FS5 S-log tips and gotchas

[Cliff Totten]

Originally Posted by Alfred Okocha

Hi there!
I just got a job for next week where I'll shoot s-log for the first time. (S-log 3 to be specific.) I won't grade it, they'll have experienced people for that. I just want to know I get the exposure right.

I just went out and shot some seconds using Dougs third rule up there. I applied the pre made SONY s-log 3 in FCPX and the exposure looks quite right. (I brought down the highlights a little notch since they were a bit over 100%)
1. Is it really that simple? (Considering all the warnings everywhere about shooting it.)
2. What should the zebra 1 be set at for skin tones?
3. They want some shots at late evening. Any tips?

Thank you very much!

Just out of curiosity, what camera are you shooting SLOG-3 with? Are you using the internal CODEC or are you shooting with an external recorder? SlOG-3 is extremely tough on a long GOP 8 bit CODEC. That's allot of contrast stretching on the other side to normalize it. ProRes 8 bit won't help banding problems too much but can help with compression artifacts.

One tip: Shoot only at 0db or the lowest ISO allowed. If you are in low light, and need brightness, it's much better to open up and let more light in than it is to add any gain.

For lack of a better term, SLOG "compresses" the gamma brightness. Or, another way to think about it is, SLOG "suppresses" brightness by certain ratios.

In bright light, this is fine, but in low light? SLOG is going to fight you back and make getting more brightness difficult. Remember, ISO/Gain is not "light"....only shutter and IRIS give your sensor more light.

ISO/gain is only a "post" process that is done later, after your sensor is done with the light it collected.

If you are wide open and your shutter is as slow as you dare to go and you STILL can't get enough brightnesss at 0db?....it's probably best to switch back to a rec709 gamma and not use SLOG for that shot. You can then crank up your gain and not be slammed with a ton of noise.

CT

[Alfred Okocha]

Thanks Doug and Cliff!

No zebra 1 for skin tones. No gain! I'll use the FS5. It's the client that asked for slog3 but I'll only use it when there's enough light then.

Seems straight forward, just wonder what kind of lesson I'll learn the hard way...

To something different, if I have understood things right it's better to overexpose than underexpose since it's fine to bring the curves down and no noise is added, with s-log. When you underexpose and bring the curves up you'll get a lot of noise. Correct? Have I understood that correctly? If so, why don't we set zebra 2 to over 100%? 110-120 or whatever? I'm I making some kind of mistake here?

[Cliff Totten]

I totally wont give you any advise on zebras 1 & 2. I'll let the others do that for you. Everybody has their own experience.

For me zebras are vital measurement tools. They tell you what objects are sitting at what brightness levels in the spectrum. You have two choices for each zebra:

1.) What object are you measuring?
2.) Where do you want that object to live on your scopes?

What objects you "should" care about and where you think they "should" belong on the scopes is totally your creative call. You can watch 100 commercials on TV and second guess their exposure all day long. It's funny,..ever tired doing that?...."Nah,...too bright,..too dark,...OK, just right" You can do it with movie scenes and drama's or commercials...it's endless. What I think is under exposed, someone else thinks is perfect and so on.

For me? I use different values for different things, I dont do things exactly one way only ALL the time. For me it's very "scene dependent" and sometimes I deliberately shoot a stop over or a stop under based on the narrative of the scene.I just cant subscribe to the "do something this one way and you will always be safe" idea. You have to develop good judgement and learn to trust it over time.

For SLOG, yup 1.5 or 2 stops over. (often, but not guaranteed all the time) When grading, it's beneficial to stretch contrast in a "downward" direction. If you ever have to stretch "upward" you are going to bring noise that is already high, even higher.

You can press SLOG-2 to see deeper into shadows and increase your DR but whatever you see jammed up into the top, (if you do, like clouds or strong whites) could be tough to recover because there is a bit higher gamma compression up there. So whites can sometimes get smashed even though they are not exactly clipped per say.

SLOG-3 clips much lower than SLOG-2. (I think 94 IRE?) So dont expect to see any zebras if they are set higher than 94. SLOG-3 is easier to grade because it's more linear that SLOG-2. It doesn't "arc" as much. It's pancake flat and your deepest black is,...jeesh....15 IRE? Test it because I dont remember exactly.

Please shoot a few test hours of SLOG first before you do a paying job. Also, knowing how to grade it in post will help you shoot it in the field. Honestly, and this is just me, I dont think you can shoot SLOG in the field without have some experience grading it. In my mind, the two must go together. Maybe that's just me but when I shoot SLOG, 50% of what is going through my mind is as I shoot: "OK, I'm doing this or that to this shot with my tools in post" as I watch it. I dunno, maybe that's just me.

Oh,....dont under expose SLOG-3 or your colorist will kill you....especially with the FS5. ;-)

This is just my $.02 on SLOG. Others with have their own advise. Take it all with a grain of salt as you will learn more from shooting hours of SLOG and grading it for hours and hours. That's where you really learn it and develop your instinct.

CT

p.s. To be completely 100% honest, SLOG-3 is not really designed for 8 bit. It really requires 1024 steps per RGB channel instead of 256. If you are not the one grading it, and your client is asking for SLOG-3, make sure he/she is aware that you are delivering 8bit files. (unless you have a Shogun with the FS5 raw license) It would be really bad if the colorist was expecting 10bit.

