Lighting – a short walk through the minefield of location lighting for Film & TV
This is a short article examining the most popular lighting fixtures and technologies concentrating on their advantages, limitations and applications. As with all such equipment the pace of change and development can sometimes disaffect the end user who will understandably stick to known and trusted tools rather than seeking out new fixtures and technology which are now available. It is equally the case that just because a piece of lighting kit is introduced with a new feature or bulb technology it doesn’t mean that it is intrinsically better than existing lamps in terms of cosmetic performance and indeed may fall well short of fixtures that have been around for more than half a century.
Whilst it is also the case that manufacturers want us to buy the new kit and they use the technology advancements as a marketing tool, it is certainly true that there is a drive for electrical efficiency and portability which is percolating down to the end user and making life easier on some difficult location shoots. This can be seen as a bit of a seismic shift from traditional Tungsten Halogen and HMI/MSR mains fittings to LED and LED Remote Phosphor units that are much more efficient in terms of their power requirements, allowing virtually all LED lamps to be able to run on battery power which as a consequence improves portability and set up times.
This is our view on the most popular fixtures and main lighting technologies available at the time of writing and is split into three sections, concentrating on the various categories of bulb technology, fixtures and fittings and finally a small section on some common usage.
We have also focussed on discussing equipment that is mainly portable and therefore lends itself to location use rather than permanent studio or theatre applications
There are several useful links at the end of this article, including a link to the excellent BBC guide to low energy lighting for those who wish to learn more plus some useful videos as well.
Section 1: Lighting Technology defines the 4 main categories of lighting technology (Tungsten, HMI, Fluorescent and LED).
Section 2: Fixtures and Fittings then explore the differences between hard lighting vs. soft lighting; open face lamps vs Fresnel lamps; Soft lights and beauty lights and accessories
Section 3: Common Lighting Setup Examples introduces some common interview lighting setups.
Section 1: Lighting Technology
1. Tungsten Halogen Lighting
Tungsten is the most traditional form of TV/Film lighting still in use having replaced expensive and dangerous Carbon Arc fittings over the course of the last half a century. It produces light incandescently based on being heated to a high temperature by an electric current and is based on a filament made of tungsten sitting in a bulb that contains iodine or bromine (the halogen bit). The halogen gas produces a chemical reaction with the decaying tungsten particles which encourages them to re-attach to the filament thus prolonging the life of the bulb.
Tungsten lighting is less popular today than in the past due to the availability of modern alternatives, although tungsten light has some very useful qualities which are highly valued by cinematographers. In particular, tungsten generated light has a very even and continuous colour spectrum which allows for very smooth dimming although there will be mired shift (colour temperature shift) to the red end of the spectrum as incandescent lamps only glow as a by-product of heat and therefore reducing the electrical current will reduce the heat and the glow will become more red. This can be an advantage when wishing to emulate candle light or other such warm natural sources and which is why despite being inefficient and hot on set (a 2000w blonde fitting emits the same heat as a 2 kilowatt heater) they remain a popular and versatile tool.
Tungsten fixtures are almost without exception mains-powered, as the power draw required is too high for battery applications and you may think that the incandescent nature of the light would be suitable for high frame rate shooting. However, because the electricity supply is AC, the lamp is switching off 25 times a second (based on 50Hz supply) and so any frame rates above about 100fps will be able to detect this rise and fall of the glow and it will be seen as mild strobing.
The light generated has an orange hue of 3200K, which can be colour-corrected to match daylight using blue (CTB) gel but with a very large loss in light output.
