Light Graffiti, London, United Kingdom

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.
Aperture is also an important variable in light painting. Smaller apertures such as f16 or f22 generate a sharper image and preserve a large depth of field, creating deep focus. This technique requires longer exposure times but creates interesting results. Larger apertures such as f5.6 or f2.8 often blur the lines drawn by a light pen or LED source.