Focal plane aperture conversion

Generally, the value of t is always greater than the maximum aperture of the lens, and the difference between the two represents the loss of light in the transmission process. In short, the closer the T value is to the F value, the better the transparency of the lens and the brighter the exposure effect.

The lens of a camera is made of a series of glass or transparent substances. Its task is to focus all kinds of light directed at the lens on the focal plane and make the film sensitive. It is the shutter and aperture that determine the sensitivity and effect. Usually, the shutter speed of the camera is fixed at one fiftieth of a second, and the film is at 24 frames per second.

It is mechanically moved to be exposed to light through the film door. In front of the door, there is a metal blade turning. Every time a frame of film is exposed, the blade covers the film door in time so that the next frame of film can reach the correct exposure position.

A shot often contains one or several different pictures, and each picture consists of many identical or different frames. The frame of the lens is a horizontal rectangle. The aspect ratio of ordinary screen movies is 1: 1.375, widescreen movies are 1: 2.35, and 70mm movies are 1:2.2.

Individual shots are shot by special methods such as occlusion, and special pictures such as circle, triangle, vertical row and multi-screen can be obtained. Picture is the premise of the lens picture, in which all the contents of the film are displayed.