• Cheap fittings and bulbs
• Full spectrum of colour (no spikes or greenish hue)
• Stable colour rendition
• Wide selection of fixtures, including open face and Fresnel
• Small size of light source and direction control of light output
• Smooth dimming
• 3200K colour temperature only,
• Daylight correction will cut the light output by approx. 1 2/3 stops
• Generates a lot of heat (around 95%)
• Mains power only
• Short service life of the bulb
• Not very good for high speed photography
The most popular tungsten fixtures are 2K 'Blonde' (shown right), 1K, 800W 'redhead', 650W Mizar, 300W Mizar, Dedo 150W and Dedo Panaura Octodome
2. MSR/HMI Lighting
HMI/MSR lighting uses a different process to produce light than tungsten filament lighting and is effectively an arc lamp based on heating mercury vapour across 2 tungsten electrodes. As a consequence of this system, the same wattage HMI/MSR bulbs produce a higher light output than an equivalent tungsten filament and with less waste heat output they are demonstrably more efficient. However, HMI/MSR fixtures still generate a lot of heat and with rare exception, they can’t be powered from batteries due to the very high power draw required particularly during start up when high voltage is needed to get the arc struck.
HMI (Hydrargyrum Medium-arc Iodide), and the more recent variant MSR (Medium Source Rare-earth), are very well established technologies. Although there is a distinction in the name, the type of light generated is identical.
Similarly to other mercury-based high intensity discharge lamps, HMIs generate ultra-violet light, so each HMI light must have a UV safety glass cover used for protection. In fact, an unprotected HMI lamp can cause severe burns to a subject so as a consequence all fittings have a no-strike safety feature if the cover glass is not properly closed. HMI bulbs will last for about 1000hrs of operation and most fittings will have an hours of operation monitoring system to allow the user to gauge the remaining life.
HMI/MSR lighting fixtures require a separate ballast to work as it is this that absorbs the negative part of the AC current and it is also the ballast which permits the dimming function (which because of the nature of the lamp does not affect colour temperature in the same way as incandescent fittings). High Speed square wave ballasts permit frame rates of up to 1000 fps without experiencing a flicker effect, but above this fps you will need specialist fittings to avoid flicker.
• Daylight colour temperature
• High light output fixtures
• High colour rendering (no spikes or greenish hue-unless the bulb is nearing the end of its life)
• Wide selection of fixtures, including open face and Fresnel
• Can work with high speed photography (must use high speed ballasts)
• Generates large amounts of heat
• Heavy and large fixtures
• Mains power only for almost all fixtures (except for 200W pocket par)
The most popular fixtures are ARRI 1.2K HMI (shown right), 575HMI, M18 1.8K HMI, and 200W MSR but HMI lamps can be up to 18K and the largest lamp to be able to be plugged into a domestic 13 amp socket is a 2.5K HMI.
The new Photon Beard 1.2K HMI (shown right) is an open face version of the popular 1.2K but housed in a ‘blonde’ style housing borrowed from a very popular tungsten lamp design. The absence of a Fresnel lens means that the light output is increased (due to less optical loss through the lens) and the weight and size of the fixture is reduced as well.
Fluorescent lamps are low-pressure discharge lamps that work by using mercury to emit ultraviolet (UV) radiation. This is converted into visible light by fluorescent substances (usually phosphor based) deposited on the inner surface. An inert gas fills the tube making the ignition easier and controlling the discharge. This method of producing light is several times more efficient than incandescent fittings with the same light output.
Fluorescent lamps produce diffused light from a large surface area, making them a popular option when soft or cosmetic lighting is required and as a consequence, compact fluorescent lighting is widely used in all productions, to the extent that because of the similarity to domestic fittings, these lamps often appear in shot as part of the light source.
Although fluorescent tubes are available in many colours, they are generally supplied in matched daylight (5600K) and tungsten (3200K) colour temperatures to enable use in varied environments. To change the colour temperature of the lamp you simply change the tubes inside the fixtures which also means you can mix and match to obtain a colour temperature somewhere between the 2 if you so wish.
This high efficiency means that fluorescent lighting fixtures are much cooler when running than equivalent tungsten and HMI lighting. Unfortunately, most fluorescent lights are not sufficiently efficient to be battery powered. Although there are some smaller fluorescent fixtures that have this capability, though these are still the exception, rather than the norm.
