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TWP251435542air
Participant
July 6, 2022
Question

lumitry Luts (help) Sony A7s III

  • July 6, 2022
  • 2 replies
  • 3317 views

Hey guys.

 

I need help to figure out how I get the best lut for camera Sony A7S III.

Its very hard to understand how luts / color grading works. My company wanna start film with S-log3, but for that, I need to do a several tests.

 

I download sony luts for that camera. And I saw a youtube guy using this lut called: 2_SGAMUT3CINESLOG3_TO_LC-709TYPEA.CUBE

 

Then, result was this:

https://mega.nz/file/pp4VjR6B#3OglPDGWqjAw8Bsk0vcvpNuIrhExlnSn7ZfoO4cYHkU

 

But still kinda bad? 

We wanna the video looks like a cinematic, but is similar with a normal shot.

We see the footage without personality or no difference between slog3 / normal filming .

What we are doing wrong?

(Im not a colorist, I just a video editor, I didnt learned Color, but Im trying but is very complex to my brain!!!)

 

Thanks

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2 replies

A
Andy 1968
Inspiring
July 7, 2022

You are not doing anything wrong. 

In a nut shell shooting in log or using RAW files allow for more flexibility during the editing process but you usually have to apply a LUT or do some color grading to make it look decent. To me it just wastes time. If you are good with a camera you don't need to worry about having more flexibility during the editing process.  That being said some people love shooting in log formats. 

You can use the Lumetri color panel and test things out for yourself instead of using a LUT. Change the gamma, contrast, saturation, shadows, midtones etc. The Slog usually effects the gamma settings more than anything else but all the log profile settings can be altered by the users. For some log profiles you want to be two stops over exposed and for the other log profiles you want to be two stops under exposed.  It all depends on the picture profile settings in the camera. 


    R Neil Haugen
    R Neil Haugen
    Legend
    July 6, 2022

    Ahh, you drew the short straw and got told to fix the color! Congratulations!

     

    And yea, it can break your brain at times. Totally normal, and really you get pretty much used to that after a while ... sigh.

     

    Log encoded media is shot as normal, but recorded to file with a logarithmic curve ...  more difference per value of change on the low end of exposure, very little on the high end. It keeps a wider dynamic range (dark to light) within usable data values. And also "compresses" color response (visible saturation).

     

    So we need to "normalize" log media on Rec.709/SDR (standard dynamic range) sequences. Which means expand the contrast to fill out a visibly normal look dark to light, and with pleasing saturation. Some LUTs can work well at this. But depending on the clip, a LUT can at times 'clip' the whites too much or 'crush' the blacks too much.

     

    Thankfully, it's pretty easy and fast to "normalize" manually. I'll cover that below. For either of course, use the included Color workspace.

     

    Oh, when working color ... ALWAYS have the scopes showing! They're more important than your eyes! I use Waveform YC (no chroma) to see tonal contrast, Vectorscope YUV to see color saturation and accuracy, and ParadeRGB to see color balance/cast.

     

    First, there's an option in the project panel you should check out ... right-click one or more selected clips, Modify/Interpret Footage. If the option for space from file near the bottom shows S-log3.cine as an option, select that. It can do a great job of 'normalizing' the S-log3 clips.

     

    If that control is available, that may fix your S-log clips sweet. If not ... here's a quick guide to rolling your own normalization.

     

    The two controls to work with first are the Contrast and Exposure controls of the Lumetri panel's Basic tab. Contrast spreads out the data (signal in the scopes), Exposure 'lifts' the data sorta.

     

    Looking at the left side scale of the Waveform scope, "Contrast" will push the signal out from the 50 "nits"/IRE line in the middle on the scale, evenly up and down. For some log clips, simply expanding Contrast will get you pretty close to a normalized look.

     

    But some clips may look too light, others too dark ... so you use the Exposure tool to lift dark clips or darken light clips.

     

    But ... you use the Exposure control to adjust the total image up/down so that contrast control works evenly getting image to dark enough and bright enough at the same time. Look what should be the middle values of the image ... if they're too light, take Exposure down. If too dark, take exposure up.

     

    I work these two controls and can get most log media 'normal' in a couple seconds. Occasionally I'll use a touch of Highlights or White to set the high end, and Shadow to adjust the bottoms.

     

    Now you've got your tonal ranges neutralized. It's time to add in some Saturation if necessary.

     

    Your image should be ready for typical color corrections now. Matching to other clips and to the Look you want to get to.

     

    And of course, you can do the above manual work and save that as a LUT yourself. From the little 3-bar menu at the top of the Lumetri panel, use the "save as cube LUT" option. You can then apply the work via the Lumetri panel, and you can even have several slightly different ones to try to see which does best with any one clip.

     

    Or ... say the work as a Lumetri Preset, that you can apply to clips even in the Project panel.

     

    Neil

     

     

     

     

     

    Everyone's mileage always varies ...
      T
      TWP251435542airAuthor
      Participant
      July 6, 2022

      Hey Thanks.

