Evaluating D800 images shrunken to 12 or 16mp defeats the purpose.

Started Mar 10, 2012 | Discussions thread
Luke Kaven
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Re: Evaluating D800 images shrunken to 12 or 16mp defeats the purpose.
In reply to DocS, Mar 12, 2012

DocS wrote:

Luke Kaven wrote:

DocS wrote:

Shrinking virtually any photo artificially makes the camera's ISO performance look better. The D800 should be an improvement over the D700 at their respective native resolutions.

Think in terms of "aggregating" instead of "shirinking."

A major source of noise is high frequency noise, as in shot noise. By downsampling, you eliminate high-frequency noise because you are eliminating all high frequencies .

The D700/D3/D3s/D4 achieve good 100% pixel-level results because they are -- in your way of speaking -- pre-shrunk .

That’s not a good description at all, because these cameras simply don’t have high resolution to begin with. Their pixels are simply larger, and there are fewer of them on the same size sensor. Comparing the D700 and D800, for every three D800 pixels covering a certain surface area on the sensor, there is only one D700 pixel. This has the advantage of inherently producing lower noise, and the question at hand is whether or not Nikon found a way to put three pixels in place of one pixel while maintaining overall less noise from that patch of sensor real estate. (I realize that’s an oversimplification of what actually takes place on a sensor, but you get the idea). If they didn’t, then the D800 really hasn’t been an improvement (sensor-wise) over the D700. It simply has more pixels that can’t be taken advantage of unless the shooting conditions don’t produce noise (e.g. low ISO settings in awesome light).

If you read Martinec, he explains why, for a wide range of pixel sizes, the light-gathering ability of a sensor of a given size is more or less equal. Implementations varied, lending false credence to the notion that "big pixels" had an inherent edge in performance. With the Exmor sensor in its third generation, and the D3/D3s/D4/5DI/II/II sensors in their third generation, both design approaches have honed the edge very closely with respect to one another.

The D700 is two generations behind at this point. The D800 sensor compares with it pixel-for-pixel at this point. But overall, in terms of performance per unit area of the sensor , the D800 and the D4 are more or less on a par. You can freely aggregate pixels from the D800 (e.g., to match the 16MP D4) when the photons are scarce, and exploit all the pixels when the photons are plentiful.

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