Cameo lighting in movie is a spotlight that accentuates a single person and a few props in a scene . It creates an ‘angelic’ shot, such as one where God is shining down and a light shines down on this person.
Cameo lighting derives its name from the art form in which a light relief is set against a darker background. It is often achieved by using barn-doored spotlights . It helps focus on the subject and not its environment. A problem with cameo lighting is that it can lead to color distortion and noise in the darkest areas. 
- Jump up^ Television Production Handbook, Zettl, pg. 173.