F5: When less is more (an ode to SGamut3.cine)

Grug

Grug

Veteran
Hey guys,

I've just wrapped (at 5am this morning) my second feature film (first on the F5). And it's led to some interesting discoveries about the camera.

We started production shooting in my default non-raw workflow for the camera - SLOG2/SGamut in Custom mode (which allows for false colour monitoring in the EVF and noise reduction - two hugely useful features).

I've always been able to get excellent results from this combo, as false colour allows me to easily confirm perfect exposure on every take, and mid-level noise reduction yield an exceptionally clean image (which I'll usually apply film grain to afterwards for texture). I also prefer SLOG2 to SLOG3 for its superior highlight rendering.

Those reasons have kept me from delving into CineEI mode, and SLOG3/SGamut3.cine in much detail. But on a short that we shot with the R5 last year, I discovered that the combination of SLOG2 and SGamut3.cine yeilds far-and-away the best colours and the most filmic highlight rendition the camera can produce (and the easiest to grade).

It's a real shame that specific combo (SLOG2/SGamut3.cine) isn't available for compressed recording in camera. Since I’d shoot it exclusively if it were available - in the meantime, false colour and noise reduction have kept me shooting in Custom-Mode/SLOG2.

However on this feature, which I used a lot of coloured gels on to craft a slightly surreally-coloured world, I found that trying to pull the colours into line in the grade was quite a challenge with SLOG2/SGamut.

This led me to take a chance on SLOG3/SGamut3.cine to see if the more restricted colour gamut would yield more easily managed results (as it had on the short I shot in 4K raw). So three days into the picture I changed the recording mode to CineEI and held my breath… after I got that third day’s footage into Resolve that evening, it was a small revelation. The dominant colour in this film is green, and I’ve always found that it’s red and green that tend to cause the most trouble for grading when shooting SLOG2/SGamut (they go nuclear compared to everything else when you up your saturation, or add in film emulation LUTs). However shooting SGamut3.cine, the greens didn’t go out of line whatsoever. They were massively more pliable in Resolve, and roughing in the graded look I wanted took a fraction of the time it had shooting regular SGamut.

So while I'm still not super keen on SLOG3 and its reduced highlight detail compared to SLOG2 (and I HATE losing false colour monitoring in the EVF) I think I can say quite confidently that SGamut3.cine is the best thing that's happened to the F5(5) in some time. We always go on about wanting more, more, more. But the reduced colour gamut of SGamut3.cine is SO much easier to work with and yield pleasing colours from than the original SGamut or SGamut3, that it's almost foolish to shoot the cameras in any other setting IMO.

It did force me to rely solely on my light meter for exposure, which I haven’t done in a while. But the results are worth it.
 
Hi grug,
I have a question for you. The SLog3/Sgamut3 color space, is available in CUSTOM mode and can be converted to Slog3.cine via a Sony provided LUT
http://community.sony.com/sony/atta...r-camera-F5-F55/22185/1/SLog3SG3toSG3Cine.zip
The Slog3 gamma is preferable over the slog3.cine gamut because it's a master color space that can be archived with a much bigger color space than slog3.cine. have you played with the LUT conversion to see if you can color correct the LUTted slog3->slog3.cine material with the same ease as native slog3.cine?
 
Slog3 should work better with RAW recording or future 12bit 444 codec.

Also due to different Colour Filter Array on F5, I doubt SGamut3/SGamut3.Cine on F5 are the same as F55/F65
 
Ben Scott said:
Very interesting. Would love to see a still or two if you're allowed to show anything.
Click to expand...

Can't show anything yet, but I will once I'm allowed.

cuervo said:
Hi grug,
I have a question for you. The SLog3/Sgamut3 color space, is available in CUSTOM mode and can be converted to Slog3.cine via a Sony provided LUT
http://community.sony.com/sony/atta...r-camera-F5-F55/22185/1/SLog3SG3toSG3Cine.zip
The Slog3 gamma is preferable over the slog3.cine gamut because it's a master color space that can be archived with a much bigger color space than slog3.cine. have you played with the LUT conversion to see if you can color correct the LUTted slog3->slog3.cine material with the same ease as native slog3.cine?
Click to expand...

I haven't looked into SLOG3 in custom mode, mainly because if I'm going to lose the functionality of false colour, I at least want the functionality of MLUTs to compensate.

I'd always assumed more is better, but as you toggle through gamuts with raw files it becomes rapidly apparent that SGamut3.cine falls into line MUCH more easily than the other two. So I'm not really sure what benefits the wider colour spaces can actually offer. Neither SGamut or SGamut3 can save the camera from weirding out on bright magenta or blue coloured light sources.
 
