Are S-LOGS More Destructive Than They're Worth?

[maxotics]

1 hour ago, cantsin said:

But the simple truth is that you need extended dynamic range (and thus more than standard Rec709 capture) to record an image like this (where Rec709 may be the display color sapce):

...unless you use an incredible amount of reflectors and on-set lights as Sergio Leone's DP probably did for this scene. (In addition to using negative film stock with its much extended dynamic range over reversal/positive film. It also helps to think of Log video as an equivalent of negative stock and of Rec709 capture as the equivalent of reversal film.)

Today, we can capture such scenes without artificial light thanks to the high dynamic range of modern cameras. But if the above picture would have been shot with an in-camera Rec709 profile, the house front would be black, the sky would be white and Charles Bronson's face would likely be unrecognizable. 

So this is why we need Log (if we don't use Raw capture) - even if we end up displaying the image as an 8bit Rec709 or RGB in 8 stops of dynamic display range as above. And images like the above, without cut-off shadows or clipping highlights, are exactly what we associate with cinema-quality images as opposed to the classical video camera look.

Everything you say it right.  It's important information to know for a filmmaker.  However, when you post such things it suggests to some people that the issue I'm raising is not valid.  So why get off-topic like this?  How many times do I have to ask the question?  In a scene of DR NOT OUTSIDE THE CAMERA'S default settings what is the DIFFERENCE in quality between Rec709, say, and a LOG capture?  Have I ever once, in this post, talked about how to use LOG in physical scenes of extended dynamic range?  That's a subject covered in excruciating detail all over the internet. 

[cantsin]

33 minutes ago, maxotics said:

In a scene of DR NOT OUTSIDE THE CAMERA'S default settings what is the DIFFERENCE in quality between Rec709, say, and a LOG capture? 

None. But scenes with only 7-8 stops dynamic range hardly exist in real life (not even indoors if you film a living room with a desk lamp on), only in studio settings where you light for 7-8 stops. 

In all other situations, you get clipping highlights and/or drowned shadows. Given that EOSHD consists of perhaps 90% filmmakers who never or rarely shoot in studio light, the limitations of Rec709 are a fact. In former (camcorder) times, it simply meant that run-and-gun video filmmakers had no choice but put up with the "video look" of crushed shadows and clipping highlights.

Let me also quote your initial posting:

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8-bit video captures roughly 16 million color values

Human vision is around 12 million (but let's call it 16 million)

Human vision, is around 5-7 stops of dynamic range (without pupil change)

CONCLUSION ONE: 8-bit color can deliver a complete color representation to a human; that is 16 million colors over a 6-stop gamut, let's say.  

Yes, but your conclusion only talks about display color, not scene color. It leaves out the fact that 8-bit Rec709 color and 7 stops of dynamic cannot deliver a complete representation of a scene. You make one fundamental mistake here: The human eye, because it's wired to the brain, does not see like a camera, so - sorry to be harsh - all our 8bit and 7 stops arithmetic is meaningless. When we look outside the window and see a street or a landscape, which typically has dynamic range of 14-20 stops in daylight, we do not see clipped highlights and drowned shadows, because our eye roams and adapts, and our brain creates a composite image.

So, in order to create a photographic or filmic image that correctly represents a scene, we have to offer the same range of visual information to the eye, and not cut out shadows below and highlights above the 7 stop spectrum./

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In S-LOG, one is widening the dynamic range to 10 stops, let's say, and spreading color information across the fixed 8-bit data space, which means we're losing saturation compared to the 16 million colors over 6 stops?

This assumption is only true for Sony's consumer cameras which, in SLog mode, indeed do what you described above. In the meantime, we have established that SLog2/3 was engineered for cameras that record in high-bitrate 10bit codecs.

 

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Compounding the above's theoretical question, a sensor becomes noisy or erratic a few stops above and below a range where is can accurately do #4;  Therefore, doesn't one trade 16 million colors of better saturation for few colors and noise? (that's my finding after doing some experiments).

Yes, one does, but the only solution to that is to shoot in perfect studio light like Hollywood from the 1930s to the 1960s - and not shoot documentary, and not shoot in the cinematography established with the Nouvelle Vague and New Hollywood. 

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My current conclusion is S-LOG is not really about dynamic range, 

 

As said, it is - it is about capturing the dynamic range of a scene as good as possible.

