In an article of mine published earlier this year by DVINFO.net titled “Replicating CineEI mode in Custom Mode on the F55“ I tested a way to simulate the look of S-Gamut3.cine in Custom Mode on the F55 camera using the built-in matrix presets. One of the obvious conclusions from the test was it showed just how different color is rendered between shooting modes (Custom vs. CineEI) on the Sony F55 camera. (The same color differences are also applicable to the F5 and FS7 cameras – however these cameras do not have the same matrix presets as the F55.)
To date there are two distinct sets of official Sony 3D LUTs exist to coincide with the two specific color gamuts on the F5/F55 & FS7 cameras. The two color gamuts are S-Gamut/S-Log2 and S-Gamut3.Cine/S-Log3. Each set of Sony 3D LUTs include four LOOKS (3D LUTs) in total: LC-709, LC709 Type A, S-Log2-709, Cine+709. For more information on these LOOKS consult the PDF publication by Sony.
So for this blog post I decided to take the color charts I shot from my previous test and apply the appropriate Sony LOOK (Sony 3D LUTs) to them and compare the results. What I was most curious to see is if after applying a 3D LUT designed for each color gamut on the camera, if the final result would be identical. In other words apply the SLog2-SGamut_To_LC-709TypeA LUT to the S-Gamut/S-Log2 image, and the SGamut3CineSLog3_To_LC-709TypeA LUT to the S-Gamut3.Cine/S-Log3 image. I was hopeful to see that they might produce the same final result!
Below are the results. I used Davinci Resolve to apply the 3D LUT and also to view the color on the built-in vectorscope:
S-Gamut/S-Log2 with SLog2-SGamut-to-LC709A LUT
S-Gamut3.Cine/S-Log3 with SGamut3CineSLog3-to-LC709A LUT
Conclusion: Despite the correct input color gamut, after the appropriate Sony 3D LOOK (3D LUT) is applied the output colours are drastically different. Why I believe they should have been identical at least with the 3D LUT applied is because Sony officially released the LC709-A to match the look of REC709 mode from the ARRI Alexa. So here we have a discrepancy when using the 3D LUT between modes.
Since CineEI mode has the ability to select color space, I thought it would be prudent to also test its S-Gamut/SLog2 color space using the same process as above.
Below is the result of applying the SLog2-SGamut-to-LC709A LUT to the S-Gamut/S-Log2 color space selected in the CineEI mode:
Conclusion: Using S-Gamut/S-Log2 color space in either mode do not produce the same color rendition or results! Another discrepancy with color science between modes!
Consequently in Custom Mode if you use the Matrix Preset SLog3-SGamut3.cine LIKE, the output results after applying the appropriate 3D LUT (SGamut3CineSLog3_To_LC-709TypeA) are near identical. The main difference is the saturation level of color but the hues themselves are quite bang on.
Downloads: You can download high resolution versions of these test result screen shots through the following link.