A shutter is a rotating device with a single blade or multiple blades used to interrupt the light source as film is pulled through the gate. The shutter "blanks" the light from the lamphouse as the intermittent pull down motion happens. Shutters also prevent the heat of the lamp from hitting the film plane continuously.
- If the shutter isn't timed properly you will see a travel ghost or ghosting on screen. This happens because the shutter isn't completely blanking out the light onto the film plane as the pull down motion of the intermittent occurs.
Types of Shutters
(some examples of projectors who use them) The type of shutter used depends on the type of projector, the pull down speed of intermittent mechanism, the desired light efficiency, among other variables.
- single blade (Kinoton, Ernemann)
- dual blade (Simplex XL)
- dual blade counter rotating-dual shutter (Century JJ)
- 3 blade (often used for variable speed)
- 3 blade counter-rotating dual shutter
- 5 blade single (pretty rare, used for studio machines involved with telecine.