SLOG3 question

[dudyka]

Hello, I am a beginner shooting in SLOG3 so please excuse my ignorance.

I am trying to shoot outdoor scenes with a lot of dynamic range.

My camera is Sony RX10M4 and I am recording in PP8 ( S-Log3, S-Gamut3.Cine) with the Atomos Ninja V.  using ProRes HQ.

I have very hard time figuring out how to color grade the footage in Premiere Pro 2020.

I tried to apply LUTs from Sony (1_SGamut3CineSLog3_To_LC-709.cube; 2_SGamut3CineSLog3_To_LC-709TypeA.cube and others) but none of those worked. 

I tried to color grade with lumetri color without lut and no success.

Surprisingly when I change the Atomos Ninja V monitor setting to HLG, the video clip appears in vivid colors, with high dynamic range displayed correctly (only on the Ninja V screen) The clouds pop and look almost as it was in reality. That is the look I would like to achieve.

Is there a LUT which converts SLOG3 to HLG I could apply to my footage in Premiere so it looks like on the monitor with HLG setting?

Here is the video sample clip I shot in S-Log3, S-Gamut3.Cine with the Atomos Ninja V.  using ProRes HQ:

https://drive.google.com/file/d/1nPDTdXjU2EAjpbdSsB1PLBr2rQJc2xgz/view?usp=sharing

Please someone explain to me how to bring out the most dynamic range and colors from this SLOG3 footage!

I know the recorded file contains all the information needed to display the high dynamic range, I'm sure I'm doing something wrong.

[R Neil Haugen]

Um ... a beginner working in SLog3 is a bit of a challenge.

First ... LUTs are called by pro colorists "the dumbest math out there" ... and can be very tricky as they can easily and quickly simply blow out whites and crush blacks. Turn saturation to cartoon colors ... induce artifacts ... so they take some testing and care to apply. It is heavily recommended that they be applied to a second step of the grading process. The first step is then used to "trim" the media into and through the LUT.

So Premiere's Basic Tab input LUT slot is usable only if you use mulitple instances of Premiere. In the second instance (the lower one in the ECP panel) apply the LUT in the Basic tab. Then go to the first instance (higher in the ECP or the list of Lumetri instances in the Lumetri drop-down list) and use any controls you prefer to adjust the image ... start probably with overall contrast, then white point and shadows, then saturation.

See if that makes things look better.

Neil

[Meg The Dog]

Are you trying to end up with a file that is actually HDR for playback on a true HDR monitor (and looks correct only on a HDR monitor),  or a rec 709 file that has the apperance of high dynamic range for playback on SDR monitors?

MtD

[dudyka]

I guess I am trying to achieve an HDR looking video in rec 709. With my sony rx10M4 I had better looking videos coming out with no picture profile than with SLOG3. I am recording planespotting videos and I would like to have good looking airplanes with nice colors, nice clouds against blue skies and also beautiful sunsets. I heard about the HLG but unfortunately there is no small camera with built in 600mm zoom which is capable of HLG that I know of. 

I own a Atomos Ninja V and when I record SLOG 3 through the RX10M4 HDMI and I view the footage with the Atomos monitor set to HLG it looks fantastic. I cannot recreate that in Premiere PRO. I tried to apply the SLOG 3 to HLG 709 LUT but it's very far from what the ninja v is displaying.  Is that because the atomos ninja V is a HDR screen and my PC monitor is not?

Let's say I would be able to create HDR videos and uploaded to youtube. Some people who doesn't own and HDR capable TV or monitor would see the same video in crappy colors? Are the latest phones all HDR content capable?

Thanks a lot for the help.

[R Neil Haugen]

First, most screens still are not fully HDR capable technically. They may be brighter than before, but what they do for 'HDR' is simply remap the brightness of the image to the screen. You're not really into full-on HDR unless you're cracking 1,000 nits or better with a lot of dimming-zones for black areas as no current screen technology has the brightness/contrast range necessary for "native" display of full HDR. So ... the device sees an area with data below X brightness, it drops the 'floor' of black for that area essentially. (Not a perfect technical explanation, but works for mental concept.)

Next ... I don't know if you understand actually what Log capture is ... it's a way of encoding the capture data to card so that the dynamic (luma) and color (chroma) data are pulled in together such that the outer ranges of especially the dyamic/luma data are recorded with full separation of values. Log media looks "flat" with nothing approaching black or white, everything looking very low-contrast, and at the same time very low saturation. The idea is that this keeps the widest range of data for use in determining later in post how to set contrast/black/white/saturation.

