The Fresnel Spotlight

The Fresnel spotlight gives an adjustable beam spread with the flexibility of changing from a spotlight to floodlight with 15 to 70 degrees in one light fixture. The Fresnel fixture produces a directional beam, which has a very soft edge and is thus used basically to provide color wash lighting.

Fresnel spotlight derives its name from the French physicist Augustin Fresnel (1788-1827) and is a basically a form of plano convex lens, with portions of the glass removed in parallel steps. The lens is much thinner, lighter and has an increased efficiency, much improvised than an equivalent plano convex lens.

Fresnels are low cost lighting fixtures as compared to ellipsoidal reflectors but do not have a provision of projecting a pattern or producing sharp beam cut off edge as a feature unlike ellipsoidal reflectors. Fresnels are very similar to plano convex spotlights both in functions and features while the main difference is that fresnels use fresnel lens and plano convex use a PC lens.

A fresnel lens can be easily recognized by a series of concentric rings on the surface. Added to that is the ‘stipple’ etching done on the back of the fresnel lens, to further soften the beam. The wattage of the fixture determines its weight, so with higher wattage larger housing is needed along with larger lens diameter to withstand the intense heat generated by the lamp fixture.

The major application of a fresnel is that it provides color washes to acting areas or to the scenery. Usually, 27 fresnels are arranged over the stage to light up or illuminate 9 areas with three fixtures each. Such an illuminated area will be known to have 3 colors wash. The inbuilt functions of dimmer control, colored filters allows for higher flexibility for mixing colors combinations over each areas. One negative aspect of using Fresnels is that it tends to flare up more than ellipsoidal fixtures; with the result they are used with a barn door accessory to help eliminate any light from spilling.

Fresnels are available in wattages of 150 to 5000 watts with a lens diameter of 3", 6", 8", 10" and 12".These units are usually used on stage and have a 6" 1000 watt or 8" 2000 watt fresnel. The usual type of fresnel manufactured have the beam spread of 15 to 70 degrees variable with the 500 to 5000 wattage. The fixture provides a round beam with soft edges and the only accessories are barn doors .The power cord is included in the kit. While optional accessories include lamp, color frame, electric connector, safety cable, lens safety mesh, pipe clamp and barn doors.