One early attempt was ‘Polyvision,’ which used three separate projector screens to show either related footage as a single panoramic shot or differing images as a kind of triptych. Unfortunately, this method was expensive and time-consuming, meaning films using it could only be shown in large cinemas such as the 1,979 seat Palais Garnier in Paris, and vastly increasing the time needed to shoot the film, as well as the necessary budget.
Polyvision as seen in Abel Gance’s epic Napoleon (1927), in which the seams between the shots can be seen. This early method of split screen was only shown a few times at the time of its release and abandoned afterwards because of the difficulty in displaying it in most cinemas at the time, but the grand widescreen scenes it could result in helped to portray the vastness and grandeur of its subject matter
There are several motivations for using this technique. In some films, a seamless split screen, like that in The Parent Trap (1961), is used to overcome a special effects challenge in which the same actor, playing two characters, must appear in the same frame, or one character requires special makeup or lighting which would make it impossible to take one shot. When using film, this is usually done by filming two separate negatives on the same set and then combining them into what’s called a ‘composite.’
Hayley Mills was shot in a split screen format for The Parent Trap, requiring her to be shot with costume and makeup changes in the same scenery in order for her to play twins Sharon and Susan.
Elvis on Tour took advantage of the usual presence of multiple cameras for concert filming to capture the energy and vibrance of Elvis’ tour through the use of split screens throughout the film.
In its more recognizable form with clear borders or separations and different actions on the screen, a split screen will be used to juxtapose separate actions in the same frame. These can be complementary or contrasting, humourous or tense. It can suggest individuality or distance, or show characters as opponents or to indicate a slew of other interactions. An advantage of this juxtaposition is that the audience can make connections between the two (or more) images even if what’s shown is quite slow or simple. It can also create a sense of dynamism that simpler footage might not have, as in the concert sequences in Elvis on Tour (1972). In that documentary, split screens were used both to convey the energy of his performances and the enthusiasm of the crowd in response, as well the hectic nature of life backstage.