Do ALL LOG Profiles Require / Benefit From Significant Overexposure?

[Inazuma]

Log on the C100 requires it too

[KnightsFan]

9 hours ago, Eric Calabros said:

I think the overexpose is not the right term here. Exposure is light, filtered by time, filtered by aperture. Period. ISO has nothing to do with that.   But, basically you use higher ISO to "underexpose" and get equal brightness of normally exposed image (which is important for action photographers, they can use higher shutter speed without the image "look" darker). So in case of log, they don't tell you to overexpose, they just ask you to Not Underexpose! 

I had a chance to play with an FS7 recently, and I felt something was off with exposure. So I did a comparison with my NX1. I set my NX1 to ISO 800 and the FS7 at its "base ISO" of 2000. In Resolve, I added the builtin SLOG to Rec709 to the FS7 footage, and it was darker than the NX1. ISO 2000 vs ISO 800. So I check with my light meter, which unsurprisingly agreed with the NX1.

So in what world was it ISO 2000? One where you make middle grey from the washed out SLOG3 file remain middle grey after grading? In other words, one where you either keep the washed out-ness, or clip the top four stops of highlights.

Whether you want to say "overexpose" on set or "underexpose" referring to post, doesn't matter. The issue is that it's universally accepted (except by the manufacturer) that you should pretend that your camera's ISO reading is actually a stop lower than it says.

Hence:

4 hours ago, Robert Collins said:

If you think about it - a camera (as in say the A7iii) which has a base iso of 100, why would it really choose to shoot SLOG at an iso of 800 (lets forget about the dual iso bit for the moment)? If it did so, it would effectively reduce dynamic range by close to 3 stops and increase noise by close to 3 stops. The answer is it doesnt record slog at iso 800 but at iso 100 and therefore you have to 'overexpose' to 'expose' correctly by +2EV+.

Exactly... That was basically my thought. Changing to log doesn't change the analog gain that Sony (or Panasonic, etc) is using, it just lets them put up some far-fetched number for "low light" performance.

The truth is, everyone should test their camera extensively and find out what exposure works best, regardless of what the numbers say.

 

[Mark Romero 2]

25 minutes ago, jonpais said:

Switch out of S-Log while doing white balance? LMAO

Well... according to the sony help guide scroll to the bottom of here: http://helpguide.sony.net/ilc/1420/v1/en/contents/TP0000435736.html ), that seems to be what they are saying:

"Setting [ITU709(800%)] or [S-Log2] may cause an error in the white balance custom setup. In that case, set the exposure bright first and then perform custom setup."

Although it is hard for me to interpret that...

[AlexTrinder96]

I'd recommend Alister Champman's blog, he goes into great depth on how to expose and use S-log!

I think it is vital that when using S-log (more so than other log curves) that you use a waveform and lut to help expose. 

I personally found using an ei of 800, with one of Sony's M Luts helped prevent noise creeping in. (sony f5)

 

 

[seanzzxx]

1 hour ago, Mark Romero 2 said:

Thank you for the input. Have you had a chance to try the HLG profiles?

Unfortunately not, sorry! I'm using an A7R/S II most of the times.

[jonpais]

@Mark Romero 2 Re: The help guide, there's also this:

When using S-Log2 gamma, the noise becomes more noticeable compared to when using other gammas. If the noise still is significant even after processing pictures, it may be improved by shooting with a brighter setting. However, the dynamic range becomes narrower accordingly when you shoot with a brighter setting. We recommend checking the picture in advance by test shooting when using S-log2.

There are no such instructions in the a7 III help guide.

Shooting S-Log2 at whatever ISO, 800 and above, custom white balance seems just fine, and exposure is pretty straightforward just using zebras set at 100+. 

I don't use view assist or waveform monitors when shooting S-Log2 and I haven't been applying any special LUTs to the footage (except for the Leeming LUT Quickies in the screen grabs I shared to add a bit of drama).  

I'm really liking the highlight roll-off when compared to the Cine2 profile I had been using, and skin tones look okay to my old eyes.

In sum, I kind of enjoy shooting S-Log2 and will probably stick with it for the time being.

[AlexTrinder96]

The Mlut/cine IE helps with rating the camera at a different iso to what's it actually recording; so you can set the lut to show at 800 or 640 when you're actually recording at 2000. 

 

I also forgot to attach the Recommended Ire values from Sony themselves. It's can be helpful as a starting point if you don't monitor in rec709!

