The question came up recently regarding a Red Epic camera and IR Filters. Here’s the background. Digital cameras are very sensitive to light, and the infrared spectrum can cause your blacks to look red, also known as IR Contamination. The sensor cover glass in the camera is calibrated to remove Inferred light to give you the best colour rendition. ND filters will block light, but not in the infrared spectrum, so the more light you block with ND filters, the higher the ratio is of IR light. Over a certain level, the built in filtration is not enough. Arri recommends the use of IR Filtration at and above ND.9. I haven’t yet seen any specific recommendations from Red so I think it calls for a test.
This is a quick and dirty test we threw together on the one sunny day we’ve had in a long time. You will note the shadow of my head in the bottom of a few of the frames. I think it adds character personally. Please comment with your own findings in the field. The more info we have the better the recommendations we can pass around.