Using different gamuts when shooting raw with the PXW-FS5

This topic comes up a lot. Whenever I have been in discussion with those that should know within Sony they have made it clear that the FS-Raw system is designed around S-Log2 for monitoring and post production etc. This stems from the fact that FS-Raw, the 12 bit linear raw from the FS700, FS7 and FS5 was first developed for the FS700 and that camera only had SGamut and S-Log2. S-Log3 didn’t come until a little later.

The idea is that if the camera is set to SGamut + S-Log2 it is optimised for the best possible performance. The raw signal is then passed to the raw recorder where it will be recorded. For a raw recorder that is going to convert the raw to ProRes or DNxHD the recorder converts the raw to S-SGamut + Log2 so that it will match any internal recordings.

Finally in post the grading software would take the FS-Raw and convert it to SGamut + S-Log2 for further grading. By keeping everything as SGamut and S-Log2 throughout the workflow your brightness levels, the look of the image and any LUT’s that you might use will be the same. Internal and external recordings will look the same. And this has been my experience. Use PP7 with SGamut and S-Log2 and the workflow works as expected.

What about the other Gamuts?

However: The FS5 also has SGamut3, SGamut3.cine and S-Log3 available in the picture profiles. When shooting Log many people prefer S-Log3 and SGamut3.cine. Some people find it easier to grade S-Log3 and there are more LUT’s available for S-Log3/SGamut3.cine than for SGamut and S-Log2. So there are many people that like to use PP8 or PP9 for internal S-Log.

However, switching the FS5’s gamma from S-log2 to S-log3 makes no difference to the raw output. And it won’t make your recorder convert the raw to ProRes/DNxHD as S-Log3 if that’s what you are hoping for. But changing the gamut does have an effect on the colors in the image.

But shouldn’t raw be just raw sensor data?

For me this is interesting, because if the camera is recording the raw sensor output, changing the Gamut shouldn’t really change what’s in the raw recording. So the fact that the image changes when you change the Gamut tells me that the camera is doing some form of processing or gain/gamma adjustment to the signal coming from the sensor. So to try and figure out what is happening and whether you should still always stick to SGamut I decided to do a little bit of testing. The testing was only done on an FS5 so the results are only applicable to the FS5. I can’t recall seeing these same changes with the FS7.

DSC Labs Chroma Tru Test Chart.

For the tests I used a DSC Labs Chroma-tru chart as this allows you to see how the colors and contrast in what you record changes both visually and with a vectorscope/waveform. As well as the chart that you shoot, you download a matching reference overlay file that you can superimpose over the clip in post to visually see any differences between the reference overlay and the way the shot has been captured and decoded. It is also possible to place another small reference chart directly in front of the monitor screen if you need to evaluate the monitor or any other aspects of your full end to end production system. It’s a very clever system and I like it because as well as being able to measure differences with scopes you can also see any differences quite clearly without any sophisticated measuring equipment.

Test workflow:

The chart was illuminated with a mix of mostly real daylight and a bit of 5600K daylight balanced light from a Stella LED lamp. I wanted a lot of real daylight to minimise any errors that could creep in from the spectrum of the LED light (The Stellas are very good but you can’t beat real daylight). The camera was set to 2000 ISO. The raw signal was passed from the camera to an Atomos Shogun Inferno where the clips were recorded as both ProRes Raw and also by using the recorders built in conversion to S-Log2 for internal recording as ProRes HQ. I did one pass of correctly exposed clips and a second pass where the clips were under exposed by 1 stop to asses noise levels. The lens was the 18-105mm kit lens, which without the cameras built in lens compensation does show a fair bit of barrel distortion as you will see!

The ProRes clips were evaluated in DaVinci Resolve using the DaVinci Color Managed workflow with the input colorspace set to S-Log2/Sgamut for every clip and output colorspace set to 709. I also had to set the input range of the ProRes clips to Full Range as this is what S-Log2 files always are. If I didn’t change the input range to Full Range the clips exhibited clipped and crushed black after conversion to 709, this confirms that the clips recorded by the Shogun were Full Range – which follows the S-Log specifications.

I did also take a look at the clips in Adobe Premiere and saw very similar results to Resolve.

I will do a separate report on my findings with the ProRes Raw in FCP as soon as I get time to check out the ProRes raw files properly.

So, what did I find?

