Quantum efficiencies for Canon DSLRS

Started Feb 12, 2010 | Discussions thread
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Chrisk99 New Member • Posts: 17
Quantum efficiencies for Canon DSLRS

Dear all

I assume that some of you are familiar with sensor quantum efficiency. I was always asking me how different the Canon DSLR are with regard to the QE. Then I found the very good website http://www.dxomark.com/ where sensor Image quality is measured based on RAW CMOS data. From those data it is then possible to calculate the specific QE of the DSLRs. I evaluate the full SNR data to calculate the Full well in electrons. The DXO-lab measured ISO sensitivity is then converted into number of photons per pixel area. The ratio of the Full well in electrons and the number of photons per pixel area is the quantum efficiency. The following picture shows the QE of some Canon DSLRS. The calculated QE is denoted as relative QE, since there might be an multiplicative factor for all QEs. But my opinion is that the range 23 – 40% is quite true for CMOS sensors.

Here is the result:
DSLR QE + -error
10D 23.9% 1.4%
350D 26.9% 0.5%
20D 30.0% 0.2%
5D 23.2% 0.2%
5DmII 32.3% 0.1%
1DsmIII 29.7% 0.6%
40D 30.3% 0.3%
450D 30.4% 0.2%
1000D 32.2% 0.8%
500D 36.4% 0.4%
50D 36.1% 1.0%
7D 35.6% 1.7%
Nikon D3 40.2% 0.9%

It is interesting to see that the 5D is one with the lowest QE. On the top there is the Nikon D3 with a QE of 40%. The very good result of the canon 7D indicates that the filling grade of the tiny 4.3µm pixel is indeed optimized by canon (microlens etc.).

Best regards
Chris

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