RED ONE Build 14 Latitude Tests
My goal was to see if RED’s 5000k chip is limited in exposure latitude under tungsten lighting conditions due to a tendency for the red channel to clip early. This seems to be the case, but I’m told there’s a post fix for this problem that I hope to learn about in the near future.
Here’s what I did:
-Shot a Kodak 18% gray card, with some texture to it, at different exposures to see where the camera clipped and to see where significant underexposure noise occurred.
-Shot two tests, one under tungsten light and one under tungsten + full CTB, to see how the camera did under both kinds of light.
-Originally set exposure by setting gray at 50 units using the camera’s Rec 709 output, which turned out to be a stop slower than REDLog would have me believe. Zone 4 on Rec 709 turned out to be Zone 5 in REDLog. (The ASA appears to be a true 320.)
-Took the darkest three tones for each lighting situation and boosted them to 18% gray value to better see noise; also isolated each color channel to see where the noise was coming from.
-Included histograms for each clip from Red Alert.
-Captured in RedCode28, 4K 2:1, 23.98 fps and 1/48 shutter.
I wasn’t able to check underexposure latitude as far down as I wanted because of the ambient light in the test location.
The process was: open .R3D in Red Alert and export clip; then reset white balance to 5600k and capture the histogram to see what the daylight-balanced chip was doing in each situation. The clip was scaled and output as a ProRes HQ Quicktime, 1280x720, and assembled on a ProRes HQ timeline in Final Cut Pro 2. It was then output via Compressor using H.264 VBR encoding at 1k/sec. bit rate, where I tried to keep the file size down without letting the noise get lost or exaggerated by the compression process.
Enjoy!
Art Adams A native of Northern California, Art Adams spent ten years in LA--first at film school (Loyola Marymount) and then working in the film industry. He started out as a camera assistant on low budget features and worked his way into spots, music videos, features, sitcoms and episodic television shows. He transitioned from assistant to operator to DP by the time he returned to the San Francisco Bay Area in 1993.