A computer-animated film usually shows a new pose every frame and blurs fast motion. Spider-Verse wanted to look like a comic book that moves, and its head of character animation, Joshua Beveridge, found that smooth motion betrays that look. After about a year of tests the team switched motion blur off and held most poses for two frames: "it's crisper, it's pop art". Hand animators used twos to save drawings; here hair, cloth and camera all had to be reworked to step. The internet's favourite theory says Miles is on twos while he's clumsy and on ones once he's Spider-Man. We couldn't find one filmmaker saying it. Beveridge says every animator could go in and out of being on twos in every moment: a shot might run sixteen frames on twos, a three-frame hold, then ones. "Something musical." In 1987 Pixar's John Lasseter had called motion blur the most realistic solution to strobing; Spider-Verse switched it off and kept one boundary: stay away from strobe and mush.

The figure, ball and frame strips here are our own drawings, not images from the film.

Which movie trick should we take apart next?

Sources: Barbara Robertson, "Imageworks Artists 'Break the Mold' to Create an Alternate Spider-Verse", VFX Voice, 2018; Dan Sarto, "Creating a Stylized Universe for Sony's Spider-Man: Into the Spider-Verse", AWN, 2018; Spider-Man: Into the Spider-Verse, The Official Movie Special (Titan), via io9; John Lasseter, "Principles of Traditional Animation Applied to 3D Computer Animation", SIGGRAPH 1987.
Sounds: Apple iMovie sound effects.