Light Trails
Continuous streaks recorded when a moving light source crosses the frame during a long exposure.
Measured in
seconds
In depth
Vehicle headlights and tail lights are the classic source, giving white and red ribbons that describe a road's geometry. Exposures of ten to thirty seconds at f/8 to f/16 are typical, and the deciding factor is traffic density — a gap in the flow leaves a broken trail that reads as a mistake.
Examples in practice
A twenty-second exposure from a bridge draws unbroken white and red ribbons along the carriageway below.