A7sii slog3 avoid banding (especially in skies)

llirik

llirik

Well-known member
Hey Everyone,

At first, slog3 was great in my use, especially in more controlled lighting or just darker areas... but now I've run into extreme banding issues when it comes to sky - way more than I had with slog2.

Here's a shot of the footage before anything, and then after LUT and grading. Note, I am using slog3 optimized luts (tho there are few of them online), and tried luts that take slog3 to slog2, or slog3 to rec709.

Screen Shot 2015-11-09 at 10.49.28 PM.jpgScreen Shot 2015-11-09 at 10.49.36 PM.jpg

The weird thing about this is that slog2 I would almost exclusively use on such bright, outdoor shots as it kept my DR... but now it seems to be more turned for darker scenes.

Granted, perhaps the LUTs i'm using are still not terribly well calibrated... but you can actually see the banding in the untouched image.

Any advice is appreciated. And if anyone knows of "smoothing" plugins or tricks that would work well in FCPX to fix this up, it would be appreciated.
 
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I don't think there is any DR advantage for Slog3 over Slog2 in A7sii...They clip at the same white point, and the deep shadows are not gonna be usable anyway.

I tried to shoot slog2 + Sgamut3.cine, and then you can apply a Slog2 to Slog3 LUT, and then you can grade it as Slog3, if that's important to you. Recording at Slog2 is a lot forgiving with banding, and I don't think you lose anything with DR in the case of A7sii.
 
pacinoho said:
I don't think there is any DR advantage for Slog3 over Slog2 in A7sii...They clip at the same white point, and the deep shadows are not gonna be usable anyway.

... and then you can apply a Slog2 to Slog3 LUT, and then you can grade it as Slog3
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Curious, where did you find a Slog3 to Slog3 LUT?
 
blafarm said:
Curious, where did you find a Slog3 to Slog3 LUT?
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I think it was with a plugin update, most likely Color Finale, or maybe some other one that I've done recently. I'm not certain though, as been picking up every slog3 thing i can find.
 
Another issue I'm finding... is white balance shift in between frames... i.e., in the same shot. Would that be the AWB messing up? I haven't had the issue before on the a7s, so not sure if it could be something else.

Screen Shot 2015-11-10 at 12.52.07 AM.jpgScreen Shot 2015-11-10 at 12.52.14 AM.jpg
 
The banding is in the shot so it's not the LUT. It just shows up more after grading. these cameras are great but we have to be very careful since it's razor thin with 8bit 4:2:0. I don't shoot Slog3. I barely shoot Slog2 I think the CINE gammas are a nice medium for a 8bit camera. We tend to get close to REC709 anyway and this DR chasing is coming at a steep price for IQ. YMMV.
 
Check out LUTCalc, you can generate a Slog2 to slog3 LUT with colour space pass through, or converting to many other gamma curve.
 
* AWB is pretty good, but these issues are horrible. There should be an option for AWB without changes while recording (actually that should be the default bahavior).
* No DR advantage by using slog3 --> stick to slog2, with sgamut3.cine if you want it. slog3 is just going to create more banding issues.
* LUTcalc is awesome.
 
If you want to grade a lot then Slog2 and sgamut3.cine will produce an extremely flat image. I would use caution because the image will break if you try to push it to hard. Log mode is for contrasty images. Use it for what it's meant for. The CINE gammas are easier to work with.
 
I don't have an a7S II, I've never played with sgamut3.cine. By what I read on this thread, slog3 is pointless, sgamut3.cine is good. But go there and see what knowledgeable people with hands-on experience are saying...
 
banding in an 8bit 420 file in super flat and aggressive gamma curve like Slog3 is not a surprise at all. You need a 10bit recording for Slog3. An external recorder should be able to remedy. Internally, I'd shoot in Slog2 or Cine 2/4.
 
k0bayashi said:
banding in an 8bit 420 file in super flat and aggressive gamma curve like Slog3 is not a surprise at all. You need a 10bit recording for Slog3. An external recorder should be able to remedy. Internally, I'd shoot in Slog2 or Cine 2/4.
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i did not know that the A7sII has 10bit out? even if the recorder can record 10 bit, if the output is 8bit, recording it in 10bit does not improve the bit depth...
 
k0bayashi said:
banding in an 8bit 420 file in super flat and aggressive gamma curve like Slog3 is not a surprise at all. You need a 10bit recording for Slog3. An external recorder should be able to remedy. Internally, I'd shoot in Slog2 or Cine 2/4.
Click to expand...

A7s II is 8bit 4:2:2 out from HDMI. Going to an external recorder gets you a much better codec with less compression but doesn't get you 10bit color. It's 8bit color recorded in 10bit. No magic here it is what it is.
 
Samuel H said:
* AWB is pretty good, but these issues are horrible. There should be an option for AWB without changes while recording (actually that should be the default bahavior).
* No DR advantage by using slog3 --> stick to slog2, with sgamut3.cine if you want it. slog3 is just going to create more banding issues.
* LUTcalc is awesome.
Click to expand...

For now, I'm going to stick with shooting in slog2 as I have more experience and it does seem a bit more forgiving.

I HAVE noticed an improvement with slog3 in one particular instance: it helps greatly to keep away blown out windows. In SLOG2, i needed to always be mindful and expose just barely to keep detail outside the windows, but still have good exposure inside the vehicles. SLOG3 definitely increases the DR in this instance.

But the AWB issue is terrible. I didn't notice it on my a7r2... just the a7s2.

Here's how the video turned out. Not terribly happy with all the issues I had to contend with image wise compared to my previous a7s + shogun setup... but it DID allow me to get unique angles due to the small size and weight.

 
In A7sii Slog2 and Slog3 clip at the same white point. How does it help with blown out window in slog3?? Unless you set lower exposure?
 
pacinoho said:
In A7sii Slog2 and Slog3 clip at the same white point. How does it help with blown out window in slog3?? Unless you set lower exposure?
Click to expand...

Well yes, but the detail that's retained in shadows is higher than in slog2, giving for a more balanced result with less work recovering involved.
 
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