Filament fade

In stage lighting, filament fade refers to the lag time between when the electricity is removed from an incandescent lamp and when the lamp cools to the point where it emits no light. While this occurs in incandescent bulbs regardless of the application, it is of interest in stage lighting due to the stringent timing requirements involved.

The exact length of the filament fade depends on the instruments and lamps in use. Hotter, brighter lamps generally will take longer to fade than cooler, lower power lamps. In most cases, the fade will last a small fraction of a second.

Depending on the desires of the lighting designer, filament fade may be helpful or hindering. If the lighting designer wants to generate an instant blackout, he will need to take precautions to ensure that the filament fade does not ruin the effect, such as lighting the stage with more instruments running at lower power rather than fewer instruments running at full power. However, some lighting designers will use the fade to provide a very short but noticeable fade out of the lights that may be difficult to achieve through other methods.