Motion Blur Shutter Speed Calculator

Motion Blur Shutter Speed

Freezing motion and deliberately blurring it are two ends of one spectrum, and where you sit on it is set by how fast the subject crosses the frame. That depends on its speed, the direction it is travelling, and how much of the frame it fills.

The rule this calculator uses:

Shutter denominator = subject speed (mph) × direction factor × 50

So a cyclist at 18 mph passing sideways gives 18 × 1 × 50 = 900, which rounds to 1/1000. The 50 is empirical, and it assumes normal framing: the subject filling a decent part of the frame at a typical working distance. Fill the frame tighter or use a longer lens and it moves faster across the sensor, so add a stop. Shoot it small in a wide landscape and you can drop one.

For reference, freezing motion typically needs:

A wing is not a body, and that is where these numbers usually go wrong. A swallow flies at 20 mph, but its wingtip sweeps through an arc several times faster than that, so freezing the bird and freezing its wings are two different shutter speeds a couple of stops apart. Same with a car: the body might need 1/1000, the wheel spokes 1/4000. Pick the option that matches whichever part you need sharp, not the one that matches the animal.

Direction adjustment:

What blurs the image is the part of the motion that runs across the frame. Motion straight at the lens barely moves the subject in frame at all, which is why a car heading toward you looks sharp at a shutter speed that would smear the same car passing sideways.

• Sideways: the full speed crosses the frame. This is the baseline
• 45° angle: cos(45°) = 0.71 of it crosses the frame, so you can afford about half a stop slower
• Toward / away: roughly 0.4, so 2 to 3 stops slower is fine

Camera shake is a separate problem, and the calculator does not cover it.

Everything above is about the subject moving. Your own hands moving is a different limit that applies on top, and it scales with focal length:

Min shutter speed (handheld, no stabilization) = 1 ÷ (focal length × crop factor)

A 200 mm lens on full frame wants at least 1/200 for shake alone. Stabilization buys back three or four stops of that, and none of it helps with the subject. Take whichever of the two numbers is faster, because you have to satisfy both.

For panning shots (intentional motion blur):

• Slow pan: 1/30-1/60, strong streaks, fast subject blurry
• Medium pan: 1/60-1/125, moderate streaks
• Fast pan: 1/125-1/250, subtle blur, more keeper rate

Panning technique: track subject smoothly, press shutter mid-track, follow through after release.

For long exposures (waterfalls, light trails):

• Smooth water: 1/2 to 4 sec
• Moving clouds: 30 sec to several minutes
• Light trails (cars at night): 5-30 sec
• Star trails: 10-30 minutes (or stack many shorter exposures)

Image stabilization caveat:

• IBIS (in-body) and OIS (lens-based) help camera shake but not subject motion
• A 1/30 sec exposure may be sharp from camera shake but still motion-blurred from subject
• For sports / action: always prioritize fast shutter over IS

Auto-ISO trick for action: Set the camera to shutter priority + auto ISO for sports. ISO will rise to keep exposure correct as light changes, while you control freeze sharpness.

Burst mode: Action that’s hard to time (peak of jump, ball release): use 10+ fps burst at 1/2000+ to nail the decisive moment. Modern cameras do 30+ fps with electronic shutter.