I was reading a piece on the comparison of APS-C to full frame sensors. In this article, it mentioned that full frame sensors can have larger individual "photo sites", and can therefore capture more light.
Here is the quote...
It is not the number of pixels that really counts - APS-C models such as Canon's EOS 7D and EOS 550D have almost as many photosites, thanks to their 18-million pixel count - but the size of the photosites is crucial to image quality.
Bigger individual light sensors capture more light - and this means that less electronic noise is created. You notice this most as you increase the ISO setting - with this noise creating a coloured mosaic pattern that is particularly noticeable in shadow areas.
Is this true? If I control for variables like aperture relative to the sensor, would a full frame sensor get higher exposure?
Answer
The full frame sensor will not be brighter under the same exposure conditions (Same light in scene, same focal length and f-number, same exposure time, etc.). It will collect more light, but it will also spread that light over an equally proportionally larger area. The brightness, which is defined as the amount of light energy per unit area, will be the same. The advantage of the larger pixels will not be in increased brightness, but in reduced noise (due to the averaging of the random nature of light - what we call shot noise - over a larger area) and increased dynamic range if the pixels are larger on the FF sensor (due to higher full well capacity for the same thickness silicon wafer).
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