PURPOSE: To illustrate how Fresnel lenses are used in theatre spotlights.
DESCRIPTION: The lens of this spotlight has a very short focal length, yet is quite thin and light because it is a Fresnel lens. The bulb in the spotlight can be moved along the optic axis to change the size of the area lit by the spotlight.
SUGGESTIONS: This rolling spotlight is also useful in lighting demonstrations for TV.
REFERENCES: (PIRA unknown.)
EQUIPMENT: Fresnel spotlight on rolling stand.
SETUP TIME: None.
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