The spotlight is the most import light of all. The spotlight is a high-powered source of light that is made more effective by use of a lens and usually a reflector as well. The following are different types of spotlights.
The Plano-convex Spotlight was the first incandescent spotlight, and for many years it was the only kind. When focused on a flat surface, the Plano-convex spotlight's beam pattern is circular with a sharp, distinct edge. The P-C, as the Plano-convex spot is frequently called, can be obtained in three sizes. The 5-inch lens burns 250 and 400-watt lamps, the 6-inch burns 500- and 1500-watt lamps, and the 8-inch lens burns 2000-watt lamps.
The Fresnel spotlight has a short focal length to its lens. This makes a long movement of the lamp unnecessary. The Fresnel spot throws a beam of much greater intensity than the Plano-convex for the same current consumed. The beam pattern of the Fresnel is smoother and without a sharp edge. It is difficult to find an edge to the beam, permitting easy blending of two or more beams without a noticeable break. The Fresnel spotlight comes in a number of sizes. The smallest has a 3-inch lens and burns a 150-watt lamp. The 6-inch Fresnel burns 500- and 750-watt lamps. The 8-inch Fresnel burns 1000- and 1500 watt lamps. The Fresnel type of spotlight is also sold with lenses from 10 to 20 inches in diameter.
The Ellipsoidal also has a short focal point to its lens. Its reflector, however, is built in the shape of half an ellipsoid so all the light rays that strike this reflector are diverted through a second focal point. By placing a lens just in front of this secondary focal point a spotlight of great efficiency and power can be constructed. This type of instrument is almost invariably used with its nose tilted down about 45 degrees from the horizontal so lamps that are to be burned base up only are used. These two types of lens cause the beam pattern to be much smoother and to have a fairly soft edge, making blending much easier. It comes in a 4.5 inch lens that burns 250 and 500 watt lamps and 6- and 8-inch sizes, some using 500- and 750-watt lamps and others those of 1000, 2000, or 3000 watts. The 12-inch model uses a 3000-watt lamp for a very narrow and extremely powerful beam, intended primarily for follow-spotting from a distance.
A floodlight is, as its name suggests, a device for throwing a broad wash of light over a wide area. The floodlight reflects a smooth wash of light from its boxlike hood and white-painted interior. Most floodlights are about 15 or 16 inches in diameter and burn general-service PS lamps of up to 2,000 watts. There is also a small 10-inch model that uses 250 and 400 lamps, or occasionally gives good service with a 100-watt lamp when only a very low illumination is required.
The Strip light consists of a series of lights adjacent to each other. In its crudest form, the strip light is often found as footlights--the only light source on a small, ill-equipped stage-a row of bare bulbs, sometimes as far apart as 12 inches, extending the entire width of the proscenium opening. While permanently installed footlights of better design may be useful; on some stages, the more general approach is to have strip lights prepared in lengths of between 3 and 9 feet. These sections may then be placed about the stage, including the usual footlight position on the apron's edge, or hung from overhead. The lamps used in strip lights usually have 6-inch centers with 150- or 300-watt lamps.