What is the physical nature of noise in small-sensor cameras? Is it thermal noise in the semiconductor?

Is there hope that in a couple of years, noise in small sensors will disappear, and small sensors might give the same quality as large sensors as found in SLRs?

Or is small-sensor noise here to stay forever, because inevitable physical properties of small pixel size on a small sensor plus thermal noise guarantee it?

  • \$\begingroup\$ See also What types of noise can be present in digital photographs? \$\endgroup\$
    – mattdm
    Commented Apr 26, 2012 at 18:53
  • \$\begingroup\$ Wow I did not know I am asking so difficult question. Maybe I need to take it to physics.stackexchange.com. \$\endgroup\$
    – Andrei
    Commented Apr 28, 2012 at 11:00
  • \$\begingroup\$ Small sensors will always exhibit more noise than larger ones because they integrate less noise sources per fraction of area, which doesn't mean small sensor noise can't be pushed below an acceptable threshold for a given application. \$\endgroup\$
    – Christian
    Commented Apr 28, 2012 at 15:43

2 Answers 2


A good starting point in your journey is Bill Claff's site. He has a primer on Sensor Analysis and goes into some detail on what noise is and how it is measured. Keep in mind that he is not going to go into depth on things like Quantum Efficiency so you'll need to take his points and statements as indicators of things to study next. His home site has some additional information that will be helpful.

Another person to look into is Thom Hogan. A search of his site will show a number of articles where he talks about noise in sensors and how it relates to size and efficiency. His books have an entire chapter on exactly what you're looking for as it pertains to the particular Nikon camera in question.


The primary sources of noise in images are electrical noise from the sensor and photon noise from the random emission of photons by light sources.

Electrical noise can be lower for small sensors. When using a lens with the same f/stop a small sensor captures the same light per unit area, but due to its size, less light overall.

Photon noise is a property of physics, no amount of development will ever allow a small sensor to perform as well in low light as a larger sensor.


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