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This article was automatically translated. ORIGINAL

Different light, vanishing magic

What did halogen lamps mean for the theatre? Can technology replace them?

Oscar Frosio

Lighting Programmer
16th January 2021

1September 2018. A day like any other, for almost all people... not for the European Theatre. That day is remembered as a "melancholic" day. The moment when a fundamental element of the technical and artistic journey of modern theatre, present since the arrival of electricity, retires. Like all the most precious workers, with their pockets full of anecdotes and stories, it was also her turn... the halogen lamp. Perhaps most people will laugh when they read something like this, almost as much as I do, after all, what are we talking about? A light bulb that retires? well... yes, that's exactly what it is... 1 September 2018 is the day on which the section of the EU Directive 244/2009 that prohibits the manufacture of the halogen bulb comes into force, and now that we have opened the door to 2021 even the specialist shops are struggling to find that type of light source, between old factories surviving and equally old stock lost and dusty. But exactly what is the problem? In this article I will try to explain why the European Theatre, and especially its lighting designers, have become a little more "melancholic";  from 1 September 2018 thinking of her, now at the count-down, together with her magic.

 LED: An infinity of objective advantages

I won't open a long chapter on the objective advantages of this choice in terms of energy and economic savings. Suffice it to say that in a Europe without halogen lamps, but almost exclusively LEDs and energy-saving lamps, we would save as much electricity per year as Portugal, not to mention almost 15 million tonnes less carbon dioxide than is usually emitted into the environment by 2025. For the end user, who literally has to take the ladder and change the burnt-out lamp, well, he too will notice a big change: if he buys a good quality LED lamp for just under 20 euros, he will be able to store the ladder in his closet for at least 7 or 8 years, if not longer. And maybe with the money he saves from buying bulbs all the time he might choose to go to a concert, or a show.... at least I hope so...


Warm white... cold white... what does that mean?

I'm sure you've all bought an LED lamp at the supermarket, in an electronics shop, on the internet... well, what's one of the things that (I hope) most people overlook when buying? the famous words "warm white", "cold white" or "neutral white". It is very simple to explain: warm white is the colour that tends towards amber, cold white tends towards blue, and neutral white is more or less the same colour as a white sheet of paper seen in sunlight, so a very balanced white (not too warm, or cold, in fact). Any halogen lamp developed for theatre projectors, by physics and construction, emits a light that is somewhere between neutral and warm white [3200 degrees Keelvin]. Manufacturers have always tried to make this light source as neutral in colour as possible, but for a number of technical and physical reasons it always tends to be warm, or 'yellowish' in other words. This is also the case with the lamps that until a few years ago filled our homes, restaurants, libraries, places where we spent time, public and private buildings with light.I'm sure you've all bought an LED lamp at the supermarket, in an electronics shop, on the internet... well, what's one of the things that (I hope) most people overlook when buying? the famous words "warm white", "cold white" or "neutral white". It is very simple to explain: warm white is the colour that tends towards amber, cold white tends towards blue, and neutral white is more or less the same colour as a white sheet of paper seen in sunlight, so a very balanced white (not too warm, or cold, in fact). Any halogen lamp developed for theatre projectors, by physics and construction, emits a light that is somewhere between neutral and warm white [3200 degrees Keelvin]. Manufacturers have always tried to make this light source as neutral in colour as possible, but for a number of technical and physical reasons it always tends to be warm, or 'yellowish' in other words. This is also the case with the lamps that until a few years ago filled our homes, restaurants, libraries, places where we spent time, public and private buildings with light.


Adjusting the intensity, the beginning of “magic”

When I was a child, I had a small Abat-Jour on my bedside table. I could adjust the brightness of the lamp by means of a small wheel on the electric cable, and when I was falling asleep, I liked to keep it on at a very low intensity. It reminded me of exactly the same light as a candle. And that's the crux of the matter: filament lamps, and therefore halogen lamps, are able to change colour at the slightest change in intensity. They do not reproduce the warm amber colour of a candle at all, but rather the "neutral-warm" colour we were talking about earlier. But if you have the possibility of varying the intensity of those lamps, for example by bringing them to half of their luminous potential, or even less, you will notice perfectly that the colour changes, a lot. For years and years, the theatre has been making light on the basis of this assumption: a lamp is able to emit a certain colour in relation to the amount of light it produces, and the more we vary the intensity, the more the colour changes: downwards the colour tends to warm, upwards the colour tends to neutral.


Why did halogen lamps arrive in the theatre (and in our homes)?

