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Z6 with N-log 10bit serious video flickering issue at certain ISOs


T.S

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I tested the same desk setting today again. The flickering does not come up when it is only lit by sun light. When I  added a desklamp (with a normal light bulb, no LED) the flicker was there again. The Nikons flicker reduction did not change anything, whether set to „automatic“, „50 hz“ or „60hz". maybe there is a problem with the flicker reduction, not working when recording externally? but I wonder if it really was like this that there are not more people reporting this problem?

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31 minutes ago, mrtz said:

I tested the same desk setting today again. The flickering does not come up when it is only lit by sun light. When I  added a desklamp (with a normal light bulb, no LED) the flicker was there again. The Nikons flicker reduction did not change anything, whether set to „automatic“, „50 hz“ or „60hz". maybe there is a problem with the flicker reduction, not working when recording externally? but I wonder if it really was like this that there are not more people reporting this problem?

have you tried keeping your camera and recorder on for longer time and retesting. It seemed to disappear last time I checked. Will retest again. And yes, this could only be observed with artificial light. 

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I tried again with artificial light and RAW (N-LOG OFF - btw I do not quite understand the difference between RAW with N-LOG ON and RAW with N-LOG OFF - does this make any difference?). This time there was fo flicker at 100 or 400, but again flicker at 160. All clips were about 3-5 minutes long.

I do not know if it really is that some ISO settings always produce flickering and others not, or if it depends on the light situation you are filming.

If so, it would be impossible to know if there will be flicker when filming with artificial light. This would make the camera unusable.

 

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Do you have a way to spin something at a fixed speed and see if shutter speed or fps change a tiny bit while changing ISO?

Maybe a macro lens and a record player under natural light. It would look like a speed calibration test but used in reverse to check the camera instead.

Might have to do some math and print a test chart if you are testing other frame rate than 50/60 depending on where you live.

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mrtz contacted me, because I own the same combination. Did some quick tests and also was able to see this kind of flickering. But only with N-LOG external recording at ISO 4000. Files can be found here: https://www.dropbox.com/sh/6ivc9wodfymeoi4/AADX6umNfdTPP7zawN7ntkrqa?dl=0

Could it be the combination of N-LOG and lowlight? Never noticed anything comparable with properly exposed images.

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You can also test this by displaying the zoomed in Vectorscope of the Ninja. When I input a ProRes RAW HQ Signal, the signal in the vectorscope is moving/flickering at ISO 160 and other ISOs. This flickering will also show in the final file. You can not stop the flickering by choosing other shutter speeds or apertures. It stays.
At other ISOs, when the vectorscope is not moving, there will be no flickering. This is indeed a very strange observation. 

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  • 2 weeks later...
  • 3 weeks later...

I just purchased a Nikon Z7 to shoot NLOG video with the ninjaV. I’ve set up a test shot in a naturally lit interior, no artificial lights, and I see flickering which ruins the shot. It’s visible at multiple ISO’s. I’m running the latest ninja 10.2 and Z7 3.0 firmware

 

This looks like the same issue posted here from a year ago on a Z6 with firmware V1.01

 

https://www.eoshd.com/comments/topic/28747-z6-with-n-log-10bit-serious-video-flickering-issue-at-certain-isos/

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Not sure if this thread is still active but in case anyone else comes by looking for an educated guess:

Ive been shooting video on Nikons for the past 8 years now and I’ve had this issue with everything from my first D3200 to the higher tier D850 and Z6. As far as DSLR’s go, Nikon cameras demand more on the person behind the camera unlike Canon or Sony where the camera does the heavy lifting for you. You gotta really know how to expose your shots and how to set your lenses for the situation which is great for making you a better cinematographer but it’s also a massive pain in the ass if you just want to pull out your camera and get some quick shots. Nikons are really particular and fussy cameras but when you learn them they’re a joy.

