In the study of convex lens imaging, when the object distance is more than twice the focal length, the image distance is between one focal length and two focal lengths, and the real image is reduced by inverted image.
When the object distance is between a focal object and two focal lengths, the image distance is greater than two focal lengths, and the real image is inverted and reduced. When the object distance is equal to twice the focal length, the image distance is equal to twice the focal length, forming a real image such as inverted head. When the object distance is less than a focal length, there is no image on the screen, and the virtual image is vertically enlarged.