Sony FS7 RAW DR Test

There was a good debate on the SIC FB group about Sony FS7 RAW, recording with the Odyssey 7Q+, the issue of getting 14 stops of dynamic range into 12 bit linear RAW output, and banding in the shadows. As I recently upgraded from the Sony F3 to the FS7 and using it with the XDCA RAW extension and the Odyssey 7Q+ in RAW mode most of the time, I thought it would be good to get to the bottom of it and make sure I use the ideal settings.

This video has a series of clips shot with different Codecs and Settings to see the results. The Camera was setup on a tripod with Odyssey 7Q+ and XDCA extension. The camera was configured to CineEI mode, S-Gamut3.Cline/SLog3. Noise Suppression was enabled at mid-level. The camera has firmware 4.0. The Odyssey 7Q+ has firmware 16.10. There was a dual color target setup near the camera lit with a Arri L5C first in daylight, later in Tungsten. There was a second target setup about 10 feet further back, originaly unlit, later ever so slightly lit with a small tungsten LED light. The goal was to keep the exposure between the two targets at 14 stops, as measured on a lightmeter in EV mode / spot meter. On the back target the EV was measured on the 2nd darkest grayscale chip (bottom row, 2nd from right).

This was not done on a single target that has a 14 DR range, but in a real life scene where a front element was light by a key light and further back in the room was an object that was supposed to be lifted out of the black with at least minimal separation. I believe that is a more realistic way of judging DR for everyday use, though may not be as scientific as a single target.

The ProRes and XVAC-I clips were brought into Resolve and the standard Sony SLog3SGamut3.Cine.ToLC709 LUT was applied at clip level. For the DNG clips, the instructions from this article by Convergent Design were followed by first applying the compensation LUT to bring the DNG into SLOG3 and then the same SLOG3 to LC709 LUT was applied. The timeline was in LC709 color space.

There are 11 clips with different settings (title at bottom). The clips are repeated a second time with the upper half of the screen having an offset of 256 on the scope applied to see deep shadows the screen cannot display.

The most telling clips are #8 (Internal XVAC-I recording at 11.5 stops DR) and clip #11 (Odyssey 7Q+ DNG recording at 13 stops DR). In both clips in non-adjusted version the highlights have ever so little headroom (picker values can be found at 253/254 8-bit), while the raised version of the clip allows ever so little detail visible in the back target to be made out (background noise is at 64, target starts showing a few 65). 

Thus the conclusion of this test is that with current firmware and these settings, shadows and black are quite clean. However, the effective dynamic range is more in the 12 to 13 stop range with no significant difference between internal recording and external recording, giving the Odyssey RAW option the upper hand because of its much more flexible Codec choices and many other useful features.

Screenshot: Scope and Color Grab showing ever so slight head room, and very faint back target at 13 stop DR:

 

Color Grab showing back target slightly better at 11.5 DR:

If anyone has suggestion on how to improve this test for additional conclusions or verification, feel free to comment or reach out at jan@janklier.com.

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