Now I’m not 100% sure what the root of the issue is because every time I think I’ve figure it out, it pops back up. I do know it has to do with lighting and frame rates and I’ve noticed it most when the video is shot in low light and 24fps. Changing the aperture speed has helped in the past for me in some situations and using infrared or ND filters can sometimes solve the issue if I need it darker but have the aperture wide open, which first led me to believe it’s an issue with noise or light pollution in the shadows. But then by coincidence I noticed after a shoot that clips shot in the same lighting and same lenses on the same settings on the same camera body had this flickering issue for clips shot at 24fps but not for clips shot in 60fps. Playing with that in post I noticed that the flickering lasted exactly one frame in a 24 FPS timeline. Now frame rate alone isn’t the solution, because with that knowledge I went to a shoot and even at 60 FPS it could still get bad in low light...but frame rate is half the solution and the other half appears to be exposure.

Given that I’ve only had this issue on Nikon cameras, my conclusion is there’s definitely some kind of imbalance specifically with how Nikon hardware processes light at lower frame rates, and I suspect that the camera is given too much time to expose an individual frame before the next frame is processed, leading to this flickering. Since increasing your frame rate is not a sustainable option, the next best thing is to keep ISO permanently locked at 800 or below and control exposure exclusively through lens aperture, shutter speed and onsite lighting equipment. 

As for a solution in post to solve it if you’ve already shot and can’t go back to shoot again, duplicate the clip, overlay it on top of your original clip and move it forward one frame. Play with the Blending or Transparency options in your editing software on the top layer until the flicker disappears. The reason this works is because the two frames’ flickering compete with one another and only last for a frame, so by blending the flickering clips together you’re essentially neutralizing the flicker effect. This has the added effect of creating a sort of simulated motion blur which can work in your favor or to your detriment depending on whether you shot in 24 or 30fps and what you plan to export it as.

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  • 2 weeks later...

I am running into this issue now as well. Mostly on indoor product shoots. I first noticed when I was using the Loawa Probe lens, and I thought it might have just been the lens (needs a huge amount of light). But alas, this is a continuing problem. And this is a problem! This is very frustrating. Anyone heard any new info on this? I've invested a ton in the Z series, and if they don't fix this I will need to trade in for the S1h. This is unacceptable and makes the footage unusable. 

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On 2/14/2020 at 7:06 AM, mrtz said:

I was called by Nikon Support yesterday, and they told me that there will be a firmware update for the problem, maybe in the next or the one after the next. 

I haven't followed the firmware updates. Has the problem been solved?

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  • 2 months later...
  • 5 weeks later...

Just got the Atomos Ninja V to pair with my Nikon Z7. Shooting a properly exposed image in natural or artificial light causes a very subtle flickering accompanied by a green/magenta shift. Codec set to Pro Res HQ - N-log. Very disappointed :( Shooting flat in camera is flawless in comparison. I'm sad to see this thread was started so long ago and it hasn't been fixed yet. Guess I'll be sending the Ninja back.

 

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On 8/14/2020 at 10:33 PM, jpjd said:

Just got the Atomos Ninja V to pair with my Nikon Z7. Shooting a properly exposed image in natural or artificial light causes a very subtle flickering accompanied by a green/magenta shift. Codec set to Pro Res HQ - N-log. Very disappointed 😞 Shooting flat in camera is flawless in comparison. I'm sad to see this thread was started so long ago and it hasn't been fixed yet. Guess I'll be sending the Ninja back.

 

Just to update on what I wrote here. It's a problem with the Nikon not the Atomos. I did several tests directly to Nikon in Flat mode and the problem is there as well! More enhanced in 12 bit N-Log.

Here's my tests...

https://youtu.be/1w69jYu-cIU

and here's the HQ version for download...

https://www.dropbox.com/t/vNjH4yBSImvAhK8H

Hope Nikon can / will fix this. Very annoyed.

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  • 3 weeks later...
On 1/28/2020 at 4:35 PM, Zeng said:

Noticed the same with the first few shots using prores RAW.  But it seemingly disappeared after a while as if the camera needs to "warm up". Will test again. Weird. And flickering was at different ISO settings compared to mrtz's findings. 

Hello Zeng, I’ve noticed the same thing. My issue went away after using the camera and Ninja for a bit. It seemed to “warm up.” Has your issue stayed away?

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