In the images below the reference file has been overlaid on the very center of the clip. It can be a little hard to see. In a perfect system it would be impossible to see. But you can never capture the full contrast of the chart 1:1 and all cameras exhibit some color response imperfections. But the closer the center overlay is to the captured chart, the more accurate the system is. Note you can click on any of the capture examples to view a larger version.

Digi-ChromaMatch-Lt Using different gamuts when shooting raw with the PXW-FS5
This is the reference file (by the time it gets posted on my website as a jpeg I would no longer guarantee the colors etc. But when you look at the images below you will see this superimposed over the center of the clips.

Below is Picture Profile 6 (PP6) SGamut with S-Log2. It’s pretty good match. The camera didn’t quite capture the full contrast of the chart and that’s to be expected, reflections etc make it very difficult to get perfect blacks and shadow areas. But color wise it looks quite reasonable although the light blue’s are a little weak/pink.

SGamut_1.1.1 Using different gamuts when shooting raw with the PXW-FS5
SGamut and S-Log2

Below is Picture Profile 7 (PP7) SGamut3 with S-Log3. Straight away we can see that even though the camera was set to S-log3, the contrast is the same in the S-Log2 color managed workflow proving that the gamma of the recording is actually ProRes recording from the Shogun is S-log2, confirming what we already know which is that changing the log curve in the camera makes no difference to the raw recording and no difference to the raw to ProRes conversion in the recorder.

Note the extra noise in the greens. The greens appear to have more color, but they also appear a little darker. If you reduce the brightness of a color without altering the saturation the color appears to be deeper and I think that is what is happening here, it is a lightness change rather than just a saturation change. There is also more noise in the darker bars, grey and black really are quite noisy. Light blues have the same weak/pink appearance and there is a distinct green tint to the white, grey and black bars.

SGamut32_1.5.1 Using different gamuts when shooting raw with the PXW-FS5
SGamut3 with S-Log3

Below is when the camera was set to SGamut3.cine with S-Log3. Again we can see that the recording gamma is obviously S-Log2. The greens are still a touch stronger looking but now there is less noise in the greens. Cyan and reds are slightly lighter than SGamut and yellows appear a bit darker. This is also a little more noisy overall than SGamut, but not as bad as SGamut3. When you play the 3 clips, overall SGamut has the least noise, SGamut3.cine is next and then SGamut3 is clearly the noisiest. As with SGamut there is a distinct green tint to the white, grey and black bars.

SGamut3cine2_1.6.1 Using different gamuts when shooting raw with the PXW-FS5
SGamut3.cine with S-Log3

So that’s what the images look like, what do the scopes tell us. Again I will start with SGamut and we can see that the color response is pretty accurate. This suggests that Atomos do a good job of converting the raw to S-Log2/SGamut before it’s recorded and confirms what we already know which is this is that this is clearly how the system is designed to work. Note how the Red strip falls very close to the R box on the 2x vectorscope, yello almost in Y, green very close to G, Blue almost in B. Magenta isn’t so clever and this probably explains why the pinky blues at the top of the chart are not quite right. Do remember that all these test were done with the preset white balance so it’s not surprising to see some small offsets as the white balance won’t have been absolutely perfect. But that imperfection will be the same across all of my test examples.

Screenshot-2019-03-06-at-12.23.31 Using different gamuts when shooting raw with the PXW-FS5
SGamut + S-Log2

Below is SGamut3. The first thing I noticed was all the extra noise on the right side of the waveform where the greens are. The waveform also shows the difference in lightness compared to SGamut with different colors being reproduced at different brightness levels. The greens are being reproduced at a slightly lower luma level and this is probably why the greens appear more saturated. Also notice how much more fuzzy the vectorscope is, this is due to some extra chroma noise. There is a bit more red and magenta is closer to it’s target box, but all the other key colors are further from their boxes. Yellow and Green and Cyan are all a long way from their target boxes. Overall the color is much less accurate than SGamut and there is more chroma noise.

Screenshot-2019-03-06-at-12.23.53 Using different gamuts when shooting raw with the PXW-FS5

And finally below is SGamut3.cine. There is less noise on the green side of the waveform than SGamut and SGamut3 but we still have a slightly lower luma level for green, making green appear more saturated. Again overall color accuracy is not as good as SGamut. But the vector scope is still quite fuzzy due to chroma noise.

