Why do we use so much lighting?

[karl]

This probably seems like a really daft question but it's been bugging me, on and off (no pun intended), for a while.

 

Imagine a 7m x 5m room in a house. To light it at night you might have one central ceiling fixture, a few wall lights and may be a couple of table/standard lamps. In total they would probably use well under 1Kw (even with non energy saving bulbs).

 

So how come a box set of similar size on a stage will often require > 20Kw of lighting?

 

I've tried to figure out this discrepancy many times but can't come to a definite conclusion. Is it because in a real room light gets bounced around from surface to surface but on a stage light can escape due to the lack of a ceiling and fourth wall? Or is it because in a real room the lighting is for the benefit of people in the room (close by) whereas in a theatre the viewers are further away? Could it be related to theatre lighting being more directional?

 

Can anybody illuminate me on this (pun intended!).

[timsabre]

Or is it because in a real room the lighting is for the benefit of people in the room (close by) whereas in a theatre the viewers are further away?

 

This one, I think. Brightness diminishes by the square of the distance, so if you are a way off it needs to be a lot brighter to look "normal".

Also your 20kw, or whatever, of light is often not used at full or is not all on at once, or is pretending to be the sun coming through a window.

Interesting question though.

[paulears]

It's because your room in your house looks like .... a room in a house. It's usually a bit uninteresting - a ceiling light provides illumination - and with a shade, it's quite even and soft. On stage we're creating the illusion - so light and shade are important. Shadows can be deliberate or a problem to be solved. In your house most people will be looking at other people lit from above so you can see faces. On stage the audience mean light from the front. Light from the front spills onto your set, so if you don't want shadows of bigger people on your set - very unrealistic, you'll have to fill them. This makes the set brighter, so you need brighter front of house. Mood changes, so maybe light has to come in from the window - it has to be a certain brightness, and then you have to consider the audience has width - so the edges have to be able to see the actors - so in most cases, lighting is split left and right, doubling everything. On TV and film, you may be able to light for a single viewpoint, and this means maybe 3 or 4 lights could be enough. Multiple viewpoints in theatre are different. On top of this we have extra for effects, and so on.

 

You could (and it's been done fairly often) light the stage with a single point source - a 100W single domestic bulb. After a minute or two your eyes adjust, and it looks quite bright. However, there will be plenty of shadow. If you want this bare Brechtian look - then fine. Trouble is, there will be stair lighting, exit sign lighting and other distractions in the audience - which could be brighter than the on stage light - and the eye gets drawn to the brightest source.

 

If the show requires emphasis to shift during the proceedings, then you're into lights for areas, focused tighter, increasing the number again. In your living room, how would you do the Agatha Christie plot point when the lighting subtly changes leading your eye towards the villain slipping the poison into the victims handbag?

 

There are cases for having simple lighting, but what can you do with one or two light sources? Switch one off? What would the result be?

[karl]

Tim, the inverse square was my first thought but a couple of things made me question if this alone explained the effect.

 

Firstly if I put the lights on in my front room at night and then go out to the other side of the road and look back I don't find myself thinking "My goodness it's dark in there, I can hardly see a thing." Secondly I always wander around the auditorium during the tech to check the lighting from various locations. I can't remember thinking that it's too bright when I'm at the front of the auditorium and then that it's too dark when I move to the back.

 

I guess this could be a combination of the way our eyes work and how are brain 'corrects' for different circumstances.

 

Paul, it's not so much the number of light sources that puzzles me but the amount of light. I've often thought how odd it is that we put so much effort into trying to create nice even lighting on sets when in real life you'd rarely get such smooth coverage.

[Nicktaylor]

Well your first lighting experiment should be hang a 100w bulb in the middle of you set with nothing on and then get some one to walk around while you look at it from the audience!

 

Tim, the inverse square was my first thought but a couple of things made me question if this alone explained the effect.

 

Firstly if I put the lights on in my front room at night and then go out to the other side of the road and look back I don't find myself thinking "My goodness it's dark in there, I can hardly see a thing." Secondly I always wander around the auditorium during the tech to check the lighting from various locations. I can't remember thinking that it's too bright when I'm at the front of the auditorium and then that it's too dark when I move to the back.

 

I guess this could be a combination of the way our eyes work and how are brain 'corrects' for different circumstances.

 

Paul, it's not so much the number of light sources that puzzles me but the amount of light. I've often thought how odd it is that we put so much effort into trying to create nice even lighting on sets when in real life you'd rarely get such smooth coverage.

The inverese square law is more about the amount of light reaching the subject. Not how much light you can see reflected as a scene. ie double the distance from source to object and the amount of light reaching it will quarter. So double the distance of you bulb in the living room then say the lighting has not changed

[paulears]

I suspect in a room, a 60W lamp bounces around in modern pastel rooms so much there aren't many shadows. My old grannie used to have dark flock paper on the walls and despite a 150W lamp it always looked dim. Path from lamp to object ok, but no bounce from the walls. The inverse square law does show how much you have to increase the source as just a few metres get added to the path length. Mind you, it's quite popular in opera to have a huge single backlight for the main lighting, and that never looks bright, does it?

