Demystifying set lighting and colour temperature

[ 0 ] March 9, 2016 |

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Set lighting is a very important aspect in the creation of a film, due to it having a direct affect on how the film looks.  It is for this specific reason that the Director of Photography deal directly with the lighting department. With so many different types and colours of light, one can easily become overwhelmed, but thanks to Premium Beat we are able to demystify all of that below:

Kelvin Scale

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  • The kelvin scale is used to measure light
  • A kelvin(K) is a unit of measurement for temperature, meaning it starts at zero and only increases
  • The lower the Kelvin, the more Red the colour
  • The best way to remember this would be to think of a candle light or lit match ranging from 1000k – 1900k e.g. Fire = Red

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  • As you go higher up on the scale you progress through yellow, white and blue lights
  • Halogen lights can be found at around 2500k -3000k
  • Direct sunlight can be translated to 4800k
  • Daylight is normally around 5600K
  • Cloudy sky or cool white found between 6000k -7500k
  • Clear blue sky at 10 000k

This progression can be seen in the colour temperature chart above, and in the light bulb representation below

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Types of Lights

There are many different types of lights, so we decided to focus on the lights most commonly seen on a film set.

Tungsten Lights (-3200k)

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  • Tungsten lights are very similar to home light bulbs
  • They produce an orange hue
  • Lamps require large amounts of power and get very hot
  • Offer higher colour temperature than incandescent tungsten bulbs
  • Lights can be dimmed, allowing you the option of adjusting
  • Add blue gels to create daylight

 

Hydrargyrum Medium – Arc Iodide (HMI) Lights (-5600k)

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  • HMI lights are often the most used light on set
  • HMI lights emit a UV light with blue hue
  • To power up, you require an electrical ballast
  • Ballasts limit the current to prevent flickering
  • HMI lights are 4X the power of incandescent’ s
  • HMI lights make a very loud noise when powering up, requiring lighting technicians to shout “striking” to notify all on set.
  • Brand new bulbs will have a colour temperature of up to 15000k
  • Bulbs should be left on to reach an optimum level of 5600K, close to daylight
  • Bulbs should not be used halfway past their lifetime
  • Bulbs require more voltage and colour temperature will continue to decrease 1 kelvin every hour
  • HMI lights are expensive, but are much more efficient
  • Bulbs can be dimmed to 50% but causes colour temperature to rise to a stronger blue
  • If blown out or dropped, HMI bulbs will explode hot glass and mercury vapour
  • Very important to have a knowledgeable lighting technician on set when using HMI lights.

 

Fluorescent lights (2700k – 6500k)

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  • Fluorescent bulbs are known for flickering and have a very ugly orange hue
  • With the development of new technology, bulbs are flicker free, offering multiple colour temperatures
  • Has a very soft light, more efficient than an incandescent bulb  and can offer an output similar to HMI lights
  • The colour temperature can range from tungsten up to natural daylight, depending on the phosphors mix in the bulbs.
  • Fluorescent bulbs are much often packed into small fittings, allowing them to be compact and lightweight.
  • Fluorescents are much cooler than any other bulb option.

 

Light Emitting Diodes (LED Lights) (White 3000k- 5600k)

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LED lights are becoming more and more popular on set. While LED lights are most commonly seen in white, they can be manufactured in every colour.

  • Diodes are designed to offer directional light
  • Very efficient but limited in overall output, normally used on small budget productions
  • LED lights only produce single wavelengths of light

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  • To create white light, you will require red, blue and green LED’s
  • White can also be created with the combination of phosphors and ultraviolet LED
  • LED lights provide soft and even lighting
  • Incredibly high efficient, can be battery powered
  • Can easily be dimmed and moved along the colour spectrum
  • LED’s have a long lifespan and wont explode

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