 

[Mark Romero 2]

45 minutes ago, jonpais said:

@Mark Romero 2 Re: The help guide, there's also this:

When using S-Log2 gamma, the noise becomes more noticeable compared to when using other gammas. If the noise still is significant even after processing pictures, it may be improved by shooting with a brighter setting. However, the dynamic range becomes narrower accordingly when you shoot with a brighter setting. We recommend checking the picture in advance by test shooting when using S-log2.

There are no such instructions in the a7 III help guide.

Shooting S-Log2 at whatever ISO, 800 and above, custom white balance seems just fine, and exposure is pretty straightforward just using zebras set at 100+. 

I don't use view assist or waveform monitors when shooting S-Log2 and I haven't been applying any special LUTs to the footage (except for the Leeming LUT Quickies in the screen grabs I shared to add a bit of drama).  

I'm really liking the highlight roll-off when compared to the Cine2 profile I had been using, and skin tones look okay to my old eyes.

In sum, I kind of enjoy shooting S-Log2 and will probably stick with it for the time being.

Thanks for sharing your experience!!!

[kye]

3 hours ago, KnightsFan said:

The truth is, everyone should test their camera extensively and find out what exposure works best, regardless of what the numbers say.

Absolutely. I did this for my XC10 in C-Log and luckily there were no significant differences a stop either way of where it exposes skin tones in auto (how I shoot) so I just don't worry about it.

Unfortunately I sympathise with the OP wanting to know about cameras they don't already own.

Unfortunately this level of performance testing doesn't often overlap with non-cinema cameras so the comparison probably isn't on vimeo somewhere

[KnightsFan]

29 minutes ago, kye said:

Unfortunately I sympathise with the OP wanting to know about cameras they don't already own.

Unfortunately this level of performance testing doesn't often overlap with non-cinema cameras so the comparison probably isn't on vimeo somewhere

Of course! I suppose I was getting a bit off topic as I wasn't directing that part of my post towards the OP.

[Deadcode]

4 hours ago, Mark Romero 2 said:

Thank you for the input.

I can understand your findings. I guess the sadness for me is that the highlight rolloff of Cine4 is... how should we say it... pretty bad... So having the hghlights clip is pretty upsetting to me.

Your testing seems to confirm my (rather haphazard) comparisons between Cine4 and Slog 2. There is not a whole lot more DR in a SLOG2 shot that has been overexposed by two stops. It seems that the main benefit in this case is that SLOG2 gives a less harsh rolloff though.

All other things being equal, in regards to skin tones, would you say that Cine4 at 0 EV gives better skin tones than SLOG2 at around +2 after grading? Or are they about equal? You said with regular grading they both look about equal, so i am assuming that also refers to skin tones being on par with each other when exposed optimally. (I haven't been able to test on skin tones really.)

Yes, that is definitely a concern. Cine4 is much easier to use in the field (on an a6500) but the rolloff is nasty. Even using in-camera LUT (I don't know what sony calls it exactly... gamma assist???) when shooting SLOG2 the issue is that they recommend switching OUT of SLOG when doing your white balance, which is really difficult on a gimbal with the tiny buttons on an a6500.

 

Actually Cine 4 has a very nice highlight roll-off. But it uses 0-255 data level, and even Davinci Resolve cant recognize this in Auto mode, you have to switch it manually.

So technically you have worked with Cine 4 like you throwed away the darkest 0.5 stop and the top 1-1.5 stop DR. (where the roll-off is actually happening :D)

Exposing for Cine 4 properly means 50-60 IRE luminance level for the skin tones, and not 0EV AE

4 hours ago, seanzzxx said:

The reason I stopped shooting Slog was the fact that by overexposing by two stops the skin tones get really pasty and thin most of the times. I much rather have good skintones than some extra dynamic range, however I agree with you on the fact that the Cine curves have terrible highlight roll off.

Actually exposure does not really affect skin tones if it's above the noise level, which is around 40 IRE (ok, this statement is true mostly when recording in 10 bit)

Mark Romero 2

"Well... according to the sony help guide scroll to the bottom of here: http://helpguide.sony.net/ilc/1420/v1/en/contents/TP0000435736.html ), that seems to be what they are saying:

"Setting [ITU709(800%)] or [S-Log2] may cause an error in the white balance custom setup. In that case, set the exposure bright first and then perform custom setup."

Although it is hard for me to interpret that..."

