Shutter speed & motion
Freezing versus blurring, the minimum-shutter rule, and panning to imply speed.
- Choose a shutter speed to freeze or to blur motion on purpose
- Apply the minimum-shutter rule for handheld sharpness
- Use panning to keep a moving subject sharp against a blurred background
Shutter speed decides how a slice of time lands on the sensor. Short slices freeze motion; long slices let it smear. Neither is right or wrong — each is a choice about what you want movement to say.
Freezing
To freeze motion, outrun it. Rough floors:
- A still person, handheld: 1/125 is plenty.
- A walking person: 1/250.
- A running child or a pet mid-leap: 1/500 or faster.
- Sport and birds in flight: 1/1000 and up.
The faster the subject crosses the frame, the faster the shutter must be — motion straight toward you needs less than motion across you.
The demo is a conceptual illustration: as you slow the shutter, the streak grows and each subject crosses from “frozen” to “blurred.” It is not a photo of your scene — it is a picture of the trade.
Blurring on purpose
Slow the shutter and motion becomes a gesture: a waterfall turns to silk at a second or two, taillights become ribbons, a crowd blurs around a still subject. This needs a steady camera — a tripod or a firm brace — and often a small aperture or an ND filter to keep the exposure from blowing out in daylight.
The minimum-shutter rule
For handheld sharpness, keep the shutter at least 1 over the equivalent focal length: about 1/125 at 70mm, 1/30 at 20mm, remembering the ×1.5 crop. This is the same rule you set as your Auto ISO floor in Lesson 4. IBIS lets you go slower for static subjects, but it cannot freeze a moving one — for that, only shutter speed counts.
Panning
To imply speed while keeping the subject sharp, pan: choose a moderate shutter like 1/60, track the moving subject smoothly, and fire mid-swing. The subject stays crisp while the background streaks into motion. It takes practice and a forgiving keeper rate, but nothing else says “fast” so clearly.
In the field
Find running water. Shoot it at 1/1000 to freeze every droplet, then brace the camera and shoot it at half a second. You now own both ends of the shutter — the frozen instant and the flowing gesture.