The AE Lock Feature
One of the available options is the ability to lock your exposure. You can lock the setting in your camera temporarily if you want to recompose your image—for example, if you’re in an environment where there is sufficient lighting on your subject, but the background is significantly brighter or darker (Figure 4.5). The metering in your camera is continuous, meaning it will change depending on where the center of the viewfinder is pointed. If you compose the image so the person is off-center, the camera will meter the wrong part of the scene.
Figure 4.5 Because so much of the scene includes shadows, it was important to lock the exposure based on the highlights in order to ensure that they weren’t overexposed.
To correct this, you can meter for one part of the image (in your subject), lock those settings down so that they don’t change, and then recompose the scene and take your photo.
For more on how to use the AE lock feature, turn to Chapter 3.