Camera ISO

ISO controls the sensitivity of the camera. This means that it doesn’t control the amount of light entering the camera, but how the camera should interpret the light coming in.

A higher ISO means higher sensitivity, therefore a brighter image for the same amount of light captured. It’s useful to raise the ISO when there’s no other way to increase brightness (e.g. a slower shutter would add blur and wider aperture would decrease depth of field).


The increased sensitivity comes at the cost of higher noise, resulting in a grainy image. A grainy image is better than a dark image, so it works as a last resort.


Noise can be handled in post-processing, but in general it’s best to use the “base ISO” (the lowest available) whenever possible and control brightness via exposure.