FS700 S-Log2 settings

B

Baddgsx

Well-known member
Hi friends!!!

I got the upgrade for the FS700 and am playing with the Slog2 settings. Indeed, Slog alone has an increase in detail in the low end while retaining good highlights opposed to Cine4. Im wondering if lowering the knee point and slope might retain more detail in the highlights. Has anyone played with the settings for Knee? I noticed the color mode and level have no effect on Slog , ex. standard,still,pro


Thanks,
Chris
 
I too am wondering about Knee. Not sure if it has an effect. The only thing that really seems to have an effect is the Color adjustment on Red.

I need to play with S-Log more, but probably won't until I get my 7Q.
 
im playing with Knee now and noticed the whites are more pleasing with point lowered and the slope lowered. Im going to try a couple tests, unfortunately i dont have a built in Waveform monitor on the smallhd ac7 but i placed my clips in Edius NLE and checked the waveform there. gonna run some more tests.

BTW, New Jersey Sony Service Center is really cool to allow walk ins for upgrade.
 
No need for testing. Slog2s 90 white is at 59ire. U cant go under 75 knee in the manual setting, so Slog2s Knee is much earlier. I cant believe that the setting will overwrite the Slog gamma so the knee setting is absolute senseless when Slog2 is activated.
 
SKYLIKE said:
No need for testing. Slog2s 90 white is at 59ire. U cant go under 75 knee in the manual setting, so Slog2s Knee is much earlier. I cant believe that the setting will overwrite the Slog gamma so the knee setting is absolute senseless when Slog2 is activated.
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when slog2 is activated on the fs700 , knee and slope can be adjusted to users requirement. im seeing changes on the waveform monitor in Edius and in the exposure assist setting in the smallhd ac7 monitor. 75% is the lowest , 105% is the max , and the sony default is 95%knee with a slope of +5
 
Yes but its senseless to Do so. Slog2 gamma has a knee and slope u cant reach with those Manual settings. The settings are there for rec709where it does make Sense to go for 75%. Slog2 is at 59%. U dont get more Highlight information. By setting a Manual knee u will loose Information.
 
Black gamma also has an effect too. Quite often it's difficult to get a 0 level black from Slog, playing with black gamma seems to offer some darkened values but because there is so little shadow detail in 8 bit i'd caution against using it unless you can test your post workflow fully.

I don't know *why* these settings affect the SLog2, they're not really supposed too!

cheers
paul
 
Yes Knee definitely has an effect and cannot be disabled even with Slog2, and I usually set it by eye, looking for the visibility of the slope point (point your camera at a bright gradient) and making sure the clip point is where I want it. I find that 77.5%, +1 gives you pretty nice looking legal highlights that stop at 100%, but otherwise if you dont care about broadcast safe, it's usually the default 95%,0 or 105%,0 to keep the knee point as invisible as possible. Generally knee is a terrible thing since it introduces an unnatural hard angle into your gamma curve, so you'll get the best highlights if you can effectively disable it even though the FS700 doesn't technically let you turn it off.

I just got my FS700 upgraded yesterday and while I'm excited to see that the two new gamma curves completely bypass the terrible NEX color matrix that turned bright highlights different colors, the fact that REC709 800% literally clips off several stops of highlight latitude and trades it for a lot of noisy shadows and that Slog2 completely disables a lot of important PP settings that prevent you from getting a good out of the box look with it makes it a bit hard to see how they will be used in everyday shooting. I was really hoping that Canon Log, I'd be able to use the Slog2 gamma curve and tweak it a bit to a flat but useable final image. Canon's log does this really nicely, but with Slog2 you can turn down your black gamma to bring back contrast a bit, but there is no way to restore saturation or remove the reddish color cast that comes with Slog2. I guess I'll have to wait for the CD 7Q since that will really give us the options we need with LUT monitoring and even recording LUTs to deliver nice looking images on set.

That said, if your workflow involves using a pre-designed SLOG2 LUT in post, it may be best to just shoot with all settings at default so you dont affect the LUT, since it is expecting completely vanilla Slog2 as an input.
 
nyvz said:
I just got my FS700 upgraded yesterday and while I'm excited to see that the two new gamma curves completely bypass the terrible NEX color matrix that turned bright highlights different colors, the fact that REC709 800% literally clips off several stops of highlight latitude and trades it for a lot of noisy shadows and that Slog2 completely disables a lot of important PP settings that prevent you from getting a good out of the box look with it makes it a bit hard to see how they will be used in everyday shooting. I was really hoping that Canon Log, I'd be able to use the Slog2 gamma curve and tweak it a bit to a flat but useable final image. Canon's log does this really nicely, but with Slog2 you can turn down your black gamma to bring back contrast a bit, but there is no way to restore saturation or remove the reddish color cast that comes with Slog2. I guess I'll have to wait for the CD 7Q since that will really give us the options we need with LUT monitoring and even recording LUTs to deliver nice looking images on set.

