2008

Hotspot/Falloff
Hotspot and falloff cones, highlighted in red.
You've seen how a flashlight or a theater follow spot casts a circle of light.
Depending on the quality of the flashlight, or the adjustment of the follow
spot, the edge of the cast pool of light is either blurred or sharp.
In the case of a blurred pool of light, the bright circle in the center is the
hotspot, which has an even intensity. The outer extremity of the light, where
it meets the darkness, is the falloff. The difference in circumference between
the hotspot and the falloff determines the relative sharpness of the pool of
light. For example, if the hotspot and falloff are nearly the same size, the pool
of light has a sharp edge.
The hotspot angle of a spotlight must always be smaller than the falloff angle.
Put another way, the hotspot must always be inside the falloff.
You can hold down the Shift key to have the hotspot and falloff values affect
each other. If you increase the hotspot to be larger than the falloff, the falloff
is increased as well. Likewise, if you reduce the falloff to be smaller than the
hotspot, the hotspot is also reduced.
Glossary | 7811