S-Log for dummies?

J

Jay Birch

Well-known member
Can someone explain, in simple terms... how S-log works? (shooting and post)

I have read through various PDFs on the subject, but can't quite get my head around it.

Thanks in advance, Jay.
 
The video in this thread talks about it but this iswhat I understand:

Its Sony's version of shooting RAW !
Basically the s-log files will be files that are untouched, not a baked in look. S-log looks very flat.
There are no contrast, brightness,color etc values applied to the image that has been recorded . It's not compressed like xdcam, avchd or hdv for that matter. It' s as uncompressed as one get nowadays:).The files are going to be huge !
It will, from what I've read, retain a good amount of detail in the highlights and shadows
This works great if you want to do colograding and VFX work.
S-log wont be necassary for every production but seems like a good option for Big budget productions.
Hope this helps !

Add: Feel free to correct me where Ive said something incorrect ...just to get the ball rolling !
 
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Thanks guys...

I have used RED One, so I guess it will work in a similar way (nail your exposure, in camera... do the rest in post)? I really like working in RAW, so if it is similar, that would be great.

I really love the look of the F3 and it hits my budget, as I take the step up from my tired HVX and DSLRs. It sounds like a system that I can get more involved with as I add to it and learn more with each project.
 
Everts said:
It's not compressed like xdcam, avchd or hdv for that matter. It' s as uncompressed as one get nowadays:).The files are going to be huge !
Click to expand...

RAW, S-Log and compression are all different things. You can compress both S-Log and RAW data and almost all cameras do.

S-Log is a gamma curve that stretches blacks and compresses highlights so that you can manipulate the image extensively in post. It can theoretically be recorded to any codec although it really needs a high end codec (10 bit and moderate compression) due to the heavy manipulation that HAS to be done in the grade. Native S-Log looks flat and horrible.
 
Here's what I think would really help this out, because I'm still a tad bit hazy on this myself, it'd be sweet if they would publish a sort of white paper detailing a beginning to end scenario of how to get the s-log material into an editor like FCP. Like what kind of transcoding software/hardware is needed/supported, what kind of support is there/workflow for the material in Apple Color, or DaVinci Resolve, etc. I mean a thoroughly detailed from beginning to end kind of instruction manual. We all know WHAT S-log is, what I want is a white paper that tells HOW we get it into FCP and work with if from there.
 
My understanding is that Slog is an extreme gamma curve and nothing more. This is visual, and will not need anything special in post. Just like using a cine gamma, the curve is allowing a greater dynamic range to be captured. This is "burned in" the footage. Slog can then be graded to look like how you want.

This is how it was explained to me at least.
 
Sony likes to call S-log "digital negative" because it captures the entire tonal range of the sensor. Confusing because Adobe's RAW standard DNG is also refereed to as a "digital negative". RAW itself is also bit of marketing speak, as some RAW (even on stills) also have NR applied and are compressed. A/D conversion is also done in different locations (on and off the sensor) in CCDs and CMOS so data 'off the sensor' can also be misleading.

The meanings we associate with 'raw' are gastronomic; usually something more primal like meats. That there needs to be a process that happens before we reach our final product we can consume. I suppose we could apply those meat terms to images as well, 'rare', 'medium-rare", "well-done", etc to the amount of compression, grading, debayering, etc., but then again any amount of 'cooking' by definition is no longer 'raw' (even a rare steak isn't raw). Which is why its all a misnomer if you aren't referring to uncompressed images off the sensor, but there really is also no point in being pedantic with the semantics.

Its a layer of marketing abstraction. What really matters is what you can do with the product as well as what you don't need to do. In the case of S-log it gives you a large latitude in grading but it won't give you options with demosaicing and you'll be working with 1080p rather than the effective resolution of the sensor (which is suppose to be ~3.4k). Sony's perspective is that they want to remove the unnecessary busy-work, your time is money, and that some things are better handled within the camera rather than off. You can argue both sides of this, and there are both up-sides and down-sides associated with each perspective.


There are whitepapers on S-log for those interested:

PDF:
http://www.sony.co.uk/res/attachment/file/66/1237476953066.pdf
http://pro.sony.com/bbsccms/assets/files/mkt/cinema/solutions/slog_manual.pdf
 
Yay for concise, egghead free explanations. Thanks Steve. It is my feeling as well that Sony is trying to find the sweet spot in time/expense/flexibility, and quietly say as much, rather than speak in hyperbole and extremes.
 
What non-linear editors can interpret the S-log files? I'm particularly interested in integration with Premiere and After Effects CS5, and FCP. I can't find much info around in regard to posting S-log.
 
Just checked. You can use the Cineon convertor utility in Premiere CS5 to convert S-log to linear, but I don't have an S-log clips so experimentation will have to wait... but it looks promising!
 
S-Log isn't a very aggressive log curve. As read somewhere else, most colorists just work with it as is without applying a LUT, and from what I've seen of S-Log I'd do the same in my Davinci. You can do the same with levels and gamma filters in any NLE.

A true Log encoded file, like a log DPX, or LogC from an Alexa is a bit more extreme and you're probably better off finding a LUT to decode.
 
