ISO is the final piece of the exposure triangle. Understanding how ISO works will allow you to take shots where it normally wouldn’t be possible without working knowledge of how ISO actually works. ISO is basically the light sensitivity of the camera’s image sensor (or film). ISO is usually rated at 100, 200, 400, 800, 1600 and even 3200. In this article we’ll take a look at an easier way to think of ISO, how ISO can help with faster shutter speeds and ultimately how it affects your exposures.