What is the "black box" in the camera?

Camera obscura (English: camera obscura), also known as cassette, is an optical instrument, which is a device for installing photosensitive film on a camera. It has a compact structure and never transmits light, so it can project images on the screen.

The length of the camera box is equivalent to the image distance, and increasing the length of the camera box means increasing the image distance. This is the reflection of the external scenery on the film in the camera box, except that a small lens is installed in front of the "small hole" of the camera.

So the picture it gets is clear and bright. Of course, this picture can't be very bright. If you open the hole wider, the picture may be brighter, but it will be less clear.

The principle is a sealed box with a small hole, and the scenery outside the box passes through the small hole to form a reflection on the completely dark inner wall of the box, which is also the earliest form of camera.

Extended data:

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.

A.D.11/Yan Yi of Materia Medica, written by Kou Zongxuan, a pharmacist in the Northern Song Dynasty, mentioned that the Bodhisattva should shine on it with colorful light. This is the light of various colors refracted by sunlight through prism-type crystal, which is the dispersion phenomenon in photography.

In the18th century, black boxes were widely used, and gradually appeared small black boxes convenient for depicting portraits, still lives and indoor paintings, as well as portable, lightweight and compact black boxes for outdoor scenes. These black boxes were all made by skilled craftsmen, and the products were exquisite.

With the development of photography technology, a method of preserving photos has been invented. Photographic machines and tools such as cameras, photographic materials such as photographic negatives and developers, and even images that change from black and white to color.