shutter speed
US /ˈʃʌt̬.ɚ ˌspiːd/
UK /ˈʃʌt̬.ɚ ˌspiːd/

1.
the length of time that a camera's shutter is open when taking a photograph, which determines how much light reaches the sensor or film
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A fast shutter speed is essential for freezing motion in sports photography.
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For low-light conditions, you might need a slower shutter speed.