As we enter this second decade of this new century energy consumption is a very real concern. Lighting Designers now have viable tools to help in the effort to reduce our consumption. Lighting has long been an area where the amount of lumens generated has been a very low percentage of the power provided. The incandescent lamp is one of the most inefficient light sources on the market. This decade we will see the switch from incandescent to LED for almost every lighting need.
I recently had the chance to test out a fixture from Altman Lighting, the Spectra Cyc 100. This fixture is designed as a wash fixture for large areas of either a wall or in the theater, a Cyclorama drop.
If you are familiar with any LED wall wash fixtures, the typical fixture consists of a long rectangular shape with rows of LED’s with a mixture of Red, Green, and Blue colors. In order to cover a wall from top to bottom they use a Lenticular spread lens to focus the light across more vertical space.
The drawback with this approach is the lumens that are lost to the lens.
Altman has been making lighting fixtures for lighting cyclorama’s for a long time and has been a leader in the use of specially designed reflectors to help spread the light evenly across a large vertical area. So it is no surprise that they are the first manufacturer to make use of a reflector instead of a lens to spread the light. Their new fixture looks very similar to there Econo-Cyc fixture which uses a “J” style reflector with a “T” style lamp at the corner of the “J”. They have placed a single row of LED’s in a similar style of reflector with the LED’s behind a specially designed lens to blend the colors and reduce pixelization at close range.
In order to test out the fixture, Altman provided me with seven fixtures to use during a production of the musical “Rent”. I was replacing the existing six Altman 3 cell Sky Cyc’s, with the seven Spectra Cyc’s. The first test was to see how one of each fixture performed in one color.
The Sky Cyc has a more defined hot spot while the Spectra Cyc is more even across the entire field. The coverage is almost identical between fixtures both horizontally and vertically.
Another very important difference between the Spectra Cyc and other LED wall wash fixtures is the makeup of the colors. The standard has been to provide the three primaries: red, green, and blue. Altman has gone one step farther by adding a fourth color to the mix: amber. By adding this color they can create a better white, and subtler colors. The problem with using the three primaries has to do with the width of the frequency that the LED produces. LED’s emit light in very tight frequencies, so when you try to blend them to make other colors through additive color mixing you have trouble creating subtle pastels or colors beyond their frequency. An example is a very deep blue: you can only get a blue as saturated as the primary, the addition of Red, or Green will not make a deeper blue.
This brings up comparisons between the two fixtures. When you install the Spectra Cyc you need a lot less power. The six 3 cell Sky Cyc’s each have 1500 watt lamps per cell, so you need 18 2400-watt dimmers to control them. The Spectra Cyc only consumes a little more than 100 watts per fixture, so I plugged all seven of them into one wall outlet. The fixture also comes with a pass through power connection so they easily daisy chain. These fixtures do not go through the dimming system. They are what I like to call Multi-Attribute fixtures. You supply them with regular power and data from the lighting console.
The next thing to install is the data, and again they have pass through connectors so they can daisy chain. The last thing to do is set the DMX address for each fixture after you power them up. This fixture has eight different personalities using from 4 to 10 channels. The fixture has three parameters that makeup the personality: Resolution, Master, and Smoothing. The difference between the personalities is broken down by how much control you want over the colors, whether you want a Master, and whether you want Smoothing.
Resolution is a choice between 8-bit and 16-bit control over the RGBA colors and the Master. The Master allows you to have proportional control over a color that you have mixed, so that when you dim the fixture the color doesn’t shift, but stays the same hue.
The simplest personality assigns a channel to each of the four colors. The most complex personality provide 16 bit resolution over each color and the Master, with Smoothing turned on. This last personality uses 10 channels of DMX, now if you add that up you have 4 colors and the master, times two channels each for a total ten channels. So where is the smoothing channel, Smoothing is a software option that is either on or off, so it does need a channel since the user cannot adjust the amount of Smoothing.
Smoothing is an option that helps to reduce the “steppiness” found when you dim LED’s over a slow count. LED’s react so quickly that as you dim them slowly you can see some step changes. The Smoothing option helps reduce this through software built into the fixture.
The real test of the fixtures came in use during an actual show, the production of “Rent” I referred to earlier. The show had around 230 cues and the Cyc lighting figured prominently in the show. The Spectra Cyc’s allowed for a wide range of color choices including a wonderful amber, typically not available when using the 3 cell cyc lights with red, green, and blue gels.
The dimming curve does have some very minor steppiness at the lower end, but smoothed out nicely above 30 percent. The stepping was not an issue in this production but could become a problem when used in a video environment.
I found the fixtures to perform without a flaw throughout the run of the show and I would recommend them for anyone looking to replace the traditional incandescent source with a more energy efficient source.
There are three benefits to making the change. First is the reduction in power usage both by the fixture itself and the savings in air conditioning. The LED fixtures produce significantly less heat than the incandescent.
The second is never having to change the lamp, which is especially nice if the fixtures are not easy to reach. Never having to change the gel is the third benefit. In the theater I work at we typically have to change the gels in our Sky Cyc’s six times a year at minimum.
After testing out these fixtures I can see that LED fixtures for use in the theater is a reality. The day is not far off when there won’t be any dimmers in the theater only fixtures that are controlled through a data network. So begin to learn how to setup data networks and run consoles that easily control multi-attribute fixtures.