Some back-of-the-envelope calculations

[grillo]

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Others like to play Leica CEO, I'd like to play Leica engineer for a while. These are some back of the envelope calculations:

 

Assumptions:

 

1) M9 gives 1-stop improvement in noise in prints

2) 1 ISO stop = 100% improvement in SNR (3 dB)

3) This improvement comes from two independent factors: higher resolution and improved signal processing/technology in the sensor itself

4) SNR is directly proportional to pixel area

 

Calculations:

 

Total Improvement factor = (pixel size factor) x (resolution factor) x (technology factor)

 

M9 data:

pixel size factor = 1 (same size pixels)

resolution factor = sqrt(18/10) = 1.34

total improvement factor = 2

 

which implies a technology factor of 2/(1x1.34) = 1.5

 

If Leica had decided to use a 12MP sensor for the M9, the improvement would have been:

 

pixel size factor = 18 / 12 = 1.5

resolution factor = sqrt(12/10) = 1.1

technology factor = 1.5

total improvement factor = 1.5 x 1.1 x 15 = 2,5

 

So, if Leica had decided to use a full-frame 12MP sensor instead of the current 18MP, we would have had a camera with a slightly better SNR, but with lower resolution.

 

Given the realities of the market, I think they did the right thing.

 

I'm not an expert in this, so I'm sure I made some mistakes in my calculations. What are your calculations?

 

--J.

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