What is the clear standard of photography? What are the factors affecting the depth of field?

Clarity, brightness and visibility 1. Clarity is also called "image boundary", and the imaging of photographic lens shows the ability of clarity in fine texture. The reflected light points of an object gather into a focus (actually a circle of dispersion) through a lens, and its size can determine the sharpness of the lens. If the diffusion circle is large, the image boundary of the lens must be soft and scattered, and fine texture cannot be displayed; If all the scattering circles are small and the synthesized image can distinguish the fine texture, then the image boundary of the lens can be said to be good. This belongs to optical clarity. In addition, the low resolution and overexposure of photographic negatives, as well as the strong properties of developers and inappropriate development methods will affect the clarity of images, which belongs to photographic clarity. 2. lightness photography terminology. The visual brightness produced by light. Brightness is different from lightness, it is a subjective feeling and a psychological impression, which cannot be measured directly. Visibility usually refers to the maximum distance of objects that can be seen with normal vision. Here refers to the clarity of the movie picture (reflected on the screen) seen by normal vision at a certain distance, so it is also called "brightness". Visibility is limited by many factors, such as the resolution of the camera, the weather and light when shooting.