Max, with all due respect and whatever you tried to get across - your initial postings did not make a clear differentiation between scene dynamic range and display dynamic range, between Sony's S-Log and other log curves, and between Sony's S-Log in the 8bit consumer cameras vs. the 10bit pro cameras.

[maxotics]

1 minute ago, cantsin said:

 

1 minute ago, cantsin said:

Max, with all due respect and whatever you tried to get across - your initial postings did not make a clear differentiation between scene dynamic range and display dynamic range, between Sony's S-Log and other log curves, and between Sony's S-Log in the 8bit consumer cameras vs. the 10bit pro cameras.

Cantsin, you're not giving me any respect.  One can poke holes in anyone's question.  You're not working with this post,  you're working against it.   Instead of addressing the core issue I brought up, you keep lecturing me as if I'm some newbie film student about DR in the real world, the eye, all stuff I've studied in some depth and have decided are not relevant to this question.  Your bringing them up 50 times doesn't convince me, sorry.  

FOR ALL THOSE READING THIS, PLEASE READ THIS:

In video, LOG allows you to capture more dynamic range from the physical world.  For example, point your camera outside on a partly-cloudy day at someone wearing a gray shirt under an umbrella and it will capture both detail in a gray cloud and detail of a person’s gray shirt under the umbrella.  If you take out a light meter and measure the difference in brightness, between the cloud and shirt, you might find a difference of 15 stops between them.  

If you exposed the person with the camera’s default settings, and exposed for their gray shirt, the cloud would be washed-out and not visible.  The reason for that is a camera is configured, from the factory, to record 16 million shades of color between around 5 stops of brightness.  The cloud’s brightness would have been beyond that range.

The drawback of LOG is that it captures less color in the middle tones of the image and it will add noise because the values in the extreme ends of the dynamic range are noisier.  Whether this is acceptable for you is a complex and difficult question to answer.  

What you’re up against is the fixed memory size of your camera. Whether you shoot LOG, or the camera’s default settings, you can only record 24 bits of data, 8 bits for each primary color of red, green and blue.  Your video palette is 16 million colors, whether you use the camera’s default settings or LOG.  That cannot be changed.

A camera’s default settings maximize the quality of image the camera can record that will match the dynamic range of your monitor, cell phone, TV or tablet.  A camera’s default profile, out of the box, is the best image it can get under ideal lighting, whether the camera has LOG or not.

When you shoot LOG, the 16 million color shades you get have a different quality compared to the 16 million shades you get in the camera’s default setting.  So understanding how LOG differs from the camera’s default capture of 16 million shades is what we’re going to discuss today.

When we talk about dynamic range we want to be careful which type of dynamic range we’re dealing with.  There is the dynamic range of your monitor, which really isn’t dynamic at all, but usually fixed with 6 stops of brightness.  Then there is the dynamic range of our physical world, which ranges from absolute darkness to light, so bright, looking at it would blind you.  

If you took philosophy in school, you may remember Plato’s cave.  He used a cave as an analogy to separate what we can study and what we cannot, which are the metaphysical questions.  Similarly, our displays are what we see in our cave.  The physical world can never be shown on our cave wall.  All we can do is record the physical world, best we can on a device, and come back and show it.  

Imagine that your viewers are people who have never left the cave.  All they see are what we show on the wall, or their display.  If that display only has 6 stops of dynamic range what would it mean for them if we say to them “our video recorded 12 stops of dynamic range”?  If you think about this for a few minutes you will have that “ah-ha’ moment.   If you keep trying to explain to them was the 12 stops means, at some point they’ll say “All I see are 6 stops, if you say your video has 12 stops well, that’s too metaphysical for me, dude!  You need another beer.”

I don’t want to study what a camera can record in metaphysical sense, but what it can do in the practical world of display technology.  I need some images to show on it which do everything it is capable of.  To do this, I have acquired images with all 16 million colors we have our in a 24-bit color space.  Because the monitor can only display 2 million at a time, I have to break them up into separate images and assemble those into a video that will show all colors when played in its entirety.

What I want to do is quantify the palette of colors that are captured using various camera settings within our viewer’s real world experience.  Yes, we don’t shoot monitors for our content.  But most scenes, especially indoors, are within 5 stops of dynamic range.  Even outside, in a cloudy day, dynamic range is narrow.  There are DEFINITELY scenes that call for LOG.  However, how should we choose in scenes that could go either way?  Can we acquire data that helps us make a better decision?

