Heavy banding and noise - a7s II / S-log3

[Isaak]

Hello, I'm finding a huge amount of noise and banding in the sky in footage from my last video shoot with my a7s II. It's probably unusable, so I'm looking for some help in identifying the issue and finding better settings for future shoots.

Attached to this post are screenshots from Premiere of the raw footage, and the same clip after adding a basic S-curve, 100 Contract, and 200 Saturation, using the Lumetri Color effect. Also, a closeup of the noise so you can see how bad it is. 

As you can see, I tried to overexpose so that my blacks and shadows were all above the 50 mark on my waveform. The meter on the camera read 2.0 exposure. I was on 1600 ISO, which I believe is the native level that should produce the cleanest image. The only other factor worth mentioning is that I had a variable ND filter on, though I'd be surprised if that could cause this sort of issue. The rest of the settings are listed below.

I understand that it's an 8-bit camera and a blue gradient like this can be tricky to reproduce, but surely there must be a way to film a clear blue sky in S-log3 and achieve at least decent results. Or should I simply avoid using this log profile for sunny days and gradients?

I've seen a lot of other threads on this topic and tried to use recommended practices in this shoot – especially the standard procedure to overexpose by 2.0 – but the results are so bad that I'm wondering if I'm missing something bigger.

Thanks!

CAMERA SETTINGS:

• Shutter 1/50
• Aperture F7.1
• ISO 1600
• WB 5500K
• XAVC 4K / 24p 100M
• Picture Effect: OFF

PICTURE PROFILE:

• Black Level 0
• Gamma > S-log3
• Black Gamma > Middle / Level 0
• Knee > Auto
• Color Mode > S-Gamut3.Cine
• Saturation 0
• Color Phase 0
• Color Depth 0
• Detail > Level 0 0 0 0 

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[Makeev]

This is a codec problem in the entire A7/A6XXX variations.

[Isaak]

2 hours ago, Makeev said:

This is a codec problem in the entire A7/A6XXX variations.

Thanks for your answer. So, you're saying that there's simply no way of properly shooting a clear blue sky while using S-log3? The footage will always have this kind of noise and banding?

[Makeev]

43 minutes ago, Isaak said:

Thanks for your answer. So, you're saying that there's simply no way of properly shooting a clear blue sky while using S-log3? The footage will always have this kind of noise and banding?

You can try to use the Atomos Ninja V recorder. But our Sony cameras are limited to 8-bit via HDMI. So the solution is only partial and post processing will not be complete anyway. We should wait for Sony A7s3 or similar.

[VTC]

Log3 is a tough puppy to grade. I've never found those nasty artifacts or such severe banding in the Log2 I shoot using same camera.

Pulled this example from 2 years ago. Shadows -100%. Midtones - 87%. Global saturation 21%. No LUT applied yet and still not the banding or artifacts your Slog3 is producing. The external recorder files recorded would yield better results but this shows what 8 bit Slog2 internal produces. You generally won't appreciate the difference 10 bit makes until it's placed SxS on a frame where color is important. 

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Edited April 30, 2020 by VTC

[VTC]

This the first time noticing this or shooting Slog3? How about Drop Boxing a short segment that hasn't been rendered in Premier and let me see what it looks like in DaVinci or Final Cut. Premier could be contributing to this somehow.