Can LEDs Replace Tungsten?

To kick off LDI 2013 I sat in on Phillips’s class, Can LEDs Replace Tungsten, held at 2 P.M. on November 11, 2013.  The question is obviously loaded, surely sparking many an argument in Las Vegas bars this weekend.  It’s also a question I approach with a bias.  

 

Bobby Harrell, Product Marketing Manager of Phillips, ran us through the basics of LED technology, which is an immensely helpful thing to do when framing any discussion.  We discussed where LEDs come from and what makes them work.  Harrell also ran through terminology, facts, and concepts which are quickly becoming required knowledge for all industry participants.  By this point, if you don’t know how a LED emits light, then you’re behind the curve.

 

So what do LEDs do well?  As we discussed quite a lot, actually.  The obvious stuff we all know.  LEDs are incredibly efficient and have immensely long lives.  Their environmental track record is quite positive.  Most are mercury and lead free, a direct contrast to CFLs, which means less poison seeping into the water table from landfills.  They require less power, which means a smaller drain on the power grid.  However even while using less power, they are several times more efficient than incandescent sources.  The small size and power draw allow them to be used in once unusual circumstances, as inside costumes or small scenic elements.  In TV we use (what seems like) miles of LED tape in sets nowadays.  The HVAC savings with all LED rigs cannot be ignored.  

 

There are some less obvious benefits as well.  Museums love LEDs because they do not emit any infrared or UV light.  This means they do not degrade the artwork’s pigments through either heat or high energy particles.  In some cases museums are setting the color temperature of the light lighting the artwork to match the color temperature the artist created the piece in.  How crazy is that?  Now if an artist created a painting outside, it can be illuminated in a light dialed to daylight without risk to the piece.

 

LEDs also require significantly less infrastructure.  Fewer physical dimmers and wires mean less copper, which saves quite a bit of money.  Less cable means less weight on truss, which means less rigging gear.  That also means fewer electricians and riggers.  All this reduces the “true cost of ownership,” as we discussed in the class, which can help alleviate the sticker shock of some LED products. 

   

Regardless of these successes we still must contend with a variety of problems.  Chunks of the visible spectrum are still M.I.A.  You can’t mix to a color that isn’t there.  Dimming remains iffy, though manufactures are making enormous strides.  Pixelated sources still cast multiple shadows, which makes barn doors work less effectively.  Subtractive color mixing between various source types still causes consistency issues.  LED chips themselves may be rated for a gazillion hours but the circuitry driving them probably is not.  The fan noise required to cool brighter chips can be a deal breaker in many applications.  Efforts to control that fan noise may result in diminished output and shorter lamp life, which no designer wants to hear.  As LEDs age they dim which I find less preferable to just blowing out. 

 

Some prior complaints are becoming non-issues.  LEDs are much brighter than they used to be.  Certain units have gamut matching modes, which ensures that different colored LEDs units match.  Sure, you lose some saturation, but you save time not having to color balance multiple units at the console.  The prices are coming down to more affordable levels, especially when you factor in other costs (like less dimmers, cable, power, and crew).  Single source LED, or homogenized sources, create the single shadow we’re used to from traditional lekos.  Holographic filters help eliminate the weird “color donut,” plus give us some finer control over beam spread.        

 

In many ways we’re spoiled by tungsten sources.  Collectively we’ve set that as the gold standard, which by definition is difficult to beat.  We also are used to the peculiarities of tungsten sources and accept them.  So much so, we rarely give them much thought (things like lamp inertia, dimming red-shift, hot spots, or an embarrassingly low efficiency rating.)  Perhaps by not accepting LED’s peculiarities, we create an unfair double standard.  

 

Ultimately it was a very interesting course.  So can LEDs replace tungsten?  More and more, the answer is yes but it’s largely a qualified yes.  In other words, it’s complicated.  Phillips estimates that by 2020 70% of the market will be comprised of LED sources.  LEDs are not going away.  The onus falls to us -- designers, client representatives, and consultants -- to spec appropriately.  

 

As our tool bag has grown in size, so, too, must our perspective and knowledge.

 

 

Lance Darcy is a Lighting Director for The Lighting Design Group, based in New York City.  He also writes the LD On The DL blog for Live Design.

 

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