Are bigger pixels less noisy?

Started 4 months ago | Discussions thread
OP JahnG Veteran Member • Posts: 3,323
Re: Quantum efficiency and signal to noise ratio

J A C S wrote:

JahnG wrote:

Thank you for your comments.

My actual questions in my first post were about pixel size, pixel count and sensor size, vs noise, SEE BELOW. And at the beginning of the post I asked whether it would be possible to have any consensus concerning my questions. I tried to ask the questions as clerly as I was able to, and I got excellent answers, so anyway not much problem for the experts to give excellent, detailed answers. So thank you to everybody. (As often is the case, the headline was not the actuall full question(s))

You cannot get a straightforward answer because you did not ask a straightforward question. What does even "less noisy" is? In (2) below, you seem to include shot noise in addition to read one. Sensors do not generate shot noise but they can have an effect on how much it is recorded. On the other hand, sensor, plus everything else around them generate read noise, etc.


obviously I did not ask enough straightforward questions. Anyway, I started asking questions as I did not have a very good knowledge in these matters and because in other DPR forums there are much contradicting discussions where you get contradicting views. As I don't have a good knowledge in some matter I might not be able to ask straightforward enough questions... Anyway, regardless of how clear or unclear my questins were I received good answers concerning pixel size, pixel count and sensor size, vs noise.

  1. Is it possible to generally say that FF sensors with fewer and bigger ”pixels” are/ are not, less noisy (to any practical degree) than FF sensors with smaller ”pixels”. (Same for APSC sensors)

This is an easy "yes", and for that, you need one (counter) example only. This does not tell you the whole story though, as you can see by reading the responses above.

  1. Some DPR members also dispute whether FF sensors (regardless of pixel count ?) are less noisy (better for low light photography) than smaller sensors. One argument is that the existing difference in noisiness between FF cameras and small sensor cameras basically depends on the fact that small sensor cameras have smaller lenses and thus the lens collects less light. According to this FF sensors and smaller sensors would be equally noisy?"

According to this smaller sensors would be noisier buy only according to this.

Once you include shot noise, you have to think about noise as a function of the signal. You can have a sensor with very low read noise but low QE vs. a sensor with high read noise but higher QE. In the deep shadows, the first sensor wins. Away from them, the second one does. This is at a fixed ISO.

Noise is not a number, so "low" and "high" are not enough to describe it. You may have pattern noise, channel non-linearity (creating color cast in the very deep shadows), non-uniformity which in particular can create very low frequency noise, a longer exposure noise, etc.

Ok, thanks.

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