Grading s-gamut3

J

JoeThePro

Well-known member
I will be getting a Sony cam soon with s-gamut3 color. Ive read that you must use a LUT to properly convert the colors, but that you also must use the proper LUT. For instance, using the same LUT for shots with different exposure or white balance wont work properly. Is this really the case, or can you use the same LUT as a general first step in bringing the colors into the proper space?

Does Sony provide this LUT?
 
To answer your question on how to use LUTs, this is what I recommend with specific reference if using Davinci Resolve.

1st node - exposure and white balance
2nd node - 3D LUT for your slog3
3rd node - start your actual grading here ie. contrast, color wheels, saturation, etc..
 
starcentral said:
To answer your question on how to use LUTs, this is what I recommend with specific reference if using Davinci Resolve.

1st node - exposure and white balance
2nd node - 3D LUT for your slog3
3rd node - start your actual grading here ie. contrast, color wheels, saturation, etc..
Click to expand...

Isnt it hard to white balance log footage pre-LUT? And maybe Ive misunderstood the settings with slog... Do slog and sgamut always get paired in cam, or can you use slog with more of a standard color space? And if so, dont you need to get separate LUTs for each color space to be displayed properly?
 
If you white balance before the LUT, just turn on both nodes (1st and 2nd) so you can still see the final image. So basically you would start with two nodes turned on. But you can also just white balance after the LUT node as well, for sure, that works too. The main thing is to put your exposure node before the node with the 3D LUT.

Regarding slog and gamut pairing, it depends which camera you are talking about. For example F55/F5/FS7 put newer sgamut3.cine with slog3, not slog2. The way around this is to shoot RAW with the AXS-R5 where you pick the slog and color space combo in post. Pretty neat. Most people don't know you can do this.

Yes you do need different set of LUTs for the paired combo. Great catch! To date Sony has only released LUTs for the following combos:

slog2/sgamut (Sony original color space)
slog3/sgamut3.cine (Sony newer color space)
 
other options are;

using a transform, ie; Nick Shaw's DRX (assumeing you are working in Resolve that is)

or just using the tools you have already to grade from the log encoded

or use ACES with it's IDT's... not easy to use without some experience tho
 
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If i've got a LUT for Slog 2/sgamut can I still use that LUT for slog2/sgamut3.cine or would that be too conflicting?
 
To be honest, I wouldn't use any LUT other than a technical gamut/gamma transformation or quick look.
But if you want to work on the final look of your piece of film, do it manually.

If you use LUTs made for the original S-Gamut with S-Gamut3.cine footage you'll end up having to much magenta.
This is because the original S-Gamut is wider especially on the green axis.

Other than that the combination of SLog2 for gamma and S-Gamut3.cine for gamut is wisely chosen for situations, where your highlights do matter more than your shadows.

Bt it's not that easy to grade manually as SLog3 is. Dial in some contrast and saturation and you're almost there.
When you use SLog 2, you have to bring back the highlights more carefully and push the midtones a little more.

More on this here:
http://www.dvinfo.net/article/acquisition/sonyxdcam/sony_sgamut_vs_sgamut3.html

or here:
https://community.sony.com/sony/att...ry_for_S-Gamut3Cine_S-Gamut3_S-Log3_V1_00.pdf
 
theprestige said:
If i've got a LUT for Slog 2/sgamut can I still use that LUT for slog2/sgamut3.cine or would that be too conflicting?
Click to expand...

No you can't really, since the color spaces are different. S-Gamut(1) and S-Gamut3 have the same color space, but SG1 has some kind of strange reference to the white point. SG3 is just a bigger color space. S-Gamut3.cine is a bigger color space (less saturated on a Rec.709 monitor), but still aligned with the Rec.709 pirmaries. Therefore it doesn't look off, just desaturated.

That means, you need a dedicated LUT if you use S-Gamut3.cine with S-Log2. You can do this easily with LUTCalc though.

Additional information:
http://www.xdcam-user.com/2014/05/what-is-a-gamut-or-color-space-and-why-do-i-need-to-know-about-it/
 
Yeah I've tried it for fun and it produces nasty results. By the time you try adjusting the color so that it would work, I think you'd lose whatever look or purpose the LUT was providing in the first place.

Best to get the right technical LUT.

Most luts come in both versions.
 
I see. I'll steer clear of Sgamut 3 then! I've been using a Slog 2/Sgamut that i'm perfectly happy, just wasn't sure if it would work if I used the other Sgamuet. I'll check out those other LUTS, thanks guys
 
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