Fixed beam profile luminaires utilise a precision optical system that comprises of an ellipsoidal reflector and a lens, some designs use two lenses, to provide a light beam that can be focused to a soft or hard edge and accurately shaped by framing shutters inserted into the gate.

Most profile luminaires provide a slot to allow a gobo holder to be inserted into the gate adjacent to the framing shutters so that gobo patterns can be projected onto the stage. The ability to function as a pattern projector is one of the benefits the precision optical system provides.

Profile spots are often called ellipsoids, because of the ellipsoidal shape of the reflector, or simply referred to by their model name such as as Acclaim Zoomspot. Overseas they are commonly referred to as ERS (Ellipsoidal Reflector Spotlights). The ellipsoidal reflector is a critical component in the optical system of profile luminaires. Ellipsoidal reflectors are designed to focus the light from the lamp into the focal point of the optical system, and they do so very efficiently.

The position of the lamp in the reflector is usually adjustable to provide light distribution across the beam width that is either even from edge to edge (flat) or brighter in the centre of the beam (peak). Peak distribution allows the beams of adjacent profiles to be overlapped without creating 'hot spots' whereas a flat setting is best for projection of gobo patterns.

Zoomspots vs Fixed Beam Profiles

Zoomspots allow the size of the light beam to be readily set to the size needed for any particular purpose, minimising the light and energy wastage that may otherwise result from large shutter cuts. This also eliminates the need for lighting designers to calculate the exact beam angles required for each luminaire so the appropriate luminaires can be rigged for each show. The down-side is that the extra lenses and variable beam width makes zoomspots a little less efficient. The wider the zoom range the less optimal the optical system becomes. This is why manufacturers make a series of zoom lens systems with limited zoom ranges rather than a single lens system that zooms all the way from pin spot to wide flood. When luminaires are routinely moved to different positions within a theatre, or toured to different theatres, the versatility of zoomspots makes them the obvious and popular choice for multi-purpose venues and repertory theatres.

Fixed beam luminaires allow the manufacturer to optimise the optical system to achieve the best performance from the luminaire, at the specified beam width, to provide a more efficient luminaire with superior light beam characteristics that is simpler to use. When the luminaires are permanently rigged at the same positions in a theatre the need to calculate beam angles from one show to another is largely eliminated making it practical to select luminaires based more on efficiency and light quality than versatility.

Given that modern engineering has reduced the performance and efficiency differences between zoomspots and fixed beam profiles to a minimum, much of the choice also comes down to personal preference.

Typical Uses

Profile spots are mainly used to light the front areas of the stage from Front of House (FOH) spot bars above the auditorium and for lighting upstage areas when maximum control of the light beam is desired. In addition they are often used when tightly focused specials are required, particularly from FOH positions, and for pattern projections.