably also just make it a red blob.
 
Canon Cinema cameras tend to see red with more yellow, thus orange, but if overexposed could turn yellow. You can correct this in a color profile (if not shooting C-log) but it may effect skin tones if that is an issue. The only way to solve this is with heavy ND on the sign and then adding green/blue in a color profile to make the red read correctly. Just had to do this to a baseball logo that was reading orange even though it was red to the eye.
 
Shooting into LED lights always causes problems for me, especially cheap LEDs that DJs use at weddings. I don't really have a suggestion for you other than to shoot with he knowledge that you'd have to fix color in post.
 
On my c100, Red would always come out as yellow orange, even in clog. I've been doing a secondary cc in resolve to fix it which has been working. It's annoying how off my smpte one shot chart looks on it. Turquoise has issues too. I'm thinking possibly it's an issue with mine's color matrix but I'd be surprised if Canon would let that be the issue. That color on my c100 has always been frustratingly inaccurate but it gets the job done.
 
Canon has always been known for having pleasing looking colors geared toward skin tones at the expense of color accuracy. In a lot of cases this doesn't matter but once I was shooting for vogue on C300s and getting a blue-green dress to look right in camera was basically impossible, we ended up having to change the wardrobe.
 
OK here's the update, did the shoot today. ALL CAME OUT CORRECT. The set was a real office, stopped down the red was seen as red on the Panasonic, I left the C100 as a back up in the van. I guess the reason that red came out as yellow in the C100 test was that I was way over exposed. I had thought the client would want to set up his sign invention in dark areas. So I dodged a bullet and was looked upon as a Video God.

However, I was getting a slight flickering/strobing. I locked on with clear scan and all was well- BUT JUST FOR A FEW MINUTES! Seems these things drift after awhile. In one shot he had 4 signs of different colors so I had to use a trial and error combo of several shutter settings with various clear scan settings until the majority looked good, and quickly do a take. Ugh.

Since I am also doing the editing I grabbed individual shots where the clear scan was spot on, so that's how I will save that scene, cut to tight shots.

Thanks everyone for your input. I had 3 rolls of various ND with me, scissors and scotch tape.
 
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