In today's world of computers and CGI, split-screen imagery is a common way to illustrate multiple aspects of a story all at once. But there was a time, before computer wizardry, when it all had to be done by hand.
And someone had to do it first. For feature length films, that someone was Richard Fleischer - and the talented crew on The Boston Strangler.
Shot in 1967-68, the filmmakers had to literally hand-design each multi-pane shot and then assemble the footage piece by piece. It was an enormous undertaking - and one that is still celebrated for its ingenuity and foresight.
Read the comprehensive article written about it in American Cinematographer in May 2020: Multiple-Image Technique for The Boston Strangler
From Mark Fleischer, Richard's son:
Some years ago my father, Richard Fleischer, was directing the movie “Barabbas” in Rome. One of the most dramatic scenes of the movie was the crucifixion of Jesus Christ. At the time that my father was preparing to shoot that scene, a total eclipse of the sun was scheduled to occur at nearby Sienna.
Being an adventurous and creative soul, my father moved the entire company to Sienna to shoot that scene during the total solar eclipse, something that no one had ever done before.
This being the first time, nobody had a clue how to light the set. Using their best guesses, my father and the director of photography set up three cameras each with different settings, crossed their fingers and waited for the sun to almost completely disappear, at which point my father yelled “action.”
The world darkened, a strange and eerie light embraced the assembled crew and, against this backdrop the crucifixion of Jesus Christ was re-enacted. The filmmakers’ guesses turned out to be correct, and one of the most uniquely beautiful motion picture scenes came into being.