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     áòèé÷ :: Filmscanners
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[filmscanners] RE: Newish Digital Tech



Hi Robert...

> Yep, shot noise = photon noise. And yes it's sqrt(S). So when the
> signal is
> twice as big then the noise only increases by sqrt(2) which improves the
> SNR.

Err....aaaa...  Hum.  You have to add the noise floor to it though.  For a
noise floor of 25:

# of Electrons  Noise

10                      25+sqrt(10)     = ~28
20                      25+sqrt(20)             = ~29.5

100                     25+sqrt(100)    = ~35
200                     25+sqrt(200)    = ~39

1000                    25+sqrt(1000)   = ~57
2000                    25+sqrt(2000)   = ~166

10000                   25+sqrt(10000)  = ~135
20000                   25+sqrt(20000)  = ~166

I’m not seeing a sqrt(2) in noise increase for a doubling of electrons
here...but clearly the SNR is better as the signal gets larger, for one
reason because the noise floor is increasingly less of the overall signal,
so of course that happens.

Austin

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