I saw this well-written, informative article by Mr. Sayer here.
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Pro Production: A Guide To LED Stage Lighting
Mar. 28, 2013, by Rob Sayer
The market in LED based lighting fixtures has possibly seen the biggest growth area in the stage lighting industry in recent years. All of the major stage lighting manufacturer have dived into the LED market while cheap imported lights mean that every church, small band or DJ can get a slice of the action too.
Rental companies are now expected to stock a wide range of LED units alongside their tungsten conventionals and discharge moving lights and the technology is developing rapidly. If you are new to using LED lighting or are thinking of adding LED to your inventory, we present a guide to LED stage lighting.
What’s so exciting about LEDs?
LED (Light Emitting Diode) technology has now developed to become a usable source of light in live performance and recorded media. LED fixtures have some advantages over ‘old’ tungsten based instruments and are particularly attractive to the events and concerts market right now. Manufacturers specializing in theatre and television equipment are also developing more sophisticated LED based fixtures to answer the needs of those shows too.
Let’s have a look at what lighting folks like about LEDs.
- Low Power Consumption – Because LEDs draw a comparatively small amount of power, you can use a lot of fixtures on smaller supply such as a wall socket. This is great for small band lighting rigs and the disco/party DJ. Bearing in mind that 20 years ago we were still working with large rigs of PAR cans, there are also benefits of low(er) power requirements for the large show too.
- Low Heat – Although LED stage lighting does produce heat, fixtures produce light without getting extremely hot as with their tungsten or discharge counterparts. In some environments, the lower heat properties of LED stage lighting are very desirable.
- Lightweight and Portable – The hardware that LED fixtures are packaged in does not need to be heavy and even with the various power supplies and other elements, LED units are usually fairly lightweight. To make them even more portable, LED units can be more readily powered by battery and several products boast battery power and wireless control via DMX over WiFi. This creates a lighting product that you can place and control quickly with no messy wires and a minimum of fuss.
- Color Effects – A common use of LED for stage lighting purposes is additively mixing a combination of different colored LEDs. A fixture with all three lighting primary colors, Red, Green and Blue (RGB) LEDs blended together in different combinations gives the lighting designer easy access to many color choices in one fixture. More complex LED color mixing fixtures use additional sources such as RGBA (Amber), RGBW (White) or more such as with the ETC Selador 7 color range of LEDs. The color functionality of all these fixtures does away with creating color subtractively using gel filters completely.
- Small and Compact – LED lighting fixtures can be made in small, discreet packages which suit applications where size and appearance are important such as exhibitions stands.
- High Brightness – Looking at Low Power from the other end, this is the ratio of light brightness to power consumption. Often advertised as Lumens Per Watt, high-powered LEDs are very bright considering the amount of electrical power they use. The “additive” color mixing mentioned above means that light produced is not wasted being filtered out.
- Longevity. LED lighting manufacturers often quote the number of hours an LED light source will last in comparison to sources such as traditional tungsten halogen lamps. And we are talking tens of thousands of hours for an LED.
- Built-In Dimmer. Most LED units offer dimming built inside the fixture, so there is no need to have a separate dimmer rack. In addition, many have onboard controls that allow setting the unit to a color, dimming the fixture, or even cycling or scrolling through different looks, all without the need for a separate controller.
So, LEDs are the answer to everything now?
Not yet. There are a few things you might want to know about LED stage lighting, before you go out and buy a truck full.
- Many LED arrays can’t provide a point source like a conventional. Because there are many sources of light in the LED array, it is harder to create a LED fixture that will focus like sharp spotlight or project a gobo. Manufacturers have worked their magic on this, creating a point source with optical systems or by using a single, bright LED source. Recent developments have been in the introduction of hard edged spots such as the ETC LED Source Four but still, many LED units are designed to be washlights.
- 16 Million Colors. Just not the one you want. Because of the way colored LEDs are made, different LED fixtures have colors that they just can’t do. A good quality white light that looks great on human skin is often cited as being one of them. Because of the way that all LED source colors are mixed together and the way LEDs are made, a nice white light is extremely difficult to achieve with many fixtures. LED lights that are designed to be white light sources often lack the range of spectral colours of daylight or an incandescent.