Grug,
Sorry for giving the impression that I was asking about the CUSTOM mode, exclusively. Most certainly, shooting slog3/sgamut3 in CINEEI is my own choice. The question is still pertinent, especially for cine EI. Sony's recommendation is to shoot Slog3/sgamut3 for archival purposes, then convert it to slog3.cine/sgamut3 with their conversion LUT. THEN, any subsequent grading can be stacked ontop of the conversion LUT. My experience has been to follow this recommendation. Just as an aside, Sgamut3 is huge, bigger than DCI, and more designed to fit Rec2020. I think it's a recommended archival format so that the data is there for the future, when REC2020 is available as a monitor display color space...maybe in 10 years. At any rate, my point is why shoot slog3.cine if one can shoot the wider gamut of slog3 and convert it to slog3.cine in post via a LUT?
As another aside, one can record slog3/sgamut3.cine in Cine EI, sending the SDI output signal to an Odyssey 7Q, record to prores 444, and get a compressed slog3/sgamut3.cine format.
 
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Hi Cuervo,

Just a few corrections;

In custom mode slog3 it is not sgamut3 it is just sgamut, and the 3D LUT you are talking about to convert color spaces is designed for S-Gamut3 (not regular S-Gamut) to -> S-Gamut3.cine.

In custom mode the F5 can not shoot S-Log3 with S-Gamut3 so you have to switch to CineEI mode. Interestingly enough the F55 can deliver S-Gamut3 and S-Gamut3.cine color space by using a matrix preset in Custom mode.

I tested it out this weekend and my findings, charts, etc.. will be published online later this week. It's quite interesting.
 
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Thanx for the corrections, dennis. I got sloppy in my nomencalture, so read what I mean not what I wrote..:-) yes, slog3.cine/sgamut3=slog3/sgamut3.cine, in my corruption of the nomenclature. I never suggested using the conversion LUT with straight sgamut. Not sure why I gave everyone the impression I was talking about slog3 in custom mode. My bad.

Regardless, the question i have on the table is why shoot slog3/sgamut3.cine, when one could better shoot slog3/sgamut3, then convert it to slog3/sgamut3.cine in post(with the Sony LUT), whether you shoot custom or cine EI, or, for that matter, use an external recorder that records in Prores HD 422.
 
marvinhello said:
Slog3 should work better with RAW recording or future 12bit 444 codec.

Also due to different Colour Filter Array on F5, I doubt SGamut3/SGamut3.Cine on F5 are the same as F55/F65
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Yes I'm finding it quite interesting that the F5 can deliver S.Gamut3's in CineEI mode due to the supposed limited REC709 CFA it employs. It can only mean it is calculated, i.e. a type of color transform (3d LUT) that takes it from a lesser space into a larger one.
 
cuervo said:
Thanx for the corrections, dennis. I got sloppy in my nomencalture, so read what I mean not what I wrote..:-) yes, slog3.cine/sgamut3=slog3/sgamut3.cine, in my corruption of the nomenclature. I never suggested using the conversion LUT with straight sgamut. Not sure why I gave everyone the impression I was talking about slog3 in custom mode. My bad.

Regardless, the question i have on the table is why shoot slog3/sgamut3.cine, when one could better shoot slog3/sgamut3, then convert it to slog3/sgamut3.cine in post(with the Sony LUT), whether you shoot custom or cine EI, or, for that matter, use an external recorder that records in Prores HD 422.
Click to expand...

No worries Cuervo, it's only fresh on my mind because I've been testing and writing about it this weekend. Sorry to sound like a nit picky bastard.

In post #4 you asked why not shoot slog3/sgamut3 in custom mode which is where the confusion comes from.

Just funny you mentioned it because like I discovered and tested this weekend it IS actually POSSIBLE on the F55 camera (unfortunately not the F5). This is great because it means I can shoot with my own white balance, ISO setting, and keep it in S-Gamut3.cine space making it WAY easier to grade… now I just need custom loadable LUTs in custom mode and I will be happy.

To answer your question though about why not shoot with the wider S-Gamut3 and use the LUT to take it to the cine version - my only answer is I haven't tried it yet but not sure I like the idea of using too many LUTs in the chain.

