Z9 DX mode for video

[urbo73]

I searched but couldn't find details anywhere. Does anyone know how the Z9 (or Z8) outputs 4K when in DX mode? For stills, it's clear you're getting smaller 19MP files using a smaller portion of the FF lens/sensor, but I'm not sure what it's doing for video. If I'm shooting 4k/24p ProRes 422 HQ in FX and then punch into DX mode for more reach, I'm still getting a 4k ProRes 422 HQ file with the same bitrate. Any specifics on what the camera/sensor is doing?

 

[Nimi]

I searched but couldn't find details anywhere. Does anyone know how the Z9 (or Z8) outputs 4K when in DX mode? For stills, it's clear you're getting smaller 19MP files using a smaller portion of the FF lens/sensor, but I'm not sure what it's doing for video. If I'm shooting 4k/24p ProRes 422 HQ in FX and then punch into DX mode for more reach, I'm still getting a 4k ProRes 422 HQ file with the same bitrate. Any specifics on what the camera/sensor is doing?

Isn't DX natively 4k or so? App S35 sensor size, cropped further to 9x16.

 

[urbo73]

Isn't DX natively 4k or so? App S35 sensor size, cropped further to 9x16.

I think so, but not 100% sure. I'm only wondering if there's any image quality loss. If it's still oversampled and not binned 4K, then DX for video makes total sense to use when you need more reach. For stills, not so much - a different story. For video, it seems like great thing. Of course one can shoot 8K and zoom in post, but that's another story.

 

[Nimi]

I think so, but not 100% sure. I'm only wondering if there's any image quality loss. If it's still oversampled and not binned 4K, then DX for video makes total sense to use when you need more reach. For stills, not so much - a different story. For video, it seems like great thing. Of course one can shoot 8K and zoom in post, but that's another story.

Question to me would be about loss of dynamic range vis a vis 8k, full frame. Maybe a stop?

 

[Wes Peterson]

I searched but couldn't find details anywhere. Does anyone know how the Z9 (or Z8) outputs 4K when in DX mode? For stills, it's clear you're getting smaller 19MP files using a smaller portion of the FF lens/sensor, but I'm not sure what it's doing for video. If I'm shooting 4k/24p ProRes 422 HQ in FX and then punch into DX mode for more reach, I'm still getting a 4k ProRes 422 HQ file with the same bitrate. Any specifics on what the camera/sensor is doing?

Its certainly outputing 4k in DX mode. Im not sure HOW its getting DX 4k tho, could be oversampled 5.4k. Unless oversampling is enabled, FX 4K option in the z9 is the worst image quality (line skipping) I suspect it might actually be BETTER in DX tho I havent bothered with testing it. If you are worried about bitrate just shoot 2 separate clips of the same moving object (oscillating fan etc) and compare the files.

 

[urbo73]

Its certainly outputing 4k in DX mode. Im not sure HOW its getting DX 4k tho, could be oversampled 5.4k. Unless oversampling is enabled, FX 4K option in the z9 is the worst image quality (line skipping) I suspect it might actually be BETTER in DX tho I havent bothered with testing it. If you are worried about bitrate just shoot 2 separate clips of the same moving object (oscillating fan etc) and compare the files.

Yeah, that's the question - how is it outputting 4K in DX? I'm not worried about bitrate - I stated it's the same in FX or DX for 4K ProRes422 HQ.

Not sure what you mean by enabling oversampling. The only thing one can enable is "extended oversampling", which only applies to 4k/60 or 4k/50, not 4k/24 or 30, which I understand IS oversampled from 8K.

What do you mean by FX 4K is the worst? In what codec?

 

[Wes Peterson]

Yeah, that's the question - how is it outputting 4K in DX? I'm not worried about bitrate - I stated it's the same in FX or DX for 4K ProRes422 HQ.

Not sure what you mean by enabling oversampling. The only thing one can enable is "extended oversampling", which only applies to 4k/60 or 4k/50, not 4k/24 or 30, which I understand IS oversampled from 8K.

What do you mean by FX 4K is the worst? In what codec?

Yes by "oversampling" I mean what Nikon calls "extended oversampling"

FX 4k is the worst in every codec except h265 10 bit 4k60 WITH extended oversampling on. Without that oversampling the Z9 skips lines of pixels to get the required resolution across the full width of the frame. That can lead to sawtooth patterns on angled edges in the video when viewed closely or when 4k video is cropped to 1080. Its of little concern if no cropping is done and of even less concern when shooting 4.1k RAW. That being said RAW 8.3k, 5.4k (DX) and 2.3X crop are all pixel for pixel. That leads me to believe that DX 4k in prores 422 might actually be better as well.

 

[urbo73]

Yes by "oversampling" I mean what Nikon calls "extended oversampling"

FX 4k is the worst in every codec except h265 10 bit 4k60 WITH extended oversampling on. Without that oversampling the Z9 skips lines of pixels to get the required resolution across the full width of the frame. That can lead to sawtooth patterns on angled edges in the video when viewed closely or when 4k video is cropped to 1080. Its of little concern if no cropping is done and of even less concern when shooting 4.1k RAW. That being said RAW 8.3k, 5.4k (DX) and 2.3X crop are all pixel for pixel. That leads me to believe that DX 4k in prores 422 might actually be better as well.

Interesting. Where did you read that?

I read that the Z9 does full pixel readout at 4K FX 23.98, 25, 29.97p in both ProRes 422 HQ and H.265. Later firmware added “extended oversampling” to do the same full pixel readout at 50 and 60p.

 

[Wes Peterson]

Interesting. Where did you read that?

I read that the Z9 does full pixel readout at 4K FX 23.98, 25, 29.97p in both ProRes 422 HQ and H.265. Later firmware added “extended oversampling” to do the same full pixel readout at 50 and 60p.

I dont know you could be right, it might just be the raw 4k that sucks

 

[urbo73]

I dont know you could be right, it might just be the raw 4k that sucks

I checked, and what I posted above is true, which makes total sense. I know RAW is a lot noisier than H265, so maybe that's the issue you're seeing.

One source:

And another - pertinent quotes below the link, the second of which answers my initial question about DX (yes, it's oversampled):

Nikon Z8 Announced - Newsshooter

Nikon has announced its new Z8 mirrorless hybrid which was designed to fit into the lineup between the Z7 Mark II and their flagship Z9.

www.newsshooter.com

"Now, according to Nikon the Z8 can record 10-bit 4K UHD footage in-camera with full pixel readout at 23.98, 25, 29.97p as ProRes 422 HQ or H.265 video. You can now do 4K UHD at up to 60p with a full sensor readout. By turning this on it optimizes image readout for improved image quality when you are shooting 3840×2160 60p or 3840×2160; 50p. "

"When you are recording video in resolutions of 4K UHD or lower you can select a DX crop format This is done with a full pixel readout and it allows you to drastically increase your focal range without changing lenses."