Photography: How does the lens affect the depth of field?

Selective focusing is generally called "shallow depth of field" focusing, while deep depth of field is large depth of field focusing. Shallow depth of field is to focus on the subject, and other foreground and background are out of focus, resulting in visual contrast and highlighting the theme. This is a very basic photography skill. For a general camera, the depth of field is mainly affected by the focal length and aperture of the lens, the relative distance between the camera and the main body and background, and also related to the camera's frame (photosensitive element or film size). Generally speaking, the larger the aperture, the longer the focal length, and the farther the subject is from the background, the more blurred the shallow depth of field will be.

On the contrary, when shooting with large aperture, short focal length and close range, you can get a deeper depth of field and ensure that the background can be clearly focused.

For a simple example, girls like to take very literary close-ups They usually use a lens with a focal length of 85mm or longer and an aperture of F4 or smaller, so that the model can take close-up photos closer to the camera, so that the background of the photos will be blurred and the model will stand out. Travel or daily life photos should be the opposite. Use a wide-angle or standard lens to bring the subject close to the background (such as buildings and monuments) so as to clearly focus on the people and the background.