The following is an excerpt from a resource paper written by John Crawford.
For AVL purposes, “Lighting Systems” generally encompass any stage lighting, special effects lighting, or house/building lighting that can be controlled using the primary lighting controller which is usually located in a control booth.
Sometimes these systems are under the purview of the Electrical Contractor and AVL wants to grab control of them, and sometimes they are under the AVL umbrella start to finish. For planning purposes make sure that the AVL contractor and the Electrical Contractor are not providing equipment or lighting that is redundant or duplicated. Even the most basic of lighting systems should be reviewed by the AVL Designer/Contractor since simple things like how lights are zoned/grouped, where controls are located, how the system can be expanded or controlled later, and similar low tech but important items can have a significant impact on the overall end result as well as future use options.
Some lighting fixtures can be heavy. Don’t neglect the weight calculations when planning lighting systems as they may have a big influence on what is needed in terms of rigging and structure.
Don’t let the idea that the fixtures are LED lull you into thinking lighting won’t need much power. LED fixture power is going up every year and many stage LED fixtures are now north of 200W/fixture. They aren’t as power hungry as incandescent lights are…yet.
Even basic LED fixtures are capable of using a high number of control (DMX) channels. Pay close attention to how many channels you will need or you may find out that you don’t have enough to control them the way you want.
Most lighting fixtures provide information on beam and field angles. The “beam angle” is the cone of light in which the intensity does not fall below 50% of the maximum put out by the fixture. The “field angle” is the wider cone of light in which the intensity does not drop below 10% of the maximum put out by the fixture.
Common lighting fixture types:
Wash type fixtures (flood lights)
Short to medium throw, soft focus or no focus. The vast majority of wash fixtures are LED now as there is very little benefit to using other types for this application.
LED wash fixtures generally provide some or all of the following features:
- They are self dimming with a DMX control signal which means they plug into regular non-dimmed line power.
- They can mix colors and/or provide different color temperatures of white light.
- They can pulse or strobe.
- They can respond with built in light show programs to a sound signal via a built in microphone. This automated light show function can link with other fixtures of the same type for synchronized action.
- There is no lamp to replace.
Non-LED wash fixtures generally require an external dimmer channel or dimmer pack to allow control via DMX. Colors are possible through the use of colored gel filters or gel scrollers. Strobing or flashing may be possible via dimmer pack control; however, many have lamps that dim to zero too slowly to be effective strobes. Non-LED wash fixtures get hot and present a fire and burning hazard if touched to flesh or flammable materials.
In general wash fixtures are the lowest cost options. These fixtures are generally used on lighting bars as front lights, down lights, side lights, and specials; and these fixtures are also often used on the floor as up lights and foot lights. You may get the idea from this that they are pretty flexible and a great general purpose light which means that if you can only budget for a few fixtures these are the kinds you will probably want to get. This category includes par type lights, blinders, Fresnels, scoops, strips/bars, and cyc type lights.
Ellipsoidal type fixtures (spot lights)
These are lights that use a reflector (incandescent and HMI) or a collimated light engine (LED) as well as a lens to provide a focused beam of light. These can be soft focus or very hard edge focused beams. The size of the beam can vary significantly depending on the angle of the lens that is used with a common model providing options from 5° to 90°. Some common fixtures offer variable zoom lenses and/or the option to remove/replace a lens with the specific angle desired. These are commonly incandescent as there are significant technical challenges with providing collimated light output from LEDS.
“Significant challenges” = way more expensive. These fixtures will typically require a separate electrical dimmer. These fixtures generally can be shuttered with metal plates (included with the fixture) to allow areas within the beam of light to be blocked to accommodate things like video screens or other areas and objects that need to remain unlit even though they are next to an area that must be lit. These fixtures are generally larger because of the lenses that attach. The lenses typically get large for very small (5°) beam angles. Some lenses are variable zoom.
Remember that smaller angle = smaller circle of light, so if you want long throw go with a small angle lens. These fixtures are generally only able to mount to a bar or truss, so if you want to use them on the ground you’ll need a special base for them to attach to. Moreover since they are commonly incandescent be very careful about who and what can access/touch them on the ground as they get very hot.
