Two Cameras- Color Difference

[donovangreene@mac.com]

I shot a commercial two days ago with two RED Cameras. All settings on the cameras were identical. Build 17. One camera had a 12x Angenieux, and one had a 4.3x Angenieux. The shot was on a beach of a tourqoise truck. At that point A Camera looked much bluer than B Camera. Each camera had .9 straight ND in them. Initially A Camera had a Pancro filter and B Camera had a Tiffen, but we switched to Tiffen in both, .6 and .3 ND in one and .9 ND in the other, but it was still bluer from A Camera to B Camera.

The cameras were not black balanced at the prep? Is that the cause of the color difference.

Any thoughts?

 

[Jannard]

I shot a commercial two days ago with two RED Cameras. All settings on the cameras were identical. Build 17. One camera had a 12x Angenieux, and one had a 4.3x Angenieux. The shot was on a beach of a tourqoise truck. Both cameras looked identical in terms of color the entire day, until the afternoon when we moved to the beach. At that point A Camera looked much bluer than B Camera. Each camera had .9 straight ND in them. Initially A Camera had a Pancro filter and B Camera had a Tiffen, but we switched to Tiffen in both, .6 and .3 ND in one and .9 ND in the other, but it was still bluer from A Camera to B Camera.

Any thoughts?

I'll bet on the lenses... try swapping the zooms between the cameras and see what happens.

Just curious... what are the serial numbers of both cameras?

Jim

 

[Jonas Rejman]

We experienced a similar thing on two cameras in the 47xx series, with conseqent serial numbers.
We shot some 3D tests with a set of Zeiss Super speeds, where we matched the lens series, and also with a set of Zeiss standards.
In both occasions, the cameras colors did not match, when we processed the cameras with the very same settings in redalert.

It was a slight shift in the colors, always the same way, so one can rule out the lenses. Both cameras had fresh firmware and black shadow calibration.

Not difficult to fix in post, though, but somehow on the path through the chip, electronic and redcode there seem to be slight differences.

 

[David Mullen ASC]

I suspect that there is always some subtle variation between digital cameras; it's just that the ones doing a lot of image processing can tweak the signals to match, whereas a RAW camera by definition is not processing the color.

Plus you will see subtle variations between lenses more clearly on a digital camera.

Of course, there could be other causes of mismatching, like needing to black balance, or the fact that when using heavy ND filters, there can be dye variations in the filters. Not to mention IR pollution.

So all of these factors can combine to create mismatches, though they are usually easy to fix in color-correction later.

 

[Deanan]

ND's can have alot of variation between NDs and definitely if you compare stacked NDs to a single ND of the same strength.

The age of the NDs, batch, etc are all factors in variability.

 

[gbalaji]

I shot a commercial two days ago with two RED Cameras. All settings on the cameras were identical. Build 17. One camera had a 12x Angenieux, and one had a 4.3x Angenieux. The shot was on a beach of a tourqoise truck. At that point A Camera looked much bluer than B Camera. Each camera had .9 straight ND in them. Initially A Camera had a Pancro filter and B Camera had a Tiffen, but we switched to Tiffen in both, .6 and .3 ND in one and .9 ND in the other, but it was still bluer from A Camera to B Camera.

The cameras were not black balanced at the prep? Is that the cause of the color difference.

Any thoughts?

Check the color values!

 

[Harry Clark]

No two cameras will ever match completely. No two film stock batches will ever match completely. No two fabric color dye batches will ever match completely.
See this thread:
http://www.reduser.net/forum/showthread.php?t=26171&page=2
Here is my post on that thread:
Guys,
Hoping that two Red cameras will automatically match is a pipe dream. They're like snowflakes. Same with HD and SD video cameras. And motion picture film from batch to batch. Red does not have a magical elixir that makes their cameras match each other better than Sony, Panasonic, or Kodak. And as others have pointed out, even CT meters are all different.
In the world of video, doing a multi-camera setup, you need an engineer to match the cameras. When making a feature film with different batches of film stocks, you'll need the timer's help to smooth out the subtle differences in those batches. With Red it's even easier, and can be done on the desktop (although done best by a colorist with Scratch)
My big beef with Red and CT is that the Rec 709 preview often exaggerates the subtle variations in a person's skin tone, or makes a shadow or a hot white cyc go unnecessarily blue, all of which leads to confusion until we shoot a little bit and do a quick curve in RedAlert! The skin tone issue is particularly annoying...
I hope that the preview out on the next cameras are of slightly higher quality.
Cheers,
Harry

 

[Stuart English]

HD Preview out.

HD Preview out.

My big beef with Red and CT is that the Rec 709 preview often exaggerates the subtle variations in a person's skin tone, or makes a shadow or a hot white cyc go unnecessarily blue, all of which leads to confusion until we shoot a little bit and do a quick curve in RedAlert! The skin tone issue is particularly annoying...

With regard to that issue, I'd suggest using REDspace rather than REC709.

Reduce brightness using CURVE parameters if increased brightness is the reason for not selecting it ...

Any LOOK that you do create can of course be saved to SD card.

 

[Harry Clark]

I'll try that, Stuart.
Yes, the brightness issue is my big beef with Redspace. I'd gladly use it if I could wrap my head around the exposure... I just think it makes for underexposed footage, hence my use of Rec 709. Is it more color accurate on the preview out, once the brightness is toned down? I will experiment as you suggest.
Nice tip; thanks!
Cheers,
Harry

 

[donovangreene@mac.com]

Thanks for the responses. The color difference was not major, and was easily fixed in post, but I want to know for future shoots where it happens. The issue still existed after switching lenses. Additionally, after taking it to LightPress in Seattle the colorist, Jeff Tillotsen, felt the difference between the cameras existed in all the shots, even with no filtration, or different lenses.

Again, it was not a major color difference, although using different brand stacked ND's did exagerate it during one setup.

The only thing I can think of is a black balance, or just the natural difference between two cameras. How would any of you calibrate the metadata in a prep for the cameras to match?

 

[David Mullen ASC]

I'd shoot a MacBeth chart for both cameras (same lens, same filter, same stop, etc.) and send RED the original R3D files and see what they say, perhaps one of the cameras needs work at the factory if the color is off significantly.