The answer is very simple: money saving, less pollution and more energy efficiency. The same reasons that are now retiring the very ones that brought a breath of innovation to the world of light at the time. The first lamps, called 'balloon' or 'pear' lamps because of their shape, were simple vacuum metal bulbs containing a filament that produced light when heated. Why not continue with this method? The first reason is that the filament lamps were extremely delicate, which made them totally unsuitable for theatrical use, i.e. in a place where projectors [usually wrongly identified as 'spotlights' by the public, but in the theatre everything that is designed to emit light and illuminate people, objects, scenes, is called a 'projector'] were (and are) constantly being assembled, disassembled, used and modified, even when on. All this would almost certainly have broken the filament, leading to a replacement of the lamp, with an unspeakable waste of glass, metal, time and money. In addition, by their very nature, they were extremely short-lived: they lasted only a few months, even without ever being touched, and turned on/off with the utmost caution (among other things, in the theatre it happens very often to have to do "sudden" lighting effects, which would significantly affect the filament and shorten its already short life). This is where the halogen lamp comes into play: through a mix of chemicals in the glass bulb, which is also thicker and stronger this time, science has been able to significantly increase the life and robustness of the lamps, not to mention the energy efficiency, as the halogen lamp filaments are able to emit more light, in a more stable and extremely high quality way. All of this has made a huge leap forward in both theatre and domestic lighting technology. In the theatre, there is a fundamental need: the lamps must be able to emit a large, sometimes very large amount of light (in technical terms, the halogen lamps used for a conventional projector with Fresnel lens start from a power of 1000W up to 5000W and more, while a halogen lamp used in a domestic environment has a power of 100 to 300 watts maximum).


Theatre: The intensity, the colour, the reaction time of the filament

We are coming to the end of our short journey through the history of the halogen lamp. There is only one piece missing to conclude it all: What happens in the theatre when I vary the intensity? Because yes, as long as we play with the lamp on our bedside table we see a change of colour towards warmth, but we also notice that the brightness drops to the point where we can't see anything at all... and this is obviously not acceptable in theatre. Over the years, the theatrical world has worked with this condition in mind: lighting projects were made in which the projectors were arranged with this type of problem/advantage in mind. Because the lighting designers knew that if they wanted to create a colour tone at a certain point in the show based on the lamps alone, without artificial colours, they would have to put in many more floodlights, so as to lower the intensity without affecting the total amount of light too much. Just think, the lights of so many shows have been studied and conceived starting from these concepts (see for example Kylian's choreography "Petite Mort", as well as many other works of his): Theatrical works conceived with the only use of "white light", whose colour would then vary according to the intensity, depending on the characteristics of the lamp and the projector, and obviously with the experience of the lighting designers. A last but important feature is the reaction time of the filament: with "small" lamps, the domestic ones, it turns on and off in almost zero seconds, or at least a time only slightly perceptible to the naked eye but... think of the filament of a lamp that has the same power as an entire flat (i.e. a lamp that absorbs the same electricity as a dishwasher, a refrigerator, an electric oven and a microwave oven all together...): the filament is literally much larger, and the time it takes to heat up to emit light as well as the time it takes to cool down to turn off is almost half a second, if not more. Entire shows have been built around these features, and rules and methods have been written to try and minimise this when it has been an impediment to the lighting design.


Is it possible to use an LED lamp? Maybe put a colour on it?


So far there is no LED lamp, not even in the professional sector, that can give us the same effect as incandescent lamps. If we put a colour in front of a lamp, the problem would not be solved: if we change the intensity of an LED lamp, we would still have the same colour throughout the entire light range. There are quite complex systems, called "LED multi- colour engines" or "multi-colour chips" made up of several LEDs (5, 6, 7 or more LEDs with different colours), which seem to be starting to mimic the behaviour of halogen lamps, but there is still a long way to go. However, one problem remains obvious and insurmountable: however promising the result may be from a chromatic point of view, it is not a filament that physically heats up, but an LED source regulated by a digital algorithm.


Lamps retire, even their magic.

We have come to the end of this article. After so many examples, data and anecdotes, I would like to focus on this much-quoted 'magic'. What does it actually mean? Where does the nostalgia for these lamps come from, apart from the characteristics already mentioned that we will not find in LEDs? It's all very simple: as advantageous as it may be and as artistic and unique as it may be, LED light is extremely artificial: it is a pure human invention. The halogen lamp filament is not. As much as it is man-made, it is extremely sincere and natural in the way it emits light: it heats up as electric current passes through it, it becomes incandescent, it does the same thing that candles do. We see the light as it comes into being, we can 'touch' it. It is a profoundly different process from the emission of LED light, and the difference, in the air, on an object, a fabric, or even more so on human skin, is substantial: LED light simply illuminates, incandescent light envelops, caresses, brings out skin tones, complexion. Incandescent light in a classical ballet makes the bodies of the dancers "vibrate", just as it can be narrative, joyful, but also dramatic. It is 'complete' with all the chromatic frequencies necessary to bring out any colour, any object, without making anything 'electric' or 'saturated', limiting itself to returning to our eyes what is reality and therefore the will of a scenographer, or a designer to make us see things in a certain way. We have always been used to seeing incandescent light as a fascinating and unforgettable light... Now it is time to turn over a new leaf, now comes innovation. But we have to remember that sometimes technology should keep in mind the past, the history, to bring progress but not necessarily radical change... especially where one thing was perfect, where technique became art. Where light was synonymous with magic.


Oscar Frosio


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