"Sh! The Octopus" (1937)

A landmark special effect. No cut, transition or CGI.

Sh! The Octopus is a 1937 comedy-mystery film produced by Warner Bros., directed by William McGannand starring Hugh Herbert, Allen Jenkins and Marcia Ralston. While contract players Herbert and Jenkins frequently appeared in the same picture, this is the only movie to present them as an actual team. The film's oddball qualities have made it something of a cult favorite.

Herbert and Jenkins play two bumbling detectives, who, in pursuit of a master criminal, The Octopus, find themselves inside a haunted lighthouse full of suspicious characters, including the titular character, who appears to be an actual octopus.

The real shocker is the reveal in this scene. It turns out the old “Nanny” is the master criminal.

But how did they do that without CGI?

Nanny’s transformation — which sees a cackling, but otherwise normal-looking woman transform into a gnarled, blotchy hag — relies on the same red-blue color filtration found in old-school 3-D glasses. When you look through the red lens of a pair of 3-D glasses, you don’t see the red elements on-screen. The same is true of the blue elements when you look through the blue lens. When you apply this concept to black-and-white photography, you are able to “hide” certain colors in plain sight. It’s worth emphasizing that this optical makeup effect is only possible on black and white film. If this scene had been shot in color, Nanny would have appeared weird. But the “reveal” gag wouldn’t have worked quite as well, if at all.

Nanny’s “ugly face” makeup was applied using one color of product, exaggerating and creating unfaltering shadows, contours, and blemishes on Dudgeon’s face. Colored makeup was also used to “blackout” some of Dudgeon’s teeth. (Note: there’s nothing to specify that the color transition in Sh! The Octopus was red-blue, but for the sake of this explanation, we’re going to assume it is).

A graduated filter was placed in front of the camera lens. At the beginning of the scene, we are looking at Nanny through the red-colored filter, which is “filtering” out any red that it “sees.” Consequently, Dudgeon’s red makeup appears to blend into her skin tone and the grotesque visage appears invisible. As the filter is slid across the front of the camera lens to the blue side, the splotchy red makeup becomes visible to us. And because we’re working with black-and-white film, the red appears to darken. Whether the crew also supplemented the graduated filter with a colored light (which would enhance the effect) is unclear, but possible. ~ Film School Rejects

If you’d like to see the entire film …