What is the black box in the camera?

Cameraobscura (English: camera obscura), also known as cassette, is an optical instrument that can project images on the screen. The concept of black box appeared as early as BC. Since15th century, it has been used by artists as an auxiliary tool for painting. By the end of18th century, some photographers had carried out photography experiments in black boxes.

The film is in a black box. When light comes in and hits the film, a phase is formed. However, if the light is insufficient or too large, the exposure effect is not good and the photos will not be developed. So there should be a black box to control the exposure time of the film.

Extended data:

Black box principle

If the light reflected from a bright scene enters a dark room through a small hole, a dim scene image can be formed on the wall opposite the scene. This image is upside down, because the light from the upper part of the object can only shine on the lower part of the wall, and the light from the lower part can only shine on the upper part of the wall.

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