Electronic operation is used to ignite and dim fluorescent lamps. It is worth noting that dimming to less than half the lumen output produces a visible colour shift but from 50%-100%, the colour temperature is even. Also, whilst some fluorescents offer flicker-free operation, most fluorescent fixtures are not suited to high speed photography, as flicker will be visible.
One common feature is that fluorescents ignite immediately and reach their full luminous output after a short interval (around 1 - 2 min) and an immediate re-ignition is possible if the current is interrupted.
Architectural fluorescent lighting fixtures seen in offices and other commercial applications will often have a noticeable green tint due to the mercury element required for operation. For this reason, fixtures used in the film and TV industry use specifically designed colour corrected lamps that counteract the green spike created by the mercury element and make for a very pleasing colour for skin on screen, so be wary if you are combining TV lighting with location office fluorescent lighting-hence why some of these lamps appear in shot as they are the correct colour temperature.
Daylight balanced fluorescent T8 & T12 bulbs/tubes are often used in fashion photography and shoots due to their colour quality and soft light quality.
Popular fluorescent lamps are the 4' x 4' Kino Flo, 4 x 2Bank Kino Flo, and Kino Flo Diva 400 (shown right) and it is worth mentioning that the popular large 4x4 Kino Flow has the same output as the more portable Diva 400, which is half its size. The more modern Kino Flo Tegra (shown right) offers a very high 1K tungsten-equivalent output and more convenient wired remote ballast/dimming module, for easy operation when the lamp is mounted up high. Other smaller portable battery-operated flourescent lamps include the 15" Mini Flo and 9" Micro Flo versions.
• Daylight and tungsten matched colour temperature tubes available
• Efficient technology mean that lights run cool
• High Colour rendering
• Soft due to diffused light from a large surface area
• Mostly mains power operation.
• No spot sources possible with this technology
• Physically large fixtures
• Colour shift when dimming below 50%
4. LEDs, bi-colour LEDs and remote Phosphor LED
LED technology (Light Emitting Diode) is a product of the semiconductor, industry which until the mid-80s was only used in instrument panels as warning and operating lights but the technology has gone through some exciting recent developments to produce some significantly advantageous fixtures, which offer such features as infinitely variable colour temperature, full range dimming without colour shift, both spot and soft lighting fixtures and also high light output too in fittings that are portable and battery operable. LED arrays require DC electrical current which allows for battery power to be used and also as a consequence of always being ‘on’ are very useful for high frame rates as they do not produce any flicker.
LEDs can be expensive and it is worth spending the money to buy the very best fixtures, since these offer superior performance over low cost ones. If you have been put off by early examples of this technology then the very latest lights are really worth looking at as their performance and functionality have improved markedly over the past two years. To give an example, the Rotolight Annova V2 (shown right) offers the same output as a 1K tungsten light, yet offers fully adjustable colour temperature adjustment and permitting battery operation and is also fully configurable and remote operable via an iPhone - you can even control and dim multiple lamps if you wish. The Rotolight Neo shown beneath, also offers location lightning and TV effects as well.
LEDs are extremely efficient, so for a given power draw they emit a much higher light output than the equivalent tungsten or HMI technologies up to 100 lumens per watt. With the increasing popularity of LED fittings in the home, this technology is manufactured on a global scale, therefore standards are hard to control and as a result each batch of LEDs can generate a slightly different hue of light to the next. Whilst this is acceptable for the home, this can be a problem for film and TV.
It is little-known that individual LEDs cannot supply true white light alone, so as a result, groups of multiple colour LEDs are used in arrays deploying some clever electronics in order to create a consistent colour temperatures, including perfect 5600 white light. The use of different colour LEDs enables the colour temperature to be varied across a very wide range from approx. 2000K-6000K.
