In the September 1978 issue of Theatre Crafts, Robert Benson wrote an article titled “Purchasing Guide for Ellipsoidal Reflector Spotlights.” In the quarter-century since that article was published, much has changed. Honestly, almost everything has changed. Only one unit on the market in 1978 is still being sold. Step lenses were common and reflectors were made from plated metal. The FEL had yet to rise to its prominent position. The important feature in shutters was how easy they were to replace, and how inexpensive. Moreover, a “speed cap” was something you wore when driving a convertible.

Fast-forward 24 years. Step lenses have disappeared and smaller, more efficient aspheric lenses are replacing the Plano-convex lens train. The FEL became the most common lamp type and, with the introduction of the compact coil filament (CCF), is disappearing faster than diffusion at a focus call. Shutters are no longer considered an expendable, and “speed caps” have assumed a place of dominance that leaves dinosaurs like me pining for those three brass screws that made everything so precise.

Most manufacturers offer beam angles ranging from 50° down to 5° My goal here, as with the original article, is not to tell you which particular mix of instruments is best for your space but, to make you aware of the changes in technology that have occurred in these deceptively high-tech theatre tools. However, I will say that you should consider the whole line of each manufacturer, rather than just the beam angles you are considering right now. If, in a year or two, you decide to add some long throw units or zooms to your inventory, you would like to have everything come from the same manufacturer. Considering the advantages and disadvantages of the whole line can make you happier later.

Possibly the most dramatic change in ellipsoidal technology in the past quarter century was the development of the compact coil filament (CCF) for ETC's Source Four ellipsoidal. Taking a page from the four coil filaments used in BTNs, BVTs, etc., the CCF lamps took the large ungainly filament used in the 1,000W FEL lamp and broke it into four smaller filaments. Packing these four filaments into a tighter space keeps the source of the light closer to the focal point of the reflector, making the marriage of lamp and reflector more efficient. By making the lamp more efficient, manufacturers are able to get more lumens out of the lamp while using fewer watts than previous lamps. Every ERS on the market at press time has a compact coil filament lamp available for it.

Operating hand in hand with the advance in lamp technology is the reflector. Twenty-five years later, only the overall shape remains the same. Materials have changed from polished aluminum in every fixture to a variety of polished aluminum and glass reflectors depending on the manufacturer. Glass, originally thought too heavy and too fragile, has come a long way in 25 years. The glass reflectors have dichroic coatings that reflect visible light and allow heat to pass out the back of the unit. The reflectors have spring mounts that allow the reflector to suffer some abuse without breaking. (I've actually had two full crates of Source Fours fall on their backs without one reflector breaking.) The aluminum reflectors have been redesigned for the newest lamp technology and one manufacturer then bounces the light off a cold mirror to remove the heat from the optical path. The reduction in heat through the front of the unit lengthens gel, template, and shutter life.

Another major advance has been the shift in lens technology, from the step lens to plano-convex lenses and the current move away from the PC lens train to aspheric condensing lenses. Sales reps will talk your ear off about how wonderful the aspheric lens is and how it works, but it all boils down to focusing more light with less glass. An anti-reflective coating helps the lens focus as much light as possible without kicking any back within the unit. The advanced lens design makes the modern ERS a much sharper template and effects projector.

Accessories — the technician's daily version of root canal. In the late 70s, lens size (and thus accessory size) varied from 3" mini-ellipses to 10" PC spots. Some units had template slots. Irises were an option only available from the factory. While the situation has gotten better over the years, it is still not perfect. While the big three (Strand, ETC, Altman) have the same size gel frame, this is where the crossover ends. Every manufacturer has made the template slot standard, but the size varies from brand to brand, and in some cases, differs between models of a single manufacturer. The drop-in accessory slot has become a near standard, allowing every unit to gain an iris quickly, and even to hold template rotators and other special-effects units. It is worth considering what units you can buy that are compatible with the accessories you already have in stock.

Let us not forget how important the opinions of current users can be. Sales reps for every unit will be more than happy to provide references of designers and facilities using their product. (Moreover, if they are not, that should raise a warning flag.) Talk with people in the field using the product and get their impressions. What have they discovered that is not in the sales literature? What kind of service have they been getting from the manufacturer? Would they purchase more of those fixtures if given the option?

Prioritizing what you need the unit to do is the first step. Is output more important than flexibility? Is service more important than output? As always, cost ranks high in any discussion of features. If you are willing to compromise on some of the features, a good ERS can be purchased for under $200. The bulk of the field finishes in the $250 range for fixed focus units with the zooms and more feature-laden brands tipping the scales around $400. Bear in mind that the list price for a fixture includes almost nothing. You will still have to buy lamps, plugs, and safeties for each model and some manufacturers have stopped shipping clamps with the units. So add $25-$30 per unit to cover the cost of getting it ready to for use.

A lot to think about, right? Makes you long for the days when one unit reigned supreme over the industry. Who knows, that day may come again, as designers and technicians exercise their market muscle. Nevertheless, until then, weigh all the pros and cons of a unit and get the one that makes the most sense to you.

Stephen Litterst is the technical supervisor for the Ithaca College Department of Theatre Arts. He can be reached at


  • What lamp type/socket series is used in the unit? Are these lamps/sockets compatible with units already in your inventory?
  • What is the construction of the unit body? Cast aluminum? Sheet metal?
  • What is the reflector made of? Coated glass, Polished Aluminum? If glass, how is it protected from shock?
  • Do the shutters operate in two or four planes (will they interfere with each other in normal operation?)
  • Do the lenses have a non-reflective coating?
  • Are the lenses easily accessible for cleaning, replacement, etc? Does the mounting fashion protect the lenses from shock?
  • Is the locking mechanism on the yoke durable and does it provide a solid lock?
  • How noisy is the unit? Is the filament audible during warm up? Are there the tell-tale ticking noises as different materials heat up/cool down at different rates?
  • How hard is it to adjust the position of the lamp in the reflector? How well can you lock the lamp in that position?
  • How difficult is it to change the lamp? Is there enough space between the cap and yoke that you can change lamps without refocusing the unit?
  • Is the wiring well protected where it leaves the unit? Does it go through strange contortions that might damage it in the end? Is the strain relief effective *and* easy to replace?
  • What is included with the unit? C-Clamp? Color Frame? Lamp?
  • Is it possible to install an inappropriate lamp? Is it *easy* to do so?
  • How do current users feel about the Unit?
  • How long has the unit been on the market? Have all the “undocumented design features” been ironed out?
  • What does the unit come with? How much else do you have to purchase (lamps, clamps, etc) to make the unit usable?