The first category of photography deals with those images that are using the motion of objects to their advantage. This means that we are making a conscious decision to use a slow shutter speed not because we have to (see the next section) but because it will artistically benefit our images. For example, we can choose to use a slow shutter speed to demonstrate speed by either blurring the object that is moving quickly or panning with that object to use motion blur in the background.
Another common use of motion blur is to make moving water look smooth and blurred. For example, by using a slow shutter speed when photographing a waterfall, the falling water blurs together in a smooth curtain. Using a fast shutter speed gives a generally less pleasing result. Similar to waterfalls you can apply the same concept to streams, waves on a beach, fountains, or nearly anything with moving water.
Need For Light
The second category of photography that may use a slow shutter speed would be those situations where you need more light and are forced to use a slow shutter speed to attain it. This often translates to taking pictures at night time. For example, taking photographs of cityscapes that are lit up during the evening would require a very slow shutter speed in order to capture the light necessary.
Astrophotography often involves taking pictures of extremely faint objects. If you are imaging constellations, star trails, nebulae, galaxies, or anything else deep in the night sky, a long exposure of 1 minute or MUCH longer is sometimes needed.
A third style of photography similar to this is to start a long exposure (on a tripod) and capture some something that occurs while the camera is exposing. An example of this would could be lightning photography, fireworks, light painting, a car driving on a night road, fireworks, lighting a lighter or a match, the list goes on. The common theme here is that you more than likely need to use a slow exposure since these events are taking place in a dark environment and you need the light.
How to Take Long Exposures
Now that we know when it may be advantageous to use slow shutters speeds for photography, I will give you a basic run down on how to do this with your digital camera. Before even setting a single setting on your camera the first thing you need to do is determine approximately what length of exposure you are going to need as some require much longer exposures than others. For those images made to show speed you will want a speed slower than 1/60th of a second but fast enough to leave enough of the image in clarity. 1/30th of a second is a good place to start and you can adjust from there. Moving water images work very well with approximately 1 second or longer if possible. For those in the second category you will have to play around with exposures everywhere from 5 seconds to 15 or more minutes.
Although we want to use a shutter speed of close to one second you may actually run into the problem of having too much light. Even if the aperture is stopped all the way down the desired shutter speed may not be attainable with the current setup. There are a couple of things that you can do in order to extend the maximum exposure length possible. First, if at all possible, shoot when (or where) there is less light. If changing the time or the place of the photograph is not possible there are a couple of pieces of equipment that you can use. The official filter that we can put onto a lens is a neutral density (ND) filter who’s sole purpose is to lessen the amount of light that gets into the camera. These "sunglasses for your camera" come in all sorts of strengths (less and less light being let in) to extend the possible exposure time. In a pinch, a polarizer can be used to limit the light that enters the camera as well (although not as effective as a ND filter).
In this article we have investigated the photo techniques involved in using a slow shutter speed. We saw how it can be used to aesthetically blur images to show motion or creativity or to make up for the lack of light in a scene. We also found out that using shutter priority or manual (or even aperture priority) modes on your camera will often help you attain these images. Although these modes are preferred you can still possible trick your automatic camera into giving you the shutter speed you desire. Finally, you saw that too much light may actually be a problem when getting slow shutter speeds, but this does not mean it is impossible. If you haven’t already, grab your camera, get out the door and try out some of these slow shutter speed photography tricks.
All images were taken and processed by the author.