Sensor Size The digital camera sensor consists tiny units known “ pixels. ” For example , 20MP sensor 20 million tiny light-capturing units.When shutter open light reaches camera ’ sensor , pixels measure intensity light counting number photons hit unit.If compare two 20MP sensors—one Full Frame size another APS-C size—on full frame sensor , area pixel 2.3 times larger area APS-C sensor.As result , full frame sensor capable measuring intensity light recording greater accuracy.Sony biggest manufacturer digital sensors world.Most mobile phones , point shoot cameras , even professional cameras use Sony sensors.It surprising Sony produces one best cameras terms low light performance.ISO Performance In film photography , ISO refers film sensitivity light determines fast light recorded means chemical reaction .