Long-exposure photography

45-minute exposure taken on a dark and clear night so typical of Paranal, the stars leave trails in their dance around the Celestial South Pole (left).

Long-exposure photography or time-exposure photography involves using a long-duration shutter speed to sharply capture the stationary elements of images while blurring, smearing, or obscuring the moving elements.

Technique

A long exposure photo of a watch in the dark. Note the appearance of the second hand as it rotates, showing that this was a 30 second exposure. The hour hands (which hasn't moved) is clear, while the minute hand is slightly blurry from a minute movement.

When a scene includes both stationary and moving subjects (for example, a fixed street and moving cars or a camera within a car showing a fixed dashboard and moving scenery), a slow shutter speed can cause interesting effects, such as light trails.

Long exposures are easiest to accomplish in low-light conditions, but can be done in brighter light using neutral density filters or specially designed cameras.

Night photography

By exposing an image for an extended period of time (eight seconds in this case), not only can detail be seen in the dark areas of the scene, but the headlights and taillights of vehicles on the highway become streaks.

Long-exposure photography is often used in a night-time setting in order to produce a near daytime effect in the photo. By leaving the camera's shutter open for an extended period of time, more light is absorbed, creating a brighter product. If the camera is stationary for the entire period of time that the shutter is open, a very vibrant and clear photograph can be produced.

Light painting

Example of light painting

For more details on this topic, see Light painting.

In this technique, a scene is kept very dark and the photographer or an assistant takes a light source—it can be small penlight—and moves it about in patterns. The light source can be turned off between strokes. Often, stationary objects in the scene are illuminated by briefly turning on studio lights, by one or more flashes from a strobe light, or by increasing the aperture.

Water and long exposure

A 30-second-long exposure sharply captured the still elements of this image while blurring the waterfall into a mist-like appearance. Debris in the swirling water in the pool forms complete circles.

Long exposures can blur moving water so it has mist-like qualities while keeping stationary objects like land and structures sharp.

Solargraphy

A Solargraph taken from ESO's APEX at Chajnantor.

A solargraph is a long-exposure photograph which shows the path taken by the sun across the sky. One example of this is a single six-month exposure taken by photographer Justin Quinnell, showing sun-trails over Clifton Suspension Bridge between 19 December 2007 and 21 June 2008. Part of the Slow light: 6 months over Bristol exhibition, Quinnell describes the piece as capturing "a period of time beyond what we can perceive with our own vision." This method of solargraphy uses a simple pinhole camera securely fixed in a position which won't be disturbed. Quinnel constructed his camera from an empty drink can with a 0.25mm aperture and a single sheet of photographic paper.

External links

Media related to Long-exposure photography at Wikimedia Commons

• Article about series of solargraphs in the ESO Messenger
• Bob Fosbury's Solargraphs
• Tarja Trygg's Solargraphy page
• Long Exposure Photography inspirations
• Solargraph taken from Bayfordbury, UK at the APOD archive