1 electron = 1 photon?

Started Apr 12, 2013 | Discussions thread
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Bernard Delley Contributing Member • Posts: 644
Re: QE: 1 photon above the CFA -> ~0.15 electrons?

Jack Hogan wrote in the initial post:

"Or could the fact that the responsivity at 760nm is more than 3 times that at 380nm mean that, for instance, sometimes 1 photon produces two electrons?"

As Eric Fossum already told authoritatively, that is almost never happening!

Now you say ~0.15 electrons per photon ! You forgot to mention a reference to the detailed procedure on how this result is obtained.

Of course I qualitatively agree that the average efficiency is about there at ~0.15.

Going from say 0.6 at the spectral peak that I mentionend. You have to count that only a about third of the full visible spectrum is caught by each photosite -> makes 0.2.  Moreover, the Bayer color transmission is below its peak value everywhere else -> so the average goes quite a bit below 0.2

Jack Hogan wrote:

The D7k's Effective QE as described earlier appears to be around 13.2%.  Compare this to newer DSLR's like the D4's 15.9% above, the D800e's about 15.5% or the D7100's around 15.3%.  I think this Effective measure of QE has mainly relative, as opposed to absolute, value.  But it's probably more representative than the normally quoted number for light at the peak of the green filter's passband (around 50%)

The effective quantum efficiency has naturally several somewhat arbitrary choices in its precise definition than the more often quoted efficiency at the green standard wave length. Both measures lead to similar conclusions about the relative efficiencies of various cameras --  But, that comparison was not the focus of interest here.

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