Tell me about S-Log, Native ISO and Grading workflow

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dylansmith

Well-known member
Hi guys,


I currently have a Canon 6D using ML RAW and GH2 with Flowmotion, thinking of switching to a6300 soon. Have some questions regarding S-Log 2 and S-Log 3:


1. If the native ISO is 800 in S-Log, does that basically mean I am sacrificing a clean image for higher DR?
2. If I choose a ISO below 800 (e.g. 200), how much DR will I sacrifice by doing so?
3. Is S Log much harder to grade than a "natural" profile (i.e. Non Log gamma)? I asked because I feel it is a lot harder to grade my 14 bit RAW video from 6D, rather than the 8 bit 420 video from my GH2. It takes me a lot of time to get back the 'original colors'. Is there any preset I can use to bring a Log ungraded video to the 'default state'? Input LUTs don't seem to fulfil the purpose from what I've seen so far.




Separately, I have a question for E mount lens selection.


What is the widest, low light prime that is suited for the a6300? SEL 35/1.8 or? Ideally, I'd love to have a 24mm (FF equivalent) f1.4 for general filmmaking purposes. This is given that he 24-70 f2.8 G master is way too heavy for the APS-C body.


Do let me know your comments and suggestions!
 
Hey Dylan,
I can't speak for the a6300 since it's 8 bit, but FS700 Slog2 native ISO is 2000 and it's very clean in 10 bit. Whatever the base/native ISO is I'm sure it'll be pretty clean.

S Log 2 can be pretty tricky to grade. BUT, there are a ton of great LUTs out there to get you at a great starting point. Impulz, FilmConvert, Neumann. They all have some outstanding looking LUTs built specifically for S Log 2.
Not very familiar with E Mount lenses. I mostly use Nikon or Canon with E Mount Speedbooster.
 
Hello,

Do help me to understand as I came from the stills side.

So does native ISO 2000 mean it could be as clean as say, ISO 200 in stills mode? Doesn't that also mean a ND filter is absolutely needed (given such a high base ISO)?
 
ND filters are pretty much necessary I daylight, yes. Also because you shoot at 1/50 shutter speed. In SLog your only way to control exposure is aperture, ND filters and lighting. If you have a certain aperture you want to shoot at, only ND and lighting remains.

SLog usually benefits from a slight over exposure and then taken down in post.

SLog is not always the best option in 8bit. Or at least it becomes much more important to nail exposure.
Also in dark environments in 8bit, SLog isn't the best option either.
 
The lowest iso of 800 for slog is definitely going to be a bit noisier than iso 100, but the a6300 looks to be really clean with slog through iso 1600. 3200 you start to really see some noise, 6400 has alot of noise and really starts losing detail. But you will always be pushing the levels way back down during the grade so its not a huge deal. ISO 6400 should be usable.
 
I'm not totally sure that my logic is correct, but regarding ND filters it might turn out to be less of a problem with this camera (compared to A7s for instance). There was a common practice to shoot with exposure to the right in S-log, basicaly +2 Exp comp, so with a 6300 shooting with S-log profile and exposure to the right should theoretically be equal to shooting with ISO 200. Correct me if I'm wrong.
 
A 6D with M.L. RAW?
uhh...I don't think you're going to be too happy with anything from the Sony Alpha series.

Sure...you'll get that life changing 4K (..sarcasm..) but I think after getting used to Canon color in RAW....Sony 8-bit is really pretty much never going to feel like you're equaling that.
If you're having trouble getting the 6D RAW "back to normal" but not the GH2....eek, then my feeling would be there must be something in your primary correction workflow that's not what it should be.

(*Note my signature - I have both cameras. And Blackmagics, and a Samsung NX1 for 4k.)

But I know the a6300 is cheap...and really portable. So I get the appeal.
S-LOG3 I think is always better than S-LOG2. 2 was like a half-way measure. I hate it. But 3 is a different story.

If you had just said "GH2" then I would say "oh, you'll have a gee-ole time".

My point here is that I think you need to be prepared to feel that the Sony never hits a mark you've become accustomed to. That's all.
 
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1) not really

2) no idea - not possible on the bigger Sonys

3) The manufacturer should issue a LUT that takes you perfectly in one step from log to a nice 709 style image. Any manufacturer that doesn't should be avoided.

Sony do issue some LUTs for the 10bit cameras and they are 8/10 for being a 'go point' IMO. These LUTs may or may not work with the 8bit camera.


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For general film making on a FF camera I feel I need to be able to offer the director a 'master wide shot' - a 24 may cover this a 20 would be safer, a 16-35 zoom perfect, a 35 does not have the FOV to present a master wide of a typical domestic or industrial interior. If you are filming hotel bathrooms or other tight spaces you may need anything down to a 14mm

S
 
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As others have said, noise isn't a big issue. On the a7S I routinely overexposed by one stop, though, because it was a bit noisy in the shadows otherwise. The extra DR on that one was approximately one stop; it may not sound as much but it was definitely noticeable in challenging situations.

And regarding grading, I use these (I don't like LUTs, because they are not editable; these are curve presets, which you can then tweak to taste).
 
After having owned the a7s and now the a7sii, the ''why so much noise'' can be summed up in the following lines

- When using Slog,slog2,slog3 on an 8 bit AND 10bit (because s-log is also noisy on the 10bit FS7-f55, just to a lesser degree. I have used the f55 quite a bit and i can assure you that) - YOU NEED TO OVEREXPOSE by easily 1-2 stops. Give the sensor as much light as possible(but do not clip the highlights). When you reduce the blacks in post the noise will fade away.

- Why is it that way? Well, 8bit/10bit only has so much information that can be written - so you have a choice - do you add noise but get more dynamic range? or less dynamic range but less noise?
To me, i can live with noise and i can use a denoiser to clean my image. Clipped highlights however are usually unrecoverable, and you are stuck with them. Its choosing the lesser evil to be honest. But as a general rule from my observation, the untrained eye will dislike blown highlights more then noise. This is also the case for me - if i have to choose between blown highlights and noise, i will pick noise, anyday.

Until we all have 14 bit cameras that shoot raw, there is no getting around it - If you want low noise shadows, you will need to take some of the bits of the highlights and put them in the shadows - but you are losing dynamic range.

Of course, if you can control your lighting - dont shoot s-log. Just use a cinegamma and adjust lighting so that you dont clip your highlights. You will have a great image without spending time in color grading.
 
Samuel H said:
As others have said, noise isn't a big issue. On the a7S I routinely overexposed by one stop, though, because it was a bit noisy in the shadows otherwise. The extra DR on that one was approximately one stop; it may not sound as much but it was definitely noticeable in challenging situations.

And regarding grading, I use these (I don't like LUTs, because they are not editable; these are curve presets, which you can then tweak to taste).
Click to expand...

Can't you edit LUTS in Premiere Pro as long as you are using an adjustment layer??
 
You can use LUTs, but I don't like them, I prefer curve presets: they work better (LUTs end up biting me almost every time I use them) and they can be tweaked if necessary. They should also eat up less computing power.
 
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