To understand exposure compensation, it is useful to first understand how your camera thinks.
Your camera’s metering system: the intelligence that helps it decide how light or dark an image should be, looks at the scene and compares it to a medium (grey) tone. It then chooses the settings that will achieve that exposure. Some parts of the image will be brighter and some will be darker, but the camera’s goal is average it to a medium overall brightness. That works for many situations, but there are situations where it doesn’t.
Example 1: A dark street
When you take a picture of a dark street, you expect the image to be dark, not lit up like the same scene in the daylight, right? Left to his own choice, the camera would see this dark place and think “Whoa! Need to brighten that up!” and it would end up looking too bright.
In this example, I wanted this scene to be dark to match what I saw with my eyes, so I added -1 exposure compensation.
Example 2: Beach and Snow
A snowy landscape or a beach is naturally a bright location. Usually, the camera will look at this and think that it’s too bright and try to adjust the aperture and/or shutter speed to darken this to a nice, medium tone.
To your eyes, snow is very bright. While cameras are getting smarter ever year, it still doesn’t know that it’s looking at snow. It just makes a computation based on light levels.
You need to tell it what to do. The following example uses +2 exposure compensation to have it look like I wanted.
Finding the Exposure Compensation Setting
Most cameras have a button for this that require you to turn a knob, but it’ll look like this. Consult your camera’s manual if it’s not immediately obvious.
Once you’ve figured out how to set the exposure compensation, you’ll not want to forget once you’ve set it. There, all cameras have a display item that shows you how it’s set. In this example, the camera is set to 1 stop over exposed, which means double as bright.
Don’t worry if the plus is on the left or the right, different cameras show it differently, but plus always means “brighter” and minus means “darker”.
While it seems counterintuitive to make a bright scene (to your eyes) brighter in the camera, just remember how the camera works and you’ll have no problem using exposure compensation to help the camera decide on the right exposure to match how your eyes see it.