That said, if your workflow involves using a pre-designed SLOG2 LUT in post, it may be best to just shoot with all settings at default so you dont affect the LUT, since it is expecting completely vanilla Slog2 as an input.
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Don't forget the reason for these curves is to help monitoring for RAW recording primarily. The REC709800 means that you can monitor highlight clips and shadows at the expense of mid range tones but this profile gives you a more accurate constrasty image to view (rather than Slog). So the dynamic range is all there just in the extremes. There's an article on our blog with waveforms showing the REC709800 curve.

The Slog is also for viewing although it is actually very useful day to day. However i find it difficult to pull the black level down to 0, it floats around 16-25 units and out of a possible 255 values, loosing 16 steps is quite a substantial hit. Having said that in high key work it is very nice to work with but i'm super cautious shooting normal/darker stuff on it, preferring the cinegammas.

Also because SLog2 is a well defined curve you don't want to be messing with the shape of it because the Slog LUTS won't work very well - bring down the blacks but don't mess with black gamma or knee...

cheers
Paul
 
paulcurtis said:
Don't forget the reason for these curves is to help monitoring for RAW recording primarily. The REC709800 means that you can monitor highlight clips and shadows at the expense of mid range tones but this profile gives you a more accurate constrasty image to view (rather than Slog). So the dynamic range is all there just in the extremes. There's an article on our blog with waveforms showing the REC709800 curve.

The Slog is also for viewing although it is actually very useful day to day. However i find it difficult to pull the black level down to 0, it floats around 16-25 units and out of a possible 255 values, loosing 16 steps is quite a substantial hit. Having said that in high key work it is very nice to work with but i'm super cautious shooting normal/darker stuff on it, preferring the cinegammas.
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That is not what I have found and not what "800%" would indicate. Slog and the old CINE gammas are all 1300% gammas and they all clip at the same point when used at base ISO, whereas at base ISO REC709800 clips much earlier and does not let you see that extra "500%" of the luminance range. You can easily see this if you set your gain to 0db or ISO to 400 in CINE1 so that it stays at base ISO for all other gammas. Because of this removal of the top highlight range, REC709800 is very bright and noisy compared to all the other gamma curves, and seems to me to be a very bad representation of normal exposure, unless your normal exposure involves clipping a few stops of highlights and brightening your shadows to the point where your midtones are noisy.

Without an external recorder and LUTs it seems if we want the benefits of Slog2 we are stuck shooting without knowing quite what we are getting.

Given the 8bit highly lossy AVCHD codec, I'd think SLOG2 would go a much longer way if we could push the shadows down and saturation up BEFORE compression...


paulcurtis said:
Also because SLog2 is a well defined curve you don't want to be messing with the shape of it because the Slog LUTS won't work very well - bring down the blacks but don't mess with black gamma or knee...
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Right that is what I was saying, but obviously that's only if premade LUTs are to be used in post.

Another thing that's odd is that the COLOR DEPTH settings still work with SLOG2... I hoped maybe those could be used to boost saturation a bit, but not really as they mostly affect color saturation in the shadows and highlights in a pretty unnatural way.
 
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nyvz said:
That is not what I have found and not what "800%" would indicate. Slog and the old CINE gammas are all 1300% gammas and they all clip at the same point when used at base ISO, whereas at base ISO REC709800 clips much earlier and does not let you see that extra "500%" of the luminance range. You can easily see this if you set your gain to 0db or ISO to 400 in CINE1 so that it stays at base ISO for all other gammas.
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Well from 800% to 1300% is just a half stop :>
 
SKYLIKE said:
Well from 800% to 1300% is just a half stop :>
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I know what you are saying, but are you sure? I mean I understand it is supposed to be luminance, but wouldn't that imply that 1300% is a total of about 10.5 stops? But SLOG2 1300% was designed for cameras with ~14stops...

And frankly it looked like more than half a stop on my LCD...
 
The percentage only describes the stops over 18%gray. 36% 1 stop -> 72% 2stops -> 144% 3stops -> 288% 4stops -> 576% 5stops -> 1152% 6stops -> 1300% 6,..... stops! How many stops under 18% depends on the camera.
 
My observation of the REC709 800 shows that it holds the full range of the camera (12-13 stops) but holds detail in the very upper and the very lower parts at the expense of detail in the mids. It strikes me as an exposure tool - you see clipping in the highs (esp with zebra) and clipping in the blacks.

It makes sense that the PP settings can modify some of these characteristics. The RAW files hold metadata for the PP settings and a confirmation from Sony meant that the settings are purely for how the display was monitored (i.e. there are no knee settings for linear raw). So the PP settings can tweak the LCD display for monitoring purposes.

If Sony wanted to give us a truly flexible way to record in 8 bit then they would allows us to upload LUT files so we could generate our own curves.

