Digital Video - November 2007 - (Page 41) soon spread into common use in film. Even though fluorescent fixtures were originally invented in the 1930s, they weren’t refined for use in film and video until the late 20th century. Special formulations of phosphor coatings had to be developed to achieve a usable color temperature from fluorescent fixtures. Today, videographers and cinematographers have a complex range of lighting technologies available to them. Advances in emulsion sensiotometry and electronic imaging technology have made extraordinary leaps in light sensitivity, making exposures possible in as little as a single footcandle of light. Today’s digital cameras, with their typical sensitivities ranging from 640 to 320 IE, require only 30 to 60 footcandles of light to reach an f/4, the equivalent of about two to four 60-watt light bulbs. That’s less than 1 percent the amount of light originally required for the first film emulsions. Litepanels 1x1s offer key and backlight for a simple tabletop setup. DAWN OF THE DIODE These advances in light sensitivity opened the doors for the use of new forms of artificial light in the 21st century—from fiber optics to exotic electroluminescent papers—but one of the most promising and practical is the light-emitting diode (LED), which was invented in the early 1960s based on technological discoveries made at the turn of the 20th century. Early LEDs were only capable of emitting a red light at very low intensity, but further advancements paved the way to brighter red LEDs, then orange, green and, finally, in the mid 1990s, blue. As technology improved, creating brighter LEDs, techniques were employed to coat the inside of the plastic lens with phosphors to turn the bright blue light into “white” light. Mounted to an arm, a Litepanels MiniPlus serves ENG-style. LEDs require very low power to operate, output no heat and have extraordinarily long lamp lives—typically in the 50,000 to 100,000 hour range. As a result of this efficiency, many long-term installations have already switched over to nearly exclusive LED technology. In the United States and Canada, all traffic signals have been switching over to LED lamps since the mid-1990s. Once the three primary color LEDs were perfected, large screens could be manufactured with red, green and blue diodes clustered together in “pixel” formations to form pictures, like a television screen. Many outdoor giant screens—including Megascreen, D-Lite, Starvision, Monsterscreen and Sony’s massive Jumbotron—are now made from LED lamps. These screens go as large as the Adi iConic 100, a 41-by-23-foot outdoor LED screen with a 47-foot widescreen diagonal picture—larger than most cinema screens. The advancements in LED technology have moved it into the viability range for film and video applications. Companies such as Litepanels, Nila, Element Labs and Zylight are manufacturing LED fixtures specifically for production use. The typical LED is a 5mm cylindrical shape; although they can come in larger sizes and rectangular shapes, larger doesn’t necessarily equal more light. Brightness from LEDs comes not from size of the individual diodes, but rather from clustering many LEDs together. LEDS REQUIRE VERY LOW POWER TO OPERATE, OUTPUT NO HEAT AND HAVE EXTRAORDINARILY LONG LAMP LIVES—TYPICALLY IN THE 50,000 TO 100,000 HOUR RANGE. The LEDs themselves are a fixed color, generally in a very narrow bandwidth, and they are not capable of changing color. Film and video fixtures are therefore, just like their incandescent, gasdischarge or fluorescent cousins, available in a specific color temperature. However, the small size of LEDs allows for many varying color diodes to be clustered together and activated at various intensities to create nearly any color in the visible spectrum with the possibility of dimming from one color to the next. www.dv.com dv november 2007 41 http://www.dv.com
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