The PLANO-CONVEX (or PC) spotlight is
the earliest form of theatre spotlight,
to use a lens. It consists of a simple
'box' housing containing a lamp and reflector
behind a plano-convex lens. Modern units
range from 300 to 2000 watts. Lens diameters
include 5", 6" and 8" wide.
Beam spreads typically are variable from
approximately 10 to 65 degrees in a single
This fixture provides a circular beam
pattern with a sharply defined 'hard'
outer edge. Unfortunately, the field of
light, (distribution of light across the
beam) is often quite uneven. Further,
optical aberrations in the form of rainbow
effects, are often seen at the edges of
The lamp and reflector are mounted together,
and move forward or backwards, in relations
to the lens. As they move closer to the
lens, the beam expands in size. As they
move away from the lens, the beam becomes
Plano-convex spotlights are useful in
providing ACTING AREA lighting and localized
lighting to specific areas of the stage.
They have no beam controls (shutters,
iris, barndoors) available.