Long Exposure Photography: Subjects and Techniques
The Shutter Priority Mode (Tv)
Most people who own an SLR camera are familiar with a setting labeled 'Tv' on their cameras. Not every owner of these cameras actually knows how useful the Tv mode is for taking spectacular photographs. Most photography is captured in the moment, whether it be portrait photography, landscapes, sports, or wildlife. We expect the camera to freeze the image at the moment and any motion captured would result in a blurred, discarded image. In Tv mode, however, we are controlling the shutter speed (the amount of time the camera continues to capture the image), and in doing so we are able to capture events over time in a single image.
The Tv mode is not simply for trick photography as we will see below. It is often necessary to allow an object or objects in motion to move across the image to create the effect that is most natural to us. When we watch fireworks, for instance, we expect to see the projectiles moving against the sky, leaving an arc of color as they pass. When we instead see a photograph of fireworks frozen in the instant, without the trailing arc of color, we are usually disappointed with the results, and viewers can't appreciate what we were trying to capture in the image. Using Tv mode we can create truly stunning images that convey the beauty of the fireworks display as we see them.
Understanding the Tv Setting
Before we begin we'll need a little instruction on how to use the Shutter Priority Mode (Tv). If you are already familiar with this camera setting then skip ahead to the next section for techniques. When you switch to Tv mode the camera will automatically set the aperture (the Av setting would allow you to set the aperture in much the same way that Tv allows you to set the exposure time). Depending on the model of camera the available shutter speeds will range from 1/4000 of a second (virtually instantaneous) to 30 seconds for most digital cameras. To take even longer exposure shots there is a Bulb setting that allows the exposure to continue for as long as you continue to hold the shutter open (this will require using a remote to avoid camera shake). For most long exposure photography 30 seconds is more than sufficient, but to try time lapse photography of the night sky, you'll need to use the Bulb mode).
A tripod is absolutely critical for taking long exposure photographs. The tripod does not need to be large (small portable ones are available from most camera and electronics stores), but you will never be able to hold the camera steady enough to take clear photographs at even the fastest shutter speeds without one. It's also worthwhile to buy a remote control to help avoid camera shake when you are pressing the shutter release, however, you can get around this by using the timer button which will give you a few seconds from the moment you depress the shutter release to the time the camera begins to expose the image.
The Basics of Long Exposure Photography
If there is one absolute beyond the use of a tripod to steady the camera it is that everything in the image must be stationary except the subject in order to have desirable results. If you were to take a long exposure photograph of a subject in a field of grass on a windy day, you see nothing but a blur standing on a a blurred background. In order to achieve the desirable effects it is best to position the camera and subject in such a way that you can guarantee with some degree of certainty that nothing other than the subject will be in motion.
The second absolute is that subject must remain in focus through the process of capturing the image. While motion is expected, the object while in its course of action should remain within the area of focus at all times. If the subject is moving toward or away from the point of focus the results will be little more than a blurred image.
Long Exposure Effects
1. Running Water
One of the most common uses of the Tv setting is to blur running water to soften images of streams and waterfalls. Typically this can be achieved with exposures no longer than one second, and in general the longer the exposure the more than water will appear as a flat surface without definition. Even with faster shutter speeds the effect will be disappointing without the use of a tripod or a solid surface to place the camera.
2. Fireworks
Fireworks are typically best achieved with exposure between 3 seconds and 15 seconds, depending on the rate at which each firework is launched. If the exposure is held too long the amount of light emitted from multiple fireworks will combine and the details of the individual fireworks will be lost in a bright globe of light. Too short an exposure will fail to show the true beauty of the combined launch of fireworks.
3. Lightning
Many people assume that a photograph of lightning is the result of having been holding a camera at just the right instant and catching the lightning as it occurs. Instead it's simply a matter of holding an exposure for a long duration (30 seconds is usually good) and pointing the camera at a particularly stormy sky. Each bolt of lightning will combine in a single stunning image, even though the individual bolts of lightning actually occurred in flashes through the duration of the exposure.
4. Phantom Photography
One of the more entertaining uses of the Tv mode in long exposures is to create the illusion of a phantom in the image. To achieve the effect, simply have a subject stand for one half of the exposure time (ideally 30 seconds), and then quickly leave the area of the photograph (move quickly or there will be a discernible blur). The image will appear with the subject appearing semi-translucent against the background. It is also important that the subject remain stationary throughout the initial exposure for best results.
5. Illuminated Night Sky
Another interesting use of long exposures is in the effect of having a night sky appear blue in a long exposure photograph taken at night. For best results try to use a bulb setting for at least a minute of exposure. The night sky will appear in the image as if it were daylight, but will still retain the features of a photograph taken at night (street lamps illuminated, etc).
6. Meteors and the Motion of Celestial Objects
Meteor storms can be best achieved with a very long exposure set to run for minutes (unless its a particularly active meteor shower). To chart the motion of celestial objects again use the bulb setting and hold the exposure for as long as possible. The battery life will determine the length of time this can be achieved (and your own patience).
All text and images are copyright 2013 sjaguilar
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