• Roger Clark

      by Published on 08-06-2012 07:27 AM

      This post is derived from my web article: http://www.clarkvision.com/articles/iso

      What is ISO on a digital camera?

      Reading manufacturer literature, review sites, and online discussions, one is led to believe that ISO changes sensitivity, and changes exposure. These ideas are both incorrect.

      Myth #1: ISO changes sensitivity. False! Digital cameras have only one sensitivity, given by the quantum efficiency of the sensor, and the transmission of the optics and filters over the sensor. ISO is simply a post-sensor gain applied to the signal from the sensor.

      Myth #2: ISO changes exposure. False! When you change ISO on a digital camera, two things are changed ...
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