Frozen in Motion

The whole scene holds still mid action while one thing keeps going. A room of people stopped between steps, and someone walking through them.

It puts the audience inside one character's privilege. The stopped world is what everyone else is stuck in, and the moving thread is the only thing with time left.

Everything except the live element holds a pose, including hair, cloth, dust and anything falling. The poses have to be mid action rather than at rest, because a room of people standing still is just a room of people standing still.

On set this is done with actors holding position, or with a still frame that the live element is composited into. Either way the frozen material keeps its motion blur from the instant it stopped, which is what stops it looking like a photograph.

The live element usually carries its own light. If the stopped world is lit one way and the moving thread another, the separation reads immediately.

Use it to show speed without showing motion, and to give a character a private moment inside a public one.

Skip it when nothing in the frame was moving to begin with. The effect is built entirely on the difference between the stopped and the live, so a static scene has nothing to freeze.

Bullet time gives the movement to the camera and stops everything in the world. Frozen in motion keeps the camera ordinary and leaves one thing in the world still moving.

A freeze frame stops the whole picture with no exception. If one element is still going, it is frozen in motion.

Bryan Singer stops a kitchen mid explosion in X-Men: Days of Future Past (2014) and lets Quicksilver walk through the suspended debris rearranging it. Joachim Trier freezes all of Oslo in The Worst Person in the World (2021) so Julie can run across the city through people caught mid step.

Either everything freezes or nothing does. Name the one element that keeps moving and say everything else holds mid action.

The second failure is a frozen crowd standing at rest, which reads as a still photograph. Ask for the stopped figures to be caught mid step, mid pour, mid fall.