What is the advantage of Sensor Pixel Area

Started 6 months ago | Discussions thread
preferredfault Regular Member • Posts: 328
Re: What is the advantage of Sensor Pixel Area

Even in your updated example, the M43 at 200 ISO (its base ISO), is still only directly comparable to the FF at 800-1600 ISO. Since M43 is 1/4th the size of a full frame sensor, it's pretty simple to visualize. So it takes essentially 2-3 stops before they start to display the same noise. This can't really be explained in any other way but for pixel area. And the reason why it's 2-3 stops rather than an "expected" 4 stops, is because a lot of that noise is coming from read noise in the ADC.

And the thing about SNR is that even when camera's look close in SNR (i.e. 32 vs 36), decibels are actually multiples. For example, just a 5dB difference can mean 200% more noise.

In this case, it's really about power. Sensors are "powered" by photons by creating a charge in the sensor, and this charge is dispelled to create the reading/result, which is an analog electrical signal, which is then transcribed and consolidated into a digital output of code to say X pixel has X value. More powerful signal = higher SNR. Where does it get that power? from the small amounts of light it gathers. That's why we boost the signal with ISO, but it's obviously artificial. Boosting the signal doesn't create a perfect picture, because it also boosts noise that already exists in and also becomes part of the signal. What else creates a more powerful signal? A bigger area to gather more charge.

There are only two ways to make a camera sensor's IQ better and reduce noise. A bigger pixel, or a better ADC that introduces less noise. We may not be at the limits of that quite yet, but outside of cooling your camera with something like nitrogen or having room temperature superconductors, these are hard limits that will never go away.

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