Lighting designers are constantly faced with the need to mimic nature’s lighting on the stage. Template breakup patterns or gobos are often used to simulate the effect of natural light as it passes through leaved tree limbs. The result, while a good start, is never complete, for in nature the patterns of light change as the wind moves the limbs, and the stage lighting equipment available to simulate movement like this is often prohibitively costly.

THE RIG

Described here is one device which can give stage lighting patterns the movement produced in nature. As the figures show, the rig consists of two simple additions to standard lighting equipment: a spring mounted between the C-clamp and the yoke of a lighting instrument (see Figure 1); and an operating line attached to the front of the instrument’s barrel and reeved offstage through any number of batten-mounted offset sheaves. Operation requires only that a stagehand pull the operating line on cue.

FIGURE 1: DETAIL OF ANTENNA SPRLNG MOUNT

COMPONENT AND CONSTRUCTION NOTES

The size of the instrument dictates the strength of the spring required, of course. In some cases, a spring made of or cut from the base of a locally purchased citizens’ band car antenna will work quite well. Appropriate alternatives are available overnight from national distributors such as McMaster-Carr.

FIGURE 2: SCHEMATIC OF OPERATING LINE RIG

Designers who plan to use such rigs should remember that they impose two important constraints. First, the placement of the offset sheaves will probably be adjusted during tech rehearsals regardless of what the plot shows. Thus, the location of nearby instruments, cable, and hardware should take such a likelihood into account. Second, the batten or ladder or boom base which carries such an instrument will need to be tied off so that it doesn’t move when the operating line is pulled.