How much latitude do you get to set WB and ISO in post if shooting "raw" video?
I wanted to revisit the latitude of the raw video codecs when it comes to adjusting white balance in post-production rather than setting a 'correct' white balance in camera at time of acquisition. For this purpose, I shot the same scene illuminated with 5000k video lights modified with various filters to achieve 15000k, 30000k and 45000k. In each case, I filmed once with CWB set in camera to match the illumination, and once with CWB set in camera to 5000k to see whether the WB could be rescued in post-processing.
White Balance Adjustments
For the Canon R5C Cinema RAW files and the Nikon Z9 N-Raw files, white balance and tint can be adjusted in the Color page under the Camera Raw tab. Canon Cinema RAW files can also be adjusted in a similar fashion using Canon's own Cinema RAW development app.
-
Nikon N-Raw allows adjustment of color temperature from 2000 to 50000 kelvin, and tint from -150 to +150 in Davinci Resolve. (there is no other software that works with N-Raw at the moment.) However, this is deceptive, as dialing in white balance in post to 50000k barely shifts the colors, unlike with the Canon Cinema Raw. Refer to the results under 45000 kelvin illumination below.
-
Canon Cinema RAW only allows adjustment of color temperature from 2000 to 15000 kelvin, and tint from -150 to +150. This is the same whether you process the files in Davince Resolve or canon's own Cinema RAW development app.
-
For the Sony A1 files, which are h.265, I performed the white balance adjustments using the white balance picker under the Primaries - Color Wheels tab of the Davinci Resolve Color page to compare what WB adjustments can be achieved in the same scenario using 12-bit "RAW" formats.
ISO Adjustments
-
Nikon N-Raw (in Davinci Resolve) does not allow you to adjust the ISO in the Camera Raw tab.
-
Canon Cinema RAW allow for ISO to be adjusted if you use the Decode Quality - Full Res - Canon setting. They don't allow ISO adjustments if Decode Quality is set to Full Res - Resolve
For reference, here's what the Sony A1 and Canon R5 C shots looked like illuminated with the 5000 kelvin video lights:
Already we can tell there are some differences in color science between the Sony and the Canon files. Sony files are slightly more saturated but less contrasty. Which color science you prefer might be a matter of debate..
And the Nikon Z9 at 5000 kelvin:
15000 Kelvin Illumination
Sony A1 -- WB In Camera vs. In Post
Canon R5 C -- WB In Camera vs. In Post
First, the Canon files are quite noisy. But this is because I accidentally underexposed them by around 2 stops and had to recover exposure in post. The custom white balance is also a bit off, because it's set based on the entire scene rather than a smaller selectable area like on the A1. So ignore that part (though, as an aside, it's worth noting that the raw files are noisy!!). I will see if I can reshoot this test later and properly expose it and white balance off a grey card, but ultimately it doesn't matter for the purpose of judging WB adjustment latitude.
Second, there is enough latitude in the Canon 12-bit raw file to adjust CWB from 5000k to 15000k and achieve identical results to setting it at 15000k in camera in the first place. The same could not be achieved with the Sony 10-bit 4:2:2 files. Here is the Davinci resolve Camera Raw tab settings and histograms so you can see the results are the same when you dial in the same Color Temperature and Tint to the second file in post.:
30000 Kelvin Illumination
Sony A1 -- WB In Camera vs. In Post
Canon R5 C -- WB In Camera vs. In Post
Same result here with the Canon R5 C files -- there's enough latitude to adjust white balance from 5000k to 30000k in post and achieve identical results to setting white balance in camera. With the A1 10-bit 4:2:2 files.. not so much.
45000 Kelvin Illumination
Sony A1 -- WB In Camera vs. In Post
Canon R5 C -- WB In Camera vs. In Post
Nikon Z9 -- WB In Camera vs. In Post
Same result here with the Canon R5 C files -- there's enough latitude to adjust white balance from 5000k to 45000k in post and achieve identical results to setting white balance in camera. With the A1 10-bit 4:2:2 files.. definitely not.
Interestingly, the Nikon Z9 files also appear to preserve enough latitude to adjust the white balance from 5000k to 45000k in post, but the process is a bit more convoluted. Just dialing in 50000k and +150 tint in the Camera Raw tab doesn't do it -- I had to make white balance adjustments and to the color wheels. But the ultimate result is that I was able to get to the same end. So I'd say the Nikon Z9 raw files also work, they just need a different workflow.:
Nikon Z9 processing on file with in-camera custom white balance set:
Nikon Z9 processing on file with white balance dialed in in post:
Conclusion
The Canon R5C's Cinema Raw and the Nikon Z9's N-Raw files allow you to adjust your white balance in post with similar latitude as you would get with RAW still images. This is really powerful for underwater shots. The Sony A1 meanwhile, while it does a great job with CWB when set in camera, doesn't preserve nearly the same flexibility in post if you don't get the white balance right at shooting time.
I also discovered that this flexibility is only available if you set Davinci Resolve to debayer the Raw files using Decode Quality: "Full Res - Canon". If you use Decode Quality: "Full Res - Resolve" you can't adjust the white balance as precicesly in post. With the same file, take a look at the two different results depending on which Decode Quality setting you pick. For some reason, the green channel is amplified more when selecting the Resolve debayering algorithm.
The tradeoff is that with Full Res - Canon the files only play back at around 15 fps, while Full Res - Resolve allows real time 60 fps playback. So you probably want to keep the settings to Full Res - Resolve during editing and only render using Full Res - Canon once you're done with all your edits.
