Thanks to his soft voice and puppy dog eyes, Hughes does a good job playing up the Devil as seemingly innocent. Jerome warns Ellington that “the Devil hath power to assume a pleasing shape,” but the Howling Man dispenses with any illusion once he’s free. Telekinetically forcing Ellington to the ground, he transforms from a haggard man into the regal Prince of Darkness (sprouting horns and elfen ears) and then disappears in a plume of smoke.
During the first close-up of the Howling Man’s transformation, you can notice that his face changes. Part of it is the expression; Hughes trades his earlier sad frown for a smirk. That’s not all, though — there’s a lighting change disguised by a crack of lightning. As a result, his eyebrows and cheeks sharpen while his skin darkens. His eye pupils also go from brown to silver, creating a sinister contrast with the rest of his face.
What was the lighting change here? The shot used both red and green-filtered lights. Initially, one half was lit and the other was dimmed, but midway through, they swapped that. Since the episode was shot on black-and-white film, the precise color changes were imperceptible.
Cinematographer George T. Clemens discovered this trick while working on the 1931 “Dr. Jekyll and Mr. Hyde” film. He’d even used the effect in an earlier “Twilight Zone” episode, “Long Live Walter Jameson.” There, the eponymous lead (Kevin McCarthy) rapidly ages. The wrinkled makeup applied to McCarthy’s face was red, so as the lighting slowly changed, it seemed as if the wrinkles were suddenly appearing.
“The Twilight Zone Companion” doesn’t specify the makeup used on “The Howling Man,” but if I had to guess, they painted Hughes’ skin a Satanic red. This would blend in with the red-filtered lights but pop with contrast under the green-filtered ones.
Source From: www.slashfilm.com