Special effects help create the illusions or graphics we see in films, movies and video games. Sometimes they are used to remove images from a film and in other cases they help enhance certain images. Special effects can be either optical or mechanical. In the early days of film production, special effects referred mainly to visual effects, but with the development of computer-generated graphics, there is now a distinction between the two with special effects meaning the illusions created optically or mechanically on the set.
Optical effects are those in which the images are manipulated in some way by means of the camera, either through multiple exposures, mattes or by using video editing software. Mechanical effects are those in which there are physical changes made while shooting a scene. This includes such things as used mechanical props, scenery, scale models and pyrotechnics. They are often incorporated into the design of the set.
The trick photography of Oscar Gustave Rejlander in 1857 was the first example of special effects. It was not until 1895 that special effects first appeared in a film when Alfred Clark used this technique in the scene showing the beheading of Mary Queen of Scots. During the 1920’s and 1930’s, the techniques were refined with many of them being modifications of theater illusions and stop photography. Animations were accomplished through the use of drawings and three-dimensional models.
The invention of color for use in films and movies further advanced the techniques of special effects, which science fiction movies used to the best advantage. The success of the special effects prompted movie studios to invest huge amounts of money into developing bigger and better sets and into investigating ways of bringing other special effects into the scenes. Computer generated graphics has greatly changed the use of special effects in films. Digital composting offers more freedom with the use of optical effects and more control over their use.