[cantsin]

5 minutes ago, maxotics said:

The drawback of LOG is that it captures less color in the middle tones of the image and it will add noise because the values in the extreme ends of the dynamic range are noisier.  Whether this is acceptable for you is a complex and difficult question to answer.  

To cut the whole discussion short: No, it doesn't capture less color in the middle tones if you have a 10bit or 12bit codec (because a 10bit codec captures 4x the color information and a 12bit codec 16x the color information of an 8bit codec). And only with such color bit depth, Log curves like S-Log should be used.

Btw., this discussion is not about respect or feelings, but about facts. (All the more in the Donald Trump age.)

[maxotics]

2 minutes ago, cantsin said:

To cut the whole discussion short: No, it doesn't capture less color in the middle tones if you have 10bit or 12bit codec (because a 10bit codec captures 4x the color information and a 12bit codec 16x the color information of an 8bit codec). And only with such color bit depth, Log curves like S-Log should be used.

On what f-ing camera, Cantsin?  What if I don't have a 10 or 12bit CODEC camera?  Again, you're bring up a theoretical question OUTSIDE the scope of the post.  For a person shooting 8-bit video, what are the trade-offs between the camera's default settings and LOG?

[cantsin]

19 minutes ago, maxotics said:

On what f-ing camera, Cantsin?  

A Blackmagic Micro or Pocket Camera records 10bit Log in ProRes, a GH5 records 10bit Log, even a GH4 and an FZ2000/FZ2500 records 10bit Log with an external recorder. 

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What if I don't have a 10 or 12bit CODEC camera?

We established that indeed, this is a suboptimal if not a bad case. Nobody argues with that. But this is a particular issue of Sony's and GoPro's consumer cameras that squeeze aggressive log curves into 8bit. It's not an issue of Log capture as such.

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 Again, you're bring up a theoretical question OUTSIDE the scope of the post.

No, a very practical issue. Affordable 10bit Log cameras do exist, some are even cheaper than Sony's A6300 and A6500.

The simple conclusion is, and hopefully we can agree on this and rest this dispute: If you use a Sony 8bit consumer/prosumer camera (RX10/RX100, A7x/A9, A6xxx), better avoid sLog. If you use it, reduced color resolution/color banding will be the (sometimes severe) trade-off for capturing a wide dynamic range scene without clipping highlights and drowning shadows, or for achieving postproduction compatibility with Slog footage shot with Sony's 10bit cinema cameras.

But this has been discussed on video forums for a long time (just saying). P.S.: And @Andrew Reid addressed this issue in his own way by developing more visually appealing Rec709 profiles for Sony's con/prosumer cameras.

 

[AndrewM]

27 minutes ago, maxotics said:

Everything you say it right.  It's important information to know for a filmmaker.  However, when you post such things it suggests to some people that the issue I'm raising is not valid.  So why get off-topic like this?  How many times do I have to ask the question?  In a scene of DR NOT OUTSIDE THE CAMERA'S default settings what is the DIFFERENCE in quality between Rec709, say, and a LOG capture?  Have I ever once, in this post, talked about how to use LOG in physical scenes of extended dynamic range?  That's a subject covered in excruciating detail all over the internet. 

So again, maybe I'm missing things, but let me try and focus (for myself, mainly) on what is at issue here... There are a bunch of questions, and I think different people are answering different ones. I'm going to simplify by saying "rec709 scene" to mean a scene with no more dynamic range and colors variation than can be captured by the rec709 spec. In other words, a scene that looks like pointing your camera at your tv or monitor.

Question 1: How often in real world situations do you find yourself shooting a rec709 scene?

My answer: in a controlled studio environment with expert lighting people - yes. Outside, on a really overcast day - maybe. Inside or outside, in "normal" conditions - never.

Question 2: If confronted with a rec709 scene, should you shoot with a rec709 gamma?

My answer(s): yes, if you are really good at your job, because you will get the maximum, densest information possible given your codec etc. No, if you are in a rush, or less than 100% confident in your technical skills, or if you just want to be careful because there are a lot of other people working that day whose work product (or wedding...) depends on you doing things right with no reshoots. If the dynamic range I encode exactly matches the dynamic range of my scene, and I misexpose at all, then I will have clipping at one end or the other. And (in my opinion) clipping is way worse than faint banding. Still photographers, even really good ones, bracket for a reason. Or have gear and raw formats good enough that they have sufficient margin of error so they don't have to.

