RED's Dragon sensor - 20 stop dynamic range

Started Jan 9, 2013 | Discussions thread
Press Correspondent
Press Correspondent Veteran Member • Posts: 3,345
Quantum mechanical DR limit for 36mp FF

nofumble wrote:

who are these guys, and why they can do what Canon cannot?

I live on the state line with Missouri, the SHOW ME state. So I will believe it when I see it, but until then I will be shooting with my canon

The low ISO DR of D800 at the pixel level is 13 stops limited by the read noise of about 3 electrons per pixel. This is about than 2 stops above the quantization noise. Even if the quantum efficiency is imroved and the read noise is reduced, a one shot 35-mm DR cannot exceed 15 stops due to fundamenal quantum mechanical limitations. The only ways around are sequential exposures (quick automatic bracketing) or bigger sensor or lower resolution.

DR, per DxO, is a range between the well capacity and the lowest non zero signal that is stronger than noise. The quantum noise of such signal is a square root of its value. This gives us the equation to find the lowest signal:

Signal >= SQRT(Signal) + Read Noise

where Read Noise >= 0.5 due to quantization

For D800 we have the Minimum Signal = 5 > 2.2 + 2.7

The well capacity is 44,972

Yielding the DR of LOG2(44,972/5) = 13.1 stops

If the quantum efficiency is 100% (up from 56%) and the read noise is zero, then:

the Minimum Signal = 2 > 1.4 + 0.5

Yielding the DR of LOG2(44,972/0.56/2) = 15.3 stops

This is the maximum theoretical 35-mm DR at the D800 resolution with no technological bottlenecks, but  limited only by the laws of nature.

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MOD Mako2011
MOD Mako2011
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