Didn't know where else to put this so I thought I'd try here.
When we film something with an ND filter - regardless of what camera - the picture does something that's almost impossible to recover from in post. The image just looks faded and muddy. This happens with every camera we've used... the RED, Varicam, F-900 and even the little cameras like the EX-1.
People say ND doesn't affect the image in any way other than to stop it down. I beg to differ. I can always tell when something was filmed outside with heavy ND.
So my questions are: does this bother anyone else? What are you guys doing to get a nice outdoor image with ND?
That's IR(Infrared) contamination. ND's cut visible light but not IR light. Every digital camera has an IR cut filter in the OLPF to some degree but when you lose a lot of visible light the proportion of IR to visible changes. This shows up in footage in the way you've described. The actual cut frequency varies from camera to camera. The way to combat this muddiness when using ND (ND0.9 and up on Red) is to use either an IR Cut filter or a Hot Mirror filter. You have to be careful how you use them but it will stop the contamination of your blacks.