Basic principles of photographic imaging

The optical imaging principle of photography is the same as human vision, and the camera structure is strikingly similar to human eyes.

The human eye is a perfect optical system, which can transmit the light from the external scene to the retina through the pupil of the eye to form an object image. So normal people can see the scenery in the name of visible light through their eyes.

The process of camera forming scene is basically the same as that of human eyes feeling objects. Here, the camera lens is like the pupil lens of the human eye, and the optical ring is like the retina of the human eye. The radiation of the photographed scene is focused on the photosensitive medium in the camera through the lens to form an image. But they also have differences.

First, when shooting with a camera, the image formed by the object in the viewfinder is upside down.

The image of an object falling on the retina through the lens of the pupil of the human eye is upside down physically, but after the adjustment of the human brain, the visual effect is exactly the same as that of the objective object image.

Second, their image carriers are different.

The camera carries the image with the photosensitive carrier and takes the film as the negative film to shoot the negative image; When shooting an object with a reversal film, the image obtained is positive; The image taken with a digital camera is positive. The above images can be converted into pictures by chemical or physical treatment. The influence of human eye focusing falls on the retina, just feeling and impression.

Third, the human eye has the function of automatic adjustment.

When people walk through the dark indoor aisle under the strong sunlight, they can't open their eyes and feel white. Close your eyes for a while, and you can gradually see the scenery under the strong light. On the contrary, people walk into the dim light environment, and their eyes are dark. After a while, they will slowly see the scenery in the dark. This is because the eye can automatically adjust the pupil, so as to obtain a suitable image on the retina. However, the camera lens is manually adjusted, and even for an automatic exposure camera, it must be manually set in advance.

Camera is the product of bionics, which was originally made according to the structure of human eyes. Later, with the deepening of optical research, the camera lens has been developed and improved, from pinhole imaging to convex lens single lens imaging, and then to the combination of multi-lens and coated lens. The focus on the scene through the lens is getting better and better, and the color difference is getting less and less.