D600 High ISO in DX

Started Nov 23, 2012 | Questions thread
Leo360 Senior Member • Posts: 1,141
Re: Roger's optimum pixel pitch of 5um

noirdesir wrote:

A single pixel does not have any noise. Display a single pixel fullscreen on your monitor and tell me whether you can see any noise in it.

Saying that a single pixel does not have any noise in it is not quite accurate. There is mean number of photons that is supposed to hit this pixel under given exposure. But the actual number of photons registered by it will differ from the mean by amount of photon shot noise (Poisson distribution of photon count). On top of it it is contaminated by read-noise which makes photon-to-electron conversion noisy. So the value of this pixel reading will not be exactly right. In your experiment with a single pixel filling the whole screen you will have a solid color (no spacial variation) but with the intensity slightly off. I think that what you are trying to say is that one cannot observe spacial noise variability (from one pixel to another) when measuring only a single pixel.

As far as I understand it the std. dev. is the thing that should scale with the area. And dark current is second order effect for the pixel size we are discussing here.

I have to think about it more, for it sounds counter-intuitive on the first glance. With Gaussian random processes variance is the parameter which scales and combines. I am not sure that it is applicable here, though.

Leo

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