Director Richard Donner knew that the film would only work if it could make Christopher Reeve fly believably. He therefore asked his team to invent a new method to accomplish this challenge, because nothing that existed until then could be suitable.
The person who found the solution to the problem is Zoran Perisic. This specialist in optical effects, who had worked on 2001, A Space Odyssey , invented a process for the occasion, called Zoptic .
Basically, without going into too much technical detail, it is a complex device which projects a film of a landscape (for example a background of New York filmed from a helicopter) on a large screen in front of which the ‘actor. This device also includes a camera that films the actor in front of the screen. So far, nothing exceptional. What is exceptional about this device is that the camera which films the actor is synchronized with the projector which projects the background, so that the camera which films the actor can, for example, zoom in on him without affecting the background.
So, to make it look like Superman is speeding up, the camera can zoom in on him without zooming in on the background. This is the secret of this optical trick.
The two images are superimposed, but you can act on the foreground without affecting the background.
This system also allows the camera to rotate around the actor without the background moving, thus giving the impression that Superman is spinning around.
Christopher Reeves and Margot Kidder lying on a base that we will not see on screen.
Despite everything, this method proved to be very time-consuming to implement. It took five months to shoot the film’s flight sequences…
Note that for all the landing and takeoff sequences, Christopher Reeves was simply held by cables and hung from a crane which lifted him from the ground.