D800 Power Aperture demonstration

Horshack, I watched the Live View (LCD mag, line skipping) video, particularly because this is a hot discussion topic in dpreview and because I am a still photographer. The lack of a true 1:1 display in Live View seriously compromises the ability to use Live View for manual focus, which is Live View's primary benefit to still photographers. Your video is extremely well done, from start to finish.

Having said that, some consideration should be made to the dvxuser community which is primarily concerned with video. I would suggest (and please correct me if I am wrong) that the line-skipping seen in LiveView may not be of concern -- or not the *same* concern -- to users shooting 1920x1080 resolution video.

I am wondering -- since you are hot on the line-skipping trail -- if the line-skipping in Live View corresponds neatly with the line-skipping used to generate 1920x1080 video in the D800. Here is a reference link to investigation of this (possibly similar, possibly identical) line-skipping.

Your work is appreciated!

-- Bob Elkind
 
So, can the meters/histogram etc. be left on the live view while shooting, without it being embedded in the HDMI video image? Are there any gotchas with leaving info on the live view screen, as far as recording "clean HDMI" is concerned?

Thanks
 
Stuart U said:
So, can the meters/histogram etc. be left on the live view while shooting, without it being embedded in the HDMI video image?
Click to expand...
Yes.

Are there any gotchas with leaving info on the live view screen, as far as recording "clean HDMI" is concerned?
Click to expand...
I do not own or use a D4/D800. Having said that, I've read and seen nothing to suggest that leaving info display on the camera's review screen would affect or compromise the D4/D800 "clean HDMI" output.

-- Bob Elkind
 
eteam said:
Horshack, I watched the Live View (LCD mag, line skipping) video, particularly because this is a hot discussion topic in dpreview and because I am a still photographer. The lack of a true 1:1 display in Live View seriously compromises the ability to use Live View for manual focus, which is Live View's primary benefit to still photographers. Your video is extremely well done, from start to finish.

Having said that, some consideration should be made to the dvxuser community which is primarily concerned with video. I would suggest (and please correct me if I am wrong) that the line-skipping seen in LiveView may not be of concern -- or not the *same* concern -- to users shooting 1920x1080 resolution video.

I am wondering -- since you are hot on the line-skipping trail -- if the line-skipping in Live View corresponds neatly with the line-skipping used to generate 1920x1080 video in the D800. Here is a reference link to investigation of this (possibly similar, possibly identical) line-skipping.

Your work is appreciated!

-- Bob Elkind
Click to expand...

I agree Bob, the D800's interpolated Live View preview is a significant detriment to manual focusing in certain situations. It's one of the first things I checked when I got my D800 because LV focusing is so critical to how I shoot stills. I suspect it would be critical to video users as well.

Falk's analysis shows that both Live View and video perform similar (if not exact) line skipping. To my eyes the Live View feed looks very close to the video I've recorded on the D800, so I'd venture to guess that Nikon is sharing the same processing logic to generate the two but perhaps with different parameters. I say this not just for the interpolation artifacts but also because I can see what appears to be video codec artifacts in Live View, plus it gets grainy at EV levels above where I see grain for the 5DM2's Live View, which indicates it's having to apply more gain to the signal due to the loss of light from the skipped lines.

One interesting thought though - if Nikon really is using the video feed to generate the Live View preview, that means they should be able to supply a magnified view while recording video (but they don't). I believe Canon DSLR's and the D7000 use selective readouts of the sensor to generate their 1:1 views, which is why they're so clean but also why supplying a magnified view during video recording would be hard. If Nikon is using the video feed it should be simple for them to apply the same digital interpolation for magnification during video recording.
 
Last edited:
Thanks Bob.


And many thanks for the Live View magnification info Horshack.


Does using a separate monitor via hdmi change any of the magnification quality/shortcomings?
 
horshack said:
One interesting thought though - if Nikon really is using the video feed to generate the Live View preview, that means ...
Click to expand...
But clearly the video feed is not the Live View preview, at least not in all respects.
  • 16x9 video is a crop of the 3:2 sensor
  • D800 "full" 1920x1080 video frame is generated from an additional slight (90%?) width-wise crop of the sensor

Agreed on the ventured guess: the D800 video-mode spatial compression processor is likely tossing away (skipping) the same image rows which are tossed away (skipped) in 1:1 and 1:2 LiveView display.

-- Bob Elkind
 
Last edited:
horshack said:
Here's a new followup video about the D800's magnification clarity/focusing issue:
http://www.youtube.com/watch?v=HSALyicAdj4&hd=1
Click to expand...

Adam,

The 'glass is half full' followup is helpful and reassuring.

Do you think it might be worthwhile to suggest using vertical edges and lines for critical Live View focusing, as these are not affected by the line-skipping impairment in the display?

-- Bob Elkind
 
Last edited:
eteam said:
Do you think it might be worthwhile to suggest using vertical edges and lines for critical Live View focusing, as these are not affected by the line-skipping impairment in the display?
Click to expand...

I can't remember where I heard this, but I have previously read or heard that one should go by vertical lines when focusing in live view with the D800, as this would be full res and horisontal would not. Sorry I can't be more specific.

Edit: I think I read it in a post about how the sensor samples video and the line-skipping and debayering-process, but I can't seem to find it now.
 
Last edited:
chagchag said:
I can't remember where I heard this, but I have previously read or heard that one should go by vertical lines when focusing in live view with the D800, as this would be full res and horisontal would not. Sorry I can't be more specific. Edit: I think I read it in a post about how the sensor samples video and the line-skipping and debayering-process, but I can't seem to find it now.
Click to expand...
Falk Lumo posted it here: http://forums.dpreview.com/forums/read.asp?forum=1021&message=41153343
 
How does one focus on vertical lines when they are intersected and confused with horizontal ones? Look at horshack's video sample of the cereal box, there is no shortage of vertical lines present, but how one discerns "in focus" from a very confused mush of vertical and horizontals, is beyond my thirty very successful years of image making. The "sharpening" workaround is atrociously crude.

Edit: "Sharpening workaround" criticism is aimed at Nikon. We do what we have to.
Thanks again for taking the time to test and share the results "horshack".
 
Last edited:
As Stuart asked at the start of the post has anyone tested to see if this is still and issue when using an external monitor via HDMI (hope not)
 
Unless the BM HyperDeck has a built in monitor, I think we're talking at cross purposes: Rather than view on the camera's screen, have you hooked up a second monitor via HDMI to see if this focus issue persists? Not a recorder, but a video monitor or TV etc..
 
Stuart U said:
Unless the BM HyperDeck has a built in monitor, I think we're talking at cross purposes: Rather than view on the camera's screen, have you hooked up a second monitor via HDMI to see if this focus issue persists? Not a recorder, but a video monitor or TV etc..
Click to expand...
I've tried a 40" 1080 LCD TV direct from the camera and get the same output.
 
You must log in or register to reply here.
Back
Top