[Alfred Okocha]

Thanks Cliff!

After some more testing it seems that skin tones is a lot trickier than a general view image.
Since I'm a grading dummy I just tried to do some basic grading to see what could come out of it. Is this a valid way of testing, does it give a grading expert an idea what he has to work with? I did the following; I imported in FCPX applied an osiris log LUT and expanded contrast until the whole spectrum was filled and then cranked up the colours a bit.
I realise that the end result in it self is questionable but if you had this image, could you work with it in a proper way?

Thanks!

[Cliff Totten]

I'm at work so I'm not in front of Premiere or Vegas.

Look up tables only get you in the ballpark. You gotta go the rest of the way on your own. ;-)

What was your FS5 white balance setting?. Can you upload 1 frame of SLOG-3 and I can play with it when I get home? Did you shoot any rec709 of the same scene?

CT

[Alfred Okocha]

I shot a similar view with rec709.
Can I upload an XML frame or do you need the original file for that to work?

[Alfred Okocha]

Let's see if this works...
No, can't upload... "Your submission could not be processed because a security token was missing."
Don't know what that means. The file's just 8mb so it should be possible I think...

My WB was 5200. Does it make a big difference if you shot that instead 3200? I heard that 3200 has more info, but it hurts a bit to shoot it that way...

[Cliff Totten]

WB can be shifted in post but I certainly would use a temp that matches closest to your actual scene. I mean, I wouldn't shoot anything extra cold or warm to try gain anything from that. The less 8bit correction you need to do in post the better!

Do you have a Google drive that you can post a single frame .jpg to?

[Alfred Okocha]

No Google drive but I can e-mail you them if you give me a mail.

[Alfred Okocha]

Not sure if these will do but...

[Cliff Totten]

So I grabbed your frame and did a quick grade on it. I didn't use any LUTs, just high, mid and low color wheels, AAV color lab and a touch of sharpening. In AAV, I adjusted green channel saturation and shifted slightly in the blue direction and darkened yellows a bit. Mid tone color wheel was swung a bit towards red and overall saturation increased allot.

It's just a simple, plain "mild" look, I think with a modest contrast. Nothing at all special. It's not broadcast legal 16-235, there is some that dips under 0 but who cares for this? hehe

This one is has less contrast with lighter shadows:
https://drive.google.com/file/d/0B_6...ew?usp=sharing

This one has more contrast with more crushed blacks: (center of contrast lowered)
https://drive.google.com/open?id=0B_...GF4VGI0YkhfZkE

This last one has a LUT and has bold contrast. I kept this one basically between 0 and 100
https://drive.google.com/file/d/0B_6...ew?usp=sharing

Another with more contrast and blue water pulled back:
https://drive.google.com/file/d/0B_6...ew?usp=sharing

[Alfred Okocha]

Nice work Cliff!

I'm partial to high contrast so I liked the last one best but the others are nice too!

I guess you had all the data you needed within the frame then, so I guess I got the exposure right for this one?

Thanks for your help Cliff. Very valuable to me!

[Alfred Okocha]

Hi there!

I've now been shooting with s-log 3 a bit more with varying results. It is a bit of a learning curve for sure. Both under and overexposing does not look good, at all.
I know you all say to expose for whites instead of skin tones but that has put me in trouble where I had to bring the mids up a bit and, as some one said here, welcome to noise city...

Since I do a lot of talking heads the most important for me are skin tones. If anything else is too bright I'll deal with it another way in post. (Is it really just me that prefers to adjust the iris to skin tones and not whites when you shoot log?) What would you put for zebras on the high lights on a caucasian when you shoot s-log 3? 75, 80 or even 85?

Thanks a lot for all your help. It has really made a difference!

[Doug Jensen]

Originally Posted by Alfred Okocha

What would you put for zebras on the high lights on a caucasian when you shoot s-log 3? 75, 80 or even 85?

None of those. I would never set exposure based on skin tones. Is everyone's face the same shade? No. So obviously a face is not a consistent target and should not be used to judge exposure. Otherwise you are just guessing at the exposure, and your eyes and EVF will fool you often. Why do we even have zebras, light meters, waveforms, etc. if it's just going to come down to guessing anyway? You must use bright white, a genuine 18% gray card, an incident lighter meter, or some other method that ensures you are being consistent and accurate.

Bright reflected white, measured with the zebras, is by far the easiest method of setting exposure for S-LOG and that's pretty much all you should need 99% of the time. But an equally important part of the equation is how you process the footage in post. It's good that you're showing concern for getting the exposure correct, but you haven' said a word about what you are doing to the footage in post. You can't expect good results with S-LOG if you don't have a good workflow in post.

https://vimeo.com/ondemand/resolve

[Alfred Okocha]

Hi Doug!

I understand that what you are saying is undoubtedly correct about how to expose properly. I do a lot of ENG work however. I work alone in environments that may change. England is overcast one minute and a bit sunny the next. Most of the time there is little to no time to set things up properly.

You may say that that's why we have rec709. But, there's ever pressure to deliver better, visually more interesting material. That's why I'm moving to s-log, when I know I have some time to color it before it's sent, that is.
I'm doing the post work myself with Color Finale. It works well for me I think. And I don't have to export in and out of FCP which is a good thing, for me.