Five years ago it would be unheard of to see lighting professionals using LEDs on high end commercials or feature films, but in the last two years LED lighting fixtures are on most big budget productions. LEDs are now deployed heavily into the art department for film and especially in the Sci-Fi genre. Production designers can build LEDs into a set which are partly responsible for lighting the scene and the talent. So even architectural LEDs for this application must be subject to very high colour rendering and quality control.
Another factor helping to push the development of LED technology forward is the fact that the modern camera sensors are extremely light-sensitive and this has been met with a rise in lower power lamps. LED technology provides very fine dimming capability to almost 1% of their output without any shift in colour. This is an impressive achievement in the technology and will no doubt improve as the technology develops.
Measures are being taken by some organisations, including the European Broadcasting Union to assess the performance of new LED products so that the industry understands the particular limitations of each lighting product. We have included a link at the end of this article which details some of the lighting fixtures that have been tested.
There are 3 basic LED lighting technologies for the film and broadcast industries:
Fixed colour LED or Phosphor conversion
LED lighting fixtures can either have variable colour temperature or be fixed at one colour, hence fixed daylight or tungsten lamps.
Mobile news crews will often use single colour daylight balanced units as they are cheap, have a high light output, and are great to use to balance to sunlight. This gives the user a fighting chance to evenly expose an image in situations where bright sunlight is falling on the subject or the background. This LED technology applies a phosphor coating that is used on or near the LED to produce coloured light. The method to produce the single colour is to coat the LED with a dye is effective but can erode over time if the lighting unit has poor heat management and the colour consistency of the LED will eventually be compromised.
The Photon Beard Daylight Redhead LED light (shown right) is a modern version the traditional Redhead which offers an output equivalent to a 400W tungsten lamp in accurate tungsten or daylight colouyr temperature using LED RP technology. Like the conventional Redheads, it is small, convenient and offers directional flood/spot to a degree and of course, unlike the original, can either be mains or battery powered.
Bi-Colour LED or RGB
Bi-colour LEDs exist for more demanding film and broadcast applications which allow the user to balance to daylight and tungsten colour temperatures. These units are normally more expensive than single colour units due to the additional technology required for colour change and balancing.
Early versions of bi-colour LED units used Red Green and Blue LEDs to create white light but modern versions use subtle colour variants of LEDs to achieve the same result but with greater control. Each coloured LED is then tuned to a different output to help create different colour temperatures between tungsten and daylight.
The Fiilex P360 bi-bolour LED lamp kit shown right is a very small but punchy focussable LED, which is a suitable alternative to the popular Dedolight kits. It is sufficiently small to be supplied in a 3-head kit with fresnel lenses and softboxes and travel easily. The heads offer fully accurate and adjustable colour temperature and of course are dimmable and offer battery/mains operation as well.
Phosphor conversion using Remote phosphor (RP)
RP LED lighting fixtures use an array of blue LEDs mounted a few centimetres from a single removable orange filter to produce perfectly colour-tuned 3200 or 5600 soft light (or indeed other colours too, if available).
This produces a large amount of soft light and does so without producing undue heat, due to the lack of proximity of the filter from the LEDs.
The phosphor filter also acts as a soft diffuser, which removes the multiple shadows which can be caused from conventional LED light panels.
The Area 48 superbright Phospor LED lamp (shown right) use RP technology to produce a head which offers a light output comparable with a 2K tungsten Blonde light, in a smaller more convenient housing, however has the advantage of also being battery operable, as it only draws 150W. It is supplied with RP filters to match the colour output to either daylight or tungsten temperature and will fully dimmable down to almost zero.