      I need to read everything you said more carefully. 

      I thought buy a lut / find a free one, could fix the color.

      Enter in this technical settings about colour is very hard for me to understand. 

       I just perfer find someone that can do a Lut for us, and my company pay to him.  Or do a workshop with some color specialist to help me in this matter.  That is the best solution.

       

      Thanks for your help, I will need read again to try exacly you said.

       

      My regards

      Paul

      R Neil Haugen
      R Neil Haugen
      Legend
      July 6, 2022

      Let's start by resetting expectations to Reality. LUTs are not a one-size fits all solution. Anybody telling you they are is simply trying to get you to buy their LUTs. By the time you choose which LUTs to buy, you could have easily made a ton of roll-your-own LUTs perfectly suited to your actual media.

       

      Let's look at the process used to get good color. (And ... yes, I teach pro colorists ... )

       

      Basic Color Correction/Grading 101

       

      Color correction & grading involve several steps. Typically done by doing mulitple passes down the sequence. Though very experienced colorists can start to 'blend' the steps, beginners should stay with a separate "pass" through the complete sequence for each step.

       

      1)  "Normalization" of any log or raw file to your working space. And fixing general tonal/color issues with standard media also. "Normalization" means getting a basically correct tonal range, saturation, and close enough white balance.

       

      2) Shotmatching down the sequence. Which is modifying clips to blend together visually. Decently close contrast/exposure/color balance. So that as you go clip to clip through the sequence, nothing makes the eye or brain 'jump'.

       

      3) Third pass, fixing problems like one face being a lot brighter than another or whatever.

       

      4) Finally, adding an overall "look" to the project. IF time & budget allow.

       

      You can't normally do the whole thing in one step by simply by applying a single LUT to all your incoming clips. Why? Because any LUT that seems to do that with one clip from a camera, will probably give a bit different look with clips from that same camera in a different lighting setup. Using a different camera and lens in the project can get really off results from either of the above.

       

      So getting an understanding of the realities of the process is the very first part of getting things done well and also done quickly. Have you ever heard the comment, "If you don't have time to do it right, when will you have the time to do it over?"

       

      Definitely applies to color.

       

      Doing Your Own Normalizations

       

      It's actually very simple to do 'normalization' from log by yourself. It's actually the easiest thing to do in the entire color correction process.

       

      It's far easier than say shotmatching clips down a sequence. Normalization ... piff, that's pretty easy.  I've taught people to do it in just a few minutes. Shotmatching, now ... that can be ... hard. Puzzling.

       

      As is the third step, fixing problems. In fact, the main reason to hire a colorist isn't to get a "look", but to quickly, efficiently, and correctly get steps 2 & 3 above done ... shotmatching & fixing. The hardest parts of grading. Normalization and Looks are ... relatively ... easy.

       

      Normalization means adjusting the contrast range and midtones "lie" ... meaning setting the black/white end points as well as where the middle tones sit visually. Then setting WB to 'neutral' and getting "normal looking" Saturation.

       

      It takes less time to do it than to write or read about it, or even talk through it! Everything is checked by the scopes, you don't need to interpret anything.

       

      Adjust Contrast up or down, while using the Exposure control to "slide" the image to a decent visual balance, and proper white/black points. Up the saturation to a 'normal looking' amount, and check white balance. Same process really whether working with log or 'normal' video clips.

       

      And of course, if several clips are the same, you can copy/paste the corrections to all the other similar clips. Bulk work saves tons of time!

       

      Working with LUTS

       

      Back to LUTs. Colorists call LUTs "the dumbest math out there" for a very good reason. And include a ton of caveats to using them. Why?

       

      All LUTs, whoever makes them, are simple data-in/data-out operations. X pixel data becomes Y.

       

      But they are built from clips ... so what media was used? How was it lit? How were the camera settings set? What was the white balance and exposure of the file?

       

      If you match all of those criteria with your field-produced media, the LUT probably will work for a lot of clips. But if your media does not perfectly match all of those, you can have a hot mess. And a mess that you can't recover from after the LUT is applied.

       

      Because for any clip that is slightly over exposed compared to the camera media the LUT was built from, that LUT will hard 'clip' the whites/highlights.

       

      Any clip slightly under exposed, again compared to the clip/s used to build the LUT, you will crush the blacks.

       

      And you cannot get that data back after the LUT is applied. You must alter the clip before the LUT is processed to save your data. And to get the best work out of any LUT.

       

      So ... simply using a LUT is absolutely no guarantee that your media will be 'fixed' correctly. It can't be by the nature of a look-up table design.

       

      Using LUTs in Lumetri

       

      And ... when using LUTs, as you need to "trim" the exposure/contrast/blacks/whites/saturation "into" the LUT, I recommend applying LUTs in the Creative tab of the Lumetri panel.

       

      Then after setting the LUT in place, go to the Basic tab, and adjust the image to best effect.

       

      Neil

      Everyone's mileage always varies ...
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