Introduction
ERS By Other Names
The “ellipsoidal reflector spotlight,” or ERS, has been called by various names through the years. Theater professionals may refer to it as an “ellipse” or “ellipsoidal.” “Source Four” is a brand name, and that term is used, too.
You may also hear long-time stagehands call it a “Leko,” pronounced LEE-koh. The nickname is a combination of the last names of James Levy and Edward Kook, who invented this style of stage light in the 1930s.
“One of the jobs of a lighting designer is to be an illusionist; to convince the audience they’re somewhere special,” says Donald Holder. Holder has won a lot of praise for his lighting designs, including a Tony Award® for the hit Broadway musical The Lion King.
In that production, Holder arranged hundreds of lights to turn the stage into what looked like boundless landscape. His lighting painted a brilliant African sunrise, a blue-black night full of stars, and a thunderstorm slashed with lightning. “The job for me … for The Lion King was to create a luminous world, a magical, vibrant world filled with light that evoked the majesty of the Serengeti, the majesty of natural light in Africa,” Holder commented in an interview.
Lighting designers like Holder constantly experiment with new gear to create their art. But one of their old favorites is the ERS, short for “ellipsoidal reflector spotlight.”
The ERS is famous for its bright, focused light and many uses. It can highlight performers for their big number. It can help turn a nighttime scene into a bright summer day. Other gear can be added to the ERS to shine splashes of color, unique shapes, or even special effects like rain, water, and fire.
The ERS is the go-to gear for lighting designers in theaters everywhere. Read on to find out why and how.
At Work
Other Stage Lights
Next time you walk into a theater, look up and around. You will see lighting fixtures of different shapes and sizes. Each design manages different stage lighting needs. In addition to the ERS, here are three common types of stage lights:
PAR Light
Parabolic Aluminized Reflector lights, or PAR lights, look like big cans. They cast an oval pool of light over a large area.
Fresnel

Pronounced freh-NELL, this type of light is named for its unique lens. A Fresnel lens has edges that channel a soft-edged beam of light.
Followspot

These spotlights are designed to highlight a specific performer in a powerful circle of light. Followspots are operated by hand. You can usually spot them on platforms along the back or side walls of the theater.
Different types of stage lights are called on to do different jobs. The lights hanging above the stage usually cover the performance area in general light. But imagine actors performing beneath those lights. The tops of their heads will be well lit, but their faces and bodies will be masked in shadows.
That is where the ERS shines to the rescue. This cannon-shaped light shoots a tight, bright beam across long distances. That means rows of ERS fixtures can be placed above the audience and in the back of the theater. From that angle, these lights reveal performers’ costumes, actions, and facial expressions.
ERS fixtures come in different sizes that feature different “beam spreads.” Beam spreads describe the area covered by light across a certain distance. Some ERS models cover wide areas with light. Others are built to throw a tight beam in order to zero in on a specific spot on stage.
The ERS has the ability to perform many functions in a theatrical production, from general lighting to fun special effects. No wonder this stage light continues to be a favorite tool of lighting designers in theaters around the world.