Ynot Posted June 19, 2009 Share Posted June 19, 2009 Hmmm... Interested to see splashed on the cover of the latest CPC sales mag a 50W white LED Fresnel....Advertised as equivalent to 500W halogen output, 10 to 50 degree beam.(Also has both 5 and 3-pin DMX sockets!) Would be interesting to see how this stacks up to a normal fresnel.Not cheap - you can get a Quartet or Acclaim F for not a great deal more than £100 - but might be worth a punt on the basis of theoretical nil lamp changes and lower power consumption. Mr Beesley? Any feedback would be appreciated. EDIT - tried to PM you, Chris B, but your inbox is FULL!! Link to comment Share on other sites More sharing options...
David A Posted June 19, 2009 Share Posted June 19, 2009 If you believe that, you'll believe anything, is there any photometric data or cri information?, that is a rhetorical question, there won't be.Or maybe they have developed a led 10x more efficent than a TH, but they haven't of course.Just more overblown sales pitch. Link to comment Share on other sites More sharing options...
mumbles Posted June 19, 2009 Share Posted June 19, 2009 http://www.elationlighting.com/pdffiles/el...hotometrics.pdf Ever so slightly basic though, with no idea of the outputs across the beam angle range. Link to comment Share on other sites More sharing options...
Brian Posted June 19, 2009 Share Posted June 19, 2009 Comparing the data with an Acclaim is quite interesting. With the data given the beam angle is an implied 44 degrees with no detail on what is being measured but, if we compare the 4m figures of both units, the Acclaim in full flood with a 650W lamp is 208 lux and the led product is 178 lux. Correct the figures for a 500W comparison and the Acclaim will be 160 and the led unit 178. Spot the Acclaim down to 44 degrees and I suspect the numbers will be very close. As I said, interesting. [EDIT]Good leds are probably around 4-5x the efficiency of a TH lamp. It's also easier to make efficient optics for an led so I have no problem seeing a 50W led doing the work of a 500W TH lamp. Link to comment Share on other sites More sharing options...
musht Posted June 19, 2009 Share Posted June 19, 2009 LED efficiency is mebbe hitting 2 or 3 times efficency of halogen in real world temperatures. Cree LR6, 6" downlighter replacement with believable specs., is 12W and 650 lumens, bit under 60l/W, decent LV halogen will manage 25l/W. T class lamps have CT of 3200K , this LED unit 6000K , very blue. White LED has a very different spectral power distribution from halogen http://www.mvlc.info/images/photos/led/spectral3.jpg Might be great for some display applications but would think twice and then spec someat else for theatrical applications. Link to comment Share on other sites More sharing options...
Ynot Posted June 19, 2009 Author Share Posted June 19, 2009 I'm keeping an open mind on this one.A couple of years ago I'd have agreed that certainly the budget end of the LED fixture market was useful only for effects and set washing purposes. Indeed, our stock of Par 56 LEDs get used for highlighting set pieces in panto (which they actually do very well, especially when directed at 3D relief) and for visible backlights etc for dance shows and the like. But having had a handful of LED par 64s for a couple of weeks in April, I was surprised that the output from them was considerably higher than I expected, and they made an excellent backlight line. I'd accept that budget LED pars are still a ways off from being a viable people-lighter, BUT this little fresnesl seems to be the first option I've seen on the lower end of the market and has intrigued me somewhat. I am interested to see what it can actually do - and (for example) how it would cope with the more saturated gels being stuck in the front - though to be frank, I see LEDs developing more towards an RGB+W fixture so that you don't have to gel them - that way you get a reasonable light output without losing stacks behind the gel... So - let's see who gets one in first for a shoot-out..... Link to comment Share on other sites More sharing options...
