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Nikon Z6 AF Confirmed Not Working with NLog

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So as some of you know I did some testing with the new Nikon Z6 to see how it compared to the current AF champion ... the Canon 1DXMK2. That post is here if interested. In my testing I was befuddled by struggles with the Nikons Face Detect AF. In all the reviews that I had read and watched online the Nikon Z6 performed head to head against the best competitors. So say it's performance in video mode trumped the Sony A7III, which is no mean feat. But yet in my personal testing I could not seem to get even mediocre AF performance. Honestly, I was starting to think my unit was defective. It's then that I decided to methodically explore all situations when and how the AF was failing. I made sure lighting was adequate for proper exposure, while keeping the ISO low; never exceeding 800, which is the minimum for NLog. I conducted the test as follows:

1. Recording internally, 8 bit, battery powered/ac powered, Default profile (NLog not available internally) result: AF GOOD.
2. Recording externally, 10 bit, battery powered/ac powered, NLog: Off - result: AF GOOD
3. Recording externally, 10 bit, battery powered/ac powered, NLog: On. - result: AF BAD

I think it's safe to say that if you were thinking of getting the Nikon Z6 to record externally in 10 Bit with NLog, you may want to hold off a bit.  The root cause of this issue cannot be determined by this testing. It is possible it is processor load related. And if so a fix may or may not be possible in firmware.

Here is the test:

 

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EOSHD Pro Color for Sony cameras EOSHD Pro LOG for Sony CamerasEOSHD C-LOG and Film Profiles for All Canon DSLRs

Thanks for the test. So, from your results, 10 bit alone is not the cause of the problem. Is there more processing power needed in N-Log compared to other picture styles? I am not sure so. It could be another thing related to N-Log, maybe a bug, under expousre or so.

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Ok, all of this speculation about exposure is a bit much. Here is a quick test I just did with ample... ample light. As you can see, after a quick pan to the center of the room to find a different focus point, when I re-center the camera with my face in the scene again it cannot recognized my face. It just sits out of focus. If I am talking it still does not find me. I have included some shots from the Ninja. Trust me when I tell you, under/over or correctly exposed... with NLog enabled AF becomes unreliable. Hey folks it's your money. I'm just sharing what I have found. 

 

 

Nikon Z6 NLog On.jpg

Nikon Z6 NLog Off.jpg

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External 10bit N-Log with the Z 7 AF is quite good ... have not taken the time to compare as I always use an external recorder with 10bit N-Log when using the Z 7.

Is this AF on the Z 6 with the 24-70 or with all three native lenses?

 

 

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So if AF is good with 10 bit non N-Log, it does not seem to be a lack of CPU power.

The difference between N-Log and other picture style should be N-Log's BT2020 color space.

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Log profiles involve collecting a larger data set than normal and then conforming it to fit a smaller data space using an algorithm. That would require more processing than non-log, so it would not be surprising to see things like AF affected if the processor is operating near it's limits. 

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Good thing I saw this post cuz I was just about to place an order for their 50mm  F1.8. 

I can confirm this too. Z 6 video AF don't focus for shit when recording via external recorder and 10bit or 8bit and Nlog is on. This would have being a deal breaker for me if I knew it before I buying the camera. Nikon better fix this soon! All my future purchase of any Nikon product is put on hold until they resolve this problem. How can we bring this issue up to Nikon?

I am starting to feel like I should have gone with Sony. Let's wait and see what the A7S III will bring to the table.

I still don't understand how it will work on the Z 7 but not on the Z 6. 

On 1/2/2019 at 1:02 PM, docmoore said:

External 10bit N-Log with the Z 7 AF is quite good ... have not taken the time to compare as I always use an external recorder with 10bit N-Log when using the Z 7.

Is this AF on the Z 6 with the 24-70 or with all three native lenses?

 

 

I tested it with the 24-70 lens. 

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On the Z 7 there are 493 AF PDAF sites ... on the Z 6 there are 273 AF PDAF sites ... do not have a clue if this would account for the difference.

My setting for AF is AF-F Wide area ... not messing with face detect ... so it also may not be good if the issue is face detect.

 

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It already sucks that you gotta go external to shoot log on the Z but it also breaks the AF?!! WTF..

That is super wack and really should be pointed out to potential buyers.

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12 hours ago, liork said:

So the AF issue happens also in 8 bit N-Log? Hopefully looks like a bug.

N-Log is only 10 bit and only to an external recorder ... you can simultaneously record UHD 8 bit internal but not N-Log.

Nikon restricted it to 10 bit as most Log is kinda challenged with the limited color space in 8 bit. Canon has a decent 

8 bit log ... but probably because their color science is good enough people are not pushing it in post.

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2 minutes ago, docmoore said:

N-Log is only 10 bit and only to an external recorder ... you can simultaneously record UHD 8 bit internal but not N-Log.

Nikon restricted it to 10 bit as most Log is kinda challenged with the limited color space in 8 bit. Canon has a decent 

8 bit log ... but probably because their color science is good enough people are not pushing it in post.

It seems you do have the ability to install custom color profiles though, like Andrew Reid's Zlog. Its not 10 bit, but if you need auto focus seems like a good option for now. 

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Correct

I have Andrew Reid's ZLog but most of my shoots are controlled on a major tripod and video head ... external recorder ... and again ... AF seems to be acceptable

for me on the Z 7 with Nikon Z-Log in 10 bit.

If I am traveling with the camera ... without all the ephemerata of recorder etc then AR ZLog will be great.

 

 

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Just now, docmoore said:

Correct

I have Andrew Reid's ZLog but most of my shoots are controlled on a major tripod and video head ... external recorder ... and again ... AF seems to be acceptable

for me on the Z 7 with Nikon Z-Log in 10 bit.

If I am traveling with the camera ... without all the ephemerata of recorder etc then AR ZLog will be great.

 

 

Yeah hopefully its something they can fix via firmware somehow. That said its still a sub $2000 camera recording 10 bit full frame 4k. Pretty impressive with or without auto focus. 

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1 hour ago, docmoore said:

90 percent of my lenses are not AF

Nice for certain shoots but not a deal breaker...

FF 4K 10 bit is a valuable addition to the mirrorless range of cameras.

It was the Z 7 or the Canon C200 ... not missing the Canon at all.

The only competition it has is the Canon EOS R, though I don't know if that does non cropped 4k externally?

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44 minutes ago, thebrothersthre3 said:

The only competition it has is the Canon EOS R, though I don't know if that does non cropped 4k externally?

No cropped like the internal ... it is 10 bit 4:2:2 ... shame it is not FF.

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Hey @DBounce, I've just came across a dpreview forum thread talking about your video, and someone suggests this :

Quote

Turning on the 'View Assist' HDMI option applies Nikon's built-in LUT to the previewed N-Log footage in LV, which may fix the AF issue if it indeed is caused by the lower contrast of the LV video feed that's also used by the AF system.

Described in this video (0:53):

Any idea if it is relevant ?

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