The ellipsoidal, or ellipsoidal reflector spotlight (ERS), is a type of light that can be focused by adjusting the distance between the lamp and a reflecting surface shaped like an ellipse in the rear of the instrument. This surface focuses the light in a narrow path through a lens located in the front of the instrument. The ellipsoidal also employs four frame shutters to further limit the light beam.
Fresnel instruments use a lens at the front of the camera to provide a broader light pattern. Instead of the geometrical reflection surface used by ellipsoidal instruments, the lamp can be moved closer or farther from the lens to focus light. Fresnel instruments produce a soft light quality and are generally capable of providing broader light coverage than the ellipsoidal.
A parabolic aluminized reflector, also referred to as a PAR or PAR can, uses a lamp style that integrates the bulb with the lens surface in a single self-contained unit. As a result, the enclosure assembly is much simpler than an ellipsoidal or fresnel. Pars are selected according to a preset size measured in eighths of an inch. For example, a PAR light that is 8 inches wide would be called a PAR64.
Scoops are used to provide the broadest light source possible to boost overall all light levels on the stage. A scoop uses a large parabolic reflecting surface in the rear with no lens to further focus the light.
Striplights consist of a parallel array of smaller, non-focused lights that provide a broad wash of light normally used for backdrops or cycloramas (the concave curtain at the rear of the stage). The striplight often employs gels or round glass filters (called roundels) to provide a multi-color wash of light against the backdrop. Striplights may also be used as footlights when placed on the stage floor at the front of the stage.