Chris Beesley Posted June 19, 2009 Share Posted June 19, 2009 We have a demo unit up here in the office... was also on display at ABTT The products do appear to have their market - however they are no threat to traditional lamp sourced (yet). It has been fed back to the manufacturer's that for the price the output needs to be improved or the price needs to be reduced. Anybody care to do a shootout VS traditional sources? Link to comment Share on other sites More sharing options...
paradoxism Posted June 19, 2009 Share Posted June 19, 2009 Hi Chris - CADOS would be happy to do a comparison for you! In fact Rob has aready said he may be in touch as I've sent him the link and your name came up in his reply! Just wondered what the dimming was like, especially towards the low end. LEDs always seem to have an on/off effect at 1-2%. Link to comment Share on other sites More sharing options...
Ynot Posted June 19, 2009 Author Share Posted June 19, 2009 Anybody care to do a shootout VS traditional sources? Chris - that was what my failed PM was about - you need to do some weeding of your PMs it seems!! Happy to have a shootout over this way. Link to comment Share on other sites More sharing options...
David A Posted June 19, 2009 Share Posted June 19, 2009 Quote Brian-"It's also easier to make efficient optics for an led so I have no problem seeing a 50W led doing the work of a 500W TH lamp. "Considering that most optical systems are based on "point source" could you expand on your hypothesis?And what is the CRI of this "white light"? Link to comment Share on other sites More sharing options...
Brian Posted June 19, 2009 Share Posted June 19, 2009 ...could you expand on your hypothesis?Gladly... A filament lamp radiates over virtually the whole spherical space. In a lantern like a 4" fresnel the useful light will be that falling within a cone coming forwards from the lamp and that which is collected by the reflector and redirected forwards. A goodly part of the light generated will be wasted lighting up the inside of the enclosure. The closer the lamp is to the lens the more light is collected. An LED radiates over something approaching a half-sphere. With careful design, the optics can capture much of this light and direct it in a useful direction. Because LEDs generate less heat, and the heat they do generate is easier to get rid of, the optics can be made smaller to fit right over the source in a way that would be impossible for a filament source. Link to comment Share on other sites More sharing options...
adam2 Posted June 19, 2009 Share Posted June 19, 2009 Certainly sounds impressive, and I can see applications for architectural and retail display lighting as well as theatre.DMX is seldom required in such applications, I wonder if a non DMX version for non theatre use will be made ? The 6000k color temp might be prefered over halogen for display lighting.I wonder what the "lamp" life would be if lit at full power, 16 hours a day in a warm shop window ?Heat is the enemy of LEDs, and a large lantern should give better heatsinking than say an LED MR16 replacement. Presuming that the unit will stand up to continous use, the energy savings would be substantial.50 watt LED instead of 500 watt halogen, saving 450 watts, which is 4.5 pence an hour.If lit for 6,000 hours a year that is a saving of about £270 A YEAR.Thats a pretty good return on an investment of about £270 ! (yes I know that they cost more than that, but they only cost about £270 MORE than a halogen lantern) Might also be useful for small scale outdoor photoshoots/video filming since half a dozen could be worked of a vehicle battery via an inverter. Many venues cant use as many lanterns as they would wish, due to power contraints.An upgraded supply is generaly available, but often costs many thousands of pounds.I wonder if any large venues will spend say £10,000 on 40 or so of these, instead of perhaps £8,000 on a supply upgrade and £2,000 on additional halogen lanterns. I want one Link to comment Share on other sites More sharing options...
David A Posted June 19, 2009 Share Posted June 19, 2009 Heat is a major constraint and to get bigger wattages you have to have bigger areas which stuffs up the optics and the CRI is still rubbish, when I see a decent unit I'll believe it, but till then I'll keep LEDs for eye candy. Link to comment Share on other sites More sharing options...
Chris Beesley Posted June 19, 2009 Share Posted June 19, 2009 Okay guys, Brian has agreed to do the shootout - should have the figures week after next. Before then I will try and get the unit across to CADOS in Chorley for them to have a play test Link to comment Share on other sites More sharing options...
Ynot Posted June 19, 2009 Author Share Posted June 19, 2009 Okay guys, Brian has agreed to do the shootout - should have the figures week after next. Before then I will try and get the unit across to CADOS in Chorley for them to have a play test Ahem.....<points at the top at who started the thread.....> Link to comment Share on other sites More sharing options...
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