ETC Source Four

The stage lighting industry has seen a few significant breakthroughs over the ages. Here I will provide an abbreviated and probably out-of-sequence history of these developments, and then I will make a convincing argument that the ETC Source Four spotlight represents the biggest of these innovations.

Prehistory through Shakespeare: the Sun

Farmers have been watching theatre for thousands of years. The Greeks were into it, as evidenced by the fact that the Theatre of Dionysus in Athens seated 17,000 farmers. Mostly, theatre happened during the day, because that was when people could see things. This continued for a long time.

Until Electricity: the Age of Theatre Fires

One day, people figured out that they could see things at night if they wanted to, using artificial illumination. These same people decided that it might make sense to do their recreational activities at night, so as to use daylight hours as efficiently as possible doing agricultural activities, which provided a livelihood for absolutely everyone until around 1980 with the invention of the internet. (It wasn't until then that people started to spend time inside even during the day).

These same people, the farmers who wanted to be recreational at night, also thought of another reason to move theatre inside and light it artificially: sometimes it rains, and nobody likes sitting in the rain watching a play. I can tell you from several productions at the Forest Theatre in Chapel Hill, no one likes sitting in the rain watching a play. Family and sometimes friends will do it for you, but they don't enjoy it. Sorry.

What did these perplexed farmers do? They turned to the techies and said, "let's build an indoor theatre." The techies, in turn, scowled at the farmers and got to work. Within an hour or so, the techies had developed a way of lighting the stage without the sun. This method was complicated, and its details are unimportant to reproduce here. The main element of the method, however, was fire. Because fire is hot, it glows, and this glowing, if there is enough of it, can illuminate a scene on stage. Yes, it's expensive, and yes, it's dangerous, and yes, it would be a whole lot easier to just perform plays like we always have in the great outdoors, but the farmers wanted to be entertained inside and this was what it took. It was mostly out of resentment that techies set fire to many theatres during this period. This is when the ridiculous British regulations about the fire curtain were created.

As people got smart, they started to regulate the brightness of the fires illuminating the stage by regulating the amount of fuel added. Oil and gas were both used in these times. With gas pipes running all around the place with fire everywhere, fires happened. Lots of fires happened, in fact. Eventually, people started to think that fire wasn't such a great idea after all. That was when electricity was invented.

Sometime Thereafter: Edison Changes Things Up

Electric light solved all the problems of fire-based light. Things were safer, somewhat cooler, and smelled less like a chemistry lab. Farmers were even happier. Sure, it made things complicated, and it required extensive overhauls of existing theatres, but fires went down by at least four or five percent.

The Lighting Instrument

Over time, people made slight changes to the basic electric light, which began as a lightbulb. I will list these changes so you know what they were. No promises on the order of these developments.

• Somebody put the lightbulb in a can to keep the light from spilling out where we didn't want it.
• Somebody introduced the reflector by putting a flat mirror behind the lightbulb, which we will call a lamp for the rest of this article. This meant the light that used to be lost out the back of the can was redirected out the front of the can. Farmers rejoiced.
• Somebody thought they would play with the shape of the reflector. Curving it toward the lamp seemed to make things brighter, so people did this. Some people used a parabolic reflector; others make a spheroidal reflector. Neither was much of an improvement over the flat mirror.
• Some clever optician figured out that putting a lens in front of the lamp would give it some cool optical properties, and the PC spot was born. Consisting of lamp, reflector, and a plano-convex lens, this was the first spotlight, and the theatre world has never gone back. By moving the lamp back and forth between the reflector and the lens, techies could change the properties of the beam on the floor, and this made farmers very happy.
• A very clever optician named Augustin Fresnel in 1822 thought the plano-convex lens was boring. It absorbed too much of the light itself because it was so thick. Fresnel decided to think about ways to decrease the thickness of the lens. He scratched his head for days and eventually figured out the Fresnel lens, which is frosted on one side and has crazy concentric ridges on the other side. Okay, he mostly invented it for lighthouses, but techies immediately saw its relevance to theatre. PC spots were maligned from then on.
• The Fresnel was awesome, and they are still in use today. However, some lighting designers wanted a little bit more control over the photons their lighting instruments produced, so some clever sod invented the ellipsoidal reflector spotlight. By tweaking the shape of the mirror behind the lens, actually wrapping that reflector around the lens, our clever but anonymous inventor made herself a beam which had interesting optical properties. Specifically, the optical properties of the beam made it so that a pattern introduced at a certain point within the beam could be reproduced in sharp relief in the shape of the beam falling on the stage floor. Gobos, shutters, and irises were now used to shape the beam in various awesome ways. Techies and farmers alike rejoiced for decades. Stanley McCandless lived and died by the ellipsoidal reflector.
• Automated lighting came about in the rock-and-roll era for the purposes of rock-and-roll. It has absolutely no use in legitimate theatre, but it sure is cool for rock-and-roll shows.

