Ghosting occurs when the projector shutter is closing either too early or too late. The function of the shutter is to hide the film as it is being pulled down by the intermittent or claw, and reveal it while it is sitting still in the gate. When the shutter is out of time, ghosting occurs and the audience sees a little bit (or in some cases, a lot!) of the frame being pulled down. This is especially noticeable on films with subtitles, or in scenes with lamps in a dark room, for example. Because the image is being "smeared," it reduces perceived sharpness. Very bad!