Anomaly with rendering of the colours of some fabrics

[patriki]

This happened to me twice already.
It seems that in certain lighting conditions some fabrics - especially black coloured - render as brown!
First time, an exterior scene was shot in bright sunny conditions. Available light only. Shot with 5500K preset white balance. The actress was wearing a black suit.
In some takes the suit was black, but in some - brown! All other black details of the scene remained black however.
Second time - and this one it was even weirder - I was shooting an interior scene with daylight-balanced Kino-Flo lights, again with a 5500k white balance preset. I was using DIFFERENT DVX100a from the first case. Everything looked dandy until I added a tungsten 300w Fresnel light with a Full CTB color correction filter to the lighting scheme. AGAIN - the black pieces of wardrobe on the actors that were in the light of the 300w Fresnel appeared brown!
I added 1/4 CTB gel to the 300w to make it even bluer, but the blacks were still showing up as brown.
Now, I took my Sony Digital Still camera with 2/3" CCD and took a shot of the scene using the same white balance settings.
The still image showed perfectly fine blacks!
So my verdict was: the CCD of the DVX100. (Keep in mind, this was noticed on two different cameras).
But - why? And what exactly triggers this?

 

[NoahLD]

Fabrics and dyes

Fabrics and dyes

I work in theatre and we experience this a lot. Different fabrics accept black dye differently and there are different types of black dye. Some are just really dark blue. The DVX is picks up the slight differences in color that a one chip camera will not. We have good luck with velvet and nylon fabrics as opposed to cotton dyes. I'm not sure how to fix your particular situation. The slight amber in the 3200k fixtures was bringing out the red spectrum in the fabric I guess. There must be alot of contrast in your footage because you don't see this sort of problem often on film or television.

 

[Baluardo]

i experienced the same in the daylight, with black fabrics. the funny thing is that the actors were dressed completely in black (swat), but just some pieces of their clothing would show up brownish. i found out it is possible to reduce the problem underexposing (which is not really underexposing since the camera will automatically overexpose a bit with a lot of blacks in the frame), but not a whole lot. The only thing i didnt try is to switch the cine gamma off. maybe it's a cine gamma artifact?

I guess we just have to accept the fact that the CCDs (at least in cine mode) see in a slightly different way from the human eye.. and we should use fabrics which look the same both to us and the camera.

The DVX is picks up the slight differences in color that a one chip camera will not

I wonder if other similar cameras (eg XL2) have the same prob.

Andrea

 

[patriki]

I don't think it's the cine gamma, becaus ethe second case I am describing is shot with all gamma/matrix settings at "normal", as well as all other values at "0".
Can it be something with a lens? I always shoot wide open.
Anyways, I'll try to find time to do some tests - I really want to know what is causing this.