How big is the pinhole imaging hole to meet the requirements slowly?

It depends on the distance between objects and the size of the object being imaged. If the object distance is close enough, the distance is large enough, and the object to be imaged is large enough, then 10 mm aperture can also be used for imaging, for example, the objects are 500 mm apart, and the object to be imaged is a circular surface of 150 mm, then 10 mm aperture can also be used for imaging.

Pinhole imaging, China scholar Mo Zhai (Mozi) and his students made the world's first experiment of pinhole image inversion, explained the reasons of pinhole image inversion, pointed out the essence of light propagation along a straight line, and summarized similar theories more than 2,000 years before Newton. This is the first scientific explanation for the straight-line propagation of light.

Extended data:

Property application

1, ancient astronomical calendar

The linear propagation of light has been widely used in ancient astronomical calendars in China. Our ancestors made standard watches and sundials and measured the length and direction of shadows to determine the time, winter solstice and summer solstice. Install peepholes on astronomical instruments to observe the sky and measure the positions of stars.

2. Cameras and camcorders

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).