Light Graffiti, London, United Kingdom

Technique and equipment
A variety of light sources can be used, ranging from simple flashlights to dedicated devices like the Hosemaster, which uses a fiber optic light pen. Other sources of light including candles, matches, lighter flints, glowsticks, and Poi are also popular.
A tripod is usually necessary due to the long exposure times involved. Alternatively, the camera may be placed on or braced against a table or other solid support. A shutter release cable or self timer is generally employed in order to minimize camera shake. Color Gels can also be used to color the light sources.
Manual focus is often used since autofocus systems may not perform well in low light. In addition, photographers often use a slow film speed or low ISO setting on a digital sensor to minimize grain (or digital noise) and increase exposure tolerance, as evaluating exposure is often tricky.