Film: Metropolis (1927)
The Effect: Schüfftan process
Long before blue screen technology was dreamt up, a cinematographer working on Fritz Lang's seminal sci-fi masterpiece, Eugan Schüfftan, figured out a way to use mirrors to project actors into miniaturised sets.
The sets in Metropolis, which introduced Art Deco to parts of the world not yet familiar with the new style, were designed to be awe-inspiring, and thus completely impossible to build at full-scale. But Schüfftan's inventive process gave Lang the ability to shoot real people against the backdrop of enormous buildings.
In the 310 days it took to shoot the 1920 classic, dozens of innovations were cooked up by hundreds of technicians, but few compared to the enormity of Schüfftan's process, which was so effective Peter Jackson even used it as part of his Hobbit shooting in The Lord Of The Rings.