• Highly efficient, requires very little power to be operated
• Operated using DC battery power as well as AC mains power
• Can be tuned to many different colours with the turn of a dial
• Lamp life is extremely long around 30,000 hours
• Colour quality can be inconsistent
• Commonly supplied in 1x1ft square panels due to thermal dynamics issues (however this appears to be changing with improvements in the technology)
• Lamp life and colour are affected by over-heating of the LEDs and must be controlled for optimum lamp efficiency
Popular LED fixtures include the ubiquitous 1x1 bi-colour Litepanel, its replacement with more than twice its light output, the Litepanel 1x1 Astra, LED Sumo 100 (see more below), Photon Beard 'LEDHead', Rotolight Annova V2, Rotolight NEO, Area 48 superbright Phospor LED, Fiilex P360 LED Kit and the very small Litepanel Micropro kits.
Section 2 Fixtures and Fittings
Hard Lighting vs Soft Lighting
Lighting is commonly defined to be either ‘hard’ or ‘soft’ depending on the clarity of the shadows produced from it.
A hard light is any light that produces a hard shadow with a clearly definable edge when hitting an object, whilst soft light produces very soft indistinct shadows.
Soft light is more flattering light for faces, as hard shadows will draw attention to skin blemishes and both are usually used to light sets together.
Open face and Fresnel fixtures qualify as hard lights, but can be augmented with accessories to produce a soft light quality.
Despite the unflattering look on skin, hard light is perfect for shaping and controlling to help motivate objects in a scene or in the background, so are often used as back lights, background lights or to create mood as there is a sharp contrast shift between the ‘heat’ of the light and the shadow that surrounds it.
Open Face vs Fresnel
Open Face lamps, such as the traditional “Redhead” or “Blonde” tungsten lamps (shown right), have a bulb without a lens and the hard light produced can be roughly focussed with a basic flood/spot control to move the bubble forwards or backwards towards its rear reflector.
Fresnel lamps (pronounced fra-nel after Augustine-Jean Fresnel designed them for use in lighthouses and shown below) are similar to open face lamps but include a focussing lens in front of the bulb and this offers much more accurate focus capability without significantly reducing the output as the Fresnel lens is much thinner than an equivalent simple lens.
Either types of these lamps can used to bounce light onto a white wall, ceiling or poly board or to punch through a silk, diffuser or soft box in order to soften and broaden the quality of the light without compromising on high levels of output
Open face lights advantages
• Simple design
Produces a sharp edged shadow
Open face lights disadvantages
• Fixture gets very hot
• Bulbs blow easily
• Difficult to control light direction
Fresnel lights advantages
• Have a protective housing and front lens in case of bulb failure
• Produce an even and direct beam
• Are easy to control and soften
• Wide variation of beam angle control
• Beam can be augmented to create background shapes
Fresnel lights disadvantages
• Expensive comparatively to open face lights
• Get hot
• Bulbs can be expensive
• Heavier than open face fixtures
Soft Lights and Soft Light Accessories
Simply put, the larger the emitting surface, the softer the light produced from it.
As already mentioned, whilst soft lighting offers very flattering light, you necessarily need a lot of light output for it to be effective. Ideally to qualify as a soft light, the source should be larger than the subject it is lighting in order to create a wraparound effect and producing natural fill so the source needs to be large which is why on a small scale shoot diffused fluorescent and LED fittings are very popular as they have the breadth and light output required coming from an easily controlled housing.
Hard lights can be converted into soft lights by bouncing off poly boards or punching through semi translucent material (silk).
Conventional 4'x4' and 8'x8' silk frames are used as frames to punch powerful lights through and by design, these are large to transport. Alternatively, the 4'x4' and 8'x8' Fit Frames (shown right), are very versatile alternatives to be considered, as they have offer either large inflatable frames which are easy to transport and are supplied with a selection of white bounce cover, silk covers, as well as black and chroma key green (8x8 only). A powerful 1.2K HMI or Platinum Blonde shining through this makes a very effective and powerful soft light.
Alternatively, chimera soft boxes (shown right) will convert conventional 300W or 650W Mizars, 800W Redheads etc. into effective small soft light sources and many current LED kits such as the Fiilex lighting kit offer soft boxes in the standard kits.
