LED fixture in Theatre?

[ramdram]

So, we're all agreed then? LEDs do have a place in the ents industry, depending on price or application. Mention was made of Pulsar kit being OK, and it might very well be, but it has limited application:

 

http://www.pulsarlight.com/Products/LEDLighting/ChromaFlood/ChromaFlood200/tabid/156/Default.aspx

 

This mythical 100,000 hour life (of "an" LED) is only possible IF the units are not run at 100% continuously. Pulsar claim a mere 25000 hours at full power. So its back to stats again...

 

No manufacturer can know exactly how or where their product will be used and to start giving silly lifetimes, without a whole host of caveats, is tantamount to deception. Plus the lifetime stated refers to the LED itself..."amazingly" no mention is made of the electronics to drive said LED.

 

And are they really that cheap an item "at the end of the day"? Cost of R&D and manufacture never seems to be mentioned, just the running costs, and then you get the "you don't need dimmers" argument. Agreed you don't but you might need a fairly large desk with a lot of channels if you wanted to run a drama cf a musical say.

 

Mention was made too of the increased maints needed, which you would never know unless you worked with them.

 

As always a fascinating discussion raising issues you might never hear about unless you worked with them.

 

I'm happy I don't in our venue...it's the tours I will now worry about, ** laughs out loud **.

[StevieLights]

Ok, performances will inevitably use some form of led - el cheapo / mid range / top end somewhere in the design.

 

Do I think we'll ever see a house rig of ETC Desire fixtures ( or similar )? - Probably not, unless somebody has very deep pockets and even then they'll always be a use for conventional fixtures for particular scenes. LED is just another tool available to the designer, and how many of them know the ins & outs of every LED product on the market ?

 

Touring shows will however, feature an increasing range of led profiles and wash units as part of the "specials" for that look, and gradually that will filter into the house lighting stock over a period of time. I can see, a bit of a backlash, against led products comming, as the general range of units available, fails to meet the expectations of purchasers.

 

The jury will be out on this for a long time.

[ramdram]

Ah, now, ref the tours...assuming your comment was in response SL...I should have said when "we" tour to a venue which is equipped with LEDS...not "us" taking a load on tour. Apologies for not being clearer.

 

Went to one place with LEDS and 24 channels were allocated to just eight of them. Rubbish dimming curve and a bit of playing around to get a non "burn your eyes out polar bluey white". Not a particularly edifying experience.

 

Out of interest I had a squint at the ETC site and I note that the working life claim for their Desire D40 XT LED Luminaire, as an example, is given as 50,000 hours...however no mention is made, as a qualifier, as to whether this is with the LEDS flat out or an a much lower output.

 

Interesting reading this manufacturer guff...

[StevieLights]

ramdram - I was commenting on leds things in theatre in general.

 

Re the etc desire range, I attended a demo at the local theatre last week with the etc rep, there was probably about a dozen end-users at it. The demo was well presented and relaxed - no sales pitch - more a chance to see the stuff in action. Interesting - yes and well worth it. Areas of discussion - led binning / fixture compatability over the years / list price/ colour matching

 

Overall, and no plug intended for ETC - but, I think they've gone a long way to addressing the major issues that exist in a purchasers mind - it's a well made, well thought out product, but intended for the top-end of the market and the price dictates.

 

Personally, I still own some "el-cheapo" 10mm diode style leds, bought in 2007, there probably functioning about 60% of their orginal output, but still good for a few years yet. The stock added some 21x3in1 LEDs - good light output and a reasonal quality lense gives a nice beam output ( no rings)

 

The make of the control desk has a lot to do with the dimming curve in the leds, but yes there's still that pop out snap when heading towards zero :)

 

You will "tour" into a venue that has profiles/fresnels/pc's/floods/groundrows etc - all conventionally lamped

Soon they will have an LED variant of all of the above

[dbuckley]

Hmmmm™ (claiming fair use exception)

 

So all the decades of work thats been done in the field of failure analysis, lifetime prediction, MTBF etc are all just a waste of time then. Glad we got that cleared up.

[rossmck]

As someone who mainly does small scale stuff, and a lot of temporary venues, I'm (un)fortunate enough to have worked with a wide range of LED products in a 'theatre' environment (i.e. where things like dimming curves tend to matter more than, for instance, live music events of a similar scale)

 

It's obvious over recent years that the lower end stuff has got (much) better... the likes of Chauvet/Showtec/LEDJ etc now all produce RGBW and RGBWA fixtures with reasonable dimming (the Showtec/Chauvet fixtures cheat a bit interpolating that last few percent as a slow fade (so, if configured to use that curve, you 'snap' them out on the desk they fade more like an incandescent lamp would) but it works well amongst a rig of generics. These budget fixtures are at the stage where I've used them to light set, cycs, provide colour washes as backlight or toplight etc. They are not, imho, ready to replace front light.

 

At the other end of the scale - ETC Selador is pretty much unmatched - and one of the only LED products I'd use from the front, and I look forward to seeing the new Source Four LED profile launching at Frankfurt (or possibly Plasa?) this year.

 

LED provides another tool for designers, and the lower end of the market provides some great flexibility as well as being very useful in smaller venues with limited power where hanging loads of generics is simply not an option, even if the quality of light would be better, the versatility benefits from using LED often outweigh this.

