How does the D3 achieve such high ISO?

Started Feb 17, 2008 | Discussions thread
PIXmantra Senior Member • Posts: 1,637
Something seems wrong...

From your updated computations:

Sensor DR at ISO 200 illumination limit:
D3 full-scale e- count = 65,600 (Roger's number)
D3 read noise = 6 e- (my number, more conservative than Roger's)

Mk III full-scale e- count = 38,000 (Emil's number)
Mk III read noise = 4 e-

D3 sensor DR = 65,600/6 = 11,000 = 13.4 stops
Mk III sensor DR = 38,000/4 = 9,500 = 13.2 stops

Let us take a look at something:

Assuming 7.2^2 surface for 1D3 and 8.4^2 for the D3, and assuming that there are light-collection capabilities are unformely distributed on the sensels' area, and proportionally equivalent between each cam's sensels, we then have:

Surface % of D3 to 1D3: 100*(8.4^2/7.2^-1) = 36.11%
Light-gathering % of D3 to 1D3 @ ISO200: 100*(65,600/38,000-1) = 72.63%

So here we have a 36.11% advantage of actual sensel's surface, yet we have a 72.63% advantage in collected electrons @ ISO200.

This does not seem to be right... Not in my watch.


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