Light Graffiti, London, United Kingdom

Moving the light source
The light can either be used to selectively illuminate parts of the subject or to "paint" a picture by shining it directly into the camera lens. Light painting requires a sufficiently slow shutter speed, usually a second or more. Like night photography, it has grown in popularity since the advent of digital cameras because they allow photographers to see the results of their work immediately.
Light painting can take on the characteristics of a quick pencil sketch. In 1949 Pablo Picasso was visited by Gjon Mili, known photographer and lighting innovator, who introduced him to some of his photographs of ice skaters with lights attached to their skates. Immediately Picasso started making images in the air with a small flashlight in a dark room. This series of photos became known as Picasso's "light drawings." Of these photos, the most celebrated and famous is known as "Picasso draws a centaur in the air."