Jump to content
Graham Kay

Grading S-Log 3 footage from Sony F5

Recommended Posts

Hi

I'm new to working with S-Log 2/3 footage and the internet is not being helpful so far.

Can anyone here point me towards some reliable information about where to start - help separate the wheat from the chaff?

xdcam-user.com  looks intimidatingly comprehensive.

(I'm an Adobe user, though more and more tempted by Resolve)

Thanks!

Share this post


Link to post
Share on other sites

It's difficult to give general advice when I don't have any context to what you are doing or what you're trying to achieve.

Since you're saying you're new to SLOG-2/3 I guess maybe you're new to grading LOG in general? Sure, there are obvious differences between the different LOG-profiles, but color correction and grading is all about color and the result you get. So the starting point often is not that important.

I've worked with my FS7s SLOG3 for five years now and think I've got a good grip on it on how to make it the way I want. 

I usually I just use a REC709 LUT from Sony and use that as a basis for the grade. A lot of the time the client just want a natural grade, so in that case I don't do a hell of a lot of grading.

I find that shooting S-Gamut3.Cine/S-Log3 is the best LOG-profile and color space to shoot if you're doing your own grading. It makes the color space more uniform to REC709 so that when you add contrast or saturation the image responds in a more "natural" way, if you could call it that. 

Alister has some great info at xdcam-user.com. Don't know if he's on this forum, but he's quite active on Facebook in the Sony FS7 and FX9 user groups. 

Share this post


Link to post
Share on other sites

Thanks, Martin.

You're right - my post was vague.  But your advice is already helpful.

I have used log footage extensively over the past few years (Panasonic v-log, Canon C-log), but not S-log, which seems to have a bit of a reputation for being difficult to deal with.  Is this true?

As for use cases, the most likely are:

  • documentary shooting using natural and available light
  • landscape
  • lit interviews
  • lit narrative (less often)

The main question might be about how to use the Exposure Index setting for best results.  I've read Alistair Chapman's long article about "rating" the camera to a different ISO than it is actually recording - quite a new concept for me, though I'm slowly getting it.  (Does this apply to the FS7 too?)

And of course: which LUT to use.  Do you have a link to the one from Sony?  That seems like a good starting point.

10 hours ago, Martin Håndlykken said:

I find that shooting S-Gamut3.Cine/S-Log3 is the best LOG-profile and color space to shoot if you're doing your own grading. It makes the color space more uniform to REC709 so that when you add contrast or saturation the image responds in a more "natural" way, if you could call it that. 

So, where in the chain are you using the LUT?  Do you put it after white balance, exposure, saturation etc?

Thanks again!

 

Share this post


Link to post
Share on other sites

The info about Slog on xdcam-user.com is worth investing the time to read thoroughly. 

In the meantime, to get you going, here's a LUT that I use to transform S-Gamut3.Cine/S-Log3 footage to REC709. To my eye, it maps the color better and provides a good base contrast curve that rolls off the highlights more gently than the REC709 transform LUT provided by Sony. 

As to your question, yes in nearly all cases, you should adjust exposure and white balance before the LUT. 

 

 

S-Gamut3Cine_S-Log3_to_REC709.cube.zip

Share this post


Link to post
Share on other sites

Hi Jamie

That's great, thank for the LUT.  I'll give it a go - and also put a few hours into the xdcam user boards!

Cheers

Share this post


Link to post
Share on other sites

 Sony camera,s in Cine EI / Slog mode will only ever record at the native ISO.. deemed by Sony ..  f5 2000 f55 1250 ..  and only the 3 preset WB..  (Fx9 has dual native ISO 800 and 4000 and you can adjust the WB).. so in EI mode its like working with film.. you can set your light meter  to a different ISO / EI, but the film stays the same ISO as whats written on the can.. apply a MLUT (monitor LUT ) REC709 is usually the best if your used to this levels already, to the EVF and changing theEI/ ISO will effect that only .. the recorded footage will always be ISO2000 on the f5.. ie .. change the EI/ ISO on the camera to 1000 .. the image in your EVF (with a REC709 MLUT) will darken 1 stop ..  you are rating it at a 1 stop lower ISO.. so you open up the Iris one stop to compensate .. so you are intentionally over exposing your 2000 rated recorded footage by 1 stop ..  this is sort of common practice with the f5/55 to over expose shooting Slog to get less noise in the shadows ..  this is the main weirdness that trips people up .. Arri does it differently the curve actually changes .. but Sony the curve stays the same .. you are under or over exposing it by changing the EI .. they went for the same approach as shooting film and changing the EI on your metre ..  Slog3 is very similar to Arri Log C as they both copies of the old Kodak telecine curve Cineon..  

All probably described better on the XDCAM site .. thats your best bet for info all in one place ..

