more pixels are better!

Started Dec 14, 2008 | Discussions thread
attomole Regular Member • Posts: 309
Re: more pixels are better!

My own take, based on not much real knowledge and extrapolating what little I do know with some rough science, to beyond to where it is any way robust...

Two aspects of sensor quality, resolution and signal to noise (S/N) are antagonistic for a given size of sensor.

The bigger the individual pixels the greater the maximum output voltage, and therefore the signal to noise ratio of the individual pixel, so say for a little pixel with certain illumination, 10 mv may be the output,but for a big one, say a little over 3 times the diameter, would give 100mv, A better quality signal for a given illumination

However if you have less pixels you have lower resolution, therefore for a fixed sensor size, resolution and S/N are antagonistic, I would say that why Nikon have the D3 and D3x one for highest resolution with good lighting and one for highest dynamic range and lowest noise with lower light. In one case the light/dark information is best preserved and in the other the spatial resolution,

Of course there are all sorts of complications, like how good does it need to be?, our eyesight has its own limitations so there is no point in engineering a system with subtly beyond what we can perceive, ( and even if you print very large you stand further away to view it right?) and limitations of the optical system that may also limit resolution, no point in having 40 MP if your lens is only good for 10, and the photo-voltaic stuff isn't always linear like i am assuming, and there is amplification and conversion to digital all subject to there own limitations and optimizations that may impose a limit on performance.

The process of "pixel binning" that is of adding together the signal from a number of different pixels, satisfies the need to have higher headline pixel counts to impress Joe the punter, and still having good sensitivity in moderate light, you will of course loose some resolution, but on screen or printed the perceived picture quality may be better because we are not Kestrels when it comes to resolution and like with the movies, that are a sequence of frozen stills. your brain fills in and conveniently ignores many quality issues, Unless it is connected to an internet forum like this one.


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