are we about to see cheap useable led lighting?

Not yet. They sell LED lights at Home Depot (giant hardware store). They are very expensive ($60 minimum). The argument is they last a long time..... Maybe.

Pros
LED can produce any spectrum.
LED is dimmable
LED uses lower power (compared to incandescent)
LED lasts a long time - this is the one I question. We've all see the traffic lights get replaced with LED lighting. Here it is just a year or two after replacement and the ones in my town are burning out. So if I got 2 years out of a $60 bulb, I'd be upset. LEDs can last very long times when heat is not an issue. For normal electronic indicators, they can last almost a lifetime. But for lighting and signal lights, they need to be big, bright, and they are hot. There's the rub. So we'll have to see about the lifetime. I'm skeptical for now.

Cons
Expensive - like any electronic part, mass production will lower prices over time. But how far is to be seen
 
I haven't looked it up but it's the electronics not the LEDs themselves whose longevity I wonder most about. Same with CFLs. I've seen lots of the latter fail. And I've seen cheap LED lights quit too such as the ones I've purchased to plug into the USB port on my laptop to illuminate the keyboard.

I'm doubtful about the reality of the 10,000 hour plus total longevity figures and I agree that heat is likely to be a major culprit.
 
Leds do vary greatly from manufacturers, not only in terms of longetivity but also in their color characteristics and reliability as well. If you check out for example the Cree leds, especially the upcoming XM-L led, which will also be available in different color bins and CRI index, it is easy to see that leds have really been improving drastically over the past couple of years. Leds do need a driver to operate efficiently and to spec. The quality of the components in the driver determines the reliability factor. Yes, the electronics part that will do the powering job is the key factor in the life expectancy. I have seen also cheap leds that after a few hours just went dead or lost their brightness, those were the cheap ones with probably low quality control, or the drivers were overdriving the leds to their upper limits and a bit beyond. It does not take much over voltage or inadequate heatsinking (thermal management) to shorten a led's long life. Like everything else, there are the good ones as well as the not so good, but the brand name ones are reliable and should give the 25K life span or thereabouts without a problem. I believe that in less than 2 years, there will be over 50% of households that will have all their lighting needs done by leds. Time is ripe to invest in leds.
 
el presidente said:
I stumbled across this on a google led light search...
http://www.torontosun.com/newhomesandcondos/2010/12/10/16501591.html… is this as good as it sounds?
Click to expand...

If the history of film style Fluorescent lighting offers any lessons, the manufacturers of High Power AC LEDs will have to address several issues before High Power AC LED lighting can replace incandescent lamps in studios and on location sets powered by generators (particularly small portable generators.) First, as Norman99 correctly notes below, they will have to correct the relatively poor power quality generated by the SMPSs they use to power their lights (use this link for more details.)

Norman99 said:
Leds do need a driver to operate efficiently and to spec. The quality of the components in the driver determines the reliability factor. … It does not take much over voltage or inadequate heatsinking (thermal management) to shorten a led's long life. Like everything else, there are the good ones as well as the not so good.
Click to expand...

Second, the manufacturers of High Power AC LEDs will have to engineer a fixture that has the versatility and control of traditional Fresnel fixtures.

The drawback to LED light panels is that their light falls off very rapidly and is hard to control. These characteristics make LED light panels only suitable as Key sources in documentary interview set-ups where the Keys are typically positioned close to the interview subject. In that capacity LED light panels (with heavy diffusion) can generate a wonderful soft light that wraps around the interview subject without wilting them. However, in dramatic set lighting, where Key sources must be capable of throwing a distance, LED light panels have only limited applications as fill sources. The broad soft light they put out drops off too rapidly, and is too difficult to control, for them to be effective as a Key or Backlight source in dramatic set lighting.

However, progress is being made in the development of a true LED Fresnel. In September 2010, Arri introduced a prototype for their L-Series LED Fresnel at the European trade show, IBC 2010. As is evident in a demo video that was recorded at the show, Arri has finally engineered a fixture that combines the cool-burning, energy-efficient advantages of LED illumination with the controllable versatility of traditional Fresnel fixtures. The beam is continuously focusable from spot to flood; and, just like conventional Fresnels, the beam is easily controlled with barndoors and flags - enabling the light to be precisely cut to set pieces and talent. With remarkably clear and defined shadow rendering, excellent field homogeneity, and smooth, continuous flood to spot focus, Arri may have engineered the first true LED Fresnel (use this link for more details.)

For more detailed information on the Power Quality generated by LED drivers and the new Arri L-Series LED Fresnels, I would suggest you read the article I wrote for our company newsletter on the use of portable generators in motion picture lighting. In it I cover some of the basic electrical engineering principles behind LED drivers, the harmonic distortion they can generate, and how it can adversely affect generators. This article is cited in the just released 4th Edition of Harry Box's "Set Lighting Technician's Handbook" and featured on the companion website "Box Book Extras." Of the article Harry Box exclaims:

"Great work!... this is the kind of thing I think very few technician's ever get to see, and as a result many people have absolutely no idea why things stop working."

"Following the prescriptions contained in this article enables the operation of bigger lights, or more smaller lights, on portable generators than has ever been possible before."​

The article is available online at http://www.screenlightandgrip.com/html/emailnewsletter_generators.html.

Guy Holt, Gaffer, ScreenLight & Grip, Lightng & Grip Rental in Boston
 
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