VexTheMaster

I didn't understand sampling rates and resolution from the start. I've did a little research online, but I'm even more confused now. I just can't grasp the concept of sampling an image.

Why does it need to be sampled? Is it done by the ADCs? What is the signal that is sampled, photons? How can a camera take more samples?

I might be overthinking it.

I know, I know, it can be caused by various factors, like high ISO, poor lighting conditions, long exposure time, heat. (not that I know why the last two cause noise)

But where does noise REALLY come from? What is noise? What does it have to do with photons and photosites?