ICM (Intentional Camera Movement) means deliberately moving the camera during a long exposure to turn a sharp scene into streaks of color and shape. It's a creative technique: unlike accidental motion blur, the movement is chosen, timed, and repeated until the desired effect is achieved.
The tool offers six techniques, each with its own movement rhythm:
Vertical pan: move the camera gently up and down for the whole exposure, ideal for forests of vertical trunks or facades.
Horizontal pan: move the camera gently sideways for the whole exposure, effective on horizontal lines (sea, fields, architecture).
Zoom burst: stay perfectly still, then zoom quickly on the cue, creating a centrifugal speed effect from the subject.
Rotation / swirl: rotate the camera steadily and reverse the rotation direction on the mid-exposure cue, creating swirls of light.
Painterly long exposure: layer several slow, varied movements following each cue, the result resembles an abstract painting.
Freehand: move the camera however you like for the whole exposure, with no fixed path.
ICM calls for slow shutter speeds (often between half a second and several seconds), impossible to get in daylight without darkening the lens:
Measure the scene's normal exposure handheld: that's the metered speed.
Choose the target speed (ICM) matching the chosen technique: the app suggests a suitable default value.
The app calculates the difference in stops between the two speeds and shows the required ND filter (ND8, ND64, ND1000...) along with the resulting speed once the filter is fitted.
The Start rhythm button triggers an audible, vibrating metronome that guides you through the whole exposure:
A 3-second countdown before the shutter fires, to get into position.
A start cue the moment the shutter button is pressed.
Intermediate cues at key moments of the movement (start of the zoom, reversal of the rotation direction, or direction changes in a painterly long exposure).
An end cue signaling that the shutter is about to close.
Just sync your gesture with the cues to repeat the same path on every attempt and refine the technique from one shot to the next.
Work handheld for pans (vertical, horizontal, freehand): the precision of the gesture matters more than stability.
For a zoom burst or a rotation/swirl, a tripod or monopod can help keep the pivot point steady during the movement.
Close the aperture (f/11 to f/16) and lower the ISO to the minimum before adding the ND filter, to stretch the shutter speed further.
Take multiple attempts: ICM relies on the randomness of the gesture, and the best result rarely comes on the first try.
Turn off optical/sensor stabilization during the movement: it will try to correct the blur you're deliberately creating.