Depth of field refers to how much of the third dimension or "depth" remains in focus in your picture. Below, the two figures in the foreground are sharp, whereas the green foliage behind them appears as a blurred rhythm of shapes. Controlling depth of field is an excellent way to manage the viewer's interest.

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[IMAGE: Gelila Reta, a Virginia Tech engineering student, listening to a guide during a study abroad trip in India. 2018.]

Think critically: the image above is well framed and composed. But what issues of power and equity are involved in the intercultural moment that it documents?

Extremely shallow depth of field can be used to produce interesting visual effects. Shallow depth of field can be an effective way to focus on an important attribute of a complex system, for example by picking out the pressure gauge on a well pump .

A very deep range of focus, by contrast, can be useful to document as much of a scene as possible. Satellite images of a site for a potential factory or mine, for example, might bring as much of the vertical terrain into focus as possible for planning purposes. Whereas shallow depth of field is used in portrait and macro photography--creating a sense of wonder by picking out small details--deep focus is often used to capture expansive landscapes.

Learn more by looking: Brazilian Sebastião Salgado and Canadian Edward Burtynsky have produced some of the most powerful contemporary examples of landscape photographs of large-scale industrial landscapes.