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Old April 13th, 2010, 12:22 AM   #16
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As Richard said, the LEDs are not point sources.

I don't think you can remove the package that easily. The inbuilt reflector is one of the reasons LEDs are so 'powerful' plus they need a way to disperse heat.

If you take a look at places like candle power forums you see some really clever people modding torches of all things. But we can learn a lot about LEDs and optics from these guys. They've built some quite amazing stuff and it's not too dissimilar to our needs

cheers
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Old April 13th, 2010, 12:56 PM   #17
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The backstage technical forum I help run did a technical review of these LED Fresnels a while back. Here's the link

The LED Fresnel Shootout - Blue Room technical forum

Paul
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Old April 13th, 2010, 04:13 PM   #18
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Thanks for that Paul, good job. It does confirm a lot of things. You can see clearly the beam in wide mode is "fragmented" and you can see individual LED beams. They've got 9 LEDs in this unit, its easy to see from the beam.

A cookie test would have been really great or showing what happens when barndoors are closed down (does it come with barndoors?). I think we know what it would be like based on the beam pattern on the wall though.

Also you didn't say what distance your measurements with light meter were taken. One meter?

The other thing is you would expect a very small instrument but because of cooling issues and other necessities, its really huge for a "500w equivalent".

Thanks again.
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Old April 13th, 2010, 09:24 PM   #19
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That's great info.
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Old April 14th, 2010, 04:06 AM   #20
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I think Pauls review was for the Elation ELED.

From another report of the LitePanels one it seems that the focusing is electronically motorised. Reading between the lines I guess this raises the possibility of a cluster of LED sources also being moved to refocus them whilst being racked back and forth.

Pretty neat really.

Can anyone confirm this?

cheers
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Old April 14th, 2010, 08:54 AM   #21
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Yes it says that in the first line. You'd have to be pretty well connected to have a review already for the Litepanels fresnels. I was definitely interested in seeing the insides of the other fresnel as well anyway. Here's some information that someone posted on another forum who went to the booth:

Sola12 ~$6500
sola6 ~$2500
solaEng ~ $600

Fan in middle of back surrounded by heat sink.

They have barndoors. Front was not hot. I asked him to go back today and stick his hand in front of a beam shining on the wall to see how many shadows of his hand he sees...
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Old April 14th, 2010, 01:13 PM   #22
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Quote:
Originally Posted by Richard Andrewski View Post
Yes it says that in the first line. You'd have to be pretty well connected to have a review already for the Litepanels fresnels. I was definitely interested in seeing the insides of the other fresnel as well anyway. Here's some information that someone posted on another forum who went to the booth:

Sola12 ~$6500
sola6 ~$2500
solaEng ~ $600

Fan in middle of back surrounded by heat sink.

They have barndoors. Front was not hot. I asked him to go back today and stick his hand in front of a beam shining on the wall to see how many shadows of his hand he sees...
Holy Shizzle!
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Old April 14th, 2010, 04:06 PM   #23
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That's exactly what I thought. These lights will be priced way out of the mainstream. For those considering HMI's these lights could have some appeal but how many people are buying HMIs these days? They look nice but most of us won't be spending that kind of money on a single light.

I will be interested to see the shadow characteristics of these lights.

Dan
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Old April 14th, 2010, 05:56 PM   #24
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For the older and wiser among us how does the LitePanel's claim of the Sola 12 being equivalent to a 2K tungsten...

Quote:
The Sola12 draws just 250 watts yet produces output equivalent to a 2000W tungsten...
... translate into lumens? Measuring light output for the purpose of comparison seems to be the big bugaboo for consumers wishing to compare apples to apples. I propose a standard means of measurement, henceforth to be known as the Wheeler Light Test, of shining the fixture at a solar panel of known efficiency in a blacked out room and measuring the amperage generated at 1, 5, 10, 15, and 20 meters.

It probably wouldn't work but off hand I can't imagine why not.
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Old April 14th, 2010, 06:53 PM   #25
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Lumens are not how you would compare, it would be lux or foot candles measured using a light meter. You'd measure the lux / foot candles at a certain distance of both fixtures to compare. LEDs aren't bulbs so you can't compare their lumen output, that'd be like apples and orange comparisons and it wouldn't show the real power behind an LED and why they really are so much more efficient. I know that LED manufacturers do give lumen output but its misleading and doesn't tell the whole story so they automatically disadvantage themselves in comparisons. Its a young industry, they still haven't figured out a lot of things yet.

Lumens are only useful for measuring output of a bulb which radiates 360 degrees around it. Lux/foot candles are useful to measure fixtures or how a bulb has been turned into a fixture with a beam. An LED is a fixture because it already has a beam so to really find out what its equivalent to, you have to use a light meter, not an integrating sphere for measuring lumens. Integrating spheres work best for bulbs without fixtures and we would never put any fixture into a sphere because it just wouldn't work as well. They do use integrating spheres to measure lumens of LEDs in LED factories, but as I said, its misleading since the LED doesn't radiate in a 360 degree pattern like a bulb and is already a fixture.
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Old April 14th, 2010, 10:45 PM   #26
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Link to marketing interview of LitePanel Fresnel:

YouTube - Litepanels Introduces LED Fresnels

Attached is a crop of a screen capture showing the large fan and the larger finned heatsink.
Attached Thumbnails
Did they finally do it? LED Fresnels?-litepanels-sola.jpg  
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Old April 15th, 2010, 09:19 AM   #27
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Fans in lights are never a good thing when shooting interviews or dialog scenes in quiet rooms. I have yet to hear a truly silent fan. Sound guys are going to hate these things.

Dan

Last edited by Dan Brockett; April 15th, 2010 at 10:08 AM.
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Old April 15th, 2010, 09:51 AM   #28
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Like i said, big hunk of heavy finned metal on the back or a fan. Its not a great choice but with LEDs still getting as hot as they do, its the only choices we have. Water cooling anyone?
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Old April 15th, 2010, 10:16 AM   #29
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I knew two people who had the liquid cooled quad G5s. Their computers both sprung leaks. Somehow, saying that your production or post gear sprung a leak just sounds wrong.

Dan
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Old April 15th, 2010, 05:33 PM   #30
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LOL, you're right Dan, what a mess. I'd never even use it on my computer. Really a pity too because its the only other way I can think of to keep it silent.
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