Since the development of the ellipsoidal reflector at the beginning of the 20th century, very little real developments have been made in the field of theatrical lighting instrumentation. There have, however, been huge developments in dimming and control.

Dimming and Control

The idea of dimming probably came with the idea of electricity. People became convinced quickly that on and off were not the only light levels they wanted. They started to experiment with other levels, their path marked always by the technology available at the time. Theatres with electrical lighting systems started to be built at the beginning of the 20th century. The earliest systems were large, cumbersome, and frustrating to operate. They also weren't very versatile.

• The first dimmers were resistance dimmers. When you send an electrical current through a resistor before it reaches the filament, the filament glows more dimly than it would if it were receiving the full signal. That energy has to go somewhere, though, and with a resistor, it's lost as heat at the location of the resistor. This makes things very hot in the dimmer room, which, at this time, was also the booth where the lighting operator sat. Annoying.
• These dimmers were operated by hand, and they were big. Imagine pulling a lever about four times the size of your emergency brake to adjust the level of a single lighting instrument. Annoyed yet? So were the techies, until...
• A bunch of things happened in an order that isn't clear to me. Dimmers got smaller and became electronic. The thyristor dimmer was the eventual result, and most dimmers today are thyristor. These are efficient in that they don't waste the energy previously lost as heat. That gets re-used. They also became smaller. Farmers and techies rejoice once again.
• At the same time (maybe), dimmers were able to finally move out of the control booth because of the development of remote control systems which allowed the dimmers themselves to be independent of what became the lighting control console. In modern theatres, a data cable (usually DMX or, these days, Ethernet) connects the control console to the dimmers. This was an innovation which reduced the temperature for lighting operators. They were happy.
• Lately, more and more theatres are wired dimmer-per-circuit. Without going into a bunch of detail, this means that it's a whole lot easier to get a lighting instrument hung and working than it used to be.

But none of these innovations in lighting come close to matching the developments made by ETC in 1992 with the release of the Source Four.

The Source Four

For anyone who has ever laid hands on one of these, I need not sing its praises. All other people probably won't have read this far yet. Too bad.

The Source Four is a brand name of ellipsoidal reflector spotlight manufactured by Electronic Theatre Controls, a Wisconsin-based company which knows what it's doing. If it ever goes public, buy stock in this company. It's going places.

A team of engineers started by reconceptualizing the lamp. The HPL lamp used by all ETC lighting fixtures is a 575-watt (okay, it also comes in a 750-watt model) tungsten-halogen lamp which easily produces more light and less heat than a conventional 1000-watt lamp, all the while lasting longer. No one knows how this was accomplished, but it's definitely really impressive.

The next development that ETC engineers made was with the reflector. The Source Four reflector is made of dichroic borosilicate (Pyrex) and allows infrared (heat) and other wavelengths to escape out the back of the instrument while most of the visible light is reflected forward according to the same optical patterns that make the ellipsoidal reflector spotlight so versatile. This is not only really awesome, it looks cool, too. Peek in the back of a Source Four, and you'll see a really nifty opalescent reflector thing glowing a bit.

All techies understand that lights get hot when they are turned on. It's just what things do when you heat a little filament of tungsten to incandescent temperatures. It's what we expect to happen. Conventional metal fixtures get hot within a second of being turned on. The Source Four's external housing is made of a space-age ceramic material that stays cool much longer. There's also a durable composite plastic handle on the back which never gets hot. It is possible to adjust even a hot Source Four without burning oneself. This is a victory.

The Source Four has interchangeable lens tubes. The 19° Source Four can become a 36° or even 50° Source Four within moments if the proper replacement lens tubes are owned. This increases the versatility of the instrument enormously. The same instrument you used to project lightning from the back row of the house can be the instrument you use as a wide center special on first electric.

Why are Source Fours great pattern projectors? Because they have a very even field, because they can be brought into extremely sharp focus, and because of the barrel rotation knob. This knob allows the gobo or shutters to be rotated in the gate (indeed, the gate itself is rotated) by up to 25°. This may not sound great to a farmer, but a techie will understand how useful this can be.

There is also a color frame clip so that if the instrument is mounted upside-down by an oaf, it can still be used with a color.

There is also a slot for an iris or gobo spinner. This is nifty.

In other words, the Source Four is the coolest thing to happen to theatrical lighting since Stanley McCandless decided to have lunch with his buddies from the art department at Yale.

When you see a camera lens in public, it's probably a Canon. When you see a microphone in public, it's probably a Shure SM58. When you see a lighting instrument in public, it's probably an ETC Source Four. That's how good the Source Four is.