Fast motionTime running faster than it should

Fast motion is filmed at a lower frame rate than it is played back, so people and objects move quicker than in life. The audience laughs, feels pressure or sees time rushing past, depending on the scene.

Also calledUndercrankingSpeeded-up footageSped-up motion

Demo clip, 4 seconds, rendered with Seedance 2.0 Mini from the prompt on this page.

Time and motion

Why it works on screen

Speeding up footage changes the meaning of any action. Ordinary gestures become comic, slapstick or mechanical. A long task collapses into seconds. A life spinning out of control looks exactly like that. Fast motion serves comedy, satire, frantic deadlines, routines that eat a character's days and the rising speed of addiction or panic. It can also strip dignity from a scene, turning something intimate into something absurd, which is a strong tonal weapon. A scene earns it when the story wants the audience to feel time as a pressure or to see human behavior from a comic distance.

The shot list line

Size: Medium shot to wide shot
Angle: Eye level or high angle
Movement: Static
Lens: 24mm to 35mm
Duration: 3 to 6 s on screen

Undercrank to 12 to 18 fps for comic speed with smooth motion, or shoot normally and speed up in the edit, and lock the camera so only the action accelerates.

Screenplay

On the page

Fast motion is less common in scripts than SLOW MOTION, but the convention is the same: a short line such as "IN FAST MOTION" or "SPED UP" before the action, then a clear return to normal. Use it rarely and only when the speed changes the meaning of the scene, for comedy or for a rush of time. Often a MONTAGE or SERIES OF SHOTS heading already covers passing time without naming the effect. The frame rate belongs in the shot list.

EXT. NOODLE STALL - BANGKOK - NIGHT

The dinner rush. A line of customers down the sidewalk.

PIM (20s, first night on the job) stares at the wok, the ladle, the bowls, the queue.

IN FAST MOTION

AUNTIE NOK (60s) takes over: noodles in, broth, herbs, chili, bowl out, coins in, next. Twenty bowls in a blur.

BACK TO NORMAL

She hands Pim the ladle and fans herself.

AUNTIE NOK

Like that. Now you.

Storyboard

In the storyboard

Draw one panel showing the full action space, then add several ghosted positions of the character to show many actions happening quickly. Use short speed lines and small arrows around moving objects. Write the capture frame rate and the playback rate in the corner, for example 12 fps into 24. Add a note on the on-screen duration and on how much real time the shot compresses.

Pairs well with

Time-lapse

Fast motion compresses minutes, time-lapse compresses hours or days. Moving from one to the other lets a sequence scale up the passage of time, from a busy task to a whole season.

Smash cut

A burst of fast motion ending on a smash cut to stillness or silence is a strong comic and dramatic beat. The sudden stop makes the speed feel even more absurd or frantic.

Reference

Watch it in

A Clockwork Orange (1971)
Kubrick accelerates a sex scene until it becomes grotesque and comic, using fast motion to change the tone rather than to move the plot.
Run Lola Run (1998)
Tom Tykwer cuts bursts of sped-up footage into real-time sprinting, pushing the countdown energy of Lola's race across Berlin.
Requiem for a Dream (2000)
Darren Aronofsky puts accelerated footage of home and street inside his montages, showing addiction speeding up beyond anyone's control.

ScreenWeaver

Set it up in ScreenWeaver

Mark the sped-up action in your screenplay, and ScreenWeaver breaks the scene down into shots automatically, keeping that moment as its own shot. Open it, set the framing, angle and movement, and give it the short on-screen duration you want, with a fast motion note and the capture rate. Characters and locations carry from shot to shot, so the rush matches the scene around it, and the AI previsualization lets you judge the comic timing.

Start writing for free

The prompt behind this clip

This is the exact prompt that rendered the clip at the top of the page. Keep the description of the camera and the light, change the subject and the place.

Fast motion sequence in a 1930s hotel lobby with marble floors, brass elevator doors and potted palms. The camera stays locked on a wide static shot as bellhops in pressed uniforms dart between guests, spin luggage carts and flip through registration books at roughly four times normal speed, their footsteps a blur while the chandelier above hangs perfectly still. Guests check in and vanish through revolving doors in rapid bursts, motion trailing at the edges, the whole scene compressed into one unbroken, accelerated take. No text.

Common mistakes

01
Unwanted comedy
Fast motion almost always makes people look funny. In a serious scene, that can destroy the tone. Test it with an audience before relying on it.
02
Moving camera
A handheld camera sped up turns into a jittery mess. Lock the camera, or use a very smooth move, so the acceleration stays in the action.
03
No clear return
If the speed goes back to normal without a cut or a beat, the audience feels a glitch. Give the change a clear punctuation.

Questions writers ask

How do you write fast motion in a screenplay?

Put a short line such as IN FAST MOTION before the action, describe what happens quickly, then mark the return to normal speed. Keep it rare. For passing time, a MONTAGE or SERIES OF SHOTS heading is often more natural.

What is the difference between fast motion and time-lapse?

Fast motion speeds up continuous action a few times, so movement is still readable. Time-lapse takes frames at intervals, sometimes seconds or minutes apart, and compresses hours into seconds. People move in bursts rather than fluidly.

Is it better to undercrank or speed up in the edit?

Undercranking gives more motion blur per frame, which can look smoother. Speeding up in the edit keeps more flexibility, since you can try several speeds. Many productions shoot normally and decide in post.

Can fast motion be used for drama?

Yes. It can show a life slipping away, a routine that consumes a character or the dizziness of drugs. The trick is to avoid slapstick rhythm: pair it with serious sound or music and short durations.