Special effects for television studio productions

The three main methods of producing special effects which are now coming into use in television are described. They are: (a) back projection, in which additional scenery is placed behind the actors in the form of a translucent screen on to which is projected an optical image of the required background; (b) inlay, in which by electronic means the picture from one television camera is replaced over a chosen fixed area by the picture from another camera; (c) overlay, in which the result is similar to back projection but the image of the additional scenery is added electronically. Some indication is given of the saving in production cost and the widening of programme scope resulting from the introduction of these processes to the television service, and the operational difficulties introduced are considered.