What Is Exposure and Why Does It Matter?

Although most photographs are made in exposures that last just fractions of a second, that brief instant is not so much a spontaneous event as it is the culmination of a long (hopefully not too long or you’ll miss the shot) thought process on the part of the photographer — you. The process begins when you spot a potential subject, continues as you decide how to approach the subject (where to stand, what lens to use, whether the lighting is interesting enough), and ends the instant you press the shutter release button.

A lot of important questions — both technical and aesthetic — have to be (or at least, should be) addressed before you give your trigger finger permission to commit to your idea. And one of the most important issues that you have to contend with is setting the exposure. In terms of the success or failure of a particular image, probably no question you confront is as important as this one: How should I expose this scene?