Question 3: If confronted with a rec709 scene and I shoot with a wider-dynamic range codec, will I end up with a "worse" image?

My answer: duh yes. In some sense, I must. I am spending bits to encode details that don't exist in the image - lots of zeros. I am spreading the ability to discriminate much more thinly over the part of the scene where all the action is. That, mathematically, must have consequences.

Question 4: How much worse?

Worse mathematically does not necessarily mean worse visually - that's why lossy compression, on which the entire existence of digital video depends. And "worse in the real world" is not the same as "visually detectable in a scene with continuous color gradients not found in nature."

I think the goal of the OP is admirable - to try and quantify this. I just see so many variables (per camera, per camera setting, per what differences actually matter) that the task seems next to impossible.

Question 5: Is there something about "consumer" cams (hybrids, still cameras that also take video) vs "professional" cams (dedicated video cameras) that makes a difference here, relevant to the merits of log?

My answer(s): yes and no. If we are talking sensors, there is lots of variation and a lot of reasons why a dedicated video chip might be better, but the bottom line is that any consumer camera that is capable of taking raw images, even sucky raw images, is capable of capturing way, way, way more information than is available in rec709. There haven't been rec709 limited sensors in 40 years.

If we are talking codecs and data limits, then of course. The more data you throw at the scene (given equally efficient codecs) the more discrimination you get. Pro cameras often throw more data at the problem. So the big question is: given current codecs and processing limits, do consumer cams have the data rates to support log shooting? Which gets us to...

Question 6: Should we be shooting log on current 8 bit cameras if we are delivering rec709?

My answer: depends on the camera, the videographer, the colorist, and the project. If people deliver results that are better than otherwise available, then the answer is yes (for that setup and those skills) and if they don't, the answer is no.

[maxotics]

27 minutes ago, cantsin said:

The simple conclusion is...

I'm not questioning your knowledge @cantsin.  I'm questioning where and when you apply it.  I already joke to friends that I didn't understand the simple difference between S-LOG and C-LOG, that they are Sony and Canon.  Just because I'm woefully ignorant there, however, doesn't make me ignorant about how cameras work or what LOG does.  I want your help.  But please, wait your pitch   Then hit it out of the park.  No need to swing at everything   (and yes, I should follow my own advice!)

[cantsin]

4 minutes ago, maxotics said:

I'm not questioning your knowledge @cantsin.  I'm questioning where and when you apply it.  I already joke to friends that I didn't understand the simple difference between S-LOG and C-LOG, that they are Sony and Canon.  Just because I'm woefully ignorant there, however, doesn't make me ignorant about how cameras work or what LOG does.  I want your help.  But please, wait your pitch   Then hit it out of the park.  No need to swing at everything

I think we're completely misunderstanding each other. I'm just trying to drily sum up a few facts, mostly for the people who are reading this thread and using EOSHD as an information resource. This is not about you, and I am not even aware that I'd be swinging at anything.

[cantsin]

Postscript: Max thinks that I am misusing this thread and posting off-topic. So I will quit from here.

[mercer]

Okay, I find this post extremely fascinating, mostly because I am not the most technically knowledgeable person around, so if I am to understand what is being discussed here I would conclude this.

By using Log, a filmmaker can open the dynamic range of a shot more so than using a Rec709 profile.

By doing so, the filmmaker is risking losing color information because the image data is stretched so thin due to the Log curve.

But by using Log, the filmmaker gets to choose in post what details they would like that information to be used for, where as with a Rec709 profile, your dynamic range choice will be more limited, but you will have more color information within the available stops of dynamic range?

Max is trying to conclude what is lost where with dynamic range and color information, with Log compared to Rec709, to decide how to go forward with a Rec709 color space to get the maximum dynamic range and color information visible on a Rec709 monitor.

Assuming I am following this correctly, it would seem, from reading this post, Max has already concluded his thesis and has put into consideration all of the variables discussed and decided which are relevant to his findings.

But still has questions regarding the color information gain with Rec709 vs the Dynamic Range gain with Log.

Am I following this correctly? And if so, isn't it nearly impossible to empirically quantify that information without taking into account the endless variables that may be present in a specific shot that's vital to a specific scene?

[mercer]

To add, from reading Max's posts over they years, I have a sneaking suspicion, Max has developed an app that will inform the filmmaker exactly when to use either sLog2/3 or Rec709 for maximum gain with any given shot.

