A slit shutter is a narrow vertical opening placed either just in front of the film emulsion or at a similar distance in front of the lens. In this system, the film moves continuously through the camera at a constant speed, allowing the shutter to expose a long, continuous image along the length of the film.
Slit shutters are commonly used in specialised photography applications, such as panoramic or high-speed imaging, where conventional shutter mechanisms would be impractical for capturing extended or fast-moving subjects.