Sensor sizes and f stops

Started Jan 25, 2014 | Discussions thread
olliess Senior Member • Posts: 1,349
Re: Light reaching each pixel

darklamp wrote:

However, more pixels, and hence more photons, will be used to form any given area of the final image. The upshot being, the SNR normalized for the print area/resolution should still be better for the larger sensor.

This is a common presumption people make, however noise does not average as nicely as people think it does.

As SNR gets lower averaging becomes much harder, to the point it's actually useless.

You're going to have to explain that one to me. When does averaging or downscaling a correlated signal ever not help in the presence of uncorrelated noise?

There is another side effect. SNR also limits DR. Small pixels lead to lower DR. You cannot average that out. So even if I accepted the idea that averaging worked well enough, the reduced DR is a killer.

It was more pixels vs. less pixels with the same properties (same pixel density) in your example, so the pixels themselves have the same DR.

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