[maxotics]

29 minutes ago, mercer said:

Okay, I find this post extremely fascinating, mostly because I am not the most technically knowledgeable person around, so if I am to understand what is being discussed here I would conclude this.

By using Log, a filmmaker can open the dynamic range of a shot more so than using a Rec709 profile.

By doing so, the filmmaker is risking losing color information because the image data is stretched so thin due to the Log curve.

Only if shooting in a scene that would best fit a Rec709 profile.

30 minutes ago, mercer said:

But by using Log, the filmmaker gets to choose in post what details they would like that information to be used for, where as with a Rec709 profile, your dynamic range choice will be more limited, but you will have more color information within the available stops of dynamic range?

Max is trying to conclude what is lost where with dynamic range and color information, with Log compared to Rec709, to decide how to go forward with a Rec709 color space to get the maximum dynamic range and color information visible on a Rec709 monitor.

Assuming I am following this correctly, it would seem, from reading this post, Max has already concluded his thesis and has put into consideration all of the variables discussed and decided which are relevant to his findings.

No, I haven't concluded anything!  Based on some initial tests against 1 million sample colors it looks like LOG loses about 35% color in a Rec709 case.  I am posting here for people to help me get to the bottom of this.  I posted another quick test looking at "banding" which would be expected IF LOG lost 35% of color in a Rec709 case.  

 

32 minutes ago, mercer said:

But still has questions regarding the color information gain with Rec709 vs the Dynamic Range gain with Log.

Am I following this correctly? And if so, isn't it nearly impossible to empirically quantify that information without taking into account the endless variables that may be present in a specific shot that's vital to a specific scene?

Do any of you go out and buy a camera because the guy at the store says it captures the best image IF you know how to grade it?  Of course not.  Everyone here tests their cameras, looks for new techniques to get better images.  That's all I'm doing.  My acid test would be, after all the work is done, someone like @Oliver Daniel would say, "that's useful information to keep in mind"

[EthanAlexander]

2 hours ago, maxotics said:

The drawback of LOG is that it captures less color in the middle tones of the image and it will add noise because the values in the extreme ends of the dynamic range are noisier.  Whether this is acceptable for you is a complex and difficult question to answer. 

I'm pretty sure both these claims are false. 1) Log actually means in most cases that more values are being assigned to the middle tones rather than reserving 75% of the information for the brightest two stops like with a linear curve. 2) Log does not add noise, it just increases the appearance of noise (due to raised shadows).

[maxotics]

4 minutes ago, EthanAlexander said:

I'm pretty sure both these claims are false. 1) Log actually means in most cases that more values are being assigned to the middle tones rather than reserving 75% of the information for the brightest two stops like with a linear curve. 2) Log does not add noise, it just increases the appearance of noise (due to raised shadows).

We'll see!  I'm not arguing one way or another.  My hypothesis is the manufacturers have already taken that into account in their standard profile, so don't lose the sensor's brightest stops.  Yes, one could say LOG does not add noise.  But whether it comes from adding, or "the appearance" the question remains about how much color is captures in total tonality.  I'm not at the point where we can look at this issue, but YOU HAVE A GOOD ONE   And I'm not ignoring it.  Thanks!

[EthanAlexander]

2 minutes ago, maxotics said:

We'll see!  I'm not arguing one way or another.  My hypothesis is the manufacturers have already taken that into account in their standard profile, so don't lose the sensor's brightest stops.  Yes, one could say LOG does not add noise.  But whether it comes from adding, or "the appearance" the question remains about how much color is captures in total tonality.

I'm just basing this on all the reading I did yesterday clicking on all the links that were posted and going down that rabbit hole. It will be interesting to see if you can come up with a definitive guide. I don't know your time/resources situation but it'd be pretty cool if you set up real life scenes and compared actual footage and let us know your scientific findings.

[maxotics]

1 hour ago, cantsin said:

Postscript: Max thinks that I am misusing this thread and posting off-topic. So I will quit from here.

Please don't quit.  That's not what I want.  We spoke our minds off-line, let's move forrward!  Everyone will be mad at me if you quit

18 minutes ago, EthanAlexander said:

I'm just basing this on all the reading I did yesterday clicking on all the links that were posted and going down that rabbit hole. It will be interesting to see if you can come up with a definitive guide. I don't know your time/resources situation but it'd be pretty cool if you set up real life scenes and compared actual footage and let us know your scientific findings.

