ProVideo Coalition.com: News by PVC Staff (http://provideocoalition.com/index.php/news/story/litepanels_introduces_revolutionary_new_sola_fresnels/)

LED Fresnels? I hope so, we have been needing something like this for years.

Dan

Wow! The Sola12 sounds really appealing. Any word on pricing of these lights?

Thanks for the find Dan,

Garrett

LED Fresnels have been available for a while and these are from Litepanels. I'll be surprised if they're not a small fortune.

The two most powerful emitters (that I'm aware of) are the XP-G and the SST-90 and it will be interesting to find out what emitters they're using. The CREE XP-Gs max out at approx. 325 lumens each. With nine in a Fresnel fixture (yes, one should soon be available) that'd be just south of 3K in a 90mm form factor while the Luminous SST-90s pump out up to 2.25K lumens... each... but are far less efficient. The SST-90s suck batteries dry pretty fast. The CREE Fresnel that I know about varies from 10 to 60 degrees while the Litepanel blurb claims between 10 and 70 degrees so they may be manufacturing their own Fresnel lens.

Looking forward to seeing one of these in person.

Here's the beam spread from the Fresnel lens for the CREE XP-Gs that I'm aware of:
http://farm5.static.flickr.com/4017/4481120624_cee23ff95a_o.jpg

Hi Mark:

Please post a link to an existing LED fresnel that is available to buy. I have seen something called a Komet, but it retailed for $6k and was more like a PAR with multiple larger LEDs, if I recall, it did not have a fresnel lens but that was a couple of years ago that I saw it.

If you notice, these new LitePanels do not include a facility for barndoors and scrims, assuming the picture in the link is a finished product and not a prototype. A fresnel without barndoors or scrims would be pretty useless to many.

Dan

If history holds true, the two larger models will retail for probably well over $2k and probably a lot more, which relegates them as a niche product, just as HMIs are today. The specs sound interesting and LitePanels makes pretty good products for the most part. I don't think LED fresnels will find mass market acceptance until they are priced roughly at similar levels to the equivalent output tungsten instruments.

Dan

Yeah, I'd like the see the existing LED fresnel as well. Its not a fresnel unless it has at least two things: fresnel lens and focusing ability. Otherwise, its just an open faced light which sometimes have ability to focus and many times do not.

No barndoors or scrim/accessory holder on this picture. A lot of people will still want at least the ability to use a half scrim and barndoors for shaping are absolutely necessary if you really are able to give a single shadow. The whole "light shaping" thing is what a fresnel is all about and you can't do that with multiple shadows on the output.

I did some work on this back in 2007 and posted a bit about it here:

http://www.dvinfo.net/forum/photon-management/128213-led-lights-2.html

Gave up on it because I don't see at $1000 or greater a very big market. There's no reason to do a fresnel if you can't beat the single shadow issue. That issue alone means you can't use multiple LEDs. And I don't believe that the fresnel lens will save you in terms of faking the single source output. So if you use one high wattage LED, the heat sinking requirements are such that you can't make the traditional light on a sled to do focusing.

Its more like, you have a huge heavy heat sink you mount the high wattage LED on then the front of the fixture goes back and forth on the heat sink. Plus the fact that high wattage LEDs are basically a 2D device means they can't work as efficiently with PAR mirrors. A traditional "3d source" (like a tungsten or hmi bulb) which can be placed in the sweet spot of the PAR reflector works much better. Need a 3d LED basically to do that right in my opinion if you still want to use the traditional mirror to pump up the output efficiency. No mirror or inefficient mirror means you need a better and more efficient LED all alone.

This is the Fresnel fixture that I first learned of...

Elation ELED Fresnel - High Power LED White Light Fresnel (http://store.phantomdynamics.com/elelfrhipole.html)

Note that this is a (relatively) old fixture that is NOT using the higher power LEDs that are now available (as the Litepanels almost surely are) and puts out 500W tungsten equivalent.

The CREE Fresnel I referred to is not yet on the market.

Hi Richard,

Out of curiosity could you share what emitters Cool-Lights is using?

