When floodlighting buildings from locations across the street it is essential from the standpoint of people on the street to keep the light above the level of the first floor. Even though the main beam is properly directed, the amount of spill light is sometimes enough to be annoying.

Objectionable spill light must be absorbed or deflected in some manner. Spill rings, if carefully designed, are compact and effective equipment for accomplishing this purpose. However, they absorb quite a proportion of the light from the projectors and therefore they should not be used except where dose confinement of the beam is more important than efficiency. A spill shield placed on the inside or outside of the cover glass also serves to cut off spill light in one direction. Another effective and simple means of obtaining a definite cutoff in one direction is a screen built up of sheet metal or wood and placed three to four feet from the projectors to intercept the light below a certain angle. The same kind of a screen can also be employed in a vertical position to cut off spill light which would otherwise be thrown past the edge of a building into a street or area beyond.