Simple classification and structure introduction of optical lens

A lens is a structure that collects light so that the film can obtain a clear image. Earlier lenses consisted of a single convex lens. Because of poor definition and chromatic aberration, it is gradually improved into a compound lens, that is, a combination of multiple concave-convex lenses is used to correct various aberrations or chromatic aberrations, and the coating of the lens is used for processing. , Increase the amount of light, reduce glare, and greatly improve the quality of the image.

       Generally speaking, the lenses used for photography are focusing lenses. According to optical principles, light from a distance passes through a lens that has a focusing effect, and all of them are focused on one point, which is the focal point. The distance from the focal point to the center point of the lens is called the focal length. On the camera, the center point of the lens is usually located at the aperture, and the focus is on the focal plane (ie, the film surface). Therefore, the focal length of the camera is the distance from the aperture to the film when the lens focuses at infinity. According to the application, the lens can be divided into the following types:

       1. Wide-angle lens: The angle of view is above 90 degrees, the observation range is large, and the near image is distorted.

       2. Standard lens: The angle of view is about 30 degrees, and the range of use is wide.

       3, telephoto lens: the angle of view within 20 degrees, the focal length can reach tens of millimeters or hundreds of millimeters. 4. Zoom lens: The focal length of the lens is continuously variable. The focal length can be changed from wide-angle to telephoto. The longer the focal length, the larger the imaging.

       5. Pinhole lens: for concealed observation, it is often installed in places such as ceilings or walls.

       The structure of the lens can be understood as the structure of the lens, which is mainly composed of lenses. At present, the lens of any camera cannot be composed of a single lens, as are the standard lens and the functional add-on lens. A lens is often composed of multiple lenses, and these lenses will form groups as needed, so that the object to be photographed is as clear and accurate as possible.

       In addition to the number of lenses, the material of the lens is also an important technical indicator of the lens structure. At present, the materials of lenses can generally be divided into two categories: glass and plastic. These two materials are related to the technology and characteristics adopted by lens manufacturers, and there is no difference between the two materials. The lenses of the two materials also have their own characteristics: such as a stable glass lens and a lightweight plastic lens. In the market, Fuji's lenses are mostly plastic, while Zeiss and Nikon's lenses are mainly glass.