Control Depth of Field to Take Better Photographs

One of the biggest shifts I encourage my students is to make in their growth as photographers is to take control of the camera functions. In the early stages of shooting, many people rely on the camera's automatic exposure controls capability. They set the camera on Program mode, and shoot away.

One of the first steps in taking creative control in evolving your vision is deciding what the viewer's eye will focus on. Depth of field is one of the tools in accomplishing that. Simply put, depth of field is the distance in front of, and behind the point your focus on that is in focus. A photograph shot at a wide open aperture like f2.8 will have less depth of field than an image shot at a small aperture like f16.

In this example, my interest is in having the viewer look at the texture of the wooden buggy at a historical site. In the image above, the aperture is set at f2.8, so the focus is quite shallow. The background is blurred and the eye focuses on the corner near the wagon wheel. But in the image below, notice that using a small aperture of f16 allows the rocks and winter grass in the background to compete with the main subject because they are much sharper.



So my recommendation is that when you are making an image, think about what you want the viewer to see, and use depth of field as an ally to accomplish that.

Depth of Field

One of the most important concepts to understand is depth of field, which is the distance in front of, and behind the subject that will be sharp in relation to where you focus. The general rule of thumb is that the greater the ƒ-stop number, the more depth of field you will have. So, for example, at ƒ22 you will have a lot more in focus in front of, and behind your subject than you will at ƒ4.

The benefit of understanding this, is that different subjects benefit from using more or less depth of field. Landscapes, for example, benefit from greater depth of field because you can keep the foreground and background sharp. So you can keep a rock in the foreground in focus, as well as the mountains in the background.



But for portraits, the reverse is generally true. Although in environmental portraits there may be an interest in keeping the surroundings sharp, for the most part, we want to separate our subject from the background as much as possible. So shooting with a shallow depth of field is the way to go.



Just look at this portrait, taken on a basketball court. The important thing here is the personality and expression of the person, so allowing the background to go soft is a great solution.

But what if even shooting wide open (in this case, ƒ4) leaves some areas sharp because they are in the same plane of focus as the subject?



In this case, I duplicated the background layer, used guassian blur on the duplicate layer, then added a mask and protected the person’s face.



Look at the difference in this detail snapshot.





The result is that I’ve added more separation between the person, and the distracting pattern of the fence.