Screenshot-2019-03-06-at-12.24.24 Using different gamuts when shooting raw with the PXW-FS5

Under Exposure:

I just want to show you a couple of under exposed examples. These have had the under exposure corrected in post. Below is SGamut and as you can see it is a bit noisy when under exposed. That shouldn’t be a surprise, under expose and you will get noisy pictures.

SGamut_1.1.1-1 Using different gamuts when shooting raw with the PXW-FS5
SGamut with S-Log2 1 stop under (exposure corrected in post)

Below is SGamut3 and you can really see how much noisier this is than SGamut. I recommend clicking on the images to see a full screen version. You will see that as well as the noise in the greens there is more chroma noise in the blacks and greys. There also seems to be a stronger shift towards blue/green in the whites/greys in the under exposed SGamut3.

SGamut3_1.2.1 Using different gamuts when shooting raw with the PXW-FS5
SGamut3 with S-Log3 1 stop under (exposure corrected in post)

Conclusions:

Clearly changing the gamut makes a difference to the raw output signal. In theory this shouldn’t really happen. Raw is supposed to be the unprocessed sensor output. But these test show that there is a fair bit of processing going on in the FS5 before the raw is output. It’s already known that the white balance is baked in. This is quite easy to do as changing the white balance is largely just a matter of changing the gain on the pixels that represent red and blue relative to green. This can be done before the image is converted to a color image.

What I believe I am seeing in this test is something more complex than that. I’m seeing changes in the luminance and gain levels of different colors relative to each other. So what I suspect is happening is that the camera is making some independent adjustments to the gamma of the Red, Blue and Green pixels before the raw signal is output. This is probably a hang over from adjustments that need to be made when recording S-Log2 and S-Log3 internally rather than something being done to deliberately adjust the raw output. But I didn’t design the camera so I can’t be sure that this is really the case. Only Sony would know the truth.

Does it matter?

Yes and no. If you have been using SGamut3.cine and have been getting the results you want, then, no it doesn’t really matter. I would probably avoid SGamut3. It really is very noisy in the greens and shadows compared to the other two. I would be a little concerned by the green tint in the parts of the image that should be colour free in both SGamut3 and SGamut3.cine. That would make grading a little tougher than it should be.

So my advice remains unchanged and continues to match Sony’s recommendation. This is that you should use PP7 with SGamut and S-Log2 when outputting raw. That doesn’t mean you can’t use the other Gamuts and your milage may vary, but these tests do for me at least confirm my reasons for sticking with PP7.

Both Premiere and Resolve show the same behaviour. Next I want to take a look at what happens in FCP with the ProRes Raw clips. This could prove interesting as FCP decodes and converts the FS-Raw to S-Log3 and SGamut3.cine rather than S-Log2/Sgamut by default. Whether this will make any difference I don’t know. What I do know is that having a recorder that’s converting to S-Log2 for display and software that converts to S-Log3 is very confusing as you need different LUT’s for post and the recorder if you want to use LUT’s for your monitoring. But FCP will have to wait for another day. I have paying work to do first.

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26 thoughts on “Using different gamuts when shooting raw with the PXW-FS5”

  1. I was actually thinking about this topic last night!

    I know Sony recommends PP7/S-Log2/S-Gamut (when recording raw to an external recorder), but was wondering if it made a difference if I chose PP8 instead, or even PP7 and change the gamut to SGamut3.cine? So may options! So many questions.

    Thank you for clearing much of this up.

  2. I think on the F55 with 16 bit raw, where your output choice is SLog2/sgamut, Slog3/sgamut3 or sgamut3.cine, it’s not recording the raw sensor data differently, it’s just recording different metadata. And Resolve will use the metadata to display what you were monitoring, or allow you to change to the other intent.

    1. On the F5/F55 there is no change to what is recorded. I don’t think there is with the FS7 either. This is I am pretty certain a peculiarity of the FS5 and it’s odd combination of the FS700 front end with A7S processing.

      On the FS5 the data is actually changing.

  3. You mention working in Premiere with RAW. I thought that wasn’t possible as Premiere hasn’t licensed the codec with Apple yet. Is there something I’m missing? I’d love to explore RAW options with the Fs5ii but being that I use Adobe Premiere I have been holding off…. Suggestions?

    1. In these tests the raw was converted to ProRes in the recorder. You can use cDNG raw in Premiere but that workflow is a real pain and not one I would recommend.

