High Power LEDS

[BobJ]

Our smallish stage works (just about) OK with 6 Chauvet CORE 80s and 3 or 4 CORE 40s plus 3 ADJ 1000 Encore Ellipsoids on a (low) BOH bar. BUT! Despite all this I still don't think we get the real punch of a couple of regular washes and halogen Fresnels. The coloring of the CORES goes down well but I'm wondering what do the BIG guys actually use. Are there LED lamps that truly compete with the generic bulb ones? I keep searching but actually find very few. And comparing them is tough. e.g. a recent LED add said "100W comparable to a 1000W Halogen" True or not? i.e. if I paid out for one would it really be like a 1000W light?

[Don Allen]

I work on a ratio of 1:5 so for a 1000W halogen replacement I need at least 200W LED.

 

I gets a bit more difficult when you start looking at all in ones, e.g. a 200W 6in1 LED profile would have 30W of each colour, so 30 watts of LED colour equals 150W of halogen.

 

The thing to remember is LED's are great for saturated colours for dance and musical, but do not equal halogen for soft pastels in drama, as a generalisation.

[timsabre]

As you're using Chauvet, have a look at these LED profiles - other similar ones are available from other manufacturers. These are supposedly the equivalent of a Source 4 Jnr with a 575W lamp:

https://www.chauvetprofessional.com/products/ovation-ed-190ww/

 

And these are the equivalent of a full size Source 4 with a 750W lamp:

https://www.chauvetprofessional.com/products/ovation-e-260ww/

 

So with those fixtures 190W LED = 575W halogen which I think is more realistic than the figure you have been given.

[alistermorton]

Like Don I tend to work with 4:1 to 5:1 but that's really for whites and pastels. Once you start looking at saturated deep primaries an LED of say 50W per colour can look subjectively brighter than a 1000W PAR can with L120 because you aren't throwing away 98% of the light output in a colour filter.

[adam2]

Yes, as APPROXIMATION an LED fixture needs to be about one fifth of the wattage of a halogen light, for white.

 

Good LEDs now produce in the region of 100 lumens per watt , and halogen lamps used in theatre lanterns are about 20 lumens per watt. Both figures vary a bit so no great accuracy can be claimed, but to equal the light from a 1000 watts of halogen, look for ABOUT 200 watts of LED.

 

Those who claim that LED produces TEN times the light of incandescent may be referring to low wattage and low efficiency incandescent lamps used d0m3sticaly. A reasonable quality 2.5 watt LED household bulb may well equal a 25 watt incandescent.

 

 

 

[BobJ]

Quoted

The thing to remember is LED's are great for saturated colours for dance and musical, but do not equal halogen for soft pastels in drama, as a generalisation.

//

 

Oh Lordy - this broke my heart! We just went completely LED for our small stage where we mostly put on regular plays. I thought a lot of the big theaters going LED?

I found 100% red and backing off the G and B a bit I could come up with an acceptable light 'amber' for the actors faces. But is it true LED not really good for such?

 

 

 

[timsabre]

Rgb fixtures aren't good for pale tints, because a lot of the colour spectrum you'd get from a halogen lamp is missing, particularly in the yellow region. This makes pigments on stage (including people's skin) look weird.

Because of this a lot of fixtures add LED emitters in other colours - white and/or amber in the simpler ones, but also lime, cyan etc in the more expensive ones such as ETC Lustr. You often see them described as RGBW or RGBAW.

[ojc123]

We have a bunch of LEDJ 9P10 which are great for colours (RGBAW) and we CAN get an acceptable 'white' for regular plays. They're 100W and are about the same as a 500W PARCan when used open.

 

It isn't like open tungsten and we use the old school fresnel lanterns for that. I don't quite see the point of trying to emulate it with the LED fixtures when we've still got the original available. Quite often we use the fresnels for a smooth wash and the LED fixtures for adding colour as we think appropriate. Especially if the play is set in the past then we use a lot more tungsten. It's still anachronous if the play is set in Victorian times but it looks old so that's ok. However, the new-fangled tungsten lamps will never quite have the same characteristics as a show lit by candles.

 

I do like to see a show lit creatively with tungsten but it's what I grew up with. I wonder if there was the same discussion when we went from candles to gas, and then from gas to electric lamps? Is it just the change from our perception of normal? As LED lamps replace tungsten and fluorescent lamps in the home will audiences expect a different kind of 'normal' lighting? The lighting in my home is different in colour from what it was a few years ago but I have become accustomed to it. LED fixtures are improving quite rapidly and will surely become the expected light source soon.

 

No answers just a few questions.

[vinntec]

Quoted

The thing to remember is LED's are great for saturated colours for dance and musical, but do not equal halogen for soft pastels in drama, as a generalisation.

//

Oh Lordy - this broke my heart! We just went completely LED for our small stage where we mostly put on regular plays. I thought a lot of the big theaters going LED?

I found 100% red and backing off the G and B a bit I could come up with an acceptable light 'amber' for the actors faces. But is it true LED not really good for such?

Bob - It depends what you purchased and put in. My tiny theatre added Selecon PL1 series RGBW LEDs (profiles, fresnels and cycs) to our conventional stock several years ago. These can do face lighting really well - at about £1,000 each - but they are not as bright as equivalent conventionals. In a shootout with 650W Selecon Acclaims, a medium colour such as L111 was about the same output on both - deeper colours the LEDs win hands down. We find they are better employed providing the colours where we want them, and leave faces to the conventionals. We could turn the roles around perfectly well but then would need multiple conventionals for multiple colours or use scrollers... We didn't have the funds to do a complete conversion and I am not totally convinced that it would have been a good idea anyway.

 

It sounds like you have RGB LEDs? I will eat my hat if you can get a good face colour from those without a fourth colour or boosting with open white conventionals (which might just as well be tinted then). I have used simple RGB "Par" LEDs for back and side lighting for musicals quite a lot, and they are much better than conventionals + scrollers for convenience (even if dimmer curve might not be perfect). But not faces, except where a particular unusual effect is needed. Punch a deep colour with LED possibly from the front plus a conventional special picking out a singer - brilliant - but not by themselves.

 

It also depends on what you had before! If this replaced lighting that had sat in the rig year after year with gels burned in and never cleaned, then you might get away with it more easily!

[Tomo]

LEDs are (for the most part) narrowband. Red and Blue LEDs are very narrow - often only 10nm @ 50%

 

An RGB LED fixture has a bright red, green and blue but it is physically incapable of producing yellow, cyan, lime etc light.

 

That means any pigment that would reflect yellow is dark, because there's no yellow light to reflect.

 

The result of this is that when shone onto skin and paint they "pick out" individual colours, making them very bright, while the colours in between are simply absent.

This gives a really strange effect. Skin looks 'dead', because there's no depth of colour.

 

- In the extreme example, a backdrop painted yellow can appear almost black!

 

To avoid this, you need other colours of LED, either lots more narrowband ones or a smaller number of wideband ones to "fill in the gaps".

 

White LEDs are (usually) made by taking a blue LED and coating it with a wideband phosphor that glows yellow.

Amber and Lime are also (often, but not always) made using wideband phosphors, thus filling out important bits of spectrum.

 

Don't forget that all of this can be of course be used for artistic purposes - there are many quite magical effects that are only possible with LED.