The law of convex lens imaging is an optical law. In optics, an image that is formed by the convergence of actual light and can be presented on the screen is called a real image; An image that cannot be presented on the screen is called a virtual image. When talking about the difference between real image and virtual image, we often mention such a method: "The real image is all upside down, and the virtual image is all upright."

If it is a thick meniscus concave lens, the situation will be more complicated. When the thickness is large enough, it will be equivalent to a galileo telescope, and when the thickness is larger, it will be equivalent to a positive lens.

Its imaging principle is that the object is out of focus and forms an inverted real image on the other side of the convex lens. There are three kinds of real images: reduction, equal division and enlargement. The smaller the object distance, the larger the image distance and the larger the real image. When it is at twice the focal length, it will become a real image of an equal-length inverted head. The object is placed in focus and forms an upright magnified virtual image on the same side of the convex lens. The greater the object distance, the greater the image distance and the greater the virtual image. Will not be focused and imaged. In optics, an image gathered by actual light, called a real image, can be accepted by the light curtain; On the contrary, it is called a virtual image, which can only be felt with the eyes. Compared with the original, the real image is upside down, while the virtual image is upright.