[filmscanners] RE: Newish Digital Tech

["Robert Meier" <filmscanner@meierlim.com>]

>-----Original Message-----
>From: filmscanners_owner@halftone.co.uk
>> >Hum.  Do you have a source for that?  I don’t believe that is
>> >true, and will
>> >have to think about your assertion.  What is the source of the “random
>> >variations”?  I know there is some randomness in reception of photons,
>> >simply because of atmospheric dispersion, and other causes...
>>
>> I think he is talking about the quantum noise which is introduced
>> due to the
>> Poisson probability distribution of the Photons hitting the detector. The
>> resulting error in the signal is proportional to sqrt(2).
>
>Hello Robert,
>
>If he is, that’s called “shot noise” and it’s = sqrt(S), where S is the
>signal in electrons.  It certainly is the noise that limits CCD
>performance.

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.

Robert

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