- LED lighting fixtures are bright but … Although when considering power consumed for brightness LED stage lighting fixtures are really efficient, many units lack the punch of their conventional lantern relatives. A cheap PAR can with LEDs in it is nowhere near as punchy as a 1000W PAR64 CP62. Cheaper LED lighting units have neither a lens nor a reflector, the light they produce scatters and struggles to maintain intensity when thrown much of a distance. However, great strides have been made regarding the optics in the last few years and the top LED fixtures really blast out some light.
- Color Mixing And Shadows. Colored LEDs mix on a surface to create an even light, this mix improves further away from the light source. If there is much distance between the colors, the end result is multi-colored shadows that don’t get with a single-colored conventional. The latest professional and more costly LED optical systems are better at reducing these issues.
- Dimming Issues. Because LEDs don’t use traditional AC powered dimming systems, LED based stage lights don’t behave the same as traditional lighting equipment when it comes to dimming. Cheaper units can have poor or steppy dimming curves and there is the real possibility of high frequency flicker when used with cameras. At some point in the dimming curve, LEDs can snap to blackout unlike the cooling down of an incandescent filament. Although high end LED fixtures can attempt to replicate it, LEDs also don’t naturally shift in colour like a tungsten source does over it’s dimming range.
- You get what you pay for. All LED stage lighting fixtures are not the same. Even though you can buy them cheap doesn’t mean that you should and all of the above points are more apparent in cheap LED lighting fixtures. A good quality lighting manufacturer will always be more expensive but you can expect the quality of the light to be superior. If you want good colors, beam quality and optics, you must be prepared to pay for them.
Before you throw your rig of conventionals in the trash, be aware that there are serious and often complex reasons why LEDs are currently not a cure-all in stage lighting right now. These caveats encompass colour rendition, fixture life, dimming, optics and even environmental questions. Lighting designers have their reasons for choosing LEDs, along with reasons why they continue to specify other light sources.
What can I get from LED?
The color mixing capabilities of the LED fixture is often a key selling point. They come in different forms such as the lighting batten, a long strip with an array of colored LEDs or in a compact, circular array that produces a beam of light, similar to a conventional PAR can or a Floodlight. The batten are useful for lighting up flat areas, such as a wall or backcloth, while the PAR/Flood fixtures will give you a beam of light, similar to their conventional stage lighting relatives.
Moving light technology has also joined the LED fun with arrays being packaged in all shapes and sizes of waggly fixture goodness. There was also a passing fashion for the LEDs in a large, screen-like array which can be used to show colors, patterns and moving images like a low-resolution jumbo screen.
The most modern developments in LED lighting for theatre use include colour mixing Fresnels and lekos such as the ETC Source Four LED ranges. However, not all LED based units are designed to give multiple colors and manufacturers offer different versions of White only sources in a range of color temperatures commonly known as Cool White and Warm White. These fixtures can take templates and be controlled with lenses and shutters just alike an ellipsoidal reflector spot but while the White is not bad, they aren’t going to match up with your regular tungsten units.
How do I control my LED lighting?
Stage lighting systems are commonly controlled using the standard DMX512 protocol, and LED fixtures are no exception. Different DMX channels control the Red, Green, Blue or other colors while other channels may deal with overall intensity or special chases and effects.
If you don’t have a DMX lighting controller, many LED stage lighting units can be used in “stand alone” mode or can have control locally, using a local controller/power supply that enable you to change the color and run simple effects and leave them to it.
Do LEDs replace other sources?
While having their faults and limitations, DMX-controlled LED lighting fixtures are an important and welcome development in the technology of stage and theatre lighting. The rate of change means that it would be foolish to try to pinpoint if or when LEDs would replace other sources, even if we wanted them to.
If you are using or buying LED-based stage lighting fixtures, you should familiarize yourself with their limitations along with their benefits. We can look at those limitations in a future article but for now, enjoy the possibilities of LED in stage lighting—and don’t junk all your incandescent or discharge source equipment just yet. Rob Sayer is a Lighting Designer and Moving Light Programmer based in the UK with over 20 years of industry experience in a wide range of performance genres. He is currently Senior Lecturer in Technical Theatre Production at Bath Spa University and is also Editor of On Stage Lighting.
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