Or lets just concentrate on getting Linear out of the box and then we can mess with the colours afterwards. Once the O7 has the output then it's display can use LUTs or whatever the tools are available to judge exposure based on the actual data being recorded.

cheers
Paul
 
Rec 709 800% seems like it would work great in low light situations. i did some quick tests and noticed i was even using the built in ND filter indoors. With slog2 in the same lighting condition i had to bump up the gain or open up the Aperature to expose correctly.
 
paulcurtis said:
My observation of the REC709 800 shows that it holds the full range of the camera (12-13 stops) but holds detail in the very upper and the very lower parts at the expense of detail in the mids. It strikes me as an exposure tool - you see clipping in the highs (esp with zebra) and clipping in the blacks.
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Are you at 0db? That's not at all what I'm seeing. At 0db, I see highlight detail in every gamma except REC709800 where it is clipped off.

Baddgsx said:
Rec 709 800% seems like it would work great in low light situations. i did some quick tests and noticed i was even using the built in ND filter indoors. With slog2 in the same lighting condition i had to bump up the gain or open up the Aperature to expose correctly.
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Remember gamma is basically software gain and "GAIN" is hardware gain. It won't really give you more sensitivity, it just brightens those noisy shadows so you see more noise. REC709800 is taking the same data as SLOG2 and CINE4 and brightening its gamma curve which reveals a lot of noise. From everything I'm seeing REC709800 even at 0db is really heavy on the noise. A really bright gamma like that would be great since it should have a lot of highlight range except REC709800 seems to clip a lot of the highlight range you would be gaining. I can't find any BLACK GAMMA setting for REC709800 that gets rid of the significant posterization I'm seeing in the shadow areas.
 
nyvz said:
Are you at 0db? That's not at all what I'm seeing. At 0db, I see highlight detail in every gamma except REC709800 where it is clipped off.



Remember gamma is basically software gain and "GAIN" is hardware gain. It won't really give you more sensitivity, it just brightens those noisy shadows so you see more noise. REC709800 is taking the same data as SLOG2 and CINE4 and brightening its gamma curve which reveals a lot of noise. From everything I'm seeing REC709800 even at 0db is really heavy on the noise. A really bright gamma like that would be great since it should have a lot of highlight range except REC709800 seems to clip a lot of the highlight range you would be gaining. I can't find any BLACK GAMMA setting for REC709800 that gets rid of the significant posterization I'm seeing in the shadow areas.
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yup
 
nyvz said:
Remember gamma is basically software gain and "GAIN" is hardware gain.
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Just nitpicking but gamma and gain are two quite different mathematical operations.

Gain is a multiplication across all values, whereas gamma moves the mid tones only (keeping black and white the same). Gain is like contrast in a way. There's also Lift which is more akin to what Noah means (i think), lift is adding or subtracting uniformly to the signal.

So as Noah says, the hardware gain *may* adjust the signal at the sensor (no one knows exactly what the 700 does) before output. Whereas software gain would be manipulating the values after compression.

cheers
Paul
 
paulcurtis said:
Just nitpicking but gamma and gain are two quite different mathematical operations.

Gain is a multiplication across all values, whereas gamma moves the mid tones only (keeping black and white the same). Gain is like contrast in a way. There's also Lift which is more akin to what Noah means (i think), lift is adding or subtracting uniformly to the signal.

So as Noah says, the hardware gain *may* adjust the signal at the sensor (no one knows exactly what the 700 does) before output. Whereas software gain would be manipulating the values after compression.

cheers
Paul
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Hah yes thats true, but I was referring to the gamma curve which is perhaps a bit of a misnomer since gamma curves in practice do all kinds of different operations that affect black levels, white levels, shadows, mids, highs in complex ways that may not even be easily reduced to a mathematical operation. They are really designed as LUTs but someone decided to call them gamma curves :)
 
nyvz said:
Hah yes thats true, but I was referring to the gamma curve which is perhaps a bit of a misnomer since gamma curves in practice do all kinds of different operations that affect black levels, white levels, shadows, mids, highs in complex ways that may not even be easily reduced to a mathematical operation. They are really designed as LUTs but someone decided to call them gamma curves :)
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Can't argue with the misuse of the name :)

On the 700 the black gamma applies an additional gamma adjustment at the bottom range of the chosen 'gamma' curve for the main profile. The range that it affects is low med high, which isn't very useful for us, that refers to how much of the bottom of the curve is affected, the you have the positive or negative adjustment.

I really have no idea why we have one mechanism for the top of the curve (knee) and totally different approach at the bottom (black gamma)

On Slog, from my memory, adjusting the black gamma brings down the very shadow part which makes it look like it's giving you a lower black level, but on reflection i don't think it is (unless there's a bug in the PP system). I stand by my observation that with Slog you don't get black values down to 0 - has anyone managed that?

cheers
paul
 
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