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White Balance -

What falls on the earth from the sun is called radiation and the component of this that we see is termed as light - when complete this is white light.

However, white light is actually made up of the spectrum colours we are familiar with in the rainbow. If we place, say a blue filter in front of the light source this absorbs the opposite colours and we have blue light continuing on to fall on the subject.

White light is based on the rays that fall on the earth during the middle period of the day. During sunrise and sunset these rays fall on the earth from a more oblique angle and become warmer or more red orange - hence the wonderful colours we often see in a sunset. So if we take photographs in the evening that can have a warmer colour cast.

Also at night when we rely on artificial lighting- like tungsten or fluorescent lights etc. the rays are also incomplete and light with a certain colour characteristic falls on the subject. This is why many photographs taken at night have a yellow orange colour cast. The colour an ambient light has is termed colour temperature and measures the warmness red) or the coolness (Blue) of the light.

While these colour variations are projected through our eyes, our brain tends to compensate and correct the lighting more towards white and we don't see them as a camera might record the scene.

However, film and the ccd in a camera are impartial and do not correct this short fall in "complete white light" and we can end up with a colour cast in our images. With film we can buy different emulsions that allow for these variations light daylight or Tungsten film. With digital we can set the white balance for different situations which compensates for any short fall in the spectrum.

Most cameras allow the user to set the white balance - this is a reference point so white is white and the other colours within the scene are recorded as we might expect. White balance is referenced to a mid day sun where all colours within the spectrum are equally balanced - we see this as white light. However when the various colour components of light are not balanced, say there is more red, or yellow as in artificial light, the colour of the scene are recorded by the camera with a colour bias. Setting the white balance allows us to compensate for this - so we can set the camera white balance for cloudy conditions, sunset, flash, tungsten fluorescent etc. Another option is to set the white balance to automatic - here the camera senses the colour and set the white balance accordingly. For most situations this works well because the camera selects the white balance based on the lightest areas of the image which is quiet often a white within the scene. If however there is no white in the scene, say a red apple against a green wall,   the auto setting of the camera gets lost. If the scene is shot  as a raw file this over rides any white balance setting and allows us to set the white balance when we open the file in the raw converter.

Consumer digital cameras tend to have one setting - automatic - where as professional cameras offer the opportunity to specifically set the white balance. More sophisticated models allow the user to set the white balance.


White Balance settings

These are some of the settings that professional DSLR manufacturer might offer:

Auto White Balance: Here the camera automatically determines the amount of light and the colour information for the shot and after the photograph is taken it is saved as a jpg or tiff file with a colour correcting bias. While auto white balance might work for many subjects, some subjects present problems. Because the camera is setting the white balance based on the subject tones not the incident light temperature, even under daylight conditions, the auto white balance can interpret the scene wrongly. An example is when the subject has a predominance of warm or cool colours.

This image illustrates a situation where the subject is predominantly red, and so the camera mistakes this for a color cast induced by a warm light source.  The camera then tries to compensate for this so that the average color of the image is closer to neutral, but in doing so it unknowingly creates a bluish color cast.  Because of the way various cameras have been designed to save the information as a jpg or tiff the results can be quite different.  

Auto: Auto white balance will work more effective when the photo contains at least one white or bright colorless element.  So when your composing your image in the viewfinder be aware that its absence may cause problems with the auto white balance - but don't include white or bright elements for the sake of achieving this. In this case 6650


Full sun: Select this setting for outdoor situations when there is full sun about 1- 2 hrs after sunrise and up to 1- 2 hrs before sunset. 5500

cloudy: 6500

Shade when sunny:Select this setting for shots taken in the shade or cloudy days. 7500

florescent 1: Settings for fluorescent lamps might vary from camera to camera, (check the manual) but it might be for fluorescent lamps mixed with daylight 3800

florescent 2: For scenes taken under warm fluorescent lamps.

fluorescent 3: For scenes taken under cool fluorescent lamps.

Tungsten: For scenes lit with tungsten or incandescent lamps. 2850


Custom: Custom settings allow the photographer to set the white balance from a piece of gray or white card for a specific lighting situation. A reading is taken of the colour balance and confirmed in the memory of the camera. Several custom settings can be locked into the camera memory.


RAW Files: The settings in the camera are set to predetermined temperatures. However, when the camera is set on RAW, the white balance can be set to any temperature when the file is opened in the raw file converter.

Here we can select the lighting situation

we get a specific figure in this case 5500


Here the wrong white balance has produced an image with an inaccurate colour range.

Here the white balance is set more accurately



Be aware that with digital cameras - that if you are using an auto white balance the camera is a tempting to change the color and neutralize the effects of the changes in light. If your camera has a white balance function, you might like to experiment with using a custom white balance - on the other hand with the film we don’t have the same problem that kind of balance is a preset in the film – and their text and or daylight.


Multiple illuminants with different color temperatures can further complicate performing a white balance.  Some lighting situations may not even have a truly "correct" white balance, and will depend upon where color accuracy is most important. Under mixed lighting, auto white balance usually calculates an average color temperature for the entire scene, and then uses this as the white balance.  This approach is usually acceptable, however auto white balance tends to exaggerate the difference in color temperature for each light source, as compared with what we perceive with our eyes.

Exaggerated differences in color temperature are often most apparent with mixed indoor and natural lighting.  Critical images may even require a different white balance for each lighting region.  On the other hand, some may prefer to leave the color temperatures as is.

Note how the building to the left is quite warm, whereas the sky is somewhat cool.  This is because the white balance was set based on the moonlight-- bringing out the warm color temperature of the artificial lighting below.  White balancing based on the natural light often yields a more realistic photograph.  Choose "stone" as the white balance reference and see how the sky becomes unrealistically blue.






experimenting with white balance



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