"TV Technology"
06 May 2011

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TV Technology

Television Lighting: “No Dimmer Rack?”

by Bill Klages

The Studio of the Future

Looking about the entertainment lighting landscape, one thing is very apparent – many present-day fixtures, perhaps a majority, come complete with their own self-contained dimming. The early beginnings of this development can be traced to the need for mechanical dowsers on arc discharge sources whose intensity could not be controlled by simply varying the voltage to the instrument (as is the case with incandescent lamps). And today, with the obsession with LED sources, this self-containment comes as a consequence of the unique solution required to vary the intensity of these fixtures.

The Question

If you reflect upon this situation, one obvious question arises: With this local dimming feature so readily available, will dimmer racks be unnecessary in permanently installed television and theater facilities of the future? This is certainly an intriguing idea. Let us pursue this further.

Instrument Types

Many of the instrument types that a lighting designer might desire to use are available with their own internal intensity control. After powering the device, only an easily distributed control signal, usually DMX, needs to be connected to the fixture to control light output (and, in many cases, other attributes). We are very aware of the performance capabilities of the many moving lights with this internal dimmer ability, and of their use for all sorts of effects. (As well as their more conventional uses; for example, as colored washes). For simplicity, I will limit the range of instrumentation types reviewed to those that fall in the 3200şK range; in other words, replacement for normally dimmed incandescent filament instruments – the studio-workhorse types. Although it is possible that studios could be outfitted to be operated at a higher color temperature, say 5600şK, I would prefer this to be left as a special case for future discussion.

Soft-Light Sources

Consider large-aperture instruments, producing the envelope of light associated with “soft-lights.” Today, there are a number of popular soft-light units currently available that have internal dimmers. In particular, dimmable fluorescent fixtures are high performance and efficient configurations. What is interesting to note is that units that are intended for use with a digital control signal (such as DMX) will actually dim smoothly to zero; whereas their counterparts, using two-wire ballasts intended to be connected to standard phase-controlled dimmers, do not have this ability. Fluorescent units with correct lamps will meet our color temperature criteria of 3200 degrees Kelvin. These units, in my opinion, are very cost-effective.

Linear Instruments

Linear sources of light using LEDs with optical-beam shaping can be utilized to replace, with some consideration of the differences in output pattern and intensity, the common incandescent strip-light. These, again, have an internal dimmer system and can be very efficient sources of color; particularly, if the unit has a greater population of color sources beyond a simple three-color RGB configuration. So we are OK, with some slight reservation, to place this instrument type on the complement of equipment for the dimmer rack-less installation.

The Ellipsoidal Framing Fixture

At the present time, there are many very high-performance moving lights that are basically Elliptical Reflector Spotlights (ERS) with the additional features of a “mover”. Most use arc sources and come equipped with onboard dimmers. However, their color temperature is not 3200şK. Fortunately, there are some well-designed incandescent moving lights available that do have self-contained dimmers that would meet my 3200şK requirement. There is also some progress in using an LED source in this area that can be adjusted to the lower CT, but their performance does not, as yet, meet the performance of an off-the-shelf traditional instrument. In the cas e of a permanently installed and equipped theater that would require a very large complement of ERS units, outfitting the facility with instruments with self-contained dimmers seems quite remote because of the economics. For smaller complements, as in a TV studio, we could use the incandescent moving light fixtures justifying the much greater purchase price with the functionality that comes with a moving-light fixture. This may be a little bit of a stretch.

The Fresnel

Mechanical dowsers that fit Fresnel spotlight units have been available for a number of years, but have never gained popularity; a combination of cost and inconvenience. This year, there have been a number of well-designed LED Fresnel units introduced, complete with internal dimming, that approach the performance of the incandescent units. However, we are still stuck in the range of units restricted to an (optimistic) equivalent performance level of a 2000-watt incandescent unit. In most medium-sized TV studios, this certainly would not be too restrictive. There are some other minor difficulties with these units at the present time. They are a little more bulky than the units that they replace. In many applications, this could be a problem.

A Really Big Heat Sink

One very amusing aside at this point. Believe it or not, the current market for 10,000-watt Fresnel spotlights is quite strong. We will just have to leave this area alone and not even attempt to visualize a replacement with a self-contained dimmer. (Most installed studios and theaters do not have 10KW outlets anyway). However, it is fun to try to imagine what a LED “Tener” would be like.

Future Studio Installation

In the light of my very perfunctory review, the conclusion would be that there is an indication we are approaching a period in which an installed television studio would no longer require a rack full of dimmers to be permanently installed. The range of instrument types is being broadened every day with new designs, incorporating a self-contained intensity mechanism. But there is still one very elusive issue that restrains all-out acceptance. This unfortunate issue is cost. The Return On Investment of a studio installation with no dimmer rack cannot be a considered until the cost of self-contained dimmer instruments is the same order of magnitude as the instruments they are to replace. Time will tell.

Bill Klages would like to extend an invitation to all the lighting people out there to give him your thoughts at billklages@roadrunner.com