Frequently asked questions
What is a lighting plot (LX plot)?
A lighting plot is a scaled overhead drawing of a stage or venue that shows where every lantern hangs, on which bar or truss, and how it is rigged. Each fixture carries paperwork such as its channel number, DMX address, universe, dimmer, purpose and gel colour, so the crew can rig, patch and focus the rig accurately. It is the master reference document that ties the design, the patch and the focus together for a show.
What is the difference between a channel, a DMX address and a dimmer number?
A channel is the control number the operator uses at the desk, so 'Channel 12' is the handle you bring up on a fader or in a cue. A DMX address is the starting slot on a 512-slot universe that physically tells a fixture where to listen, and a moving light can occupy 20 or more consecutive addresses. A dimmer (or circuit) number identifies the power channel a conventional lantern is plugged into, which the patch then maps to a control channel.
How many DMX channels fit in one universe, and when do I need a second one?
One DMX universe carries 512 channels, so once your fixtures' combined channel footprint passes 512 you need a second universe. As a rough guide, a single moving light in extended mode can eat 30 or more channels, so even 16 movers can fill a universe on their own. Simple dimmer rigs and basic LED PARs use far fewer channels each, so they pack many more fixtures per universe.
What scale should I draw a lighting plot at?
Theatre and event lighting plots are normally drawn at 1:25 or 1:50, with 1:50 suiting larger venues and 1:25 giving more detail for tight focus areas. Pick the scale that lets the whole stage and rig fit on your chosen sheet size, typically A3 or A2 for a portable plot or A1 for a full design. Always print the scale and sheet size in the title block so anyone reading the plot can measure off it correctly.
What do the centre line, plaster line and proscenium line mean on a plot?
The centre line runs up and down the middle of the stage and is the left-right zero reference, with positions called out as so many metres stage left or stage right. The plaster line is the architectural face of the proscenium opening and serves as the upstage-downstage zero, while the setting line is a working line set just downstage of it. Measuring every fixture and scenic element from these reference lines keeps the plot consistent and lets the rig be marked out accurately on the deck.