Recording in Log forms is actually rather trickier than many realize, it's far more difficult to get right in all situations than shooting 'normal' files. Because if your exposure isn't exactly correct for the scene contrast/brightness, you are still clipping potential image data, but you can't see this typically in the camera monitor. Hence using LUTs in camera to expand the view. But ... LUTs are the dumbest math out there, remember?

So when using Log files, the user needs to have some experience in every step of the process in order to build the pipeline from capture through editing/post. You have to know how to control your exposure in-camera for different situations. Plus, you have to know how to convert the captured Log data to 'normalized' data for each exposure/contrast/brightness setup you shoot.

Meaning ... you may very well use one corrective/normalization LUT for X situation, and a different one for Y. How do you know which to use? Testing and the experience that comes with it.

Now we get into your shooting situation ... shooting planes against clouds/sky and bright sunlight. Yowza.

It is going to be SO easy to either clip some cloud data or risk losing data in the plane's shadow sides. The contrast range is high, and even capturing in Log is not a panacea. It looks like to me you're expecting to get a one-size-fits-all solution, and I doubt you will. For looking at an image that is at 90* from the line of the sun, you will have one contrast range and exposure need. Shooting more towards the sun, you will have a higher contrast range, shooting away from the sun, a different range. You will have to adjust for each situation. Yea, I've done this with footage I shot/prepped from an airshow.

There are several LUTs that 'ship' with Premiere for Log corrections, you see those listed in the drop-down list for the Basic tab in the Color Workspace/Lumetri panel. As with any corrective/Technical LUT, you should be able to modify the view of the image before the LUT is processed but through the LUT ... so if you use the Basic tab for LUT application, you should do so in a SECOND instance of Lumetri, and use the first instance to then 'trim' the image black/white/contrast/saturation/exposure to get what you want to see.

Of course, you can manually create Lumetri instances to normalize LUTs (as many colorists do) and save them as presets.

Neil

[dudyka]

Neil, thank you so much for the detailed explanations. I think the best solution for me is to keep shooting the way it works for me now and keep testing the slog3 in between.

I really appreciate the help

Attila

[R Neil Haugen]

Shooting in log is very helpful with some cameras to capture wider contrast ranges, no question. It does make the post work more complicated in some ways, and there are massive, long discussions by colorists on the value of various LUTs for normalization even made by the camera manufacturers.

If the colorists are struggling with the use of LUTs, well ... less-experieinced video post folks need to understand they are not an easy cure-all/fix-all solution. They are a potentially useful step, but one that needs direct and intensive testing for identifying the potential problems, when the are likely to occur, and how to ameliorate them as needed.

As I noted ... following the advice of the top teaching colorists ... I would never apply a tech/corrective LUT as the first step of working a clip. Tech LUTs are normally built on "perfect" shooting situations for color balanced lighting and camera exposure.

You aren't ever going to get a clip captured under the same situation the LUT was built for. Close, yea at times. But not close much of the time. And if the LUT is not 'perfect' for the clip as it is, then it will clip the whites, or crush blacks, or over/under saturate something. And those pixels have now been altered beyond fixing. You're working with a messed up image trying to recover what the LUT itself damaged.

That's why when you apply a corrective/tech LUT, you need to be able to correct the image pixels before the LUT, while watching your Parade RGB, Vectorscope YUV, and probably I'd suggest the Waverform in YC-no chroma mode. It's a tech correction ... check it by tech. Make sure your darks go down close to but not to the black point, your whites approach white if appropriate, and your saturation is not running outside the limits graticule but at the same time is adequately filling out space in the Vectorscope for the indication of decent color satuation.

And also ... do a bit of adjusting the highlights and shadow areas to neutral color while at it.

Within Lumetri, that means either using the Creative tab to apply the tech/corretive LUT, and using the Basic tab to do your trim of the clip through the LUT, or ... applying a second instance of Lumetri via the dropdown option at the top of the Lumetri panel. Apply the LUT in the Basic tab of that second instance.

Then go to the first instance, the 'upper' one in the drop down list (and in the ECP) ... and do your trim work as noted above.

Then go back to the second instance with the tech LUT applied, and start doing the rest of any adjustments you visually wnat to the clip to "look" as you want it to.

Note, some colorists would say leave the second instance named for being the LUT application instance, and don't do anything else in that instance. Create a third instance, and name that for grading whatever you're doing next, and go from there. In that scenario, the 'top' or first instance you'd call Trim, the second LUT, and the third grading or clip matching or whatever.

Neil