A] SHUTTER SPEED
The shutter speed setting determines how long the camera’s sensor is exposed to light. The more light there is available, the shorter the exposure time can be. Very fast shutter speeds are measured in thousandths of a second, but exposure times can stretch into hours in extremely dark conditions, such as when you’re photographing stars in the night sky.
Fast shutter speeds have several advantages. They can freeze movement, allowing you to reveal detail you couldn’t normally see with the naked eye. They also enable you to take sharp pictures while holding the camera – at slower shutter speeds you may need to fix the camera to a tripod to prevent the image being blurred through camera shake.
The extended exposures afforded by slow shutter speeds allow you to capture creative motion blur effects, such as turning crashing waterfalls and waves into a silky-smooth haze.