  • Like 1

Share this post


Link to post
Share on other sites

@Graham Kay I think you'll be able to work with SLOG3 just fine. Yes, it might not be as easy as say CLOG1, but that curve is very mild and only offers 12 stops of dynamic range. If you're using the 709 LUT as a base then you can get great results very easy from there. I actually often just throw on the Arri 709 LUT on FS7 footage as it works fine as well, since the LOG-curves are so similar. I own and shoot on an Amira and I use the FS7 as B-cam all the time.

As to Robin is saying, working with CIne EI is very different from a regular video camera. It's difficult to get your head around and I think the best way to learn is to listen to Alister talk about it in a video. Think there is some on YouTube, but I forget. What I usually do is to shoot at 1000 EI on the FS7, as that makes me overexpose the image when looking at the image in the monitor. The FS7 in Cine EI-mode always records at 2000 ISO, which is kinda weird if you're not used to it. When you learn it though at get used to the workflow it's quite simple. I actually prefer to shooting this way as it makes it easier since you don't have a lot of options. 

Share this post


Link to post
Share on other sites

I'd also recommend reading and understanding Alister's guides on XDCAM-USER. A real treasure trove of useful information. Also http://www.hingsberg.com/category/pmw-f5/ has a great "Ultimate ExposureGuide" too.

For best results, in my opinion, it's worth taking time to understand some of this stuff. When I first got my F5 back in 2013 it took me a few months to fully get to grips with it all... but I'm better for it (and now a bit of a nerd on these matters, haha). But I've seen countless mistakes made by others along the way.

Here are some top tips:

  1. CineEI mode was originally designed for RAW... to even if recordingXAVC, think of it terms of RAW: very limited in camera image control (other than exposure), with the idea that everything is done in post, in the grade. Hence the white balance being locked to those three presets (though in the VENICE and FX9 this changed).
  2. slog3/sgamut3.cine is designed to have a gamma curve that feels familiar to colourists used to working with Cineon material. Similar to Log-C also. The gamut is designed to meet rec709 primaries, so be easier to grade than the full sgamut (F55 only really) which has extreme "out of standard gamut" colour capabilities. slog2/sgamut however is arguably better for scenes with a really wide dynamic range (though it's what put some people off and made some people think Sony material was harder to grade).
  3. slog3 is data levels... so if using a LUT to convert to something like rec709, ensure it converts to legal. Also ensure any post software realises the slog3 is data levels... some don't read the flags correctly and need to be set manually. This is a very common mistake when people record slog3 to a ProRes file... because ProRes is typically video levels, and it won't capture the metadata... so need to tell post software to treat it as data levels.
  4. It's worth noting that Sony's published "base ISO" for the F5 and F55 when using slog2/3 are not actually 0dB. Rather, they are the mid-point in the gamma curve where equal amounts of highlight and shadow latitude are captured. This is why some people thing that slog3 is noisy: because at 1250 EI (F55) or 2000 EI (F5) the sensor is actually at +6dB. So you'll read a lot about "rating the camera higher, then bringing it back down in post". What I like to do is:
    • Rate my camera at 800 EI (this is 0dB on the F5... I think on the F55 it's 640). Even if it means sacrificing a little highlight headroom (though I'd reconsider depending on the scene).
    • Use a rec709(800) LUT in my EVF (because I'm using a Gratical Eye) that is exposure compensated for 800 EI.
    • Then either use a similarly exposure compensated LUT in post, or just manually bring the levels back down in post to compensate.
    • This allows me to see a familiar rec709 image in my EVF when shooting... so I know to place white at around 90%, Caucasian skin at around 70%, etc.
  5. You can make your own exposure compensated LUTs with a free program called LUTCalc.
  6. If you look at the native slog3 image be aware the levels are different (I cannot tell you the amount of times I've seen people expose slog3 as if it's rec709, thus massively over exposing and clipping their highlights. For slog3 on a waveform monitor (or when setting zebras), the clip point is 94% IRE (I'm not sure why it's not 109%), white is 61% IRE, middle grey (18%) is 41%, and black is 4%. Also bear in mind that very few monitors (and certainly not EVFs) will be actually visually showing you the full dynamic range if looking at the flat slog3 image... as most are only capable of 6-10 stops, rather than 14 stops. Another reason it's better, in my opinion, to use a rec709 compliant LUT (and to trust tools like a waveform monitor).

I hope that's all helpful.

  • Like 1

Share this post


Link to post
Share on other sites

Robin explained similarly above. So to clarify, when I rate my F5 at 800 EI to get it at "0dB", the camera, as Robin says, is still actually at 2000 ISO... but I'm monitoring it as if it were 800. As such, when I view the image in post it may look over exposed. But using an exposure compensated LUT in post, or manually bringing the levels back down to make it look correct will, in turn, be reducing the noise floor.

