January 9, 2017 at 1:04PM

5

Weird Noise in slog-2 on the sony a6500

Hey guys,

I recently bought a a6500 to shoot in slog. I come from the 5D mkiii's magic lantern raw footage, and wanted to change because the workflow is a hassle and the files are just too big.

After shooting a few times with the a6500, i started noticing weird pixels or noise in my footage after applying a LUT. I crush the blacks to try to remove it and add a denoiser, but some of it still stays.
I shoot in slog-2
Do i have to light my scenes better or is there something i can do in camera?

Here are some examples

https://drive.google.com/open?id=0B2NqWwOlQErjaTBUeHVuTmhvVlU

Thank you!

8 Comments

s-log2**

January 9, 2017 at 1:14PM

0
Reply

That's "banding" caused by the CODEC compression and the 8-bit format you're recording with.

You can minimize banding by adding a very small amount of gaussian-noise to your video image, which will make your image look slightly grainier but it should get rid of most of the banding.

I've also heard of people adding film-grain to their footage and getting similar results to adding a tiny bit of gaussian-noise.

January 9, 2017 at 5:14PM

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Guy McLoughlin
Video Producer
33299

Thanks! I'll look into it :)

Andrew Tchernilevskii

January 11, 2017 at 12:20PM

It does seem as if part of the problem is banding, but even after adding noise/grain and change it to 16/32bit, i still get this here https://drive.google.com/file/d/0B2NqWwOlQErjSnloQkZnS2R0LVk/view?usp=sh...

Can you tell me if this is still banding or something else?

Thanks!

Andrew Tchernilevskii

January 11, 2017 at 12:49PM

Your original footage is still 8bit.

January 12, 2017 at 5:18PM, Edited January 12, 5:18PM

5
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Keith Kim
Photographer
1636

>>>It does seem as if part of the problem is banding, but even after adding noise/grain and change it to 16/32bit, i still get this here. Can you tell me if this is still banding or something else?

That's 8-bit macro-blocking. Here's a picture of the same sort of problem from a Sony FS5 camera : http://www.eoshd.com/wp-content/uploads/2016/01/fs5-blocking.jpg

The problem occurs because there is not enough chroma ( color ) information to properly record the actual color range being displayed, so the encoder dithers the image to try and make up for this missing data.

Sometimes you can reduce this effect by shooting in 4K and then down-rezzing your image to 1080p with a CODEC that will generate 1080p 4:4:4 color from the original 4K 4:2:0 footage. ( I use the free Cineform CODEC to do this for green-screen footage )

Lastly you can use an external recorder that can record 4:2:2 color at a much higher data-rate than your camera can, and this will often fix the problem.

This is one of the reasons I'm hyped about the new Panasonic GH5 that records 10-bit 4:2:2 internal video, as it should eliminate banding and macro-blocking that I sometimes see with my current GH4 beastie.

January 12, 2017 at 6:13PM, Edited January 12, 6:17PM

2
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Guy McLoughlin
Video Producer
33299

Wow! Really helpful. I shoot in 4K and was manually downsizing to 1080p!

Andrew Tchernilevskii

January 15, 2017 at 7:26PM

And one other thing you should definitely try if you edit with DaVinci Resolve, Vegas Pro 13 or 14, or Final Cut Pro X...

Recently I've been experimenting with Jacob Balazer's free Logarist LUT system...

www.logarist.com

Which is kind of blowing me away with the results I am getting using several different Sony and Panasonic cameras, including a Sony X70 ENG camera I use. ( mainly shooting Sony Cine1 (HyperGamma 4) footage )

The Logarist system is giving me much better color and contrast control compared to other tools I've tried, and there's a chance it might help with your footage.

It's free, so it's definitely worth investigating.

January 17, 2017 at 5:42PM, Edited January 17, 6:06PM

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Guy McLoughlin
Video Producer
33299

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