When building large soft frames setup time can become a consideration, so dedicated soft lights are now available which are speedier to setup
Arri, Dedolight and Kino Flo are well established for manufacturing soft lights but there are now many more using the advancements in fluorescent and LED technology to beneficial effect. Dedolight produce a PanAura light (shown right) that uses an Octodome shape with either a 1K Tungsten or a 400W HMI bulb (kits come with both tungsten and HMI heads).
This produces an even light 5ft in diameter but also has a shallow depth fixture which is helpful on location.Kino Flo have their 4ft 4bank fluorescent fixture, Arri have their new LED Sky Panel as well as their more established 2.5K & 5K Arrisoft units.
The Sumo 100 kit (shown right) is worth a mention here, as it is a robust LED fixture which combines both high light output with outstanding light quality and is supplied complete with a soft box and versatile large Chinese lantern kit.
Whilst this has a separate section, there is no true category for Beauty lights, as these are soft lights which offer pleasing light and gentle shadows. These are often smaller and used in close proximity to talent compared to conventional soft lights and may be used just to light the face of the subject.
As such, Ring lights fall into this category and have a very unique look as they reflect in the pupils of the talent as a ring of light. F&V make the R300 (shown right) which is very effective and the camera shoots through a ring of LEDs to softly light the face creating this look.
The challenge is to control the output of the light to allow shadows in the image to be soft but at the same time not overexposing the frame, so combinations of lighting fixtures are together to enable the DoP to light each element of his/her set effectively. The large soft lights, hard sources, flags and trace frames all work in harmony to create the perfect lighting setup.
Section 3 - Common Lighting Setup Examples
The Three Point Lighting Setup
The classic old textbook lighting setup is the three point lighting technique; this will almost always consist of a Key light, Fill light, and Back light.
The Key light will always be the largest and strongest of the three light sources for the setup, it can be soft or hard but will always dominate the scene and determine the correct exposure level that the other lights will balance to. Generally the three point set up is applied to a human subject and the Key light source is coming from the same side of frame that the subject is looking at- if the eye line is to the right of frame then that’s where the Key should be positioned.
The Fill light exists to balance the Key light and will usually be placed on the opposite side to the key. The Fill light will be less intense than the Key light usually by 1-2 stops and depending on the style of the shoot its main purpose is to illuminate the shadow side of the subject to create some detail and shape without matching the intensity of the Key which would cause ‘flattening’ of the lighting.
The Back light is placed behind the subject to try pull them out of the background to help create a more dynamic image. The backlight can be placed in a range of different positions for different effects, but the usual position for it would to be pointing towards the back of the subject’s head from the same side as the Fill light which as the darker side of the face would emphasise the effect more than being on the Key light side.. The back light isn’t always essential, but it performs an important cosmetic job and if shooting on green screen it is almost always necessary to help to separate the subject from the green screen.
Two person interview Lighting Setup
This lighting setup is often used for interviews where two people will need to be lit at the same time, normally the interviewer and interviewee who are covered by two cameras at the same time.
This setup still uses three lights but utilises individual lights as both a Key for person A and a Backlight for person B and vice versa for second Key/Backlight light with a common Fill light for both subjects. This works as a variation on the above three point scenario as one subject will be looking left and one to the right to match the eye lines. The advantage is speed of set up and the continuity of covering two subjects at once.
The disadvantage is that the positioning of the Key/Backlight will be possibly too ‘front on’ on the Key side for a proper cosmetic effect and if the lamps move to improve the Key the Back light will not be in the correct spot. This lighting setup is useful to documentary makers ENG (Electronic News Gathering) crews because it is fairly quick to setup and does not require too much equipment to achieve.
Any Other Business
Lighting is about emulating and enriching reality and the technical balance needed to expose correctly. There are a myriad of fixtures and accessories and a wealth of talent out there so it is almost impossible to frame (pun intended) any sensible advice on the craft of lighting on the written page but there are a few truisms that we can share with you..
