Monkey Business: LED Education 101

Article by Seth Scott, Monkey Wrench Productions

The founder of Monkey Wrench Productions, Seth Scott is a working professional technician with tremendous experience with all manner of lighting systems in just about every type of venue out there.
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The Storyteller looks on in The Miraculous Journey of Edward Tulane at Stages Theater. Pictured: Jennifer Kirkeby. Photo Credit: Megan Engeseth Photography. Conventional Tungsten for highlight with LEDs for color. Lighting Design: Wu Chen Khoo.

The Storyteller looks on in The Miraculous Journey of Edward Tulane at Stages Theater. Pictured: Jennifer Kirkeby. Photo Credit: Megan Engeseth Photography. Conventional Tungsten for highlight with LEDs for color. Lighting Design: Wu Chen Khoo.

Not since the invention of putting colored water in front of a light source (later colored gel) has something so single handedly changed the way we light our stage as the Light Emitting Diode. LED has become more than a fashionable buzz word in our industry, it has become a way of life. 10+ years ago we were lucky to find something that fit our needs let alone our budgets. Such a product seemed to be a figment of our imagination. Fast forward a few years and you can hardly swing a two-fer without hitting a LED fixture. It has reduced our power consumption, weight of transport, and brought the demand for gel to a steady crawl. I’m here to shed some light on the advancements of this technology and talk about how not all budget LEDs are bad.

First lets talk about the technologies. Gone are the days of 3/5/10 MM LEDS and what I lovingly refer to as the “tic tac” fixtures - LEDs that more resemble something you would find as an indicator light on a current model than anything you would want to light a stage with (10MM LED tic-tac Fixture). Gone too are the days of individual colored LEDs and the dreaded tri-color shadows they cast. Today most LEDs are a multi-color chip under a single lens. These multi-colors come in many flavors from the basic RGB to RGBW or RGBA to RGBAW to the now ever popular RGBAW+UV or HEX LED’s as many manufactures refer to them. This is not all that this lovely diode has to offer in recent years. COB (Chip On Board) technology has come on strong and has some great features that lighting designers, grips, and audience members alike will all appreciate. The largest plus being that you can use barndoors with the fixtures and get a cut with them. They also appear to be a single source thus removing the complaint of “I don’t like to see all of those dots.”

Manufacturing costs and overall fixture cost have come down in large part to demand and other industries taking on the green initiative and saving the planet one 60W light bulb at a time. I’m not going to do the cost comparison between LEDs and par cans / S4 pars (that’s a numbers game that will always be won by the LED), but I do want to talk briefly about the quality of light since this is something that always comes up in retro fits. I’m a big fan of seeing is believing, so please get a demo of any light you are planning on replacing in your current inventory and spend time with it or find 2-4 and do a shootout. You will quickly see every manufacture has things they do well and things they don’t. Don’t rely on online videos or a friend’s option that had them on one gig. Any retailer should be more than happy to provide you with a demo unit.

LEDs, like any other product, come down to a few definable variables - I’ll be using color, dimming, optics, cooling, and build.  

Color:  The most common objection to LEDs that I run into is just this: color. “How do I know that that color on stage is R80 (or insert color of choice here)?”  My reply is usually, “Why does it have to match the swatch if you aren’t using any lights with that color?” LEDs take us away from a cookie cutter way of designing and let us use our eyes to create whatever color or shade you want. We all have our go to colors that we use time and time again. If you have to match colors, I recommend setting aside an hour or so and set up a par with your gel of choice and your LED fixture, then mix until you match it.  Record the values and now you know that this matched your R80 or whatever colors you use the most. Colors do vary from manufacture to manufacture and can be an issue, but in large part LED binning (the process of matching exact colors in LEDs) has become an exact science and is no longer a concern from any reputable manufacture. 

Dimming: Dimming curves in LEDs are the 2nd hot button issue of contention and it’s true that they can strobe with the best of them and they do struggle with low intensity levels, but I ask you how often are you really using lights on stage at 15 % or less? If the fixture does not have a dimming curve that matches your tungsten lekos, then take this as an opportunity to learn how to make a split cue or use split timing and programming to make them match. Once you do it you will find that no one can tell the difference. As for the difference in programming time, just think each electric could be a single circuit vs 10-20.

Optics: Let’s face it, we have all tried to put a piece of diffusion on a LED fixture and have seen the output go from cyc light to flashlight. The problem is diffusion was designed for a large single source with punch and lots of visible light spectrum to see it through, so simply diffusing/spreading a tungsten source works great. LED relay on smaller power sources that have very narrow spectrums and many small point sources of finely chosen spectrum with very little unneeded light (this is the binning process). So you end up with a muddy mess when using diffusion. The solution comes to us from the auto industry. Many manufactures have taken to using holographic filters as a secondary lens option. These filters were originally developed for taillights.  If your LED fixture has a 30 Degree beam spread, simply add one of these and it will be 10 degrees wider in all directions or my favorite for washing walls is a 1x60, meaning your 30 degree par becomes a 31x90 degree beam spread! Because the filters are holographic, the transmission rate of 92% is much higher than diffusion so you don’t lose nearly the light output you do with diffusion (Filters).  This brings me to another misconception about LEDs. You need to think about your fixture as a system of smaller lights all working together to create one big one. If it has a 30 degree beam spread, each one of those lenses is 30 degrees making a 30 degree beam. Because it’s not a single source like a par can, every lens has the appropriate beam angle. This is the largest contributing factor to why barndoors don’t work with LEDs other than COBs I mentioned.  Zooming LEDs have been around for a few years now with varying degrees of success. It may add to the cost of a fixture, but makes it useable as a wash or a spot since many of them can zoom from 10-60 degrees. The zoom is achieved by varying the distance of a secondary lens from the lens that is mounted on the LED itself. Think of it as a motorized Fresnel lens (Zooming LED).

Cooling: Other than water, heat is the LED’s archenemy. Fans are a necessary evil. Even many budget level fixtures offer a fan channel to control fan speed. Some fixtures offer convection cooling or cooling without fans, but as we keep increasing wattage to get more punch, these are quickly becoming abandoned. Yes, in an empty theater with no one talking and only 2 people breathing, you can hear 20 fans running. By the time you add in audience noise, HVAC, and anything else that you are running, the chances are “fan noise” becomes a moot point in the save my 65Q crusade.

Build: Unlike conventional fixtures which are usually stamped and formed steel, LED fixtures can be made from anything from aluminum to plastic. They come in a variety of shapes and sizes from flat pars, that more resemble a pancake than a lighting fixture, all the way to fixtures that look very similar to a source four par. In most cases the size of the heatsink and number of LEDs dictates size, but the form is up to the manufacture. When selecting one for your application, keep in mind that not everyone needs a stout can. If you never change your Rep plot, why spring for a top of the line overly protected unit when something less heavy duty will do the job.

This is just touching on the surface on what LEDs have to offer. Cyc light replacements have long been in the cross hairs of LEDs and Elipsoidials are next on the list. I’ll save these are for another time, though.

There is no perfect replacement, but if you are willing to compromise on a few small details that only a select few people might notice, you can enjoy infinite colors, lower power bills, less maintenance, cooler actors, and more versatility in your rig.


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