The shutter is like a door to the film in film cameras or Image sensor in digital cameras to light (from this point on I will use the phrase image sensor but it will be the same as film in a film camera) that opens to let in light and then closes to cover the sensor back up. The length of period that the shutter is open is called "Shutter Speeds". The longer the time, the more light hits the sensor and the greater the overall exposure will be. So as a photographer you can increase the exposure by setting a longer shutter speed, or decrease the exposure by lowering the shutter speed.

Shutter speed is measured in fraction of seconds, 1/125th being 1/125th of a second. Full stops of shutter speed are:

• 1sec
• 1/2sec
• 1/4sec
• 1/8sec
• 1/15sec
• 1/30sec
• 1/60sec
• 1/125sec
• 1/500sec

1sec is slower going to 1/500th of a second faster. Each stop of shutter speed going from top to bottom in this list lets half as much light to the sensor. For example 1/2sec shutter speed lets half as much light in than 1sec . Now in the Previous lesson we talked about Aperture and the relation of F-Stops and how each stop of them also had the same relationship where the next smallest aperture let half as much light in than the next biggest aperture.

Here is an examples of the same scene with different shutter speeds

The shutter speed on your camera is displayed on your camera as follows:

• 1sec - 1"
• 1/2sec - 2
• 1/4sec - 4
• 1/8sec - 8
• 1/15sec - 15
• 1/30sec - 30
• 1/60sec - 60
• 1/125sec - 125
• 1/500sec - 500

and so on.

So the general rule is the smaller the number the slower the shutter speed and the larger the number the faster the shutter speed. the exceptions are when you get to 1 second and longer these are number on your camera that will be a number and a quotation mark. like 1 second will be 1" then 2 seconds will be 2" on your camera.

Another general rule is that if you are hand holding the camera you will want to have your shutter speed no longer than 1/60th of a second or 60 on your camera to have a sharp picture. If you hand hold the camera for a longer shutter speed for example 1/30th of a second or 30 on your camera you run the risk of having camera shake and a blurry picture. For any shutter speed lower that 60 on your camera you should use a tripod.

Another factor of shutter speed also depends on what lens you are using. The general rule for this is take the MM you are shooting at and that is the lowest number you should use when hand holding the camera, for example for a 250mm use 1/250sec or faster, but remember to try to stay over 1/60th of a second so for a 30mm shot you shouldn't go to 1/30sec, you should stay at 1/60sec or use a tripod for anything slower. Some lens have and image stabilization that would allow you to handhold at slower shutter speeds. Just remember that image stabilization can only go so far and that it is not a magical cure for camera shake.

Shutter speed also determines motion blur in your photos. The Faster your shutter speed, the sharper a moving object will be. So if your shutter speed is 1sec the moving object will have more motion blur than if you chose a faster shutter speed of 1/500sec. You also need to take into consideration the speed of the moving object. the faster the object is moving the faster your shutter speed needs to be to freeze the motion.

Here is an examples of the same scene with different shutter speeds

Distance also plays a part of the shutter speed needed to stop the action of a movement. For instance a fast walker at a speed of 5MPH if you're at 25 feet away 1/125sec should stop the motion, at 50 feet away 1/60sec, and at 100 feet away 1/30sec should freeze it but better use a tripod to stop camera shake. Now for Fireworks you should always use a tripod so you can use a slower shutter speed so you can get the trails of Fireworks in.

Here is an examples of the a long shutter speed for fireworks