Fashion Photography: Shutter Speed & Runway Motion Blur

Camera Settings

Shutter speed 1/125s

Aperture f/8

ISO 100

Model pace 1.0×

Live readout

Exposurecorrect

Motion blur0.0 cm

Background bokeh1.0×

How it works

Three camera settings control how much light hits the sensor. At ISO 100 the exposure value is:

EV100 = log2(N² / t)
EV    = EV100 − log2(ISO / 100)

where N is the f-number (aperture), t is the shutter time in seconds. The studio strobes here are calibrated so f/8, 1/125s, ISO 100 is exactly correct. Any other combination that gives the same EV looks identical in brightness — that's the "exposure triangle": you can trade shutter speed against aperture or ISO and keep the same exposure while changing everything else about the shot.

Motion blur comes from the shutter staying open while the model keeps moving. This sim renders the walk as a pure function of time, then integrates 10 samples of that function across the open shutter window — exactly what a real sensor does while collecting photons:

blur spread ≈ | position(t) − position(t − shutter_time) |

A fast shutter (1/1000s or faster) samples a tiny time window, so all 10 samples land almost on top of each other and the runway walk freezes sharp — the classic look for capturing a garment's exact silhouette. A slow shutter (1/30s or slower) spreads those samples across real motion, producing visible streaking — an intentional editorial technique to convey movement and energy.

Aperture also sets depth of field: a wide aperture (small f-number, e.g. f/1.4) throws the background lights into large soft discs of "bokeh"; a narrow aperture (large f-number, e.g. f/16) keeps them small and defined. The background lights here are rendered as one instanced mesh so hundreds of bokeh discs cost almost nothing to draw.

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