      1. Would you recommend I switch to final cut in order to play around with 16 bit Proress RAW files? I would still have to invest in SSD’s that are fast enough and a bit more storage but the thought of getting that much out of the camera is pretty intriguing. SO far I am very happy using the PP1 Venice profile. Thanks for all your wisdom and awesome articles!

  4. Question: Will the data from my FS5 ii output 4k data in 10-bit if I send via SDI to Inferno Shogun (recording at ProRes422 HQ) using PP1? Or does it output to the recorder at only 8-bit if I’m not using anything other than slog2/slog3?

    I’m interested in using the “Venice profile” for quick turn around with some leeway in post.

    I know Sony recommends slog2/sgamut which is what has me a little confused.

    Much appreciated to anyone who can clear that up.

  5. Alister,

    I noticed this as well a while back and did some tests and noticed that when changing the PP when using the FS5 with a Shogun inferno, the gamma never changed when I switched from PP7 to PP8. But that confused me because you always recommended staying on PP7 when outputing RAW yet Atomos advertised on their website that the Shogun could capture both SLOG2 and SLOG3 from the FS5 when shooting RAW.

    I went ahead and called Atomos to figure out what was going on behind the scenes and after a long phone call, it was revealed to me that the Atomos Shogun Inferno will add a specific gamma curve depending on what you have selected for monitoring under the AtomHDR tab on the recorder. So if you have it on SLOG2, Sgamut, it will record those curves. If you select SLOG3, Sgamut3.cine, it will apply that curve to the data REGARDLESS what what PP gamma is selected in camera.

    This was tons of news to me. I wish there was a way to apply a Cine4 curve to the footage for scenes that don’t require lots of dynamic range.

    1. Sorry but that’s incorrect. If you are recording raw, you are recording raw. Sony’s 12 bit linear raw does not have a gamma curve and nothing you change on the recorder will ever change that. The AtomHDR function is a monitoring function and it only affects the monitoring. I wish people would understand that raw is raw and is not affected by gamma curves in the same way as conventional recordings. The gamma curve is added in post production after the raw data has been decoded into a colour image.

      1. Sorry, I didn’t explain myself well enough. When I said RAW, I meant when you’re recording RAW off the sensor but having the Atomos save it to ProRes. So bypassing internal compression of the camera and using a ProRes flavor instead.

        I understand ProRes RAW and CDNG is straight camera data that needs to be debayered to be viewed and a curve can be applied later.

        But what I said previously only stands if you’re doing RAW to ProRes off the Atomos. When shooting, the Atomos will take the RAW sensor read out and save it to a ProRes file with the gamma curve that is selected in the AtomHDR tab.

        Sorry about that misunderstand, it’s super hard to communicate with all these terms!

        To recreate what I’m saying, choose ProRes acquisition on the Atomos and set the FS5 PP to 7 or 8. Then, record one shot with the AtomHDR set to SLOG2, SGamut and then another shot with AtomHDR set to SLOG3, Sgamut3.cine. The files will have different curves applied to them.

        This was surprising to me because like you said, I assumed the AtomHDR tab was strictly for monitoring and had no affect on footage. Again, this is what Atomos told me when I called them.

        1. But I am certain the Shogun always converts to S-Log2 regardless of the atom HDR settings. This has been my experience and this is how the system is designed to work. If you look at the scopes on the shogun, which show the recording levels, the levels shown are always S-Log2 and the never change no matter which Atom HDR settings you choose.

          1. That’s the impression I was under too but Atomos told me that the AtomHDR has a direct impact on what curve is applied to the footage. After doing tests, it seems to be correct. After comparing internal SLOG2 and 3 with AtomHDR’s SLOG2 and 3, there is a change in the footage gamma curve when I switch the AtomHDR selections. This is definitely something that Atomos needs to be more clear about because it doesn’t state that in the manual. If you do the test I mentioned before, you’ll see the same results.

            It’s really weird. I guess that’s Atomos’s way of allowing the user to choose which curve it applies to the raw data before saving it to ProRes.

  6. The FS700 does not have s-gamut. I’ve looked in my PP7 with slog2 set and the color mode section does not include the s-gamut option. Am I missing something here? I have the FS700R with the 4K upgrade.

