EX3 captured colour inaccurate

[Greg Hawkes]

During post production of a recently filmed dance show we noticed that some of the numbers had inaccurately captured colour.
The two set of stills show two numbers close up and wide shot. The blue seen in both cases should have been a medium pink. Can anybody offer an explanation why this has happened?
Also what about the dirty shadows below the dancers feet?

The two EX3s were both set to 3200K white balance and + 3 db gain.
Shutter 1/100 sec
Format 1920 x 1080 25 fps (50i)
The lenses had the Tiffin IR cut filters.
The picture profile used for both cameras was.
Matrix turned on and set for HIGH SAT.
Detail level -10.
Cine4 gamma setting.
Master Black level -3
Black Gamma -2.
.
As originally suggested by Doug Jensen and used for the last four years .

We talked to the lighting man and he tells us a new Italian LED light was used for the back screen.

Clay Paky - A.leda Wash K10

The blue on the floor is we presume a reflection from the back screen. The floor is a polished wood stage.

Do LED lights give this sort of problem with the EX3 and similar CMOS sensor video cameras?

Any help greatly appreciated.

[Daniel Epstein]

If you were in 3200K white balance for the cameras you could easily get this color if the LED's were at 5600K. Doesn't matter what camera you have. Lot's of theatrical lighting is in mixed color temperatures. Often requiring a compromise white balance unless you can go scene by scene. You can probably color correct in post to some extent

[Chris Medico]

LED lighting causes trouble with most cameras. It looks to me like you clipped the chroma distorting the color.

Can you take a look at the images with a RGB parade waveform? What do the waveforms look like?

This is a situation where the traditional in camera exposure tools can fail you. I would bet that the in camera luminance values looked OK. The highly saturated colors that LEDs produce will easily send you over the chroma saturation cliff .

[Greg Hawkes]

Hi Chris

Thanks for your interesting reply.

Here is a screen shot of one of the clips in question.

[Chris Medico]

Hey Greg,

Looks like you don't have the clipping that I was expecting but for sure the blue channel is out of control!

You should be able to get something that looks OK with some serious color correction.

For sure that is a lighting thing and not anything wrong with the camera. The color balance between red and green look reasonable. It is just the blue channel that is crazy.

[Greg Hawkes]

Thanks for your help Chris and also to Daniel for the earlier posting.

Greg.

[Robert Bale]

Hi, I have found when filming shows I use auto WB, I know it's a no no, but with so many light changes it seems to work well, most times we use EX1, EX3, and a PMW200, seems to work well.

[Marcus Durham]

Originally Posted by Greg Hawkes

Do LED lights give this sort of problem with the EX3 and similar CMOS sensor video cameras?

Cheap LED stage lighting is horrible for most cameras. I've worked at conferences where they backlit the stage with blue LED stage lights and although to the human eye it looks fine, to the camera the LED's seem much brighter and you struggle to keep the subject property exposed without blowing out the background or clipping the blues (which is hard to detect on the viewfinder).

[Marcus Durham]

Originally Posted by Chris Medico

This is a situation where the traditional in camera exposure tools can fail you. I would bet that the in camera luminance values looked OK. The highly saturated colors that LEDs produce will easily send you over the chroma saturation cliff .

This seems to be what happens. All the zebras are fine, the histogram is fine but when you look back at the footage afterwards the chroma is clipped.

[Dave Sperling]

All in all, I'd say you're lucky that they weren't aiming any of the deep blues at the performers directly, and that they had some other light on them. I've had no end of problems (using any number of different cameras - ccd and cmos - with the deep blue color that a lot of Broadway shows use. (Heavily saturated theatrical.) It can cause major problems, from fuzzy faces to actual inversion (black highlights). If we know we're going to have the problem in an important scene, we try to get them to give us a special video call when we can have the lighting designer tweek the colors to show up properly on camera. I've never found a camera setting that can fully eliminate the problem by itself.

[Marcus Durham]

Originally Posted by Dave Sperling

All in all, I'd say you're lucky that they weren't aiming any of the deep blues at the performers directly, and that they had some other light on them. I've had no end of problems (using any number of different cameras - ccd and cmos - with the deep blue color that a lot of Broadway shows use. (Heavily saturated theatrical.)

That's interesting as I'd always blamed it on cheap lights. Seems they all do it!

[Alister Chapman]

Blue led's are a big problem. They can often emit some very intense ultra-violent and far blue light beyond our visual range. In addition the blue contains some big spikes at narrow wave lengths and this really upsets most video cameras. Led stage lighting is designed purely for it's visual aesthetic, no consideration is normally given to how it might appear on a camera.

[Greg Hawkes]

A big thank you to all who have contributed to my original posting.

[Leonard Levy]

I would echo the complaints about blue LED's in stage shows. I was burnt recently but not nearly this bad.
I am a little confused though that you said this problem showed up in postproduction. Didn't anyone notice this during the shooting?
Some LED's will do this to any camera and the EX-3 was probably fine.

Probably you could not have done anything anyway once the show was underway ad to your credit you didn't clip the blues, though I not sure it would have made a difference.

It does bring home the importance of getting to see the lighting before you shoot. I like to give a monitor to the lighting director if I can. But if you're just hired to come in and shoot the performance you often don't rate any rehearsal time. Maybe just note to whoever is hiring you that a lighting rehearsal for camera can be essential if they want good footage. If they could have turned them down maybe you would have been OK, but I'm not sure if they ever work.