The meaning of lens caliber

Lead: With the development of digital technology, numbers have been integrated into us. The aperture of the lens is also called absolute aperture and effective aperture, which means the maximum incident aperture of the lens, that is, the maximum aperture of the lens. The size of the aperture is expressed by the aperture coefficient f, F= lens focal length/maximum aperture diameter, or it can be expressed by the reciprocal of the f coefficient, such as F2.8 or 1: 2.8. The smaller the f, the larger the caliber. For the zoom lens, we will see the expressions of F3.5-5.6, which are the maximum aperture of the wide-angle end and telephoto end of the lens respectively.

The significance of lens aperture The larger the lens aperture, the greater the practical value. The advantages of large aperture lens mainly include: it is convenient for hand-held camera to shoot with field lamp in dim light; It is convenient to capture the effect of small depth of field and combine the picture with reality; It is convenient to use a higher shutter speed to cure the moving body. However, the manufacturing process of large aperture lens is complicated, so the larger the aperture, the larger the lens and the higher the price. Usually the caliber is from first gear to half gear, and the price doubles several times. For example, Canon EF 50mm F 1.8 is around 700 yuan, EF 50mm F 1.4 USM is around 3000 yuan, and EF 50mm F 1.2 L USM is around 10000 yuan.

What's the lens?

The lens has two fingers in film and television. One is the optical element used by film cameras and projectors to produce images, which consists of multiple lenses. Different lenses have different modeling characteristics, and their application in photographic modeling constitutes an optical expression means; The second finger refers to the picture taken continuously from power on to power off, or the fragment between two editing points, also called ytterbium head. One finger and two fingers are two completely different concepts. In order to distinguish, one refers to the optical lens and the other refers to the lens picture.

The lens referred to in film and television is not a physical or optical lens, but a lens that carries images and can form a picture.

The lens is the basic unit of the whole movie. Several shots make up a paragraph or scene, and several paragraphs or scenes make up a movie. Therefore, the lens is also the basic unit of visual language. It is the basis of narration and ideographic expression. In the early shooting of film and television works, the lens refers to the sum of an uninterrupted picture taken by the camera from the beginning to the stillness; In post-editing, a shot is a set of pictures between two editing points; In the finished film, a lens refers to a complete segment from the front optical transformation to the back optical transformation.

The main function of the lens is to collect the reflected light of the illuminated object and focus it on the CCD. The image projected on the CCD is inverted, and the camera circuit has the function of inversion. Its imaging principle is the same as that of human eyes.

Lens classification

According to the origin of lenses, mainly Japanese lenses and German lenses. Japanese lenses mainly have good color reproduction, while German lenses have a strong sense of layering. China's lens has gradually occupied a certain market in the market, mainly because the price is relatively low.