Studio lighting: from tungsten to fluorescent

Tungsten lamps remain the most common light source in studies. They are weaker in the emission of blue increasing through green and red. Most of the electricity that causes the bulb filament to light up produces radiated heat as infrared energy, which is wasted because excessive heat must be removed by air conditioning systems, which in turn consume more energy. This implies an additional expense when building a facility for television production looking for these large air conditioning systems to work quietly so as not to cause complications in sound recording.

Traditional lighting instruments have been designed to direct the light produced by these sources, which is very hard because it comes from an incandescent filament. Traditional lamps let out the light and a basic diffused light is generated that is what fills the image. Fresnel lamps offer easy control of light intensity with their lenses and fins. Its direct light is very strong to illuminate faces, causing very intense shadows. To avoid this, lamps have been invented that deliver diffused light, but they have the problem that they let light escape and are difficult to control. If it is not verified they can flatten a scene, creating shadows to a point where the model weakens, the contrast is decreased and the colors lose saturation. The design of the lamps can help improve light control, by adding elements that restrict both the thickness of the light beam and its shape, limiting the amount of unwanted light in the studio.

Of course, lighting is not everything. Good video images need more. The set designer can also make an important contribution by separating the vertical planes, creating enough distance between surfaces and allowing there to be room for light to fall naturally. This opens up the possibility for a differential exposure between close-ups and background shots.

Introducing color as an integral part of the design helps maintain color saturation. Textures and absorbent and reflective surfaces add interest. The lighting director completes the scene by increasing the three-dimensional illusion with highlights and shadows in the appropriate quantity, quality and direction. The most interesting set will look flat and boring if it is illuminated only with a soft front light. Whatever the light source, if you are in the wrong place it will become two-dimensional.

A very important aspect to consider when installing one or another lighting system is its cost. In the case of tungsten, it can be expensive if viewed from the philosophy of energy saving. In addition to the inefficiency and problems of infrared heating the life of the bulbs is also a problem. A good tungsten bulb only lasts about 250 hours. It should also be considered that a large part of the investment for a new study goes to the suspension system of the upper lights.

The studio tungsten lamp has long been the standard for television productions. While advances in television technology are happening at an incredible speed, the basic design of the Fresnel lamp has changed very little in 60 years. It is little wonder, then, that some have begun to look for alternatives for the new millennium.

However, although many might believe otherwise, tungsten is still essential for covering large areas. Studies where dramatized with sunlight or moonlight are performed resort to tungsten. Entertainment shows with live auditorium need high levels of output, so tungsten is not dead.

Generally called cold lights because of their relatively low temperature levels when operating, fluorescents have been used since the forties. Commonly, a tube of low-pressure steamed mercury produces mostly ultraviolet light. A phosphorus coating on the inner walls of the glass reacts or acts to this ultraviolet energy by emitting visible light: fluorescence.

In the cold light tube, some of the energy transfer occurs with a small delay, producing a subsequent glow: phosphorescence. Modern tubes have an efficiency of at least three times that of tungsten, generating an increase of 75 lumens per watt. The correct mixing of three phosphors makes light visible in the red, green and blue bands.

The light output of fluorescents is not continuous in time or constant in level. Fluorescents flicker at major frequencies that may be noticeable in our most sensitive peripheral vision. A camera capturing at different frequencies can emit strobe light. However, if the lamp is at a high frequency relative to the degree of capture of the camera, there will be no oscillation.

The combination of an appropriate balance between a phosphor color and a high oscillation frequency has led to the development of successful lighting systems for production using fluorescent technology. This approach is generally referred to as sustained RGB (SRGB) and is most commonly associated with light supplier Videssence, a pioneer in many of the developments in this area.

Videssence lights use what manufacturers call tri-phosphor tubes. There are two color-balanced versions available: tungsten and daylight, so mixing these units with other forms of light is no problem.

SRGB lighting is very attractive also because its tubes have a long average life. Those used by Videssence are estimated at 10,000 hours, about 40 times more than the life of a typical tungsten tube.

The concept of electronic light reducers (dimmers) for fluorescent lights has been known for a long time, but only recently has it been possible to manufacture a small, inexpensive, and sufficiently reliable and practical control. This allows the reduction of light to a constant color temperature over a wide range of brightness.

When a tungsten light is conventionally reduced its color changes significantly, although it can be recovered by altering the color balance of the camera using the red, green and blue controls.

Fox's 24-hour news channel, which has been broadcasting to The American public since last October, has its studios in the Rockefeller Center area of Manhattan. Two of the four studios have windows into the street through which passers-by can watch the production.

There were numerous lighting considerations to take into account when designing such a space, a task for the New York City Lites, NWCL. "In studios with windows we have to deal with sunlight," says Bruce Ferri, co-designer on the project with Deke Hazirjian, director of NWCL. And we're on the air 24 hours a day, so at some point the sunlight goes away, and we have to deal with the night." This 24-hour schedule also brings other drawbacks. "When you work 24 hours replacing the lamps is something that is not necessarily done all the time and apart from maintenance we also deal with the heat," says project manager Fred Bock.

This led us to the use of compact fluorescents (CFLs). But according to Bock "we have our particular style for using compact fluorescents. We use them as another tool for the job." Ferri also agrees: "It's just another light. A soft one that consumes little energy. Some people think that if you use fluorescents, all the lights are fluorescent and no tungsten. That's a very uninteresting and very flat concept. Consequently, this has brought bad feedback from people about fluorescent lighting. When they came on the market, you couldn't balance a fluorescent light with a tungsten unless you started adding gel. The lights available today are color-corrected and balanced for tungsten." NWCL has decided to use LightTech's compact fluorescent units for its FOX project in part because Ferri sees it as superior from an engineering standpoint. "The color rendering of a tungsten image is like the curve that goes through all the colors of the spectrum," explains Ferri.

They are easier to control lights and have a different character. You have to combine them.