“Movers” and “Scanners” (robotic lights)
In the pictures above from left to right are a moving LED wash fixture, a moving HMI spot fixture, an LED scanner, and a projection based moving head fixture. These are fixtures that have the ability to move the beam(s) of light they produce. They generally fall into the two primary categories of “movers” which some significant part of the fixture physically moves like the reverse of a pan-tilt-zoom camera and “scanners” where a motor controlled mirror pivots and tilts in order to move the beam of light.
All robotic lights generally have all or some of the following characteristics which are controlled remotely over a control link (usually DMX):
- They are self dimming.
- They can change colors and/or mix colors.
- They can strobe and/or pulse.
- They can change zoom and focus.
- They can project patterns (gobos) and some or all of these patterns can rotate.
- They can project a video image.
- They can split the beam with a prism.
- They can soften the beam with frost.
- They can adjust color temperature with a color filter.
- They can move the light horizontally and vertically.
- The can iris and/or shutter the beam.
- They can respond with built in light show programs to a sound signal via a built in microphone. This automated light show function can link with other fixtures of the same type for synchronized action.
Movers generally have the following characteristics:
- These types of fixtures have a range of motion from 360°+ horizontally to about 270° vertically.
- The part that produces the light is usually contained within a motorized base that controls the motion. The light part may or may not stay within the footprint of the base, so it may be important to make sure that it is positioned in such a way that it cannot move and touch something like structure or another light fixture in a way that would damage the fixture or the object it touches.
- The motion can have physical consequences on the structure that it mounts to including resonant movement (swinging), vibrating, and dynamic loads. These are generally not significant; however, there are instances where it can be a concern. If a camera or projector is mounted to the same structure (usually something like a hanging bar or truss) the motion of the light may affect the quality/stability of the image captured/projected. Moreover, many of these fixtures operating in concert can create significantly higher forces on the support structure than might otherwise be anticipated. Structure provided may require additional bracing to minimize sympathetic motion and should employ higher safety factors to accommodate the dynamic loads.
- Movers are at home on the ground or mounted to a truss or bar as the motorized base is a stable platform when sitting on the ground. That said they can get hot, and you should pay attention to who/what can touch them.
- Movers are generally incandescent, HMI, or LED although incandescent versions are becoming less prevalent.
- Movers tend to use a bunch of DMX control channels, so be sure you are accounting for how many DMX channels you will need and where you will get them from.
- Movers can be a wash, spot, and a beam fixture although most are one or the other. Note a “beam” fixture is a spot fixture with a very narrow spot on the order of 2° to 5° wide.
Scanners generally have the following characteristics:
- These types of fixtures have a range of motion from about 180° horizontally to about 120° vertically. This limited range of motion makes scanners ideally suited to positions up against a boundary where 360° motion would be unnecessary.
- Mirrors can move much faster than the entire body of the light, so scanners can move the light they create very fast. In some cases this can be fast enough to create images and/or text with the beam. In either case it is way faster than what a mover can do.
- Scanners are generally much less expensive than movers as it requires less hardware to move a mirror than the entire light.
- Scanners are at home on a truss or bar, but they generally require a mount/base to use effectively on the ground although there are many versions made to sit on the floor using built in feet.
- Scanners are generally lower end fixtures than movers although there are some significant exceptions.
This category is something of a catch-all for most everything else and there is significant overlap to the other categories. The most common types are going to be DJ effects, lasers, strobes, beacons, and black lights. All of these effects can be found in the category of movers, but the fixtures in this category are going to be more single purpose type fixtures.
Haze and smoke
Haze and smoke generators are designed to provide a suspended medium to pick up light. This medium is generally intended to show the beam of light in the air, the motion of the light through the air, a haze of color, or something similar. This medium is generally designed to by hypo-allergenic and non-toxic along with non-staining and residue free.
