Depth of Field (DOF) refers to the measurable range of distances in front of and behind the subject within which sharp images can be formed at the front plane of a camera lens or other imaging devices. Apart from depth of field, you may be more familiar with background blur in portrait photography.

What is Depth of Field

Depth of Field (DOF) refers to the measurable range of distances in front of and behind the subject within which sharp images can be formed at the front plane of a camera lens or other imaging devices. Aperture, lens, and the distance from the focal plane to the subject are important factors affecting depth of field.

Once focus is achieved, the range in front of and behind the focal point that produces a sharp image is known as depth of field.

There is a certain space in front of the lens (both in front of and behind the focal point). When a subject lies within this space, its image formed on the film/sensor falls within the same circle of confusion. The length of this space occupied by the subject is called depth of field. In other words, for subjects within this range, the blurriness of their images on the film/sensor stays within the limit of the permissible circle of confusion, and the length of this space is depth of field.