3ds max What is the depth of field effect?

Let me give you a brief introduction first. Have you ever seen this kind of photo? After taking a portrait, the person in front knows clearly that the background behind is empty, and its purpose is to highlight the subject of people!

Depth of field refers to the distance range of an object measured along the axis of an imager, which can obtain a clear image in front of a camera lens or other imager. Generally speaking, after focusing is completed, a clear image can be formed in the range before and after focusing. This range of front-to-back distance is called depth of field. Depth of field: There is a certain length of space in front of the lens (before and after focusing). When the subject is located in this space, its image on the negative is just between the two diffusion circles before and after focusing. The length of the space where the subject is located is called the depth of field. In other words, the blur of the image presented by the subject on the negative plane of this space is within the limited range of the allowable circle of dispersion, and the length of this space is the depth of field.

When the light rays with parallel optical axes enter the convex lens, the ideal lens should be that all the light rays converge at one point and then spread out conically. The point where all the rays converge is called the focal point.

Before and after the focus, the light began to gather and spread, and the image of the point became blurred, forming an enlarged circle called the diffusion circle.

In reality, images taken for viewing are observed in some way (such as projection, enlargement into photos, etc.). ). The image perceived by human eyes is closely related to magnification, projection distance and viewing distance. If the diameter of the diffusion circle is less than the resolution of human eyes, the blur produced by the actual image can not be recognized in a certain range. This unrecognizable dispersion circle is called allowable dispersion circle. There is an allowable dispersion circle before and after the focus.

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.