Take your photography to the next level and beyond...

  • NEWS
  • REVIEWS
  • INSPIRATION
  • COMMUNITY
  • COMPETITIONS

Why not join for free today?

Join for Free

Your total photography experience starts here


PortraitPro 12 HALF PRICE + EXTRA 10% OFF code EPZROS612

Guide to colour temperature

Guide to colour temperature - Light is not always what it seems. Peter explains about colour temperature.

 Add Comment

Category : Studio Lighting and Flash
Share :

Don't get down in the blues producing pictures with natural colours is easy if you know a little about colour temperature.
Words & Pictures Peter Bargh

Light is not always what it seems. Our eyes are very forgiving, so when we move from place to place everything seems normal in terms of colour. So, for example, when moving from a bright daylight environment to a room lit by a candle all that will appear to change, to the naked eye, is the light level. Yet record these two situations using colour film and the first will have a blue hue and the latter will come out with a heavy orange cast. This is because our brain can quickly adjust to the changes, making white appear white, whereas film is balanced for one particular colour and anything that deviates from this will produce a colour cast.

The colour variation is referred to as the colour temperature and is measured in degrees Kelvin. The scale ranges from the flame of a candle at around 1900K to deep blue sky at around 10,000k as illustrated by this diagram.

The light source is listed next to the degrees in Kelvin, both set against the colour of the light at each level.

You will notice that the colour next to the Average noon daylight (5500K) is white. This is the colour temperature that colour film is balanced to which means that when shooting using daylight film the photograph will record white objects as white and all the colours in an image will appear natural on the film. If you shoot in conditions that measure a higher temperature the photo will start to become bluer and shoot in conditions below the 5500 temperature and they will increase in orange.
The colours here don't just relate to daylight conditions artificial light also introduces a colour cast. With fluorescent lights this is often green and with tungsten lighting it will be yellow, while flash can be slightly blue.

If you own a camcorder or digital camera you may have read about the white balance control. Most digital cameras have an automatic colour balance. This will look at a scene and if it thinks the colour is too blue it compensates to make it natural by adding a red shift to the colours recorded. Likewise if it sees an orange scene it will increase the blue content. This

With film cameras you would have to use colour correction filters to compensate.

Photograph lighting technique

Some special professional films are designed to be used in tungsten light and have a built-in blue colour that corrects the yellow of the tunsgsten light. Use this film in daylight and your photos will come out with a blue colour so the shots would need to be filtered. Knowing which film to use with which filter can be tricky in some lighting situations, so check out our guide below.

The photo here was shot under tungsten light. Look how yellow everything is. An 80A series blue filter would need to be used to correct this.

Colour control filters are broadly split up into two categories: colour conversion and light balancing filters. The strong colour conversion filters are in the 80 and 85 series and are used for large colour changes while weaker lighting balance filters fit in the 81 and 82 series and are used for making small colour adjustments.

Film Kelvin Illumination Kelvin Filter Colour Exposure
Daylight 5500K Tungsten House lights 3200K 80A Dark Blue 1 1/3
Daylight 5500K

Tungsten Photofloods

3400K 80B Dark Blue 1
Daylight 5500K Tungsten Clear flash bulbs 3800K 80C Dark Blue 1
Daylight 5500K Daylight Shade under blue sky 7500K 81EF Straw 2/3
Daylight 5500K Daylight Shade partly cloudy sky 7000K 81D Straw 1/3
Daylight 5500K Daylight Shade under daylight 6500K 81C Straw 1/3
Daylight 5500K Daylight overcast 6000K 81A Straw 1/3
Tungsten A 3400K Daylight 5500K 85 Orange 1
Tungsten B 3200K Daylight 5500K 85B Orange 1
Tungsten 3800K Daylight 5500K 85C Orange 1
Tungsten B 3200K Tungsten lights 100W 2900K 82B Pale blue 1/2
Tungsten B 3200K Tungsten Photofloods 3400K 81A Straw 1/2
Tungsten A 3400K Tungsten lights 100W 2900K 82C Pale Blue 2/3
Tungsten A 3400K Tungsten Clear flash bulbs 3800K 81C Straw 2/3

The table above shows the film you are using in column 1 and the colour it's balanced to is in column 2. Column 3 is the light conditions you are shooting in and column 4 is the colour temperature of the light. Column 5 is the filter necessary to make the photo look natural and column 6 is its colour. The final exposure column shows the exposure increase that's necessary to adjust for the strength of the filter. This is automatically adjusted by the camera's through-the-lens metering.

The other type of light you will come across, usually in offices, factories and kitchens, is the fluorescent tube which gives off a green colour when daylight film is used. To correct this you need to use a magenta filter, known as an FL-D (Fluorescent daylight) or FL-W (Fluorescent white) depending on the tubes used. This photograph shows the typical characteristics. Photograph lighting technique

With a digital camera things are far less complicated. Just point and shoot with the camera set to auto. If there's a colour cast when you preview the photograph delete and reshoot using the relevant manual white balance settings. Some cameras also have a fully manual setting where you point the camera at something that should be white. The camera measures the colour reflected from this and adjusts to make the subject white which corrects the colour.

You also don't have to correct colour at all. Rules can be broken. Adding a blue filter when using daylight film can produce landscapes with added mood, especially when shot at dawn or dusk. While the 81 series are often used to warm up skin tones in many situations.

Some situations can be extremely tricky to correct. Take this interior. The window light is stronger than the interior tungsten light. So you get a mixture of colours to worry about. If a blue filter had been added to correct the yellow the stairs and floor would have gone blue. Professionals get round many shots like this by placing huge sheets of lighting gel over windows (yellow in this case) to balance the daylight with the interior light. They then use camera filters to correct the colour cast. I feel in this example leaving the natural colours to affect the film in their own way has worked and I wouldn't want it any other way.

Professionals also use colour meters to measure the light acurately. We have a guide to these here.

You can often correct a colour cast using your image editing program's channels or colour balance control, but that's another article!

Tip
The filters can even be used to unusual effect with flash by placing one colour over the lens and a correcting colour over a flash. Then when a photo is taken the flash illuminated subject will look natural while the background will take on a colour cast.

Photograph lighting technique

Explore More

Join ePHOTOzine and remove these ads.

Comments


26 Mar 2012 5:33PM
If you would like to measure the color temperature yourself, just download the new app I have developed for Android. Start the app, point at a white surface and click Analyze to get the approximative color temperature of the light that falls on that surface!

Join ePHOTOzine for free and remove these adverts.

7 Apr 2012 8:22PM
Thank you! very very much

Sign In

You must be a member to leave a comment.

ePHOTOzine, the web's friendliest photography community.

Join For Free

Upload photos, chat with photographers, win prizes and much more.