Camera Parts: Shutter Speed Control
A camera is a precise machine composed of many parts, and shutter speed control is one of them. These parts work together to expose an image. Exposure is determined by three setting: the ISO, the aperture and the shutter speed. The ISO regulates how much light is needed to expose an image. The aperture controls how much light is allowed to pass through the lens as it journeys to the image sensors. And, the shutter speed controls how long that light hits the image sensor.
Changing the Shutter Speed
On a digital camera, you can directly change the shutter speed in manual and shutter priority modes. You can also indirectly change the shutter speed in program AE and aperture priority modes. The amount of time that the shutter can be opened for ranges from camera to camera. It can be as long as a few seconds and as quick as 1/4000 of a second.
Why You Want to Control the Shutter Speed
You would want to leave the shutter open for a longer time in low light situations, where the aperture is either wide open or cannot be opened anymore with sacrificing depth of field. This allows you to keep the image looking crisp with a low ISO. The downside to this is that the slightest movement during that exposure time will cause the image to be blurred. If you're shooting images with quick action, then you want to have a very quick shutter to capture the action.