A camera is a device that uses the principle of optical imaging to form an image and use a film to record the image. It is an optical device used for photography. In modern social life, there are many devices that can record images, and they all have the characteristics of cameras, such as medical imaging equipment, astronomical observation equipment, etc. After the light reflected by the photographed scene is focused by the photographic lens (photographic objective lens) and the shutter that controls the exposure, the photographed scene forms a latent image on the photosensitive material in the dark box, and is processed (ie, developed and fixed) to form a permanent image. This technique is called photography, which is divided into general photography and professional photography. 1. Cameras can be divided into film cameras, digital cameras and Polaroid cameras according to their imaging media. A film camera mainly refers to a device that takes an image through a lens and applies film to record the image. The digital camera is a photographic device that uses semiconductor photocouplers and digital storage methods to record images. It is easy to use, easy to transmit photos, and easy to save. Polaroid camera, also known as a one-shot imaging camera, is to directly photosensitive the image on a special photo paper, you can see the photo within one minute, suitable for souvenir photos, etc.