Slog2 is designed to use with S-Gamut. S-Gamut has to be mapped to REC709 Gamut properly (which is not happening usually because the lack of knowledge, this is the reason why everyone is crying about how hard is to grade sony footage) and only 3200K and 5600K correction LUT's are existing right now. So if you are recording for example in 4300K, the mapped colors will be off.

I know everyone is using SLOG2 with S-gamut3.cine, but without gamut mapping the skin tones will not have enough thickness.

 

Now back to topic: every LOG footage has it's proper exposure levels for skin and 90% reflectance white, and every gamut has to be remapped to REC709 (or wider) colorspace in the grading process.

[Mako Sports]

9 hours ago, Mark Romero 2 said:

One more question for everyone: How does the HLG profiles of the 3rd Gen Sony mirrorless cameras (a7 III, a7R III) fit in to all this? I understand that 1) It isn't really supposed to be for grading, and that it is is supposed to be for "out of camera" footage that will be shown on HD TVs, but is there a benefit when shooting for (eventual) Rec.709 distribution like youtube?

For example: If shooting HLG and then editing on a Rec. 709 timeline, can I at least get the same 12 stops of DR that Cine4 at 0EV or SLOG2 at +2 provide without having the nasty Cine4 rolloff and without having to deal with the SLOG2 workflow?

I really have only seen the videos comparing SLOG2 with HLG by the one guy Scott Jeschke and they don't seem really conclusive to me (maybe I missed it).

HLG 3 seems a lot nicer than the STANDARD / oicture profiles off:

 

But not really sure about head-to-head with SLOG2

Yeah I love shooting HLG on my Z90, it sits kinda in between log and rec 709 becuase any camera that can shoot Log can shoot HLG since the color space is going to be a lot smaller.  Ive found HLG colors to look really similar to Canon stuff color wise, and the boost in DR is always welcome. I don't really grade my HLG stuff, just a light CC. If i want a filmic look I shoot Cine 2 or Cine 4. 

[jonpais]

With S-Log2, I just meter for brightest important highlight detail - whether it’s a shirt or the face - and the skin tone line on the vectorscope is usually spot-on. 

[AaronChicago]

Why not expose accurately? Use a LUT, waveform, and/or light meter.

[Mako Sports]

On 9/24/2018 at 3:43 PM, Deadcode said:

Slog2 is designed to use with S-Gamut. S-Gamut has to be mapped to REC709 Gamut properly (which is not happening usually because the lack of knowledge, this is the reason why everyone is crying about how hard is to grade sony footage) and only 3200K and 5600K correction LUT's are existing right now. So if you are recording for example in 4300K, the mapped colors will be off.

I know everyone is using SLOG2 with S-gamut3.cine, but without gamut mapping the skin tones will not have enough thickness.

 

Now back to topic: every LOG footage has it's proper exposure levels for skin and 90% reflectance white, and every gamut has to be remapped to REC709 (or wider) colorspace in the grading process.

I think slog 2 can be mapped with S gamut 3 but yeah S gamut 3.cine is made specifically for Slog 3. 

[jonpais]

10 hours ago, AaronChicago said:

Why not expose accurately? Use a LUT, waveform, and/or light meter.

my exposures are accurate - in fact, since working this way, my clips have never been so consistently well exposed.

[AaronChicago]

4 hours ago, jonpais said:

my exposures are accurate - in fact, since working this way, my clips have never been so consistently well exposed.

Sorry @jonpais I should've mentioned that it was posed to the OP.

[Mark Romero 2]

21 hours ago, AaronChicago said:

Why not expose accurately? Use a LUT, waveform, and/or light meter.

Well... that brings up the point of "what is accurate?" And how much does it differ from us using prosumer cameras (either 8 or 10 bit) and those who might be using higher model cameras.

On 9/24/2018 at 8:20 PM, jonpais said:

With S-Log2, I just meter for brightest important highlight detail - whether it’s a shirt or the face - and the skin tone line on the vectorscope is usually spot-on. 

Hi @jonpais

Can you elaborate a bit on HOW you meter for the highlight? Are you using the zebras? If so, what have you got the zebras set to when shooting SLOG 2?

Thanks in advance.

[jonpais]

1 hour ago, Mark Romero 2 said:

Hi @jonpais

Can you elaborate a bit on HOW you meter for the highlight? Are you using the zebras? If so, what have you got the zebras set to when shooting SLOG 2?

Thanks in advance.

Sure. Here are the settings I use. 

[Mark Romero 2]

7 hours ago, jonpais said:

Sure. Here are the settings I use. 

Thanks!