The great S-Log2 or S-Log3 debate.

I’ve written about this many times before, but still it comes up again and again. Which is better? Which should I use? I hear all kinds of crazy comments and a lot of incorrect information, so first of all lets dispel a few myths:

S-Log2 captures more dynamic range than S-Log3, it goes to a higher level on the waveform, S-Log3 clips the highlights sooner.

On most of Sony’s current cameras S-Log2 and S-Log3 both currently record exactly the same dynamic range as this is limited by the sensors that Sony are using. The S-log3 curve could be used in a future camera to capture up to 16 stops and in fact the new Venice camera records over 15 stops.  But as all of Sony’s other cameras sensors can only see 14 stops and the S-Log3 curve is designed to go beyond 14 stops, stop No. 14 is not recorded all the way at the top of the recording range.  S-Log2 is a 14 stop maximum curve, so the peak level is recorded right at the top of the recording range. There is no space held in reserve for anything beyond 14 stops.

In Sonys current camera range (other than Venice) the limit is 14 stops whether it’s S-Log2 or S-Log3. The chart that Sony provide showing both S-Log2 and S-Log3 is a little confusing as it shows the entire gamma curve rather than what the camera can actually “see”. In their current implementations both curves stop at +6 stops over middle grey, both capture the same dynamic range, there is no difference.

S-Log2 is brighter than S-Log3 so it must be capturing highlights better.

No, not really, see above. Playback and on screen brightness comes from the levels chosen to record something at and is dependant on the shape and range of the gamma curve. But the actual captured range is dependant on what the sensor can cope with. As we are not changing the sensor, the captured dynamic range, brightness range and shadow range does not change between S-Log2 and S-log3, both of which take the entire sensor range (they just store that same range using slightly different levels or code values). After applying a LUT or other conversion to your normal viewing gamma both S-Log2 and S-log3 will have the same brightness, same highlight and same shadow range.

S-Log3 has noisy shadows.

No, not really. Shadows appear noisy with S-Log3 as the shadow part of the curve is stored using higher code values compared to S-Log2. So when you view S-Log3 uncorrected the shadows are raised and stretched on your conventional monitor and this gives the impression of a noisy picture. In reality once you restore the levels to normal there is no additional noise. See this article for a full explanation.

S-log-levels The great S-Log2 or S-Log3 debate.
Chart showing S-Log2 and S-Log3 plotted against f-stops and code values. Note how little data there is for each of the darker stops, the best data is above middle grey. Note that current sensors only go to +6 stops over middle grey so S-Log2 and S-Log record to different peak levels.

S-Log3 is newer than S-Log2 so it must be better.

Newer, perhaps not. Better, no not really. S-Log3 is based on the industry standard Cineon log gamma curve. This curve was developed in the 1980’s to allow the digitising of film using 10 bit data. So S-Log3 matches a curve designed to work with negative film and is capable of storing more than the 14 stops that most of the current cameras sensors can see. In effect it is an old log gamma curve. As it is a curve designed for more than 14 stops, when used in a 14 stop camera some of the available recording data is empty and wasted.

S-Log2 was specifically designed by Sony to work with an electronic sensor with 14 stops of dynamic range and is optimised to match the performance characteristics of video sensors. By using a 14 stop curve with a 14 stop camera almost every bit of available data is utilised, there is no wastage. So S-Log2 makes better use of the data you have available to you,


S-Log2 and S-Gamut:

As well as the gamma curve we also have different Gamuts or color ranges. S-Log2 was originally designed for the F65 camera. The F65 sensor can capture a huge color range beyond the range that most conventional video sensors can see. So as well as S-Log2 Sony introduced S-Gamut which was matched to the very wide color range of the F65 sensor. S-Log2 is designed to be used with S-Gamut. But many of the cameras we use, like the FS7, F5, FS5 cannot see this color range (Sony’s F55 and Venice can). In addition this very large color range can be a little tricky to deal with in post production. Add to this the fact that S-Log2 is quite different to the quite common Cineon gamma curve and behaves differently to other curves in post. The end result was that in the early days of S-Log2 there were a number of complaints and comments that Sony’s S-log2 material was difficult to grade.

S-Log3 and S-Gamut3.

Because some people were struggling a bit with S-Gamut and S-Log2 in post production (Resolve and many of the other tools we have today were not as well developed 4 years ago), Sony introduced S-Gamut3 and S-log3 as well as a further Gamut called S–Gamut3.cine. S-Log3 was based on Cineon as that’s what people were familiar with. Arri’s Log-C is also based on Cineon as are many other log curves. This makes it a more “familiar” grading experience for many colorists. In addition Sony created a modified version of the super large S-Gamut to make it easier to grade.  S-Gamut3 is just as big as S-Gamut but some tweaks inside make it easier to grade (fewer color shifts). At the same time Sony realised that most users were producing content for TV, the web or digital cinema that had little use for the huge color range of S-Gamut/S-Gamut3.  So S-Gamut3.cine was developed as a smaller, more manageable version of S-Gamut3 and it incorporated a few tweaks to the color science to provide colors closer to those used by other manufacturers. S-Gamut3.cine is also a better match for cameras with sensors that cannot see the full S-Gamut range (like the FS5, FS7, F5, A7).

