Gobo Control

Individual moving light manufacturers' implementation of gobo control is frustratingly inconsistent. There are so many things these modern machines allow us to do, but there has never been a consistent method of describing what they do. Natural Language Control attempts to pull in the reins and consolidate on a common language of control.


The assembly that holds the entire gobo selection is called the Wheel. Wheels can Spin Forward or Reverse in Revolutions per Minute (RPMs) or can Select individual Gobos. Gobos can be Indexed in Degrees like hands on a compass or Rotated continuously Clockwise or Counterclockwise again at a specific RPM.




Different manufacturers use a variety of control channels to achieve all of these possible behaviors. Some use lots of channels which surprisingly makes the control of the gobo wheel easier, and other insist on bunching up behaviors on only a couple of channels. The examples below are generic and are only used to show how it could be done using linear DMX512 channels compared with how it's handled using Natural Language Control.


The first of the pair of these linear channels is used to position the wheel and select a specific gobo and do one of two things with it; either Index it or Rotate it. The second channel changes modes based on the position of the first. Here the first channel is set to about 10% and Selects the Dots gobo for Indexing. The second channel is set to about 10% which indexes the gobo 15°.


Remember, the fader doesn't show you these options as selections - you need to know them in advance!  In contrast, Choreo's display shows Gobo 1 Wheel Mode (top left), Gobo Select (bottom left), Gobo Mode (top right) and Gobo Index (bottom right). And, as well as showing "Dots" as the current selection, you can see that moving one 'tick' forward would give you "Pinwheel" and one tick backwards would give you "Open":




To rotate the Dots gobo continuously in the clockwise direction, the first handle must be placed at 60%. That changes the mode of the second handle and the 10% position is now meaningless. To see a rotation of 4 RPM clockwise, the channel must be set to 30%. (Where that value comes from is completely arbitrary. Truthfully, you would never get a answer even if you were to visit the factory and ask the firmware engineers!)


The same information is shown on Choreo's display like this:




Changing the direction of the rotation on a DMX based system means you must travel the second handle through a bunch of values that are of no interest to you. The gobo would slow down, then stop, then change direction and speed up again as you adjust the control channel. This can be very disconcerting for a designer who is watching the stage. None of those behaviors were asked for, but were necessary to reach the desired result.


With Choreo , you just nudge the g1 Mode control one tick to change the value from Rot CW to Rot CCW. The g1 Speed attribute, which controls the speed, is not changed. The DMX values will jump from the value for clockwise rotation at 4 RPM directly to the counterclockwise 4 RPM value (whatever that is).


Again, this is how it looks on Choreo's display when programming:



Next: Conditional Abstract Attributes