 

A local (small, mainly amateur) venue recently added 12x Selecon PL3s to their stock - so LED kit, even the higher end of it, is definitely creeping into the day to day venues we go into - personally anything which offers me more flexibility in how to light a show is a good thing, doesn't mean it'll always be the right tool for the job.

 

 

[ramdram]

The cost thing is interesting.

 

One place we toured only had 12 LED "Pars". Could not identify the make but they were 10mm multi colour types and only RGB. This lot went through a "basic" Jester desk via some DMX splitter stuff.

 

The venue bods (not a soul under sixty) were quite proud of their kit...and cheerfully admitted they had absolutely no idea how to drive their new desk or how to sort out/design any effects. The instruction manual was in a completely alien language, English, so was totally incomprehensible to anyone west of the Tamar...

 

Then they mentioned, including the install (onto existing bars btw), the cost was £7,000...

 

My response. "Oh...rigghhht."

[Tomo]

I may be in horrible danger of showing my ignorance here, but I was under the impression most (if not all) white LEDs where UV led's with a phosphorescent coating?

100% of "white" LEDs are a diode with a phosphor coat.

The real distinguishing features between different white LEDs are the pumping diode (near-UV to mid-blue), the phosphor mix and the phosphor deposition method.

The phosphor deposition makes a huge difference to the efficacy, while the choice of pumping diode and the phosphor mix decides the CRI, CQS and Duv.

 

- Incidentally, UV LEDs have a rather short lifetime as the UV directly attacks the encapsulation and the junction itself.

Thus they're rarely used and very expensive.

 

This is probably why Blue pumping diodes are much more popular than UV ones.

 

White fixtures vary - some are a mix of different coloured diodes, others are just sets of (possibly different) white diodes.

 

As for the lifetime thing - 100,000 hours is almost certainly the 'raw diode under perfect conditions' estimate - Tj kept at the perfect operating temperature etc - which will give a considerably better result than is achievable with a typical heatsink and fan arrangement.

- The diode manufacturer has no control over the cooling arrangements so will always quote the best possible result theoretically acheivable.

Unfortunately some fixture manufacturers just copy the raw diode info verbatim rather than making adjustments for how they've actually used them - over/under-driven, cooling system etc.

[Brian]

... will be at 70% of its original brightness after 100,000 hours of use.

£20 says it won't be.

 

I'll take that bet sir!

 

See you in 11.4 years. Shall we say PLASA 2023? 11am on the first day at the CostaBucks coffee stand outside Hall N8 at the soon to be demolished Excel Exhibition Centre where PLASA has been since 2014 after Earls Court was demolished following the 2012 Olympics.

[musht]

Hmmmm™ (claiming fair use exception)

 

So all the decades of work thats been done in the field of failure analysis, lifetime prediction, MTBF etc are all just a waste of time then. Glad we got that cleared up.

 

"lies, damnable lies and statistics"

 

Quote goes back at least 120 years ;-)

[ramdram]

Indeed DB, such predictions such as you mention are an utter, utter waste of time and bordering on fairy tales, ** laughs out loud **. You should know this anyway.

 

A manufacturer could hardly flog his kit if asked how long will this "item" work and he responded "dunno really".

 

(Sardonicism alert.)

 

Ergo a whole branch of math evolved to "prove" whatever needs to be proved. By taking known data and extrapolating or interpolating or taking a wild guess via a crystal ball.

 

Doubtless the lawyers advised the statement to include the expression "we expect".

 

We should not ignore the fact folk want to have the "next new whatever" (and even an amdram group would not be daft enough to buy old electronic kit which would be perhaps not as reliable as when new) so for all we know lanterns of the future will be as far removed from LEDs as they are from tungsten kit?

 

And who would be arsed to check out an LED fixture 11.4 years later? You could not sue a manufacturer if the output was not 70% of the original. These items will be recycled or in landfill depending where it was used...and how green a country wanted to be.

 

Plus IF a statistician WAS that good at picking winners, so to speak, then he or she would be doing just that, and "investing" in the geegees or the national lotteries.

[Nicktaylor]

Me thinks some people have lot of free time. Lucky old them! :)

[the kid]

I am sure most people saw this yesterday.

 

http://www.lsionline.co.uk/news/story/ETC-introduces-Source-Four-LED/RLGZWI

 

http://www.etcconnect.com/products.family.aspx?ID=30031

[ramdram]

Still the all encompassing 50k hour life claimed for the Leds without any qualification.

 

Why is it that the ad copywriters still produce such meaningless blurb? Shirley they don't really expect folk to swallow this tosh.

 

This is bordering on the comic:

 

ETC has already done a number of large scale tests with a number of beta sites. Armendariz-Kerr says, "Lighting designers are really happy with it. They have confirmed that we've created a useful and exciting product that people can integrate into their rigs and existing design approaches, while opening up a range of new possibilities."

 

Never see a price list either...or a comparison of cost v electricity consumption cf ordinary lanterns.

[Dom Hart]

I am quite excited by the news, it now seems that Philips and ETC will go head to head for the profile market now. This can only benifit the R&D departments, and I know that Philips Entertainment are not getting near half the funding needed in the development area currently! If these two players set the ball rolling then I believe it will be only a matter of perhaps a couple of years before we significant reductions in outlay cost and major improvements in technical ability vs cost.

 

Let the competition commence I say. I do agree though, where did this mistical 50,000 hours come from, and to what acceptable levels of lumens versus spectrum are being worked to here?