A Process for Designing Lighting for the Stage: Determining Lighting Areas (Part 4)

When the designer considers the lighting areas, he or she must consider the shape of the lighting area.  Up until this point, I have described the lighting area by diameter as if the lighting area was the shape of a circle.

Inaccurate depiction of circle-shaped lighting area

In fact, the lighting area from a single fixture, is seldom precisely circular in shape.  Consider that only if the fixture is positioned at a 90 degree angle to the plane which that beam it to strike will the resultant pool of light be circular.  Once that angle becomes shallower than 90 degrees, the resulting shape of the beam will assume an elongated elliptical shape.

Accurate depiction of elliptical shape of lighting area

To the right is a more accurate depiction of the elliptical shape of the lighting beam generated by the  Source Four 19-degree fixture with a 37′-8″ beam throw serving as a 45 degree SL Frontlight to the lighting area.   Also, recognize that a different fixture from a different position would create a different elliptical shape.

Below is the illustration of the beam that results from an instrument at a lower angle and slightly different axis.  This might be a light into this area described as “Low Angle Warm Reflected Sunlight” in the preliminary lighting key.

Elliptical lighting area from a lower angle

Note that the light fixture from this position is switched to a 14 degree fixture. This choice is because the throw distance is appreciably longer at 41′ and because the angle is much shallower.  Next time I will explore an alternate way to estimate throw distance and elaborate on the choice of a narrower-angle fixture for this axis.

That’s enough for now! Have fun!  Be safe!

SJM

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