  • Like 1

Share this post


Link to post
Share on other sites

Thanks everyone for such detailed guidance.  It does all make sense - at least in that I can follow the logic of how EI works and how using the workflows suggested will get the most out of the sensor.  

I know from experience that it is going to take some serious trial and error to actually get everything straight in my head to the point where I can reliably turn out decent images!  

Thanks again, I'm much reassured!

Share this post


Link to post
Share on other sites
11 minutes ago, Graham Kay said:

Thanks everyone for such detailed guidance.  It does all make sense - at least in that I can follow the logic of how EI works and how using the workflows suggested will get the most out of the sensor.  

I know from experience that it is going to take some serious trial and error to actually get everything straight in my head to the point where I can reliably turn out decent images!  

Thanks again, I'm much reassured!

The most easy way to shoot Sony EI mode , is throw the Rec709 800 MLUT in the EVF and SDI for monitors .. from memory I believe the f5/55 unlike the fs7 .. there is no option for the wave form etc to be reading anything but  the MLUT levels if you are using one..  or just expose by eye if your used to shooting Rec709.. if your rec709 levels are fine ,so will your Slog 3 be.. just sticking with the native 2000 .. just shoot and it will be fine .. I usually just shot at native 2000 as I wasn't editing the footage and I knew post would just think I had screwed up the exposure .. I never had any complaints about noise ..but intentional over exposure will get you a cleaner image .. its that easy shooting wise anyway .. there is also, in the assign menu only, a function called HI/Low.. this is handy as press once and it will show the Slog hi lights and press again you will see the low image.. one more press and you exit back to MLUT rec709.. its a handy feature for a quick check. 

Some people shoot with the slog image in the EVF .. how they do that I'll never know .. but some do it that way too..

But as with others I just read and re read and re read XDCAM users articles .. then suddenly it sort of makes sense .. it seems odd that you lower the ISO to get more light onto the sensor  ..  but there is method in the madness 

Share this post


Link to post
Share on other sites
9 minutes ago, Robin Probyn said:

It seems odd that you lower the ISO to get more light onto the sensor  ..  but there is method in the madness 

Because you're not lowering the ISO, you're lowering the exposure index. The sensitivity of the sensor stays the same. Just rating it differently... as you said, like film.

Share this post


Link to post
Share on other sites

Another thing to be aware of: the built-in LUTs int he camera (such as 709(800)) don't need to be "exposure compensated". They automatically shift when you raise/lower the EI.

It's only relevant if using LUTs in 3rd party EVFs/monitors, or in post.

Share this post


Link to post
Share on other sites
16 minutes ago, Nezih said:

Another thing to be aware of: the built-in LUTs int he camera (such as 709(800)) don't need to be "exposure compensated". They automatically shift when you raise/lower the EI.

It's only relevant if using LUTs in 3rd party EVFs/monitors, or in post.

This is why I use the stock monitor or EVF as it makes that change automatically. I also output to my monitor with the built in LUT.

Share this post


Link to post
Share on other sites
4 minutes ago, Martin Håndlykken said:

This is why I use the stock monitor or EVF as it makes that change automatically. I also output to my monitor with the built in LUT.

The only downside then is the inability of the camera to use its in-built LUTs for S&Q and Playback... which is why I got used to not using it (most of the time).

I use a Gratical Eye instead... but the downside with that is that the LUTs are only 1D, so only change the gamma, not the gamut.

Can't win!

Share this post


Link to post
Share on other sites

@Nezih Yes, that is true.

*irony on* This is why I usually just shoot without looking at a monitor and EVF. I just measure the framing, focus and exposure with my eyes and set the right settings. This is the way Sony intended it to be! *irony off*

  • Haha 1

Share this post


Link to post
Share on other sites
Posted (edited)
1 hour ago, Nezih said:

Because you're not lowering the ISO, you're lowering the exposure index. The sensitivity of the sensor stays the same. Just rating it differently... as you said, like film.

I know .. thats what you have to get your head around ..  but it seems counter intuitive .. 

Edited by Robin Probyn

Share this post


Link to post
Share on other sites
6 hours ago, Martin Håndlykken said:

Some say all Sony cameras are counter intuitive by nature.

Their menus certainly have been confusing .. but they have improved them in the Venice and Fx9 now..  as an owner they are not a problem .. you just set up the user menu.. but as a first time rental camera a bit of a nightmare .. was so was the Panasonic varicam menus .. put Sony to shame .. Arri is always easier as the camera,s dont really do so much either ..  the big gotcha with the f5/55 was burning in the LUT by mistake ,this happened alot on the early days .. and the whole method of using EI.. that the recording ISO doesn't change .. even though people thought they were actually changing it on the camera dial / side screen .. 

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...