1. What are the functions of depth of field and the factors that determine it?

The role of depth of field: Depth of field can make the film feel layered; Shallow depth of field highlights the subject; Deep depth of field can get clear visual enjoyment. Factors that determine the depth of field: aperture, focal length and object distance.

1. Aperture:

The smaller the aperture, the larger the range of depth of field; The larger the aperture, the smaller the range of depth of field. That is, the aperture is inversely proportional to the depth of field. When shooting, if you want the front and back scenes of the subject to be very clear, you can adjust the aperture as small as possible; On the other hand, if you want the focused object to be clear and blur other scenes before and after, then try to open the aperture as much as possible.

2. Focal length:

The shorter the focal length, the larger the depth of field, and the longer the focal length, the smaller the depth of field. That is, the focal length of the lens is inversely proportional to the depth of field.

3. Object distance:

The farther the object distance is, the wider the depth of field is; The closer the object distance, the smaller the depth of field range. That is, the distance is proportional to the depth of field. The foreground depth of a lens is always less than the back depth of field.

introduction of depth of field and introduction of heart algorithm:

1. introduction of depth of field

depth of field (DOF) refers to the range of the distance between the front and back of the subject measured by the imaging that can obtain clear images at the front of the camera lens or other imagers. Lens aperture, lens focal length 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 presented in the range before and after the focus is called the depth of field.

There is a certain length of space in front of the lens (front and back of the focus). When the subject is located in this space, its image on the negative is just between the same diffusion circles. The length of the space where the subject is located is called the depth of field. In other words, the image blur of the subject in this space presented on the negative film surface is within the limited range of allowable dispersion circle.

Second, the centroid algorithm

The blur level method is a fast centroid algorithm for quantitatively estimating hyperfocal distance and shallow depth of field. That is, the traditional focus distance is replaced by the standard height multiple of the short side of the field of view, and the blur level is introduced to combine the mental arithmetic of hyperfocal distance and shallow depth of field.