The lens of a camera is equivalent to a _ _ _ _ _ _ mirror. With the same camera, take a full-length picture of Xiaohua first, and then take a bust of him. So the photographer should

(1) The lens of a camera is equivalent to a convex lens. Take a full-length picture of Xiaohua with the same camera first, and then take a bust of him. The image on the camera negative becomes larger and the image distance becomes larger, so the photographer should lengthen the camera's black box length.

(2) As shown in the figure from B to D to C to A, the image distance gradually increases, and the image gradually becomes larger.

So. Elongation; D．