Automated lighting fixtures are changing with the introduction of LED technologies. One of the biggest changes is the control of multiple elements with similar control parameters. These multi-part fixtures can be anything from a tilting 12-cell strip light to a moving head with a segmented ring of LED, or even a grid of pixels attached to a moving yoke. Since lighting consoles do not work well with multiple identical parameters in a single fixture, programmers must learn to work with these multi-part fixtures in other ways. Luckily, many desks have implemented multi-part fixture systems and tools to assist.
A Great Example
Let’s say you have 12 new spot fixtures. Each has typical parameters such as pan/tilt, gobo, zoom, focus, RGB color mixing, and more. Plus there is a ring of LEDs around the lens separated into four segments of individual RGB control. While you could make a single fixture library that has all the parameters, you would then have to create unique identifiers for each Red, Green, and Blue color portion. It would then be impossible to share palettes/presets and copy data; plus it would be difficult to select all those individual color items.
Instead, it is better to break the fixture into four segments of control. The first would be the primary functions (pan/tilt, gobo, focus, zoom, RGB color). Then four identical sections each with RGB controls. Now you can use your RGB palettes/presets on any of these sections, copy between them, group by location, and much more.
The Desk to the Rescue
Many automated lighting consoles provide a great tool to assist with multi-part fixtures. Typically, it is called multi-part, sub-fixtures, segmented, or something else similar. In this case, the console manufacturer has provided a means of breaking a single fixture library into segments. Nearly all do this through use of a decimal within the fixture numbering. So continuing with our example above, you could simply patch a fixture as number 8, but it would also contain 8.1, 8.2, 8.3, and 8.4. Selecting fixture 8 only will select the standard bits (pan/tilt, gobo, focus, zoom, RGB color), while selecting any of the others will select each of the four RGB segments. This makes for a very quick and easy method of working with a multi-part fixture.
It is very important to note that every console manufacturer handles these systems slightly differently. Some will allow the full number (8) to select a portion with the decimal sections being the other segments. Others will make the full number (8) represent all parameters at the same time. For instance, if you select 8 and adjust the red channel, it will apply to the main color AND the four segments. In this format, the fixture library would behave as 8 being the combined library, 8.1 the main portions (pan/tilt, gobo, focus, zoom, RGB color), then 8.2, 8.3, 8.4, and 8.5 acting as the four RGB segments.
As you can see in Fig. 1, there is a different philosophy in how the multi-part is segmented and thus it is important that you understand how your console is going to split up the various parts of a fixture library before you begin programming. Furthermore, different desks respond differently to the use of the “thru” command in regards to multi-part fixtures. Some will allow you to select 1.1 thru 8.1 and only grab all the “.1” segments. Other consoles may just select all fixtures and segments within the range. Be sure to check how your console behaves, and read up on any options or shortcuts you can enable.
Layouts, Plots and Magic Sheets
The use of a screen on the console to represent actual fixture positioning has become very popular and is commonly referred to as a layout, plot, or magic sheet view. Alas, I have yet to see one that handles multi-part fixtures very well. Instead, these systems will provide you a graphic for each instance within your multi-part fixture and leave the organization up to you. While this works well for a strip light, it is not very helpful with many other types of fixtures. For instance, in the example above, with 12 fixtures, you would need to display 12 instances, each with five segments. That requires a lot of screen space and real estate. The problem multiplies with more complex grid-type fixtures too.
Ideally, the layout/magic sheet view would automatically include a true representation of the actual physical orientation of the various segments. In this manner, you could simply add in a fixture and it would include its sub-parts in perfect positioning matching the real world portions of the fixture.
Multi-Part Programming
When working with multi-part fixtures, it is best to take the time to build various related groups. I always build groups that include all fixtures organized by segments. This means all of the whole numbers (1-12), then all of the first segments (1.1, 2.1, 3.1…), then the next segment (1.2, 2.2, 3.2…), and so on. Being able to quickly select a group of all the top segments of the LED ring is a great tool. I will even place these groups on my layout/magic sheet views.
Consoles usually have tools such as buddying, wings, grouping, matrix, or other functions to easily segment fixture selections. For instance, you could use a tool to select every third segment through a range of fixtures. Alternately, you might want to chase between the four RGB segments on all your fixtures individually, but in a synchronized way. By selecting the proper groups and then applying buddying or wings, you can quickly apply an effect between every four RGB segments across 12 fixtures.
”I Don’t Have That!”
If your console does not provide a method of working with multi-part fixtures, then you are not out of luck. You can simply create multiple fixture types with creative numbering to allow you a similar level of control. Going back to our example of 12 fixtures, each with four additional RGB segments, for each “fixture,” you would need to add in one main fixture and four RGB fixtures. You could then number them as 3010 through 3124. Each of the four digits in the fixture number identifies what you are selecting. For example, for “fixture” number 10 you would number it with the main portion as 3010 and 3011, 3012, 3013, and 3014 as the RGB fixtures.
The first digit in the numbers (3) represents the fixture type, the next two digits are the fixture number (01-12), and the last digit the segment (1-4). Now if you want to select fixture number 10’s four RGB segments you would grab 3101 through 3104. (It probably sounds confusing reading it on this PLSN page, but trust me, it makes sense on the console.)
Part It Out
Multi-part fixture functionality is an extremely useful tool available to lighting programmers. Anytime you have a complex fixture that has multiple identical sections, you are going to want to make use of your console’s multi-part features.
Make sure you understand how to select and patch these fixtures, as well as building groups and layout/plot views. I am sure that the consoles will continue to evolve to better handle these fixtures, so be sure to read up on new features as they are added. Plus, check your console user manual to see exactly which types of multi-part fixture functions are available and useful for your next show.
