Canon EOS 6D: From Snapshots to Great Shots

How Exposure Is Calculated

Now that we know about the three core elements of exposure—ISO, shutter speed, and aperture—let’s take a closer look at how they relate to one another and how you can change them as needed.

Stop

The term stop refers to a single unit of exposure. For example, “adding a stop” means increasing a single unit of ISO, shutter speed, or aperture, depending on the context. So if your image is too light or too dark, you might want to change your exposure by a “stop” or two.

When you point your camera at a scene, the light reflecting off your subject enters the lens and is allowed to pass through to your sensor for a period of time. The amount and duration of the light needed for a proper exposure depends on how much light ...