Freezing Motion with the Shutter

Pro­gres­sive­ly increas­ing the shut­ter speed grad­u­al­ly decreas­es the blur­ring of your subject’s motion, and beyond a cer­tain thresh­old its move­ment becomes prac­ti­cal­ly imperceptible—the action is frozen in place. This idea of “prac­ti­cal­ly imper­cep­ti­ble” motion is anal­o­gous to the con­cept of accept­able sharp­ness (see Depth of Field): it depends on the res­o­lu­tion of your cam­era, but more impor­tant­ly, on the degree of pho­to enlarge­ment, crop­ping, and the intend­ed view­ing dis­tance.

The surest and most acces­si­ble [1] method for freez­ing move­ment in pho­tog­ra­phy is by using the fastest shut­ter speed your cam­era can achieve, which for most mod­ern inter­change­able lens cam­eras falls into the range of 1/4000–1/8000 sec­ond. How­ev­er, this tech­nique is only sen­si­ble under bright sun­light, and would oth­er­wise require fast lens­es, increased ISO, or both (see Reci­procity Law). In prac­tice, pho­tog­ra­phers tend to shoot at the slow­est shut­ter speed that freezes the action of the sub­ject in their viewfind­er (keep­ing in mind an appro­pri­ate aper­ture). Although a shut­ter speed of 1/4000 sec­ond will depend­ably freeze most action, it’s arguably exces­sive for por­traits, archi­tec­ture, and land­scape images, and requires expo­sure com­pro­mis­es that may oth­er­wise be detri­men­tal to over­all image qual­i­ty, lead­ing to increased aber­ra­tions (due to large aper­tures) and image noise (due to high ISOs) if the scenes aren’t ade­quate­ly bright.

Fast shut­ter speeds rang­ing from 1/500–1/8000 sec­ond are often appro­pri­ate (and nec­es­sary) for freez­ing the motion of dynam­ic and ani­mat­ed sub­jects, such as at sport­ing events (espe­cial­ly water-sports, due to the drops of water), ath­let­ic com­pe­ti­tions, of birds in flight, air­show fly-bys, motor­sports, and so on. With that said, it’s cru­cial to remem­ber that the subject’s speed with­in the frame deter­mines the shut­ter speed at which their move­ment becomes prac­ti­cal­ly imper­cep­ti­ble.

Choosing the right shutter speed for freezing movement

There are sev­er­al com­mon sense tech­niques to help you select the slow­est shut­ter speed that depend­ably freezes fast move­ment. Pho­to­graph your sub­jects using shut­ter pri­or­i­ty mode—estimating the shut­ter speed you believe will freeze their motion—and check your results on the camera’s rear screen. Zoom into the pho­to and pay close atten­tion to the fastest mov­ing fea­tures of your sub­ject, such as the tips of the extremities.[2] If you notice dis­tinct motion blur­ring, increase your shut­ter speed and try again. Once you’re sat­is­fied with the results, con­firm the expo­sure para­me­ters, and mir­ror the set­tings in man­u­al mode. As long as the light remains con­stant, shoot­ing in man­u­al mode will ensure that your expo­sures will stay con­sis­tent across mul­ti­ple pho­tos.

For every dou­bling in size of the sub­ject in your viewfind­er, select a shut­ter speed that is twice as fast. For exam­ple, if your quar­ter-frame pho­tos of a pole vaulter reli­ably freeze her action at an expo­sure of 1/500 sec­ond, then, use a shut­ter speed of 1/1000 sec­ond for com­po­si­tions in which her body fills half the frame. This com­pen­sates for the fact that increas­ing your subject’s mag­ni­fi­ca­tion will pro­por­tion­al­ly increase the speed of their move­ment in the frame. In sit­u­a­tions where you antic­i­pate dynam­ic shot lengths, it’s more con­ve­nient to set your shut­ter speed to reli­ably freezes action at the high­est fore­see­able mag­ni­fi­ca­tion.