How to divide the width and coverage of a movie?

Overlay movies are also called "fake widescreen" movies. It is a distortion-free widescreen system, which uses a standard 35mm film camera and optical lens to shoot. When shooting, add a frame in front of the camera to cover the upper and lower sides of the original standard frame, so that the aspect ratio of the picture is 1.33: 1, and the screen occlusion is from 1.66: 1 to 1.88. It is economical and simple to make wide-screen movies by this method, which is widely used in the world.