Introduction

Shutter speed is a time value expressing how long the camera’s shutter is allowed to remain open. Along with aperture (the size of the opening that lets light into the camera), it is one of two settings that control the amount of light that reaches a camera’s sensor. To show how fast and slow shutter speeds affect an image, we will use various shots of water rushing over Niagara Falls.

In most instances when your subject matter is in motion, like the water moving over the falls, you will choose a camera setting that gives you shutter speed priority. You select the shutter speed you desire and your camera automatically chooses an appropriate matching aperture that will give you a proper exposure.

* With white water as your subject matter, you will dial in plus 1 compensation. See the article on Exposure Compensation for more information.

The table to the right shows the standard combinations of aperture and shutter speed.

In this picture, with a fast shutter speed of 1/500^th of a second the water appears clear and sharp. (Aperture f/2.8)

We select a fast shutter speed 1/500^th of a second, the camera sets aperture of f/2.8. This combination will give us the proper exposure.

When the shutter speed is set to a slightly slower 1/125^th of a second, the water appears less crisp – closer to the way a human eye would see it. (Aperture f/5.6)

With a very slow shutter speed of 1/8^th of a second a cotton effect is achieved. (Aperture f/22)

To avoid any unwanted camera movement that would blur the picture when using a slow shutter speed, mount the camera on a tripod and use a cable release to reduce camera vibration. Generally, to obtain acceptable sharpness when holding a camera, you need a shutter speed at least equal to the focal length of the lens that you’re using. For example, if your lens has a focal length of 100 mm, you should use shutter speed of at least 1/100^th of a second to prevent camera shake.

The moving effect of the water is enhanced further with a shutter speed of ¼ of a second. (Aperture f/32)

Blurring the motion of the water suggests movement and presents an image to the viewer that differs from what the photographer actually saw.  We like the effect of this image the best. The soft cotton wool effect of the water adds an element of serenity to the fast running water of Niagara Falls.

These images illustrate how different shutter speeds capture the feeling of moving water in different ways. Freezing the water with a 1/500^th of a second shutter speed can be dramatic, while blurring the water at ¼ of a second adds an element of serenity. Both produce images that can’t be seen by the human eye.

In all these examples, you select the shutter speed to give the motion effect that you desire. Your camera will select a matching aperture to give you a proper exposure.

Conclusion

Fast shutter speeds allow you to freeze action while slow shutter speeds let you blur motion. Experimentation will be required to find a shutter speed that produces the effect you most desire. When using slow shutter speeds, we want things that are moving to appear in motion (for example water) and things that are still appear sharp. This requires the use of a tripod.