These machines use a fluid (oil or water based) to create the fog/haze. It is super-important that you don’t mix these fluids. Oil and water are immiscible and will create epic clogs in your hazer if you mix them. Even though many hazers will operate with either oil or water based haze fluid, once you use one type you must stick with the same type unless you are willing to disassemble the hazer, clean it completely, and reassemble. Even then some oil-water mixture can get into the pump and create a clog that is not practical to fix.
Foggers use heat to create the medium and generally can output a stunning amount of fog for a short time frame, but then they need to heat back up before they can discharge more. Hazers put out a small but constant amount of haze by using a pressure/expansion cycle and can generally run indefinitely so long as they are refilled.
Foggers are silent when they are not running and generally put out a moderate hiss when they are discharging. Hazers sound like a little motor chugging when they are discharging, and they are generally quiet when they are not (fan noise only).
*Fire system considerations
Depending on the fire detection system haze and smoke can be a big issue. Laser particle detectors cannot distinguish between intentional fog and the smoke from a fire. If you plan to use fog/haze then careful attention needs to be paid to the fire-detection system to be sure that fog can be used. Ionized particle detectors are more forgiving of intentional fog/haze as it has been formulated to not trigger these systems easily.
Note! Many places have been built with the express intention of having moving lights and fog as part of the experience only to find out that their fire system is incompatible. Be sure to that this is addressed in planning!
For all fixtures:
- Don’t use cheap Chinese knock offs.
- Pay attention to UL since many of the lowest cost versions will NOT be UL. (This is also true for many of the supporting items like DMX converters and splitters—this can be a big pain to manage with strict jurisdictions.)
- Do have extras for spares if you use these for house lights. (It won’t be hard to find other lights to use as replacements, but the colors, coverage, channels, etc may be different which can be a big problem.)
- Watch out for fixtures that have cooling fans. It is less of a problem now than it was a few years ago; however, fixtures with fans typically make noise, the fans are the first things to die, and you will probably need an option for remote power on/off for those fixtures/circuits.
- Incandescent fixtures get very hot. Be sure there is adequate clearance from objects, walls, and your skin if you are handling them after they have been on for more than a few seconds.
Color Gamut, Color Temperature, Color Accuracy, and Color Consistency
Color Gamut is the range of possible colors a device can either capture or reproduce. For a light this would be the range of colors it can make. The more, different color emitters a light has the larger the color gamut it can produce. Generally speaking more is better and more is also more expensive.
Color Gamut For LEDs:
- RGB (basic) – Red/Green/Blue emitters give a wide range of colors but struggle mightily with deep colors, pastels, true white, and composite colors.
- RGBA (better) – Red/Green/Blue/Amber emitters give a wider range of colors but struggle with deep colors, pastels, and true white.
- RGBW (better)-- Red/Green/Blue/white emitters give a wider range of colors but struggle with deep colors, composite colors, and true white.
- RGBWA(best*) -- Red/Green/Blue/Amber/White emitters give a wider range of colors but struggle with deep colors, and true white. *Generally best for color as far as this list is concerned. There are special fixtures with special capabilities above and beyond these.
- CW/W/A (VW) (best*)—Cool White/Warm White/Amber emitters provide the ability to hit specific color temperatures of white light. This is especially useful for matching these fixtures to other white only fixtures (like incandescent fixtures) that don’t have the ability to change the temperature of the light they create. This is critical for video recordings where reproducing a natural skin tone is essential. *Generally best for white light and specific color temperatures as far as this list is concerned. There are special fixtures with special capabilities above and beyond these.
- Special – These fixtures provide a special range of light like UV, a deep color range of single color (like blue from light to very deep), a multi spectrum white, or some other very specific type of light.
Color Temperature is a measure of the redness or blueness of white light. It has a very scientific definition that relates the light to the temperature of an ideal source at a particular temperature, measured in degrees Kelvin. You don’t really need to know how it is calculated; however, it is useful to know that low color temperatures are redder and higher color temperatures are bluer.
More importantly it is important that any white light used inside a space have matching color temperatures. Camera color is dramatically affected by different color temperatures in the same shot. The human eye quickly notices when color temperatures are not consistent, even if the human brain often doesn’t know why it looks off, weird, and/or unnatural.
