The English used in this article may not be easy for everybody to understand. (September 2011)
An optical printer is a device. It can be used to copy rolls of movies. It is made of one or more movie projectors, which are linked to a movie camera. It allows filmmakers to re-photograph one or more strips of movie. The optical printer is used for making special effects for motion pictures or for copying and restoring old movie material.
Common optical effects include fade outs and fade ins, dissolves, slow motion, fast motion, and matte work. More complicated work needs dozens of elements, all combined into a single scene. Ideally, the audience in a theater should not be able to notice any optical printers work, but this is not always the case. For economical reasons, especially in the 1950s, and later in TV series produced on movie, printer work was limited to only the actual parts of a scene needing the effect, so there is a clear change in the image quality when the transition occurs.
The first, simple optical printers were constructed in the early 1920s. Linwood G. Dunn expanded the concept in the 1930s. The development continued well into the 1980s, when the printers were controlled with minicomputers.
Sice the late 1980s, digital compositing began to replace optical effects. Since the mid nineties the conversion to digital effects has been almost total. Optical printing today is used most widely by artists working exclusively with movie. As a technique, it proves particularly useful for making copies of hand painted or physically manipulated movie.