Surveying and mapping personnel need to take photos from high altitude to the ground when drawing maps. If the focal length of the camera lens used is 50 mm, the distance from the film to the lens is

Surveying and mapping personnel need to take photos from high altitude to the ground when drawing maps. If the focal length of the camera lens used is 50 mm, the distance from the film to the lens is 0. Why? If it is slightly larger than 50mm, D should be selected.

The lens of a camera is equivalent to a convex lens. After the light emitted by the object passes through the camera lens, it forms an inverted and reduced real image on the film, which makes the film sensitive. .

Film is equivalent to a light screen. The principle of a camera is that when U > 2f, the object will get an inverted and reduced real image on the light screen through a convex lens. . When u > 2f, the image distance is between one focal length and two focal lengths. .

You should choose D.