What 1/20 s is good for#
A shutter speed of 1/20 s is typically used for silky water from a tripod, light trails and intentional camera movement.
Each step on the standard scale is ⅓ stop; doubling the time adds one stop of light. 1/20 s lets in 6.3× more light than 1/125 s.
Will 1/20 s freeze the motion?#
Image-plane blur for subjects crossing the frame at a right angle. Under ~2 pixels looks sharp; panning with the subject reduces blur dramatically.
| Subject | Blur on a 24 MP full-frame sensor | Result |
|---|---|---|
| Person walking (5 km/h, 5 m away, 50 mm) | 116.7 px | motion blur |
| Child running (11 km/h, 4 m, 50 mm) | 312.5 px | motion blur |
| Jogger (12 km/h, 10 m, 85 mm) | 233.8 px | motion blur |
| Cyclist (30 km/h, 10 m, 70 mm) | 484.2 px | motion blur |
| Dog sprinting (40 km/h, 10 m, 200 mm) | 1,833 px | motion blur |
| Car (50 km/h, 20 m, 50 mm) | 291.7 px | motion blur |
| Bird in flight (36 km/h, 20 m, 400 mm) | 1,667 px | motion blur |
| Race car (200 km/h, 50 m, 300 mm) | 2,750 px | motion blur |
| Waterfall / fast water (2 m/s, 5 m, 35 mm) | 116.7 px | motion blur |
Aperture to use at 1/20 s#
Correct exposure at 1/20 s for typical lighting, rounded to ⅓ stop.
| Light | ISO 100 | ISO 400 | ISO 1600 | ISO 6400 |
|---|---|---|---|---|
| EV 15 · Bright sun, distinct shadows (Sunny 16) | f/45 | too bright | too bright | too bright |
| EV 13 · Cloudy-bright, no shadows | f/20 | f/45 | too bright | too bright |
| EV 12 · Heavy overcast / open shade | f/14 | f/29 | too bright | too bright |
| EV 10 · Just after sunset | f/7.1 | f/14 | f/29 | too bright |
| EV 8 · Bright interior, city street at night | f/3.5 | f/7.1 | f/14 | f/29 |
| EV 5 · Home interior at night | f/1.2 | f/2.5 | f/5 | f/10 |
| EV 2 · Distant city lights | too dark | too dark | f/1.8 | f/3.5 |
| EV -2 · Moonlit landscape | too dark | too dark | too dark | too dark |
Exposure calculator#
Your metered (or known good) exposure
New settings — change aperture and/or ISO, we solve the shutter speed
Nearby shutter speeds#
Frequently asked questions#
Is 1/20 s fast enough to handhold?
On full frame, the reciprocal rule says 1/20 s works handheld up to about 20 mm without stabilisation, or ~320 mm with 4 stops of image stabilisation. On APS-C divide by 1.5, on Micro Four Thirds by 2.
How many stops is 1/20 s from 1/125?
2.6 stops slower (more light).
Last updated October 03, 2026 · How we calculate · Sources