<P> In photography, shutter speed or exposure time is the length of time when the film or digital sensor inside the camera is exposed to light, also when a camera's shutter is open when taking a photograph . The amount of light that reaches the film or image sensor is proportional to the exposure time . 1 / 500th of a second will let half as much light in as 1 / 250th . </P> <P> The camera's shutter speed, the lens's aperture (also called f - stop), the Film Speed (a.k.a. ISO), and the scene's luminance together determine the amount of light that reaches the film or sensor (the exposure). Exposure value (EV) is a quantity that accounts for the shutter speed and the f - number . Once the sensitivity to light of the recording surface (either film or sensor) is set in numbers expressed in "ISOs" (ex: 200 ISO, 400 ISO), the light emitted by the scene photographed can be controlled through aperture and shutter - speed to match the film or sensor sensitivity to light . This will achieve a good exposure when all the details of the scene are legible on the photograph . Too much light let into the camera results in an overly pale image (or "over-exposure") while too little light will result in an overly dark image (or "under - exposure"). </P>

Where is the shutter speed located on a camera