Satisfy yourself that the unit is efficient, has a large enough reflector and lens. Is the field smooth, free from ghosts and hot spots? Does the lamp adjust easily? Does your problem require a zoom system? Is there adequate expertise for adjustable field intensity adjustments in your use of the unit? Do you have a sensitive heat problem? Is the price right? Care in the selection of equipment can mean a lifetime of excellent service coupled with a reasonable price at the time of purchase. A quick selector chart follows demonstrating the selection alternatives.D 12. The mechanical features that make the unit easy to mount. simple to adjust for direction, that make shuttering easy and secure without pulling out or leaving a spill over the rear edge, that make lamp adjustment quick and direct, that make the unit durable and free from rust, all go without any added comment. Electrical provisions allow no compromise, they must be the best for the purpose. Relamping should be easy. In summary: Select the spread for the distance of throw and the area to be covered. Choose the smallest lamp consistent with the intensity desired. Spotlight Selection Chart Central Intensity Required Degrees of Spread Intensity Desired-Footcandles Circle Diameter-Feet Throw Feet 6 8 12 15 20 25 50 75 100 (Candela in Thousands) 10 20 30 40 50 60 70 80 90 100 33 17 11 9 7 6 5 Degrees of Spread 50 40 40 33 30 28 27 24 23 20 18 15 13 12 11 10 9 5 14 10 44 23 15 11 9 8 7 6 5 62 33 23 17 14 11 10 9 8 7 53 28 19 14 11 10 8 7 6 6 74 41 28 21 17 14 12 11 10 9 90 53 37 28 23 19 16 14 13 11 2.5 10 23 40 63 90 123 160 203 250 r l K SC K BC K - 1355 2457 1357/8 213/092 1355/8 BC - 213/102 K - 1357/10 BC - 213/112 SC-Strand Century BC-Berkey Colortran EC-Electro Controls K -Kliegl Theatre Design & Technology 7.5 30 68 120 188 270 368 480 608 750 10 40 90 160 250 360 490 640 810 1000 Central Candela-in Thousands Lamp Watts Manufacturers' Catalog Number SC-2211 BC - 213/052 SC - 2321 EC-7367A BC - 213/062 zoom SC - 2331 K - 1355W EC -7367A SC - 2337 BC - 213/072 5.0 20 45 80 125 180 245 320 405 500 250 5 NA 7 NA NA 500 13 12 27 43 19 750 NR 19 38 83 25 1000 NR 28 NR 91 38 16 NA NA NA NA 51 34 65 67 26 69 51 103 101 43 NR NR 140 141 62 83 119 NA 70 168 125 176 NA 94 250 NR 242 250 144 NR 183 NA 266 331 NA 490 396 410 576 I NA I I I NA I NA-Not Available NR-Not Recommended US ITT ISpring. 1978