Dimmer Curve / Law
Definition
A dimmer curve, or dimming law, is the relationship between the control value sent to a dimmer or fixture (0 to 100%) and the light output. With a linear law, output is proportional to the control value. With a square law, output follows the square of the control value, which gives finer control at low levels and compensates for the non-linear way the eye perceives brightness. Many dimmers and LED fixtures offer a choice of curves. A curve that does not suit the source produces an abrupt start at the bottom of the fader travel or a dead zone at the top.
In the field
When an LED fixture jumps on at 1 or 2% instead of fading in smoothly, one possible cause is a mismatch between the curve set in the dimmer or console and the one set in the fixture, for example linear on one side and square law on the other. The curve is then changed in the dimmer, console or fixture settings.
Related lessons
Sources
- Electrical Contractor, Ahead of the dimming curve : loi quadratique (square law) et perception non linéaire de la luminosité · ecmag.com