Projecting a Good Image

If there is any one aspect of lighting technology that has progressed most rapidly in the last half-dozen years, it would have to be our ability to include projected images in our productions.
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If there is any one aspect of lighting technology that has progressed most rapidly in the last half-dozen years, it would have to be our ability to include projected images in our productions. While cookies (cukaloris) in front of Fresnel spots have been with us since the earliest moments of the moving image, and the gobo-equipped Ellipsoidal Reflector Spot has been around almost as long, the tools that have recently become available have opened up possibilities to a whole new level.

Unlike the simple shadow projection of the cookie and Fresnel spot, contemporary projection systems are capable of producing affordable high-resolution color images at useful light levels, and frequently with a range of movement and image animation options. Some of the enabling technologies for this projection revolution are purely optical; notably thin-film coatings, high color-rendering discharge lamps and complex aspheric lenses. It is the computer industry, however, that brought about the affordable switch-mode lamp ballast, the commodity stepper-motor to provide movement for our images and the cheap microprocessors and micro-controllers to make the projection controllable.

LOW-END TO HIGH-END

The new projection systems encompass a panoply of devices. They range from Derksen's tiny GoboTop, which clips over a standard low voltage MR16 lamp to convert it into a remarkably effective gobo projector, to E\T\C Audiovisuel's 7kw xenon PIGI projectors with their bi-directional film scrolling system, and on to the Catalyst system from High End. Bringing with it a whole new way of thinking, the Catalyst combines moving light technology with digital video manipulation and video projection.


(click thumbnail)Aussies used this projection display at the 2000 Summer Olympics to bid farewell to the Games.Beyond this list, we must also consider the gobo projection capabilities of the current generation of robotic luminaires, including such devices as High End's X.Spot, Martin's Mac 2000 profile, Coemar's CF7Hex, Clay Paky's VIP 1200 and Vari*Lite's 1000 ERS and 3000 Spot. In addition to being extremely flexible production spots, with light outputs high enough to be really useful for television work, these robotic luminaires are equipped with zoom optics, multiple gobo wheels with indexed rotation and various forms of rotating prisms and break-up glasses. These fixtures have become very popular with concert LD's, some of whom are building the looks of entire shows around the fixtures' capacity to zoom, morph, rotate, animate and pull focus on a range of custom gobo images. In video production, these robotic fixtures allow us to place a projected image where we want it in the frame, in addition to offering the ability to rotate, morph, zoom, etc.

Although high-quality projection optics have been available for many decades, they have not been widely affordable until very recently. It took the confluence of the compact source metal halide discharge lamps, the lightweight electronic ballast, the cool beam dichroic reflector, and the aspheric lens to democratize projection.

Having made that sweeping statement, it is important to note that at the extreme end of town, the really big projection systems from E\T\C Audiovisuel of France and Ludwig Pani of Austria are still very expensive to own-or rent. However these behemoths do offer outstanding capabilities for large-scale image projection with scrolling, rotation and animation. If you need to cover an entire building façade, such as the Arc d'Triomphe or an entire sports arena with a projected image that reads solidly against the production lighting, then there really is no viable alternative.

THE FINE DETAILS

The revolution is not only a result of our ability to build better and brighter projectors, it also derives from the huge improvements in the design and production of the images that have become available to project. As the output from projectors grows in intensity, so too does the amount of energy being pushed through the image. The selective reflection of dichroic filters and reflectors has brought us the cool beam light source, and Rosco's Image Pro has added air-conditioning to the gate of the ellipsoidal spot. Yet, despite these advances, bright projections still require a lot of light and sharp projections require very finely detailed images.

The original cookies were made by the simple process of cutting shapes out of steel or plywood sheets with a jigsaw. However the demands of production frequently require that the images be more defined than dappled-light through trees, or a soft, window-ish shape on the cyclorama.

Desktop publishing and the widespread adoption of digital photography and image manipulation have given us readily available desktop (or laptop) tools to produce the high-resolution images required to exploit the optical capabilities of the new projection systems. Adding computer-aided design techniques into the image manipulation process enables us to project from almost any angle, on to any suitable surface, without apparent distortion or keystoning of the resulting image.

In some circumstances with cool-beam ellipsoidal spots, where the energy density from the projector system is low enough, we can even use today's inexpensive photographic-quality desktop printers to produce our finished objective slides or gobos. Images for high-output systems have undergone an even more radical change. Printed-circuit technology led us to the photographically etched stainless steel gobo in the 1970s, but it was the photolithographic processes developed for silicon chip production in the late 1980s which gave us today's etched slides and gobos. Built on a glass substrate that transmits heat, rather than absorbing it, these slides were originally just a microscopically thin and very accurate version of their chunky stainless-steel forebears.

When dichroic materials were developed to produce a range of heat-stable colors for high output fixtures, it was a natural progression to etch parts of the coating away to produce multi-colored images. Thin film technologies have been further developed for use in electronic components, magnetic disks and optical recording media, making it possible to produce full-color (CMYK) images which are very heat-stable, and in conjunction with photolithographic etching, very high-resolution.

Whether you need a dancing love-heart to enhance the "win" sequence in a game show, a series of morphing sponsor logos for a sports award presentation, or want to convert the exterior of your studio building into an accurate quarter-scale replica of Mount Rushmore, there is now a projection technology to match your imagination. How you keep the producer/director from over-using it, or applying it in bad taste, is left as an exercise for the reader.