An adjustment to the camera enables the film to run through it at half-frame when shooting, so in the end there are always three faces automatically superimposed: A+B+C= 1/24.
2012
2007
1990
1994
2011
2017
1928
2001
2004
1965
2015
2021
2024
1984
1929
2009
2014
1958
1967