Light photography such as light trails, light art, etc. Wideangle or telephoto?
Wider is better since it covers more area.. what you really need is a tripod and a manual focus setting and the ability to set your exposure to 20-30 seconds or bulb through the use of a cable release or timer.
This would depend on the intensity of the light you're trying to capture in trails, how close you can position yourself to the action and how you want to compose your shot. Assuming the source isn't too faint then almost any lens will work as long as you use a suitable aperture setting and long enough shutter speed. With each lens it will take some experimentation at different camera settings to find the ideal recipe for producing the best light trail images.