Color temperature in a lighting system can be matched by either:
- Using fixtures that have lamps at the same (or very nearly the same) color temperature.
- Using fixtures that have color correcting gels designed to modify the color they produce into the color that matches the fixtures that you are trying to match.
- Using variable white fixtures that can reproduce the color temperature you are targeting.
Color Accuracy is a measure of how close the color produced is to the color that is supposed to be produced by the fixture in question. Note this is not the same thing as Color Rendering Index (CRI) which is a measure of how well a light will reveal the colors in an object as compared to an ideal light source. Color accuracy can be a critical aspect or a non issue based on where and how the fixture is used. If the fixture is up lighting a ballroom wall for a wedding reception it is not generally a big deal. If it is providing light for a Broadway production it is a good bet that it is a really big deal. No big surprise that more expensive fixtures generally offer more accurate colors.
Color Consistency is a measure of how much deviation there is in color between multiple fixtures of the same type. Generally the better the fixture the more likely all of the fixtures of the same type will provide the correct color. Color Consistency can be a critical aspect or a non issue based on where and how the fixture is used. If the fixture is lighting a youth stage it may not be a big deal. If it is providing light for a broadcast television set it is a good bet that it is a really big deal. No big surprise that more expensive fixtures generally offer more consistent colors from a batch of fixtures. This can also be important between different fixtures of the same type or even different fixtures of different types. Many manufacturers provide several fixture types that use the same light engine so that they are consistent across that range of fixtures.
Zoning -- For all angles the stage should broken up into overlapping zones. Each zone should have fixtures specific to that zone for the angles described below. The size of each zone is determined by the distance and the angle of the light beam which is why fixtures are available in multiple beam angles. For example if the stage must be broken up into 8 zones then you would expect a minimum of 16 fixtures to supply the primary wash as described below.
The idea is that by zoning the stage the fixtures can be aimed and adjusted such that a person moving around on stage will be lit in a consistent and even way and will not step into areas where they are obviously darker or brighter than the others (unless you want them to be). In the picture below the stage has been broken up into 3 zones. Each zone is served by two fixtures. The left zone is served by fixtures 1 and 4. The middle zone is served by fixtures 2 and 5. The right zone is served by fixtures 3 and 6. If the person in the middle zone moves across the stage from middle to left he will be covered evenly.
The “I can see you wash” – primary wash. This is the light that allows the audience and cameras to see clearly without shadowing. Ideally this is positioned such that the talent on stage can also see the audience without being blinded by these lights.
The key points for this primary lighting are:
- The fixtures should be low – only 15° to 30° up.
- The fixtures should be wide—60° to either side.
Backlighting -- This is the light that provides the highlights on the top of the head, shoulders and arms that keep a person from looking flat and two-dimensional on stage. This is critical for cameras as a person without this light will look like they are flat with the background and the scene will have no depth.
The key points for this secondary lighting are:
- The fixtures should be high—60° up.
- The fixtures should be relatively narrow – 30° to either side or directly overhead if only one fixture is available.
High front lighting -- This is the light that should be used to set the tone of the stage. This can also cast intentionally dramatic shadows. Primary fixtures here are color wash and specials.
Side lighting -- This is light primarily to provide an outline for the body or fill when other options are not available. This is effective lighting for dancers or silhouetting.
So you’ve got all these fancy lights, now how do you make them do something useful?
DMX -- This is the most common and ubiquitous method for controlling stage lighting. DMX is made up of “universes” each with 512 channels. If you need more than 512 channels for your lighting system you’ll need more than one universe. Each universe needs its own cabling, so it should be planned as early as possible for built in systems.
Artnet -– This is a way to transmit DMX over a network backbone. For all intents and purposes you have unlimited channels with Art-Net although you still may have to work to manage them outside of the Art-Net network.
Microplex -– This is an older standard of lighting control that was often used for simple lighting systems. It doesn’t interface well with other types of systems, and generally you’ll only see them now in venues where they existed before and it wasn’t possible to replace it. Stay away from Microplex for any new systems.
