Getting a Handle on Exposure

In the most basic sense, exposure is all about light. Exposure can make or break your photo. Correct exposure brings out the detail in the areas you want to picture, providing the range of tones and colors you need to create the desired image. Poor exposure can cloak important details in shadow, or wash them out in glare-filled featureless expanses of white. However, getting the perfect exposure requires some intelligence—either that built into the camera, or the smarts in your head—because digital sensors can’t capture all the tones we are able to see. If the range of tones in an image is extensive, embracing both inky black shadows and bright highlights, we often must settle for an exposure that renders most of those tones—but not all—in a way that best suits the photo we want to produce.

For example, look at two bracketed exposures presented in Figure 4.1. For the image at the left, the highlights (chiefly the clouds at upper left and the top left edge of the skyscraper) are well-exposed, but everything else in the shot is seriously underexposed. The version at the right, taken an instant later with the tripod-mounted camera, shows detail in the shadow areas of the buildings, but the highlights are completely washed out. The camera’s sensor simply can’t capture detail in both dark areas and bright areas in a single shot.