How to Photograph the Invisible—a Quirky Guide From 1940

Behind the Lens illustrates techniques for photographing what can't be seen with the naked eye, including the movements of falling cats. Courtesy of the Prelinger Archive, the film stages campy demonstrations of time-lapse, slow motion, and Schlieren photography, the process of capturing unseen air currents on film. Because the documentary was produced by Jam Handy for Chevrolet, there is also an extensive sequence of a car's suspension system in action, filmed in slow motion. 

For more films from the Prelinger Archive, visit http://www.archive.org/details/prelinger.