So basically, if I'm reading everyone correctly here, I can take either the XDCAM EX files from the SxS cards or (for example) the Pro Res clips from a Ki Pro Mini with S-Log as the already applied gamma curve into my editor of choice (FCP), and start editing and grading to my heart's content right away...correct? They'll already look nice and flat and grey and dull and then I just go in there and start messing with them in the grading app of my choice? IF this is the case, this makes me very happy :)
 
Joe,

I have read at another forum that it is not possible...

Quote-

"No, that's not possible. The S-Log signal feeds out of the Dual HD-SDI ports and is 4:4:4 RGB. The Ki Pro, Nanoflash, and similar devices can only record 4:2:2, and should appropriately be attached to the single SDI spigot on the top right rear of the camera. That port is designed to be used for onset monitoring during S-Log recording, so the LUT can either be displayed or turned off, but the recorded result is baked in.

To use S-Log you would need to purchase the firmware upgrade, rent or buy an appropriate recorder, and then, (after any SxS offline editing) move to a suitable online edit suite.

I suspect if you only occasionally have use for S-Log that renting a recorder may be the most economical option."

Unquote-

http://www.dvinfo.net/forum/sony-xdcam-f3-cinealta/490530-s-log-cheap-n-easy.html#post1610185

Cheers!
 
Joe Walker said:
...I can take either the XDCAM EX files from the SxS cards or (for example) the Pro Res clips from a Ki Pro Mini with S-Log as the already applied gamma curve into my editor of choice (FCP)
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XDCAM EX is not ideal for S-Log anyway as it is only 8 bit and heavily compressed so it would likely fall apart during the extensive grading dictated by S-Log. Prores 4:4:4 would be better but would require a Dual Link recorder. I believe S-Log will only be available to those who purchase the Dual Link upgrade. Sony are hoping people will use their solid state HDCAM SR recorder and have suggested that the files generated will be able to be imported into FCP. My guess is they will be MXF files that need rewrapping to .movs.

Anyhow, once you manage to record to a suitable codec, yes you can take it straight into FCP or Colour. I'm not sure how the LUT files will interface with FCP, I'm not sure if Sony have clarified that yet.

EDIT:
As suggested below an offline-online is an option but I see no reason why a direct online is not possible on a modern, fast system.
 
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mmm said:
XDCAMSony are hoping people will use their solid state HDCAM SR recorder and have suggested that the files generated will be able to be imported into FCP. My guess is they will be MXF files that need rewrapping to .movs.

Anyhow, once you manage to record to a suitable codec, yes you can take it straight into FCP or Colour.
Click to expand...


That makes sense, thanks for that clarification and that is good news that it's directly ingestible through L&T in FCP. This is good news, I've been privately telling myself that the workflow for this S-Log stuff CANNOT be more complex than RED's workflow or people would immediately discount it.
 
Joe Walker said:
So basically, if I'm reading everyone correctly here, I can take either the XDCAM EX files from the SxS cards or (for example) the Pro Res clips from a Ki Pro Mini with S-Log as the already applied gamma curve into my editor of choice (FCP), and start editing and grading to my heart's content right away...correct? They'll already look nice and flat and grey and dull and then I just go in there and start messing with them in the grading app of my choice? IF this is the case, this makes me very happy :)
Click to expand...

Yes. Except you can't get S-Log onto SxS cards, the firmware won't let you. And there's little point anyway.

But S-Log from AJA Ki will be VERY easy to deal with. And you'll be able to make it look like something even in your NLE.
 
My understanding was that the firmware would let you (when in S-Log mode) record to SxS either with the LUT applied, or with the washed out Slog look. Of course, either way, it's only intended for use as an offline edit.
 
Viddovation said:
My understanding was that the firmware would let you (when in S-Log mode) record to SxS either with the LUT applied, or with the washed out Slog look. Of course, either way, it's only intended for use as an offline edit.
Click to expand...

I hope you're right, because even though I said it's of little use above, there are times when you need a flat look regardless, and S-Log would be the best way to get it.

It's only a problem if/when you shoot S-Log 8-bit, and you need to make it look normal or high-contrast. Then you'd be in trouble stretching that flat 8-bit image out.
 
In the Rule Boston presentation Peter Crithary indicated that when in S-log mode (which requires the paid firmware update), you can use the regular SDI output for a producer/director monitor, and you can preview with or without the LUT displayed. My understanding is that this signal could be recorded with an Aja or Nanoflash recorder. I'm not sure if the camera will permit you to use just one side of the dual link as a dedicated 10bit 4:2:2 HD-SDI out Slog for this purpose. (Meaning, if not - and recording to an Aja Ki Pro Mini, you owuld be forced to only preview the flat look while recording)

He also stated that the SxS can record either the flat look or the baked LUT look. Either way - it's XDCAM-EX compressed of course.

What I'm not certain of - is whether those are separate switches, or just one switch for both SxS and the 4:2:2 HD-SDI output. I have a suspicion just one switch flips all monitoring and recording, with the exception of the Dual link output.
 
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