Physics: What is a simple pinhole camera made of cans?

The light emitted by the object, after passing through a small hole or lens, produces an inverted real image on the focusing screen of the sealed box. The tiny holes make the light of each point of the object only reach its own image point without overlapping, thus obtaining a clear image. The smaller the pinhole, the less light passes through the pinhole and the lower the brightness of the image. Because the principle of pinhole imaging is applied, it is the linear propagation of light.

The basic part includes a sealed camera box, followed by a focusing screen; There is a small hole or a condenser lens in front of the sealed box. You can see a clear image on its screen. If you install a photosensitive film at the position of the screen, you can also take a clear picture, which becomes a pinhole camera. However, this requires a "shutter" and a slot for loading negatives. In addition, the requirements for sealing are stricter than those for making ordinary pinhole imagers.

Extended data

Some cameras and camcorders use the principle of pinhole imaging-the lens is pinhole (mostly equipped with convex lens to ensure the imaging distance of light), the scene enters the darkroom through pinhole, and the image is left on the film by some special chemicals (such as developer) (digital cameras and camcorders store the image in the memory card through some photosensitive elements).

The pinhole camera has a fixed image distance of about 64 mm and a fixed aperture of 0.4 mm, so the aperture is also fixed. Experiments show that the pore size is about 160. When the brightness of the subject is different, it can only be adjusted by exposure time. Because the aperture number of a general camera is about 22, it is impossible to find out the exposure time of aperture 160, so it can be determined according to the ratio of exposure time equal to the square of aperture ratio (that is, t 1: t2 = (f 1: f2) 2).

Baidu encyclopedia-pinhole imaging

Baidu encyclopedia-pinhole camera