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Terrible noise on a7rii SLog2 in multiple conditions


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Hi all,

 

I've been doing some tests with my A7rii, trying to get a cinematic look (of course), filming in Slog2 (pp7), and also trying some shots with Cine gamma rather than Slog. 

 

I seem to be having an issue, which is basically getting constant noise in any dark areas. I'm following all of the 'correct' procedures, overexposing by 1 or 2 stops etc, but can't seem to get rid of the noise. It's really nasty, blocky digital noise too. The problem is exponentially worse in low-light, but I get it in bright sunlight as well. Any ideas? I'm wondering about trading my a7rii for an a7sii so at least low light won't be as much of an issue.

 

I've attached some screenshots at 100% (these have a LUT on, but noise is still present in untreated footage, worse if anything). Here is a rough idea of my set up:

 

S35

variable ND filter to keep 1/50 shutter 

aperture between 3.5-5 for these shots

Sony FE 24–240mm lens

ISO lowest 800 – highest 6400 (doesn't make a difference to noise at all)

PP7 mainly

XACV S at 4K and HD, 100mbs and 50mbs, doesn't make a difference to noise

 

Cine gamma seems to produce slightly less noise...but not much

 

Thanks!

 

 

 

 

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A few more gnarly shots, taken at 3200 ISO with Slog2 (the worse one). And 1600 ISO, Cine 2, in a reasonably well lit room, a bit on the dingy side. But if I compare to this video, seems kind of strange (clean footage at 5000 ISO).   

   

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I think you are seeing the results of massive compression. Did you ever check how it looks like if you feed video straight from the camera into a TV?

 

S-log on a camera with only 8 bit 420 recording is not much more than a marketing gimmick. There's a reason why Panasonic is soon offering the GH5 with 10 bit 422. Others will be forced to follow, think A7R III …

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I think you are seeing the results of massive compression. Did you ever check how it looks like if you feed video straight from the camera into a TV?

 

S-log on a camera with only 8 bit 420 recording is not much more than a marketing gimmick. There's a reason why Panasonic is soon offering the GH5 with 10 bit 422. Others will be forced to follow, think A7R III …

Thanks, yeah I think you're right, it's basically as if the camera is faking a log look. It seems like any image where there is contrast is where the problems occur (e.g. the shadows on a bright day), although even if I just shoot the sky I get considerable noise. I haven't tried going straight into an hd monitor yet, but the noise is also noticeable in the EVF before shooting. 

 

Still wondering whether a switch to the A7Sii will make the problem better though, although i am a bit worried about autofocus issues as I rely on that while shooting with glidecam. 

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I doubt it would be better, after all it's the same sensor and still 8 bit. I own an A7S and the A7R II and both are not really good with Slog, while the noise levels in photography are impressively low.

 

I tend to use Cine4 when filming, but I have a Shogun for external recording, which improves the situation by avoiding massive H.264 compression. BTW, Slog-2 should be overexposed by up to 2 stops and then you should use a proper LUT and squeeze the shadows down in a grading application (I use DaVinci Resolve). And don't use Slog-3, it's overkill and makes things even worse.

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I doubt it would be better, after all it's the same sensor and still 8 bit. I own an A7S and the A7R II and both are not really good with Slog, while the noise levels in photography are impressively low.

 

I tend to use Cine4 when filming, but I have a Shogun for external recording, which improves the situation by avoiding massive H.264 compression. BTW, Slog-2 should be overexposed by up to 2 stops and then you should use a proper LUT and squeeze the shadows down in a grading application (I use DaVinci Resolve). And don't use Slog-3, it's overkill and makes things even worse.

Thanks again for your response and the info, yeah I'm having better results with the cine gamma, the noise is still there, it's just in the dark so not as visible. slog really lulls you into a false sense of security by making you think you have all this nice range to play with but then you have to crush it anyway, it's totally pointless. I was overexposing by 2 stops, seemed to make it worse, especially in outdoor situations where I was using an ND filter to maintain 180 degree shutter. I think I'll put a few clips together anyway just to raise awareness of the issue. 

 

Thanks for the tip with the shogun, I think I'm going to get my hands on an a7sii and a shogun for the day and work out what the best option is! Still throughly disappointed with the quality compared to my much older and cheaper GH3, and no word from Sony support but there you go!

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I wouldn't say it's totally pointless. I use Slog-2 occasionally when scene contrast ist very high.

 

But you need to understand that the DR of modern sensors is much higher than what 99% of todays displays can show to the user (normally Rec 709). Consequently, you'll need to make an aesthetic decision how to pull your shadows down (and the highlights up) anyway, like a nice cinematic S-curve. Slog is giving you the freedom of decision in post, while other profiles will burn it in while recording. But for any scene with not so demanding contrast, it's far easier to work with one of the other profiles.

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  • 2 weeks later...

I welcome comments from all but I am finding (shooting video in bright conditions) that I best results exposing to the 18% grey card and setting mid point at 32 as Sony suggests. When I ETTR and apply the Sony LUT things can easily get blown out. Your shots do NOT look anything like over exposed. If you were the windows by the Belisha beacon would be white or blown a little.

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