We tell stories with shadows- it’s not what you light it’s what you don’t.
If you have a light directly behind or on camera that is not just the tiniest of eye-kickers or a ring light for effect, then it is in the wrong place.
Using a large source soft light can also function as a fill light if the source is positioned so that it can fill the shadow side of the face. A common trick to achieve this is to bounce a point source lamp like a 1.2K HMI onto a piece of poly board and then position a roll of white diffusion hanging from a C stand at a diagonal in front of the poly so you get a lovely creamy soft light that wraps around the face sufficiently to provide a bit of fill.
Your interview with the chief executive on the 40th floor will mean that they want to show off their business prowess by having the best view in town... and they will want to look good. The key (pun intended) here is to think about the source, the balance, and the portability. Remember you could have a situation where the window is 5-6 stops brighter than the ambient in the room so you will need your source to be a least 4 stops of cosmetic light to balance the exposure. Think in terms of large fluorescent fixtures that can be stacked together and diffused to give you the power and the softness-they are also cool in proximity to their subject and are easy to flag off reflections in the window.
Look at the sources of light in the shot and pick a lamp that emulates/amplifies the natural. If it’s a candle based scene you probably want small sources with sharp shadows so think tungsten and dimmers to blend the colour temperature.
Modern digital cameras nearly all offer an extended latitude dynamic range often called Log ‘something’. Do not allow yourself to judge your lighting balance on a Log output monitor, until technology catches up with HDR, most TVs and monitors can only deliver up to 7 stops latitude so try and keep within that range and monitor on REC709.
Anything ‘vintage’ lens wise is going to be delivering less contrast to the sensor so bear that in mind and use the lighting to keep the contrast up-remember vintage or uncoated lenses and lots of ambient smoke spell trouble.
Modern digital cameras are also much more responsive and typically have base ISO rating of 800 or more which means they need less light to expose correctly. But less light does not necessarily mean smaller fittings, big sources are needed for cosmetic work and to emulate sunlight or big daylight windows, a 1x1 LED lite panel will not do this for you.
There are clearly a large number of lighting options available to image makers today, however as mentioned at the beginning of this piece, new technologies are not always a drastic improvement on the original technologies or perform a slightly different function.
Tungsten light sources still produce the most consistent colour spectrum we have seen so far but we are getting closer to matching this with other improvements every day. Unfortunately tungsten sources do produce far more heat than they do visible light which drastically reduces their efficiency.
HMI units are actually highly efficient once powered up and also produce excellent colour rendering in the daylight spectrum, but they do require large amounts of power just to turn on, but that power consumption is justified by the high and easily controlled light output which why they have been the mainstay of film and TV production for 35 years or so.
Fluorescent lighting is a great middle ground between the two as it has excellent colour rendering characteristics as well as being very soft at source and pleasing to the eye, however the fixtures can be cumbersome and fragile due to the nature of the fluorescent bulbs.
LEDs are fantastic options when the user needs to setup their shot quickly or are shooting outdoors in a field without a generator or an adequate crew. They solve a large number of control and portability issues we have been facing with older lighting technologies.
There are a very large number of manufacturers now producing LED lighting instruments designed for the film and TV industries. Some of these products tick almost every box in terms of their applications for the industry but come with a heavy price tag, others have limitations but are much cheaper.
As stated at the beginning of this article, lighting is about the correct balance and combinations of different lighting technologies to help produce a good image.
The ultimate solution is to actually use and try lots of different lighting products to know what works best in each individual situation.
An informative low energy lighting guide from the BBC
EBU information on LED product performance
Background video guide to tungsten lamps
Background video guide to fluorescent lamps
An article about the future of natural digital lighting
Lighting setups example video from nofilmschool.com
Quite a fun recreation of the voight kampff scene from Blade Runner
Basic info and diagrams of an LED from Osram
Ian Jackson, Barry Bassett & Ben Starkin