The end result is that in general most people prefer or find it easier to grade S-Log3/S-Gamut3.cine material than S-Log2/S-Gamut. Plus you can often use LUT’s designed for Log-C or Cineon with S-log3 material (this isn’t optimum, but it can work).

Gamuts-1024x632 The great S-Log2 or S-Log3 debate.
SGamuts Compared.

Getting the data from camera to post.

In terms of getting the data from your cameras sensor in to post production S-Log2 is the better choice (unless you have a Sony Venice which only has S-Log3). S-Log2 is optimised for the way an electronic sensor works. S-log3 is essentially a curve designed for negative film applications, not video and no matter how you look at it, these are electronic video cameras. However, if you are recording 10 bit or greater you have a lot of data whichever curve you use, so in practice it will be rare to see any difference in the final result.

So use the curve you find easiest to work with. It is true that S-Log 3 allocates a little more data to the shadows and less to the highlights than S-Log2, but don’t confuse data and code values with more range. S-Log3 has a few extra code values in it’s darkest stops, S-log2 has a few extra in the bright stops, but the dynamic range, highlight and shadow handling is governed by the sensor not the gamma curve. Overall S-Log3 has fewer code values than S-Log2, S-Log2  makes better use of the data available, but with 10 bit this really isn’t going to make a huge difference.

8 Bit Recording.

But if you are only recording with an 8 bit codec you are already at a disadvantage. When recording 8 bit you really need to maximise the way what little data you have is used. For that reason I will always recommend that S-Log2 is used when recording 8 bit on a camera like the FS5 in UHD or A7s or similar (FS5 is 10 bit in HD). By using S-Log2 you are using as many of the limited code values available as you can. This doesn’t mean you can’t use S-log3, it just wouldn’t be my choice.

The end result should be the same.

At the end of the day, if you were to use matching LUTs, S-log2 and S-log3 material should look more or less exactly the same after grading or application of the LUT, no matter what the scene you are shooting. If they do look significantly different then you are doing something wrong. So your choice of curve, other than for 8 bit recordings will most likely come down to ease of use rather than anything else.

If your camera doesn’t have LUT’s then S-Log2 can be easier to work with as it is more contrasty. This makes it a bit easier to focus and also makes it easier to gauge exposure. If your camera has LUT’s and you use them, then you may decide to use S-Log3 simply because you should find it a little easier to work with in post. Either way both curves capture the same range of picture information and both should give more or less the same end result.

There may be some very, very subtle differences due to the small differences in data distribution, but often these will be hard to really see in the final image.

21 thoughts on “The great S-Log2 or S-Log3 debate.”

  1. Hallo Mr. Alister, personal i have a FS5..i use this for wedding film.I never use S-log,i want to test,winch settings S-LOG is better to get nice color.Not too excessive.


  2. Hello Sir Alister, i got my fs7 last week, I had been researching a lot for a month before it, shot three episodes of a telefilm. Your tutorials were very helpful, I experimented with slog3 and hypergammas for low light situations, stayed away from slog2, avoided it on my a6300 as well, found it difficult to grade compared to slog3.
    I am very happy with the results of slog3 in daylight, it can be summed up for everyone as : ‘Don’t shoot in slog3 for low light situations, you won’t be able to fill up the light lux/overexpose it ‘ , Use hypergammas but again you will suffer ‘creative grading control because of the baked look’
    For daylight slog3 works very well, even with Premiere’s built in Arri Luts or even with BertLUT ArriLook 709 for Sony FS7 .

  3. dear Alistar,
    best wishes for the new year ahead.
    regarding slog2 and s gamut, sony cameras offer a number of extra settings under picture profile 7. any use to tweak these. p.e. I have tuned down sharpening, but there are many more settings to tweak.

    any recommendations?

    I guess using slog2/s gamut is paired with luts to use. I have been testing you 1 and 2 over luts. so any relation to pre setting the profile and lits to use in post, p.e. to minimizes grading time.


  4. Greetings sir! I commonly use picture profile 9 on my a7sii but i switch slog2 for slog 3. So I have essentially a slog2/sgamut3 mix. I havent had any problems with it so far, but I’m interested in your thoughts on the matter.

    Thanks for your feedback!


    1. You can mix and match anything you want and if it works for you then great. But you won’t find LUT’s that will give the correct color/contrast with that combo unless you make your own, so you will need to manually grade

  5. Dear Allister,
    Is there a LUT that I can place in Premiere Pro CC 2017 so I can shoot in S-log 2 (or 3) and have the same result as if I should have used the REC 709, but then with more detailed highlight and shadows?
    The most LUTs I have downloaded don’t give the same colorfull image in comparising with the REC 709.
    Thanks for your advice.

