we were finally able to introduce a heat removing socket which our tests show will deliver specified lamp life. When used in ellipsoidal systems. tungsten-halogen lamps. as manufactured. do not hold tight enough tolerances for the fi lament position of the lamp. Hence the requirement for the new rapid adjustment controls provided on the instruments. so that field adjustments can be made whenever a new lamp is put in. But even on a spotlight newly relamped. aimed and focused, offsets occur during the life of the particular lamp. Filament droop during burning becomes significantly serious to affect efficiency and beam distribution even though the lamp is still alight. If we are to stay with the tungsten filament lamp for theatre lighting we may be at a point when we must closely reexamine the design of the fixture. which now is largely frozen in the cold reality of "as inexpensive as possible." Start with the fact that the heat produced should be removed and dissipated very early on in the system and in a manner not suggested by any present design. Were it possible to remove this heat. even were it terribly expensive to remove this heat. radical changes could take place both in the downward sizing of present fixtures as well as in increases in efficiency. Body materials and shapes could change drastically. Lenses could be made of plastic. or perhaps even of liquid in a reshapeable enclosure. allowing for efficient multifocus systems. Variable color control could be a part of this new low temperature spotlight. Because the entire system would have less weight and bulk and because the optical controls would be less "sticky." refocusing and re-aiming mechanisms would become more cost effective and lend themselves to interfacing with the lighting control desk. Of course. it is also possible to change the light source in theatrical equipment. gaining theoretical starting efficiencies of 80 to 120 lumens per watt rather than 20-25 lumens per watt as with the tungsten filament. Presently such sources are associated with a considerable amount of starting and ballast circuitry which is not only bulky and expensive but noisy as well. Such equipment lends itself best at present to nonelectrical dimming means. such as mechanical shutters and dousers. Compactness is still a relative problem until some sophisticated means is found to remove the still substantial amount of heat generated by the lamp. USITI Fall. 1982 I think in theatre. as opposed to some other media - rock. television. and film for example. the market pressure is downward as regards price. Television and film people demand better mechanical assemblies. more rugged equipment. and they are more willing to pay for superior equipment. Rock people pay for "troupe-ability." It's strange that the purchaser of lighting equipment seems not to recognize that by the time he has replaced his tungsten lamp four to six times. in most cases he has paid for the equipment again - and in metal halide units one or two lamp replacements may well represent initial equipment cost. That's why "cheap" equipment may seemingly represent a best buy. but in actuality its final cost may be very dear. The cost of the initial lighting fixture complement in a typical installation represents at best only 20-25% of the total lighting equipment to be purchased. But a greater investment in this area to start. might. in fact. reduce the life-long costs of operation. When queried several lighting designers on the point as to needed Theatre Design & Technology 9