If you just keep it in cine color space then it's easy to grade from scratch for one no matter who the footage goes to and who ends up doing the grading…
 
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starcentral said:
Just funny you mentioned it because like I discovered and tested this weekend it IS actually POSSIBLE on the F55 camera (unfortunately not the F5). This is great because it means I can shoot with my own white balance, ISO setting, and keep it in S-Gamut3.cine space making it WAY easier to grade… now I just need custom loadable LUTs in custom mode and I will be happy.
Click to expand...

hmmm...weird, because on my F5(v5), I see slog3/sgamut3 whether I'm in Custom or Cine EI. I prefer Cine EI because I can use one of the LUTS with it. What I can't use in Custom mode is slog3/sgamut3.cine.

Ironic because for a while I thought if I was in Cine EI mode, the only recording option I had was RAW. I didn't realize that I can record to SStP (Sony SR) with slog3/sgamut3 by selecting RGB in Cine EI mode.
 
This sub-menu selection of gamma is the same as selecting the gamma from the side panel on the outside.

But it does not say "sgamut3" it is just regular "sgamut". The "3" is only accessible when in CineEI mode on the F5.

Do you agree or am I missing something?
 
starcentral said:
This sub-menu selection of gamma is the same as selecting the gamma from the side panel on the outside.

But it does not say "sgamut3" it is just regular "sgamut". The "3" is only accessible when in CineEI mode on the F5.

Do you agree or am I missing something?
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You know, it's undefined by Sony. It doesn't make sense, to my way of thinking, to give the user a gamma of slog3, without also supplying the appropriate sgamut. Slogs and sgamuts go together, hand in hand. Of what use would an slog3 gamma have to an sgamut(2)? We know the F5 sensor is capable of sgamut3, because it records to that in the cine EI mode. The F5/55 both are designed to support REC2020. It's simple to scale the gamut space back, but, expanding it is impossible, if not supported by the sensor.

On the FS700, the user is given the choice of slog2, no mention of color gamut. I assume this is because the sensor and memory of the FS700 is only large enough for a single gamut. Of course, Sony could have crippled the F5 by limiting the custom mode to sgamut2, and, Sony has been known to do stupid things like this before.

-Bill
 
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How I see it is if there is no mention of which sgamut it is then it's probably sgamut the "original".

As Grug points out that space is a ***** to grade and probably explains why footage from F3, FS700 was so hard to wrangle. The cine color space really seems most ideal and I wish that I had caught onto it earlier, just too much to keep up with!

Mark sorry to hijack your thread. All I really wanted you to know was that YES you can shoot slog2 s.gamut3.cine internally but only on the F55.
 
Back to my original question...why shoot the smaller gamut of sgamut3.cine, if one can shoot the larger sgamut3 and LUT it to sgamut3.cine in post? How does the conversion LUT work? Does it remap colors outside of the sgamut3.cine space or does it clip those values to get to sgamut3.cine?
 
As far as I know, F5 and possible FS7, have a gamut that is somewhere in between F55/F65 and standard REC.709. Not as pure and wide as F55/F65, but definitely larger than 709. Thus the need for SGamut3/cine to correctly record it.

The stills camera A7s also has SGamut setting along with SLog2, the manual says it's an emulation of the original SGamut, so I guess it's still bigger than 709/sRGB, maybe similar to AdobeRGB/P3 since the camera can take stills with AdobeRGB space.
 
marvinhello said:
As far as I know, F5 and possible FS7, have a gamut that is somewhere in between F55/F65 and standard REC.709. Not as pure and wide as F55/F65, but definitely larger than 709. Thus the need for SGamut3/cine to correctly record it.

The stills camera A7s also has SGamut setting along with SLog2, the manual says it's an emulation of the original SGamut, so I guess it's still bigger than 709/sRGB, maybe similar to AdobeRGB/P3 since the camera can take stills with AdobeRGB space.
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In the case where the gamut is undefined, or where it's specifically stated "it's an emulation of the original SGamut", I would agree with you Marv. However, Sony specifically calls out Sgamut3 for both the F5 and the F55. Unless they were perpetrating a fraud, they wouldn't define things so clearly. You're wrong about the F5 color space. I can't speak for the FS7. There's numerous white papers defining the Sgamut3 and Sgamut3.cine color spaces, as well as why they exist and how they were derived. None of these papers support your assumption.

Having said that, I don't doubt that the F55 debayer algorithmns are different that the F5. The F55 has a different color filter than the F5. While the F55 sensor has a larger acquisition space, sgamut3 is defined by specification. I would refer you here:
http://www.dvinfo.net/article/acquisition/sonyxdcam/sony_sgamut_vs_sgamut3.html
 
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