Originally posted by ElJamoquio Photosite size doesn't have an influence on picture noise. You're zoomed out too far for it to matter.
I disagree
Photosite size is a big factor.
The size of the photosites determines the light gathering capacity of the photosites. If the photosites are tiny and the sensor is therefore a high resolution sensor, which is what that's saying put slightly differently, the photons gathered by each photosite is therefore less, and the signal from each photosite, is therefore reduced and is lower.
The signal must then be amplified more to provide a coherent image because its weaker, the signal to noise ratio then changes because the greater magnification of the poorer signal amplifies the background noise as well, and more amplified noise is therefore generated. therefore the image carries more noise.
This surely is already well established.
Small photosites = less signal
less signal = more amplification
more amplification = more amplified noise
more amplified noise = poor signal to noise ratio
poor signal to noise ratio = more obvious noise in the image.
This is one reason why Full Frame sensors tend to have lower noise characteristics than smaller sensors, the photosites are bigger, they gather more photons, the signal is stronger and needs less amplification, the background noise doesn't get amplified as much and the noise is lower.
If you have a photosite twice the size it gather 4 times the photons and the background noise stays much the same, the signal is 4 times stronger and the signal to noise ratio is 4 times better, you then have much less noise in the image, due entirely to changing the photosite size and nothing else.
With real world losses, the truth is the difference isn't so pronounced as the raw figures would suggest but none the less noise is better controlled with larger photosites.