    1. This is one of the peculiarities of the FS700 and FS700R. S-Log2 gamma was added as a way to monitor the full dynamic range of the camera when shooting raw. It was not intended to be recorded due to the cameras very limited 8 bit internal codec. So it’s just there for monitoring purposes and is combined with normal color as SGamut would be extremely flat and washed out.

      1. Is it fair to say though, that since( at least in theory) the camera RAW out circumvents the settings, it actually will be recorded in s-gamut in the Atomos inferno? The atomos ProRes file that I have pairs excellently with your and many other Slog2 LUTS.

        1. No recording raw does not circumvent the camera settings, which is what this test is all about. It shows how using anything other than the recommended S-Log2/S-Gamut results in unexpected results. If your recording raw, you are recording raw not S-Gamut. The computer decodes it to S-Gamut.

          1. I get that, but if the FS700 doesn’t have s-gamut setting, then what is recorded into the Atomos? Does the Atomos take the SDI-Raw in and record in S-gamut anyway (even if there’s no setting option for that on the FS700)?

            I also understand that when we record proRes Raw that the computer does the decoding. I’m talking about RAW signal out and recorded into ProRes (plain Jane) into Atomos.

            Thanks for taking the time, Allister. I know you’re a busy man.

  7. Alister, I hope you can help me: FS5 Raw ->ProRes (Slog2, 7Q+, Davinci Resolve) The colors of the ProRes are totally different to the Raw files. I checked everything on the net. The raw files get the convergent design FS5 Raw to Slog2 Correcttion applied before I ads the standard lut. The ProRes go directly into the Standard LUT. Then different colors… On the website they write that you also have to convert the prores from the 7q into normal slog2 but the article is old and the prores correction luts (FS5_EE_5500K_RPR_FIX_RESOLVE.cube) are not available any more… any idea? Thank you so much…

  8. Hi Alister, When I use the Odyssey 7Q+ and record RAW-RAW DNG, the waveform values in the Odyssey sit at a completely different level to those in Premiere Pro.
    Example, I exposed a grey card at around 43% using the Odyssey’s internal waveform, and then when I put the same clip into Premiere, the waveform stated it was at about 27% and the image was much darker and slightly underexposed.

    Any idea whey this happens? I’m using S-Log2 S.Gamut as the protocol, and leaving the ISO at its base 2000 level.
    I view the image as S-Log on the Odyssey ( and sometimes enable a Lut when checking focus), but I always shoot at least 1 stop above Sony’s recommended log values.
    This monitoring issue means I can never really shoot RAW-RAW and no matter what monitoring guide i use, the end result is always darer than I expected.
    In contrast, RAW-ProRes works without any issues and always provides an accurate waveform reading.

  9. Also changing the iso on the Fs5 changes the raw files. It is not the same as put gain on the lower iso clip to match the High iso clip. The high iso recording has a lot less noise… so there must be some sort of raw denoising in camera… crazy I thought it is RAW…you can easily test it… done in Davinci Resolve… crazy enough there is not iso switch on raw recordings in cdng. Done with the 7q.
    And still trying to match raw to prores recordings to raw recordings… nearly impossible. Don’t know wat the 7q does with the prores. The raw Looks incredible…btw… really really incredibly…

    1. It’s always been known that changing the cameras gain settings alters the raw output. Using anything but the native ISO also restricts the dynamic range.

  10. Hi,

    On the sony A7III you can use the picture profiles to capture raw stills, exported as tiffs using Sony’s imaging edge raw processing software with log curve and gamut baked in. I’m unable to get an accurate color reproduction shooting a macbeth chart under daylight when compared to a reference chart values. I’m using Slog2/sgamut( PP7), Slog3/Sgamut3(PP8) or slog3/Sgamut_cine (PP9) and the sony’s provided luts for rec709 display in Nuke ( VFX comp application ). I’ve also tried resolve using the various slog input color spaces to rec709 output. Have you any experience/success with picture profiles with stills on the A7 line?

  11. Hi Alister,

    Would it be ridiculous to use the cine3 gamma when outputting RAW? The Shogun Inferno will be converting it on the fly to ProRes HQ – for 10-bit 422. I’ll be shooting a film at night throughout the autumn so I want to get the most colour information but I don’t want to shoot RAW because of the significant media storage demands, especially for a feature-length project.

    1. Using anything other than S-Log2 screws up the raw output, makes it noisier than it should be and can result in strange colours.

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