FS7: Cine EI and LUTs

[cuervo]

Its too bad they don't offer slog3.cine color space in Custom so you then could do white balance adjustments , but Maybe that's not technically possible anyway.

Since we don't know what basic gamut Sony is using in the Custom mode, it's hard to know if it's feasible. Just because they give us an Slog3 gamma, doesn't mean we have an sgamut3 color space in Custom mode. I submit that using an slog3 gamma in a basic sgammut(2) is fundamentally wrong, altho Dennis Hingsberg may disagree with me. You can always shoot slog3 gamma in custom mode and convert it to sgammut3.cine with the Sony LUT. Not having tested that, I don't know how it would work. Regardless, playing with white balance, if we could do it, in Custom mode, moves that D65 white point around and invalidates the gamma3 white point...or so I claim, throwing LUTs and post processing into a random frenzy.

 

[starcentral]

Its too bad they don't offer slog3.cine color space in Custom so you then could do white balance adjustments , but Maybe that's not technically possible anyway.

On the F55 it is possible in the custom mode when recording internally to select slog3 and chose the S.Gamut3.cine color space, but this is only on the F55. This allows you to white balance and get the benefit of CineEI color. The only way to get this color space on the F5 and FS7 is in CineEI mode, or by shooting RAW where in post you can select whatever you like.

Since we don't know what basic gamut Sony is using in the Custom mode, it's hard to know if it's feasible. Just because they give us an Slog3 gamma, doesn't mean we have an sgamut3 color space in Custom mode. I submit that using an slog3 gamma in a basic sgammut(2) is fundamentally wrong, altho Dennis Hingsberg may disagree with me. You can always shoot slog3 gamma in custom mode and convert it to sgammut3.cine with the Sony LUT. Not having tested that, I don't know how it would work.

As you said we don't know what gamut we have in Custom mode so how do you see using Sony's S-Gamut3->S-Gamut3.cine LUT to derive S.Gamut3.cine? That assumes the gamut in Custom mode is therefore S-Gamut3 but we know it is not.

 

[cuervo]

As you said we don't know what gamut we have in Custom mode so how do you see using Sony's S-Gamut3->S-Gamut3.cine LUT to derive S.Gamut3.cine? That assumes the gamut in Custom mode is therefore S-Gamut3 but we know it is not.

I absolutely agree. it's a shot in the dark that I've never tested. just a wild thought... Altho Sony has said the Sgamut3 space is the same area as sgamut. Again, I think the differences are subtle and not easily seen in Rec709, 8-bit space. But, what is gained is the color accuracy of acquisition in a larger space than the delivery space, just because it yields higher color fidelity in the delivery space....jeez...this all sounds like gobledeegook when i re-read it.

 

[starcentral]

On the F55 it is possible in the custom mode when recording internally to select slog3 and chose the S.Gamut3.cine color space

Sorry made a typo and corrected it. too many similar letters and numbers!

 

[Erik Wittbusch]

FYI:

As dvxuser FrameFarmMedia found out and I tested this back:

You can have WFM on the HDMI out (haven't checked SDi) even when using cineEI and having LUTS on your outputs!!!

Yes, it works in UHD/4k too...

I guess it will work in the next firmware too, as the processing is strong enough to do this easily.

 

[joobny]

Hey all,

Thanks for all the information - quite a lot to get my head around but it helps a lot!

I'm still a little confused about Gain VS ISO in Custom Mode. If you go into the Camera menu, then ISO/Gain/EI you can change the mode from dB to ISO or vice versa. If you select ISO, I still don't understand why you can't make Low, Medium or High settings any lower than 2000. I get that the ISO is fixed in Cine EI mode, but I don't really see why this is the case in Custom Mode? Gain seems to give you more control over exposure but I'd really rather use ISO.

Thanks.

 

[joobny]

I've also done some more tests - this time in Custom Mode, with Matrix turned off and shooting Slog3 in 4k at 25fps in Gain mode between 0 and 6dB, exported at 1080p. Here are links to view them on YouTube.

Ungraded:
https://www.youtube.com/watch?v=VPZX3QvE2aA&feature=youtu.be

Graded:
https://www.youtube.com/watch?v=xqRGW3Uf-v8&feature=youtu.be

I will have lossless copies available to download shortly.

To grade, I took the clips into Speedgrade and applied the REC 709 - NORMAL - SL - PROFILE LUT. I adjusted the white balance slightly in Speedgrade and then brought up the midtones and crushed the shadows. I then took the footage back into Premiere and applied Sharpen (amount 20), Three Way Colour Corrector (and colour-picked the shadows, midtones and highlights) and RGB Curves (to add a slight S curve and correct the white balance a little more). Please let me know your thoughts.

I think the second clip in the test looks pretty good, but the first one looks a bit ropey and I'm not sure why. When I view it back at 100% it looks very blotchy and noisy. The light was pretty terrible though, so maybe I'm just expecting a little too much...? Here's a graded 100% crop showing some nasty artefacts:

And here's an ungraded 100% crop:

 

[nyvz]

Hey all,

Thanks for all the information - quite a lot to get my head around but it helps a lot!

I'm still a little confused about Gain VS ISO in Custom Mode. If you go into the Camera menu, then ISO/Gain/EI you can change the mode from dB to ISO or vice versa. If you select ISO, I still don't understand why you can't make Low, Medium or High settings any lower than 2000. I get that the ISO is fixed in Cine EI mode, but I don't really see why this is the case in Custom Mode? Gain seems to give you more control over exposure but I'd really rather use ISO.

Thanks.

If it's anything like Sony's other cameras, ISO/gain are just a different measurement of the same thing. And in Slog3 or Slog2, 0db = ISO2000, and you can't go below 0db or ISO2000, and the difference tends to be that gain steps in half-stops where ISO steps in third-stops. CineEI is different since it does EI adjustments in software so the gain is always 0db but EI can change essentially by changing the gamma curve.

 

[joobny]

If it's anything like Sony's other cameras, ISO/gain are just a different measurement of the same thing. And in Slog3 or Slog2, 0db = ISO2000, and you can't go below 0db or ISO2000, and the difference tends to be that gain steps in half-stops where ISO steps in third-stops. CineEI is different since it does EI adjustments in software so the gain is always 0db but EI can change essentially by changing the gamma curve.

Got it, thanks!