D800: Poor LiveView interpolation

Started Mar 27, 2012 | Discussions thread
chn_andy Junior Member • Posts: 47
Re: Exmor sensors support selective readout

Recent finding by me has shown 1:1 liveview in D7k and D5100 is not window readout but rather "all pixel scan" mode! This is simply proven by magnified all the way into bottom left corner while the camera was able to recognized a face coming into the top right corner in face detection AF standby.

See my post:

Whether it uses a window readout in D300 and D3x can be deduced by its frame rate. If it is able to achieve the same speed as line skipping, I would say it's "window cut out" mode.


Horshack wrote:

Martin Grecner wrote:

Is this just in Live View, or also in still playback ?

Just Live View.

I assume it is only in Live View, and the reason for that is simple,

D800 is skipping pixels in order to be able to read the sensor out at 60 times a second for Live View display. That is where the aliasing goes from.

If they would blur it to avoid aliasing, they would make it even worse for focusing, in the aliased version you can at least tell when you are in perfect focus, even though it looks awful.

The only correct implementation would be that for 1:1 zoomed Live View they would only read the 480 lines which are visible on the sensor, that would be fast enough.

But probably it is not possible to read deliberate lines from the sensor. It is more likely divided into some sort of interlaced read-out zones or something.

My most recent Exmor data sheet is for the IMX021 (12MP sensor in the D90/D5000/Kx) and it has support for a "window readout" function, which it describes as this:

"The IMX021 includes a built-in 24 dB programmable gain amplifier that can provide fully adequate gain in the analog domain. It also includes a 'window readout' function that can read out part of the image. This function makes imaging at even higher frame rates possible by limiting the area of the image read out."

Considering that the D7000/D5100 provide 1:1 pixel views in Live View I'm assuming the 16MP Exmor supports the 'window readout' feature as well.

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