· Barn doors serve a dual purpose. First, they create a adjustable beam of light which can be used to highlight a small area. In portraiture, this type of lighting can be used a hair light or as a side light for dramatic head and shoulder shots. The shadow side can be left in darkness or can be softened slightly with the use of a reflector. · In still life photography, this narrow beam can highlight the subject while other items appear to be slipping into shadows.
· The second reason we use barn doors is to prevent light from "spilling". When light hits your lens at a angle, it causes flair. Flair lowers over all contrast of the subject or in severe cases, eliminates viewing. A barndoor placed correctly will prevent this.