Shutter Speed

So what exactly is shutter speed?

The shutter on a camera controls the amount of time that light is exposed to the film. In a digital camera, the shutter speed is either controlled this way, or it can refer to the amount of time the light sensor is on before being turned back off.

For cameras that use a traditional shutter speed method, it is accomplished by two tiny metal curtains. The first curtain opens, exposing the film or light sensor. A second curtain follows behind, ending the exposure.

You may wonder why this is necessary. Well, for slow shutter speeds, it isn't. But as the speed increases, the time that it would take to open and close a single curtain would be a limiting factor.

Even more amazing, is the fact that two curtains, fully opening and closing, might not be fast enough! For very fast shutter speeds, the second shutter begins closing even before the first one has finished opening. If you could see this, it might appear as a tiny slit moving by.

If you are using a flash, it must be precisely timed so that the entire frame is exposed to the flash. In the digital world, this timing is handled by the camera's calculations. In the traditional setting, it might be something you have to consider more often. In either case, knowing what is happening is important, especially at very high shutter speeds.

What can I use this for?

Remember the curtains in the explaination above? If you were to enlarge the concept, you could compare the shutter curtains to the curtains in your house. The window is like the lens. If you were to open and close the curtains slowly, it would be easy to see if a person walking by was walking forward or backwards.

If, however, you were to open and close the curtains in a slpit second... you would not see them in motion. Now, you could 'guess' that they were walking forward, as most people do, but you wouldn't know. They would appear to be still. Maybe they were!

Shutter speed can be used in the same way. Motion becomes a bit more obvious as the shutter speed slows down. The objects that are stationary are clear, and those in motion, have a blurry path or tail indicating their motion.

Example of a Fast Shutter Speed

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Photos by Lee Gonzalez for use on WindowsPhotoStory.com only

Example of a Slow Shutter Speed
Photos by Lee Gonzalez for use on WindowsPhotoStory.com only