1 electron = 1 photon?

Started Apr 12, 2013 | Discussions thread
Jack Hogan
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Re: Integer vs Floating Point
In reply to John Sheehy, Apr 16, 2013

John Sheehy wrote:

Jack Hogan wrote:

looper1234 wrote:

also, electron on electron shells are expressed in percentage of existence, we can never be sure as to say an event took place, we can only express it as a percentage, such is the natural of things at the quantum level.

Good point, looper1234, it's a stochastic process, right?  So does it really make sense to talk about photons as integers?  Shouldn't we really be perfectly happy with floating point, as in 8.62 photons producing 5.85 electrons, then converted to 1.26 ADUs?

And what does this say for Unity Gain proponents ?

Still unity gain proponents?  I thought they died a flat-earth death when 14-bit output showed no change in high ISO noise compared to 12-bit.  I warned Roger Clark that it meant nothing, just a coincidence of current technology, and he argued that the first 14-bit Canon would have a 2-stop increase in DR and useful high-ISO gain would increase by 2 stops, and neither happened.  Unity gain with current systems is about as absolutely meaningful as 1 KPH vs 1MPH.

Of course, a pure photon counter would need a 1:1 ratio, but that is a count, not an ADC conversion rendered imprecise by read noise.  Eve an ADC system with non-obscuring read noise (about 0.15 electrons according to Eric Fossum, and I think my estimation was similar when I emulated such, as a well-behaved Gaussian distribution has most of its values in a range about 6x the standard deviation), will need a "gain" of more than one to make sure that none of the noise swing goes over into the wrong histogram population.  You need a high enough gain such that the populations are not confused; probably about 5x to 6x for optimal accuracy (you need to distinguish the leading and trailing edges of neighboring integer electron populations).

Makes sense to me, thanks John.  Interesting paragaph, your last one.  I am going to have to play with a few 'tails' in excel myself

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