What is Depth of Field in photography?

What is Depth of Field?

Depth of field (DOF) refers to the distance in which objects are in focus. In other words, the part of a photograph that appears to be sharp. For example, in the image at right, the model is sharp but the background is completely out of focus.

How does it work?

There are 3 factors that affect depth of field:

1. Aperture:

• A large aperture (or small F-Stop) will give you a shallow DOF. That is, a smaller portion of the scene will be in focus with the foreground and background appearing blurry.
• A small aperture (or large F-Stop) will give you a large DOF, in which most of the scene will appear in focus.

2. Focal Length:

• A wider lens (ie. under 35mm) will produce a large DOF.
• A long or telephoto lens (ie. over 105mm) will produce a shallow DOF.

3. Distance between camera, subject and background.

• The closer the subject is to the camera, the shallower the DOF (ie. the background will be blurrier)
• The farther away the subject from the camera, the larger the DOF (ie. the background will be sharper)

A combination of these 3 factors can produce a variety of effects when it comes to depth of field. For example, the photograph above was taken at f/2.5 with a 50mm lens with the model fairly close to the camera relative to the background. The large aperture and distance to subject helped throw the background out of focus to help the model “pop“.

The images below show the effect of different apertures.

f/22

f/16

f/11

f/8

f/5.6

f/4

f/2.8

f/2

f/1.8

Hopefully that makes sense. The diagram below shows how the images above were photographed and the lines show roughly what is in focus on each aperture.

Why is Depth of Field important?

Because it gives us creative control over our photographs. A shallow depth of field lets us focus the attention on a specific part of the image, it lets us minimize distracting backgrounds by making them blurry, etc. This is generally desirable for portraits, for example.

On the other hand, a large depth of field lets us keep everything in the picture sharp. An effect ideal for certain types of landscapes and product photography.