5.02 - PLANO CONVEX SPOTLIGHT

1.) DESCRIPTION5.02 - PLANO CONVEX SPOTLIGHT

The ELLIPSOIDAL REFLECTOR spotlight, (sometimes known as the LEKO or LEKOLITE) is a common fixture for many stage lighting applications. The 'ER' as it is sometimes called is available from many different manufacturers and is available in a number of different sizes and beam spreads.

The ellipsoidal fixture was first introduced back in 1933 by Joseph Levy and Edward Kook, founders of Century Lighting, each giving half of their names to the new invention, 'Lekolite' or 'Leko'. About the same time, Kliegl Brothers introduced their EF fixture known as the 'Klieglight'. Although ER's are now commonly called 'Lekos', the name is now owned by Strand Lighting and correctly only refers to their ellipsoidal reflector products.

2.) APPLICATIONS

The ER spotlight provides a narrow, directional beam with a hard edge. It is able to provide a sharp focus of integral metal shutters, an iris or a metal projection template. The ability to project a metal etched pattern (template or gobo), makes this fixture particularly useful to the stage lighting designer.

All ER's also allow focus adjustments by moving the lens tube forward or backwards. This produces an adjustable beam edge ranging from very sharp and hard to very soft. Some ER's do not allow the edges of the beams to soften sufficiently for the proper blending and sometimes the edge may need to be further softened using diffusion material.

Ellipsoidal reflector fixtures have one (1) or more lenses, usually, 4.5, 6, 8, 10 or 12" in diameter. Most ER's particularly the wider units, have two lenses. Generally, the narrower the beam spread (in degrees), the heavier the fixture will be, due to the longer lens barrel and the larger diameter lens, required.

Some (American) manufacturers specify a fixture by indicating the lens diameter then the focal length. For example a '6x9' (pronounced "6 by 9"), indicates a fixture with a 6" diameter lens and a 9" focal length. This tells the designer nothing about the beam spread of the fixture. Most modern lighting manufacturers now specify fixture beam spread simply in degrees. Approximate spread angles for typical ellipsoidal reflector fixtures are as follows: (in degrees) 4.5x9 =50, 6x9 =40, 6x12 =30, 6x16 =25, 6x22 =15, 8x13 =12, 10x23 =9.

3.) TYPES

Modern ER spotlights have beam spreads of 5 to 50 degrees and are available in wattages of 500 - 2000 watts.

They are available in both fixed focal length and variable focal length (zoom) models. Standard focal lengths include 5, 10, 20, 30, 40, 50 degrees, and many others in between. Generally, the adjustable focal length units are less efficient, heavier and more expensive than their fixed focal length counterparts. Some modern 'zoom' ER's however do perform very well and may indeed be the choice over comparable fixed focal length units.

ZOOM ER'S with adjustable focal lengths have been available since the 1970's. A typical fixture might provide spread angles of 12-35 degrees or 25-50 degrees. No single zoom fixture is available to provide a wide zoom range of say, 10-50 deg.


TYPE BEAM SPREADS WATTAGE DESCRIPTION
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Ellipsoidal 5-50 (fixed) 500-2000 ROUND beam, HARD edge,
Fixed f.l. with shutters & gobo slot
Beam or image can soften
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Ellipsoidal 15-35 (zoom) 500-2000 ROUND beam, HARD edge,
Zoom (typ.) 25-50 (zoom) with shutters & gobo slot
Beam or image can soften.
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INCLUDED: - (a) power cord, (b) four framing shutters, (c) template slot, (d) removable lens tube.

OPTIONS: - (a) lamp, (b) pipe clamp, (c) color frame, (d) electrical connector, (e) safety cable, (f) template holder, (g) iris, (h) lens safety mesh, (i) special accessories including gobo rotators and color wheels.