    Best regards,

    1. The short answer is no because you are constrained by the limitations of 709 and 709 displays. You only have a limited display range and you can’t magically make that bigger with a LUT or any other 709 workflow.The best you can ever really hope for is the same range as 709. You can have more highlight info if you make the rest of the picture darker to make some more space at the top, but you can’t just cram more and more into the same space without it getting flatter and flatter as you squeeze levels that should really be a long way apart closer together.

  6. Hello Alister,

    Thanks for the great articles, you rock !

    The new sony A7 III has a dynamic range of 14.6 stops but remains an 8 bit camera. As it goes over 14 stops, would you recommend using Slog3 over Slog2 with this camera ?

    Also, if, still with an 8 bit camera, you capture night scenes featuring low lit areas and bright urban lights in the same shot. Do you confirm that Slog3, with its better shadow contrast and, its brighter mid-tone, and its extended dynamic range in highlights, would give better results for such a job ?

    1. It’s only 14.6 stops in photo mode, it’s only 14 stops in video mode.

      S-Log2 and S-Log3 both have identical highlight and shadow ranges, capture identical contrast ranges, there is no difference. It is an incorrect internet myth that they capture different ranges, look at the charts, both are the same. The data levels used are slightly different, but that will not make much difference in low light as both will be equally under exposed and equally noisy.

  7. Was just handed an A7s and I’m shooting a paid gig with it tomorrow, never having used one.

    This article told me exactly what I wanted to know (assuming it’s accurate). Good job, and thanks for posting.

  8. Good article. Could you please explain what you mean by “matching LUTS” ?
    Do you mean to say that if I have clipped S-Log3 footage that is heavily clipped at 93 IRE, with a “matching LUT” I can make it look exactly like S-Log 2 footage?

    What LUT would I use for that?

    Thank you.

    1. 93IRE is S-Log3 is not “heavily clipped”. 93 IRE is +6 stops above middle grey, the limit of the sensors performance. When you record S-Log2 the very same +6 stops from middle grey is recorded at 105 IRE. They are just different code values used by the different curves. Use a pair of LUT’s designed to give the same final result, one for S-Log2 and one for S-log3, shoot the same scene, apply the appropriate LUT and the end result will look more or less exactly the same.

  9. Hello Alister,
    Your resources on Sony cameras are incredible. Can you tell me why Sony caps Slog3 to 94 IRE? Why not use the bits above and all the way to 109? Is some data being hidden there? Also why do most gamma curve profiles outside of standard gammas have a black pedestal above 0 (2 or 3% depending on cine or log)

    With an 8-bit camera I need every value I can possibly spread my data out to. Even if these lower values are normally reserved for the deepest blacks, I don’t know why they aren’t assigned – why waste values? Is there some logic to this?

    1. Because S-Log3 is based on the industry standard Cineon log curve (as is Panasonic V-Log, Canons C-Log and Arri’s Log-C). When the first S-Log2 cameras were released colourists complained that it was too different from Cineon and that they didn’t like it (even though S-Log2 is much better optimised). So Sony produced a Cineon based curve. Cineon can capture upto around 18 stops, but because most video cameras can only capture 14 – 15 stops they only ever use part of the available recording range. The Arri cameras are the same.

      1. Thank you for the reply. Is there a reason why the black level is lifted on most gamma curves? Why am I unable to use or assign the lower bit values for use in post, if I can extend to full range over legal then why have this limitation? For cine gamma I can drop the black level (as you have suggested before) but for log or 800% curves I cannot, and do not understand why.

        1. Why would you even want to lower the bottom of a log curve? The whole point of log curves is to have a standard curve using set in stone values so that the post production software knows exactly what value represents what brightness. That way colour management, colour transformations, LUT’s etc all work as expected. If you look at the actual file from the camera you will find that code value 64(16) is used for black. This is the value used by all log curves and the values below this are used for sync data.

          When you change the black level of the cinegammas the lowest it will ever go is code value 64(16). Go below this and your blacks are clipped at CV64(16).

          1. Thank you for your reply. You’re right, below 16 is never used on these files. Are these black values different for standard gamma recordings? My waveforms show values down to zero on Rec709 recordings (itu709 or movie) but the cinegamma recordings show values starting at 16. I used LUTCalc to create a corrective lut to transform this gamma. Do you use LUTs for cinegamma recordings? I’ve gone through your LUTS extensively (they are my favorite to use) but I can only find Slog gamma luts.

          2. CV16 is the standard black value for 709 too. The issue tends to be software incorrectly handling the files, especially if recorded on an external recorder.

        1. Yes, S-log2 is better optimised for 10 bit. If you are using 16 bit raw on an F5/F55 etc then the choice of gamma curve makes no difference to the linear recordings.

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