Hi Mark,

I doubt many here would consider that Elation fresnel a serious contender for video/film work. Its got a fan in it. Maybe good for disco or theatrical but people would be seriously disappointed for video work. That's the only way however they could make a fresnel in something approaching a normal expectations of a fresnel fixture form factor. Otherwise, the heat sink for a 50w LED would be so big and heavy it just wouldn't work.

If you mean the 60w LED on the previous link I gave, that's made in Taiwan at a company called Domag. I don't consider that or any of the super high wattage LEDs I've seen to be interesting. We've seen 100w ones here in China and they just get far too hot to use in anything other than a street light or where a fan can be used.

You're a lot closer to the source then I'll ever be and your input is fascinating. A lot of issues surrounding LEDs that the consumer neither knows about nor... presumably... cares. Given the amount of lumens that Litepanels is pumping out it will be most interesting to get your input on their design.

Take care.

Right, will be interesting to see what they did and how. Things I would want to know if I was going to NAB (unfortunately I can't make it) would be:

Price?

Does it have a fan?

Why no barndoors or accessory holder (perhaps that's just a picture of an early prototype and final model will have).

What kind of LED(s) inside? Single, multiple?

If multiple, how did they lick the single vs. multiple shadow issue.

If single and doesn't have a fan, how did they do without the large heatsink?

Etc.

I've played around with LEDs and CREEs etc,. Some of those high power crees have 4 LEDs on the same chip and through the use of dedicated optics (that you place over the optics already part of the LED) you can merge the separate sources into one via diffusing or focusing the 4 together. However that only works for a certain angle - not focusable. Same for the SSTs which are basically an array of LEDs close together - so that's not a point source either.

They have to be using multiple LEDs inside there for that output, so the question is how are they claiming a single point source shadow?

About the only thing i can imagine is a custom reflector design and lens designed to focus the point sources into one which is then focused again. Perhaps something like the dedo aspherics system with multiple lenses. I gave up trying to work out reflector designs that would work. Sadly i have a day job!

I would love to see what they're up to, it's a holy grail really.

Can someone at NAB accidentally knock one over and see if you can get inside the case? :)

cheers
paul

They have to be using multiple LEDs inside there for that output, so the question is how are they claiming a single point source shadow?


paul

A Tungsten Fresnel has two light sources, the bulb and the reflector just as an openface light does; the lens focuses these two light sources into one light source thus a single shadow. Therefore, whether you have two light sources or ten in a Fresnel you get one light source and a single shadow.

Bill

There are differences. The two light sources you speak of are perfectly aligned one in front of the other and work well to make one source. The bulb and mirror alone aren't efficient so we add the lens.

Where the differences come in this case, an LED is not a bulb, its a miniature spotlight or fixture in and of itself. A bulb by itself has no projection capability other than radiating light 360 degrees around it. The mirror helps make the bulb into a fixture thus giving it a beam and projection capability. The lens completes that by magnifying a bit. Put 2 or more LEDs behind the lens and you have a bunch of spotlights projecting through a lens but should still each give its own point of light. Space them as closely as possible to each other but its still multiple sources of beams. Since the LEDs radiate mainly forward, a mirror behind them wouldn't help much. Without diffusion in the lens, it doesn't mix into one source, its just several sources trying to go through a lens and still coming through a bit as several beams. Add diffusion to the lens to try and blend them and you lose the hard shadow rendering capability we expect from a fresnel.

Would definitely be an interesting experiment to try.

In other words, the lens is designed for the application. When using LEDs you need to redesign the lens to match the new application, which is what I believe that company has done, or they figured out a work around with Fresnels design.

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
paul

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 (http://www.blue-room.org.uk/index.php?showtopic=36230)

Paul

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.

That's great info.

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

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...

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!

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

For the older and wiser among us how does the LitePanel's claim of the Sola 12 being equivalent to a 2K tungsten...

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.

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.

Link to marketing interview of LitePanel Fresnel:

YouTube - Litepanels Introduces LED Fresnels (http://www.youtube.com/watch?v=EqTvL_ZwCkA)

Attached is a crop of a screen capture showing the large fan and the larger finned heatsink.

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

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?

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

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.

Richard.


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?

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.

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.

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.