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Old April 15th, 2010, 10:50 PM   #31
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Tapered drawn optical fibre bundles? Would there be any practicality in using these to pull in light from a spread of LEDs to create a more confined point source?
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Old April 16th, 2010, 03:38 AM   #32
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Interesting idea for sure. The great thing about 5mm LEDs is that while they get a little hot, its nothing like the heat you get from the larger wattage ones. No need for heat sink or fan. And perhaps if you had a huge bundle of the fiber optics, enough to fill up a lens, all of them as close together as possible--maybe the multiple shadows wouldn't be an issue. All of the light sources so tiny and close together like pixels on a CRT, most likely will blend into one. Fresnel lens in front of that might be the finishing touch to "smish" and magnify them just enough (but not too much though).

So if you had something like the LED 600 PCB (but maybe round) in a large round but thin fixture in back and a round, shorter diameter "snoot" on the front and this bundle of fiber optics leading up to the end of snoot then you put the lens on to finish it. If all those tiny ends are bundled close enough together and you could take say 100 fibers from each LED, that would give you 60,000 (hopefully enough to fill up at least a 4.5" lens which is about the size you want to use for around a 650w equivalent). I looked up the size of fibers that can fit in a 1/2" diameter area and thats about 100.

If you did have the lens filled up with those very tiny point sources, perhaps it would be interesting, don't know what the throw or projection would be on a fresnel like that though. Something tells me it wouldn't have the same throw for example as the LED 600 spot has, that is, considering that you have something between the LED and the actual emission point of light where some light may be lost. In other words, it might end up being too diffused and weak.

Also, it would be tricky doing your spot to wide beam adjustment back and forth. Not quite sure how that would work in that scenario. If you had the fibers come out to an even end then a sled to go back and forth, its kind of messy with the fibers needing some slack to handle going back and forth like that. Or perhaps you could just figure out a way to do the beam adjustment electronically and eliminate the mechanical aspect altogether. Turn off rows of LEDs and that makes the beam more narrow, etc. A lot of experimentation necessary there to figure out the best way to do it.
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Old April 16th, 2010, 05:38 AM   #33
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Once the CREE XM hits mass production you'll see some interesting new options in the marketplace I'm sure. A 9-up XM Fresnel would (using CREE's info) produce 6.75K lumens but use less then 60W while remaining very cool. I would expect to see a boatload of Fresnels at NAB 2011.
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Old April 18th, 2010, 12:35 PM   #34
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I looked at the Litepanel fresnels at NAB, good looking units but that's about it. Let's not forget that these are prototypes although I was told they should be in production in a few months.

They have a cool digital touch panel to control the focusing and dimming, so they have a motorized focusing control that I consider an expensive overkill, difficult to use and less accurate than traditional manual controls. I couldn't tell how noisy the fan was as the convention floor is very noisy, but like somebody else pointed out, a fan is never a good thing to have when sound is important. I couldn't tell of how tight and accurate the focusing was or the spill as the light was directed toward other lit areas.

I work with fresnels a lot, I own at least two dozen lights from 150 to 2000w, I know well what a fesnel does under any lighting conditions, from what I've seen either of the Litepanel fresnel have anywhere near the throw of a 300 or a 650w Arri.

I was surprised that with such expensive and innovative items Litepanel did not have a set to properly demonstrate the lights or even better compare them to existing lights. Probably they are a good product but the demonstration was very poor.
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