What is depth of field in photography?

Depth of field (DOF) refers to the distance range in front and behind the subject measured by imaging that can obtain a clear image at the front edge of the camera lens or other imager. The aperture, lens, and distance to the subject are important factors that affect the depth of field.

After focusing is completed, the clear image presented in the range before and after the focus. This distance range before and after is called the depth of field. There is a space of a certain length in front of the lens (before and after the focus is adjusted). When the subject is located in this space, its image on the film is exactly between the two circles of confusion before and after the focus.

The length of the space where the subject is located is called depth of field. In other words, the blur of the image of the subject in this space on the film surface is within the limit of the allowable circle of confusion. The length of this space is the depth of field.

The depth of field effect refers to the range in which both the front and rear of a certain point are still clear when the focus is on it. It can decide whether to blur the background to highlight the subject, or to capture a clear background.

It is often seen that in photos of flowers, insects, etc., the background is very blurred (called a small depth of field). However, when taking commemorative photos, group photos, landscape photos, etc., the background is generally shot to be as clear as the subject (called a large depth of field).

Extended information

Aperture, lens, and distance from subject are important factors that affect depth of field:

1. The larger the aperture (the smaller the aperture value f) ) The shallower the depth of field, the smaller the aperture (the larger the aperture value f), the deeper the depth of field.

2. The longer the focal length of the lens, the shallower the depth of field, and conversely, the deeper the depth of field.

3. The closer the subject is, the shallower the depth of field. The farther the subject is, the deeper the depth of field.

Baidu Encyclopedia - Depth of Field Effect

Baidu Encyclopedia - Depth of Field (Photogrammetry and Remote Sensing Terminology)