Depth of field
Depth of field (DOF) is the distance from front to back of a subject measured at the leading edge of a camera lens or other imager that enables a clear image to be obtained. Aperture, lens, and the distance from the focal plane to the subject are important factors affecting the depth of field.
After the focus is completed, the distance of the clear image before and after the focus, which is called the depth of field.
There is a certain length of space in front of the lens (in front of and behind the focus), and when the subject is in this space, its image on the negative lies between the same dispersion circle. The length of space in which the subject is located is called the depth of field. In other words, the image blur of the subject in this space is within the limits of the allowable dispersion circle, and the length of this space is the depth of field.
Aperture, lens, and the distance of the subject are important factors affecting the depth of field:
1, the larger the aperture (f is smaller), the shallower the depth of field, the smaller the aperture (f is larger), the deeper the depth of field.
2. The longer the focal length of the lens, the shallower the depth of field, and the deeper the depth of field.
3, the closer the subject, the shallower the depth of field, the farther the subject, the deeper the depth of field.
Calculation formula of depth of field
It can be seen from the formula that the depth of field is greater than the depth of foreground.
(1) Lens aperture:
The larger the aperture, the shallower the depth of field; The smaller the aperture, the deeper the field;
(2) Focal length of lens:
The longer the focal length, the shallower the depth of field; The shorter the focal length, the deeper the field;
(3) Distance between subject and background:
Changing the distance between the subject and the background does not change the depth of field, but only determines whether and to what extent the background is blurred.
(4) Distance between the subject and the lens:
The farther the distance, the deeper the depth of field; The closer the distance (not less than the minimum shooting distance), the shallower the depth of field.
