Intelligent Lighting Systems
Definition
Moving lights (moving heads) add motorised control of a beam's position, colour and shape. They fall into three main families. Spots carry gobos, an iris and a focus system, and project sharp beams and shapes. Washes give wide, soft colour coverage. Beam fixtures produce a narrow, dense shaft of light, often used for aerial effects through haze. Pan commonly covers about 540 degrees and tilt roughly 230 to 270 degrees, depending on the model (the Martin MAC Aura, for example, is specified at 540 degrees of pan and 232 degrees of tilt), so a single well-placed fixture can reach a large part of a stage.
The guide
Each function needs control channels. A wash such as the MAC Aura uses 14 or 25 DMX channels depending on its mode, and feature-rich spots use more, because pan, tilt, colour, gobos, prism, focus, zoom and shutter each need their own channels and 16-bit parameters use two. Universes are therefore planned before patching. Each fixture also needs a unique DMX start address and a stable power supply.
At power-up, moving lights perform a homing sequence: the motors drive to reference positions so that the fixture and the console agree on where it points. A fixture that fails to home, or loses its calibration during a show, points to the wrong place until it is reset. The usual failure points are addressing conflicts between fixtures that share an address, loss of the control signal, after which many fixtures hold their last state, and a mechanical pan or tilt limit reached in the middle of a move.
The rule
Every fixture has a unique, verified DMX address before the rig is powered.
Glossary terms
Sources
- Martin Lighting, MAC Aura : pan 540°, tilt 232°, 14 ou 25 canaux DMX, RDM · martin.com
- Intelligent lighting (Wikipédia, pointeur secondaire) : familles de projecteurs asservis, pan et tilt · en.wikipedia.org
- ANSI E1.11-2008 (R2018), ESTA : DMX512-A, adresses de départ et slots · tsp.esta.org