Explanation of main parameters of industrial cameras and lenses
The focal length is the distance from the center point of the lens to the clear image formed on the glue plane (film or CCD). Note that the focal length of the camera and the focal length of a single convex lens are two concepts, because the lenses installed on the camera are many. The focal length of a single convex lens is the distance from the center of the convex lens to the point where the parallel light rays converge.
Aperture is a device used to control the amount of light that passes through the lens and enters the photosensitive surface of the fuselage. It is usually in the lens. For the lens that has been manufactured, we cannot arbitrarily change the lens of the lens, but we can pass the lens inside the lens. Adding polygonal or circular, and variable-area aperture gratings to control the amount of light passing through the lens, this device is the aperture.
Depth of field refers to the range in which the image is still clear within a certain distance in front of and behind the subject after the subject is clearly focused. The depth of field varies with the aperture value, focal length, and shooting distance of the lens. The longer the focal length, the smaller the depth of field, and the shorter the focal length, the greater the depth of field. The closer you are to the subject, the smaller the depth of field, and the farther you are, the greater the depth of field.