Shutter Speed
Shutter Speed: The fraction of time, in seconds, in which the shutter remains open while taking a photograph. The slower the shutter speed, the longer the shutter remains open, which also allows more light to enter the picture. The shutter speed and aperture together determine the amount of light that reaches the sensor. Shutter speed is measured in fractions of a second, such as 1/60, 1/30, 1/15, 1/8, 1/4, 1/2, and 1.