Spotlights

Spotlights produce a controllable (focusable) beam of light. They are used for the bulk of theatrical lighting because of their versatility. There are a number of means by which the beam can be altered, through attachments and controls. Focussing is altering of the distance between the lamp and lens which adjust whether the beam is hard or soft edged as well as the spread of the beam.

Fresnels

Fresnels produce a round soft edged beam of light which can be focused between 'flood' and 'spot'. They are typically used for back, side and down lighting. There is a common myth that fresnels aren't powerful, however this is simply not true. You can get fresnels with lamps anywhere between 300W and 5kW, although 2kW is as high as you commonly find in theatres. The lantern is named after the French physicist Augustin-Jean Fresnel who developed the fresnel lens which is constructed of lenticular rings. These rings reduce the amount of material (usually glass) required to produce a focussed beam at the expense of beam quality. Most Fresnel lenses used in stage lanterns are also frosted on the rear to prevent any ring-shaped irregularities in the beam.

Plano-Convex/Pebble-Convex Lanterns (or PC's)

Plano-Convex/Pebble-Convex Lanterns (or PC's) are often mistaken for fresnels because of the similar type of beam they produce. However unlike the stepped lens of the fresnel, the PC has a smooth convex outer lens with either a smooth (plano) or pebbled (pebble) inside to the lens. The lanterns are a compromise between optics and size and are used when profile standard optics are required with space available only for a fresnel sized lantern

Ellipsoidal Reflector Spotlight (ERS, Leko(US), Profile)

Ellipsoidal Reflector Spotlight (ERS, Leko(US), Profile) may be focused to produce very hard or soft edged beam and can give a broad beam cover, or highlight a specific area (known as a special). With a longer throw than a PC or Fresnel they may be used from further away, such as from front of house positions. They take their name from the ellipsoidal shaped reflector in the back of the lantern which creates various focal lengths, when combined with plano-convex lenses.

On a fixed beam angle profile there will only be only one lens, which will adjust the focus of the beam between in focus, where they will be hard-edged, and out of focus, where they will be soft-edged. On a 'zoom' profile, a second lens is fitted which is used to adjust the focal length of beam which allows one to widen and narrow a light beam.

Shutters

Profiles normally have four shutters (small tabs which slide into a lantern) that can cut the beam of light off a given area and can be used in conjunction with gobos and irises to further alter the shape of the light beam.

Gobos

Gobos may be considered as crude slides for a slide projector which slot in profiles. Usually they are a pattern cut in a metal stencil, though more intricate designs are etched in glass.

Irises

Irises drop in to reduce the size of the beam – effectively behaving as gobos with a circular hole in the centre.

Followspots

Followspots are specialised variants of the profile, which are (usually) manually operated by followspotters (or limies) to follow someone or something with a tight light beam. They are carefully balanced on their stand so that are smoother to operate. They are normally fitted with a blackout shutter (which is better and faster than turning the lamp off and waiting for the filament to cool), iris, a colour magazine (allows different gels to be selected easily) and sights for the limie to look through. They tend to be on independent channels, and therefore not controlled by the lighting board.

It is possible to get intelligent followspots which follow a radio pack around a given space. However these are very expensive and tend only to be used in very large productions when the followspot position is inaccessible or a very great distance from the stage.