About 80% of the knowledge in the brain is acquired through the eyes. Reading books, looking at pictures and appreciating paintings, appreciating people and enjoying beautiful scenery all need eyes. The eyes can distinguish light with different colors and brightness, and convert this information into nerve signals and transmit them to the brain.
The human eye is the benchmark of telescope magnification, that is to say, the magnification is 1, and the aperture is the size of the pupil of the human eye, which varies with the change of illumination intensity and generally fluctuates between 2-7 mm.
Extended data
The eye can change the focal length of the lens by adjusting the curvature (refraction) of the lens, so as to obtain an inverted and reduced real image.
The farthest point that the eyes can see is called the adjustment far point, and the far point that the eyes can see is extremely far; The closest point that the eye can see is called the accommodation near point, and the accommodation range is called between two points. The near point of normal eyes is about 10 cm away from the eyes.
The expression of eyes is most closely related to the sun. In fact, the development of human eyes into such a complex, dexterous and vivid optical system is the result of long evolution of human beings in the process of natural selection. Except for visible light, the electromagnetic radiation in other bands of the sun is basically absorbed by the earth's atmosphere. Since they can't "participate" in illumination, it is unnecessary for human eyes to "set" photoreceptor cells for them in the long evolution process.