The photographer took a picture of a classmate with a camera with the same focal length, and a clear full-length image was formed on the negative. How to adjust the chest circumference if you want to

The photographer took a picture of a classmate with a camera with the same focal length, and a clear full-length image was formed on the negative. How to adjust the chest circumference if you want to change it? Because: (1) When the convex lens becomes a real image, the object distance increases, the image distance decreases and the image becomes smaller; The object distance becomes smaller, the image distance becomes larger and the image becomes larger;

(2) The distance from the object to the lens is the object distance, the film can be imaged, and the distance from the film to the lens is the image distance.

Therefore, a camera with a constant focal length takes a full-body photo of a person. If you want to take another bust of this person, the image of the person will become bigger. According to the changing law of object distance and image distance, the image distance will inevitably become larger and the object distance will inevitably decrease. Therefore, in order to take clear photos, it is necessary to reduce the distance between the camera and the person and increase the distance between the lens and the film.