[gordontech]

Some lighting designers can use far far less lighting then the norm to create some amazing effects. Theres a show going in to the southwalk playhouse which isnt using more then practicals and a very clever lighting designer. But I totally agree with the above

[karl]

The inverese square law is more about the amount of light reaching the subject. Not how much light you can see reflected as a scene. ie double the distance from source to object and the amount of light reaching it will quarter. So double the distance of you bulb in the living room then say the lighting has not changed

But the light reflected from the subject (which is what enters our eyes) is also subject to the same rule. The further away the subject is from your eye the less reflected light you'll see.

 

Some lighting designers can use far far less lighting then the norm to create some amazing effects. Theres a show going in to the southwalk playhouse which isnt using more then practicals and a very clever lighting designer. But I totally agree with the above

I have had occasion to light a stage using a single practical and it can certainly be very effective. But generally, where we want to replicate 'real life', we finish up using significantly more than you would to light a real room of the same size.

[mark_s]

Something that no one else has yet mentioned is colour - we also need lots of power to get anything worthwhile out of a lantern coloured with something saturated. Maybe not so much a factor in an entirely naturalistic play, but in a significant amount (even a majority?) of shows, saturated colour will feature somewhere.

[Ashley R]

And what about those odd occasions that we are trying to replicate the sun? Well we all know how bright the sun is. SO if we lit the stage with 1x 100w Lamps. You would need straight away 20x 100w Lamps to imitate the sun.

 

And then you want to break up the stage into individually lit areas, have a few specials, a few gobo's - These would have to brighter to punch through the rest. and tada 20kw! (Although yes You can chew up 5kw quite easily trying to do a heavy green or blue wash that looks equal to the original OW Wash, so there's another 10kw gone)

[nothingatall666]

Compared to the TV and film world, theatre doesn't use many watts at all..

 

 

the sun is the brightest light source around.. many plays are set in the day time, theatres are usually windowless so it takes some wattage to make it seem like the day time..

 

and then of course there is the problem that if it is not set, then the rest of a stage is black.. a awful reflector compared to the close proximity walls in a home so that means double (or even better - triple) the amount of light needed for one 'general light'

[gyro_gearloose]

Something no one seems to have mentioned yet is that part of the reason we need X amount of Kilowatts is that theatre lamps 'throw away' most of the visible light that their lamps produce. Have a look inside a Fresnel. Any light coming from the lamp that doesn't hit either the lens or reflector is wasted light that never reaches the stage, and this gets worse depending on how far you've got the lamp 'spotted down' and how much the beam is shuttered off by the barn doors.

[Just Some Bloke]

Is it because in a real room light gets bounced around from surface to surface but on a stage light can escape due to the lack of a ceiling and fourth wall?

 

I thnk you've almost hit the nail on the head here, yes. In my house I bounce light off the ceiling in several rooms in order to soften and radiate the light more - I get a more even spread of light with a much nicer texture to it. In theatre there is no ceilng (normally) and no fourth wall either, so we are unable to use large white spaces to reflect light. What there is, instead, is a host of thngs we DON'T want the audience to see: we don't want them lookng up into the flys, at the lighting rig, at how the set is held up, at where the sound effects are coming from, at anything at all forward of the pros, into the wings and, for many shows, at areas of the stage where nothing is happening. This means that rather than spendng our time spreading the light around all areas evenly, as we would in our living rooms, we are doing the exact opposite and concentrating on areas we're not lighting. In order to keep light out of the wings, flys, auditorium etc. we need to make each light beam smaller than we would otherwise want and this means joining lots of smaller beams of light together to look like one big beam.

 

The situation is made worse, of course, when lighting in-the-round when we have to bring light in from all 4 sides so every member of the audience sees as well as the next person, and this means even more lanterns pulling an even greater wattage!

[adam2]

To add to the points above, remember that if normal d0m3stic lighting is used as practicals on a stage set, that higher output lamps will normally be required.

 

For example if a living room lit by a single pendant is to be simulated on stage, then a much higher output lamp is desireable in said pendant than would be used in the home.

Most of the light would probably come from suitably directed stage lighting lanterns, but the d0m3stic pendant should be bright enough not to look washed out or insignificant..

[kerry davies]

Simply put if you used one single light source from the audience viewpoint the scene would look completely flat, or two-dimensional. To gain perspective the scene needs modeling.

 

Take a sphere and throw a light straight onto it and it looks like a circle, chuck in two front lights at 45/45 and a key light and lo and behold it becomes a ball.

 

You can light a scene adequately from an illumination PoV with three or four floods but the more subtlety and creativity that you desire, the more available sources you require. Lighting moving objects (actors) in 3D means we need as many angles of light source as possible. We never use them all at once but they are needed creatively.

 

Lantern output and the size of light sources depends on throw, audience size, venue dimensions and lots of associated stuff including directors and designers choice as others have mentioned.

 

The main thing to remember is that grannies flock covered lounge normally has a huge reflector called the ceiling throwing three dimensional light everywhere.