Back in the old days of film photography, ISO, in its simplest sense, was a measure of how sensitive your camera’s film stock was to light. On modern digital cameras, altering the ISO value does not technically make your sensor more sensitive to light. What, in fact, happens is that the resulting image has its tonal values amplified, to simulate greater light sensitivity. Low ISO values mean the image is amplified less to simulate less light sensitivity and high values mean it is amplified to a much greater degree to simulate more sensitivity. Lower ISO means that you require more light, over a longer duration, for a good exposure and high ISO means that you require less light, over a shorter duration, for the same conditions. This assumes your camera’s…