Software vs Hardware controllers
Control is provided primarily through two different types of controllers: hardware and software based controllers.Dedicated hardware controllers (consoles/light boards) have dedicated hardware and are stand alone solutions. They may have multiple add-on options like extra control surfaces and/or screens. They are generally very expensive compared to the software options.
Software controllers require a computer to host them and (usually) interface hardware to provide the outputs necessary for them to connect to the lighting system. They may also have one or more control surfaces that emulate the behavior and interface of a hardware based controller. They are by far the most cost effective and powerful for the price, but they are subject to the vagaries and peccadilloes of the computer that it is installed on. Note unwished-for driver updates are the bane of lighting control software. Be sure that any computer running lighting control software is not connected to the internet or you may find it doesn’t work one morning when it should because the new driver is no longer compatible with the output interface.
Entry Stations -- This is the way you allow all of your lighting to be controlled by a simple switch at the door. House and stage lighting can all be included in the “walk in and turn on the lights” action that is provided by an entry station. Entry stations can be simple on/off type switches or fancier multi-button or multi-slider stations. Without a good reason to the contrary keep the entry stations simple and the main controller as fancy as you need. This accommodates regular people who just want to turn on the lights to vacuum carpet or something similar without requiring them to know anything about the bigger control system or access the area it lives in.
0-10V – This is a nearly ubiquitous way that commercial lighting systems are controlled, and since any stage type lighting system will want to have control over ALL fixtures in the areas controlled, a way to control these fixtures is also necessary. 0-10V control works by reducing the output of the light fixture in accordance with the voltage it sees on its control wires. 10V equates to full bright and 0V equates to full dim. Herein lies the rub: full dim is not off. 0-10V fixtures require the power to be physically cut off in order to turn off. A simple DMX to 0-10V interface will not provide this hard shut off, so an additional remote relay (also controlled by DMX) will be necessary to get the lights to shut off entirely. Moreover, there is a dearth of DMX to 0-10V interfaces that have a UL listing. This can be a real issue in some jurisdictions, so have that conversation in planning the overall lighting system with the EC and EE (electrical engineer).
House Lighting – This is a term describing the general purpose lights in a venue, usually over the audience area but sometimes throughout all areas. These lights are usually for general purpose illumination, but with the advent of color changing LEDs have become part of the overall lighting plan that is tied into the stage lights both on the control side as well as being an integral part of the lighting presentation.
For AVL purposes only specialized LED fixtures tend to be in the AVL scope. Normal commercial type fixtures, LED or otherwise, tend to fall in the ECs scope of work. When providing house lighting fixtures it is important to be sure that they provide adequate general purpose lighting (usually measured in foot candles) and that they provide that light evenly over the areas required. These fixtures may play a role in the performance aspects, but they must do the job of lighting up the room first.
LED fixtures are susceptible to high ambient temperatures. Don’t assume that they will work in areas that are not heated/cooled like when they are recessed into a hot attic space. Most LED fixtures must be used as pendants if the space beyond the ceiling is hot. Just because these fixtures are supposed to last for a long time doesn’t mean they will. You don’t need spare bulbs; you need to have a couple spare fixtures. Finding an exact replacement later may be problematic as the models change quickly. House lights generally have a large number of fixtures, so don’t neglect the need to provide adequate control channels. Ensure the fixtures you use don’t have fans. Maintenance issues with fans aside, a room full of small relatively quiet fans will still be pretty loud with fan noise.
Emergency lighting is designed to kick in during a power outage, fire, or other designated scenario. As such it is subject to numerous building code requirements and dedicated inspections. When an AVL system captures the overall house lighting system it is important to ensure that emergency lighting requirements are being met since in more traditional situations some or all of the house lights will be part of the emergency lighting system. Be sure that the EE, EC, and Owner are aware that the AVL house lighting operates in regards to the emergency lighting system.
Avixa/Infocomm (Extensive catalog of training courses)
Obsidian Lighting Control Software