What is depth of field?

Before and after the subject (focus), the image still has a clear range, that is, the depth of field. In other words, the depth of field before and after the subject and the blur of the image presented on the surface of the negative are within the allowable dispersion circle. The depth of field varies with the focal length, aperture value and shooting distance of the lens. For a fixed focal length and shooting distance, the smaller the aperture, the greater the depth of field.

Based on the photographer with a camera, the distance from the focus to the near allowable circle of dispersion is called the foreground depth of field, and the distance from the focus to the far allowable circle of dispersion is called the back depth of field.

When the lens of a camera is clearly focused on an object, the point on the same plane perpendicular to the lens axis at the position opposite to the lens center can form a quite clear image on the film or receiver, and the point in a certain range before and after the lens axis can also form a relatively clear image point acceptable to the eyes. The distance between all the scenes before and after this plane is called the depth of field of the camera.

Extended data:

Three important factors that affect the depth of field are the distance between the aperture, the lens and the subject.

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

2. The longer the focal length of the lens, the shallower the depth of field, and vice versa.

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

References:

Baidu encyclopedia-depth of field

Pacific IT encyclopedia-what is depth of field?