Just to give you an idea what I'm going through.  Okay, so I want to use the monitor as a test reference of a color palette.  If I used a printed page I'd have to light to mimic 5 stops of DR.  Also, I'd have to deal with the dithering issues of a printer which would create color artifacts.  Okay, so I'm using a monitor.  Now I have to deal with the fact that each color is three pixels.  Here's a fun video I did on that subject:

It would be impossible, I'd think, to get a monitor-to-camera-pixel relationship.  Somehow, I need each pixel in the camera to blend the right few pixels on the monitor.  A "rabbit hole" indeed!  Anyway, I'm just going to have to hope for a crude approximation of color capture from the camera using a monitor showing colors display along a DR curve.  

AGAIN, IF ANYONE HAS A BETTER WAY TO DO THIS, PLEASE POST!

At this moment, I did 4K footage that showed more color in S-LOG2 than PP1.  I know that is impossible from the data of these images.  So it's all a type of noise.  When I think about it, that should be expected in 4K which is greater resolution than my screen. (Yeah, I do one stupid thing after another).  Anyway, I'm off to dealing with that issue and some others.  That's where I'm at.

Here's more of the kind brain damage I must deal with   http://www.alanzucconi.com/2015/09/30/colour-sorting/

[mercer]

1 hour ago, maxotics said:

Only if shooting in a scene that would best fit a Rec709 profile.

No, I haven't concluded anything!  Based on some initial tests against 1 million sample colors it looks like LOG loses about 35% color in a Rec709 case.  I am posting here for people to help me get to the bottom of this.  I posted another quick test looking at "banding" which would be expected IF LOG lost 35% of color in a Rec709 case.  

 

Do any of you go out and buy a camera because the guy at the store says it captures the best image IF you know how to grade it?  Of course not.  Everyone here tests their cameras, looks for new techniques to get better images.  That's all I'm doing.  My acid test would be, after all the work is done, someone like @Oliver Daniel would say, "that's useful information to keep in mind"

I think this is very interesting and thankfully there are filmmakers like you willing to figure out the intricacies for other filmmakers to benefit from.

The term rabbit hole has been used on a few occasions in this thread and I would think at every turn or discovery, you will go further down it.

Since you're a Sony user, obviously sLog is the choice of Log you are using for this experiment, but with all of the customizations available with sLog, to be truly accurate, you will have to go further and further down that hole.

@Geoff CB came upon excellent settings for sLog2 with his GFilm and then there's the sLog2 Flaat settings that are also very good, so there are already tweaked sLog2 settings that help to deliver both maximum DR and color fidelity. To test every single variation against Rec709 seems like a daunting task.

Perhaps discovering the best, possible out of camera settings for dynamic range and color information in 8bit sLog2 would be a great place to start, before comparing it to Rec709?

[Ari]

Thanks for an interesting discussion, this link in particular was very helpful: https://prolost.com/blog/rawvslog 

I've done a lot of RAW still shooting earlier, and I haven't yet tried GH5's V-LOG, but one thing that I could not find information about is what actually are things like Cinelike D, or just any setting like 'Normal'? I know what they look like, and any link that I find with google just compares the look, not what is behind all that.

[Deadcode]

3 hours ago, maxotics said:

At this moment, I did 4K footage that showed more color in S-LOG2 than PP1.  I know that is impossible from the data of these images.  So it's all a type of noise.  When I think about it, that should be expected in 4K which is greater resolution than my screen. (Yeah, I do one stupid thing after another).  Anyway, I'm off to dealing with that issue and some others.  That's where I'm at.

 

I dont understand the first sentence if i want to fit it to your explanations in this thread.

I think you should go to more simple and more agressive testing: 

Point your camera to the wall which has very few color and tonality. Point a desk lamp to the wall which fills the area more or less evenly.

Record some footage in different picture profiles, and push the files in post.

What have we done here? The scene has about 1-2 stops DR. If we compare REC709 vs SLOG2toRec709 footage in post, The image will look the same, but SLOG2toRec709 will have more color noise.

If we push these images waaay further and we increase the saturation and the contrast the SLOG2toREC709 footage will have more banding and more color noise compared to REC709. But not that much more than you think. 

In conclusion: yes SLOG2 gives less color information and you should not film in that profile every time (if we talking about 8bit)

But in real world filming the benefits of using SLOG2 is worth over it's weak spots.