Using the auto mode on a digital camera gives you a point and shoot camera that allows you to concentrate on the subject while the camera makes the necessary settings to give you a well exposed and properly focused image.
But like most automatic features, knowing how they function will help you keep the camera from getting fooled in those special situations that often yield the most dramatic photos: including when your subject is backlit or off-center.
Understanding White Balance
All digital cameras have an auto white balance setting that allows the camera to detect the color of the light and balance it correctly.
When you look at a white object, say the page of a book or a sheet of white paper, it appears white to you regardless of the light source. When lit by an ordinary household bulb, or a fluorescent light, or outside in daylight, it still looks white to your eye.
But to the camera's eye, each of these light sources is different and each produces a tint of color on the white object. And unless the camera makes some sort of adjustment for this variation in light color, a white object will not appear white in your photos.
In fact, everything in your photo will have a color cast to it, it's just more obvious in the whites and near whites than in other colors. This is the function of the white balance feature in digital cameras.
Why White Balance Is Important
Light is measured in degrees Kelvin, such as 3200K or 5800K. This is known as the color temperature of a light source. With film cameras you could use different kinds of film or filters to get the correct color.
But with digital photography the camera's image sensor is your film and it doesn't change, so it is necessary to tell the sensor what color light source it is recording or it won't be able to reproduce colors correctly in your photos.
Overriding Auto White Balance
Some cameras offer an option to override the automatic setting and let you set the white balance manually. You may have a selection of several settings from which to choose.
The more common ones are: sunlight, shade or cloudy daylight, tungsten or indoor, fluorescent and electronic flash.
Go Ahead and Experiment
If your camera has the option to override the auto white balance setting, you may find it fun experimenting with the various settings. While most of the time you will want accurate color reproduction, there are times when using a deliberate color cast can be a useful tool in creative photography.
You may want to change the light balance to enhance a certain mood, or create an unusual effect that is more interesting than properly balanced color would produce. So experiment with these options and add them to your toolbox of creative controls.
Understanding Color Balancing
The human eye can easily adapt to different light conditions so that objects maintain their 'true' color. If we look at a blue ball, for example, we see the same shade of blue indoors and outdoors and under cloudy or sunny conditions.
In fact, each type of light amplifies a certain color in the spectrum. What we consider to be 'white' light only occurs during the noon hours of a clear day. Sunlight in the early evening or late afternoon gives everything a reddish tint, and cloudy days bring out the blue end of the spectrum.
Each type of artificial light also has a particular color cast. Incandescent lighting is yellowish and fluorescent lighting can be either blue or green.
All of these different lighting conditions affect the color balance in photographs.
Most digital cameras allow you to adjust the color balance for different types of light. This can be done manually or automatically, although the automatic settings can produce uneven results from one picture to another.
Manual settings can be done by selecting a preset such as 'sunlight' or 'cloudy', but these settings can be fine-tuned to match very specific lighting conditions.
Color balance is achieved by adjusting the camera so that 'white' is truly 'white'. Once the camera is set to correctly reproduce white, the other colors should appear to be their natural shade. This can be quickly checked by looking through the viewfinder of your digital camera. Holding up a piece of white paper in front of the camera will allow you to see whether it is the correct shade or not.
Some cameras can be set this way -- place a sheet of white paper in front of the viewfinder and select 'Auto Correct'.
Remember that the presets are general guidelines and may not be suitable for every type of lighting condition. If your camera has a setting for fluorescent lights, for example, it may still require further tweaking to get the correct color balance.
Although it is best to try to get the proper color balance when you are taking photographs, the color of an image can also be adjusted using software. This should not be thought of as an alternative to proper color balancing, but it can be used to good effect on some digital images.
Some computer software can automatically adjust color as well as brightness and contrast. Start out with these 'auto' settings -- sometimes the results can be surprisingly good.
If you wish to adjust the color manually, some knowledge of the physics of color is necessary. All color is made up of the three primary colors -- red, green, and blue. Three other colors called the 'subtractive primary colors' are obtained by removing one of the primary colors where the other two are mixed. The three subtractive primary colors are yellow, cyan, and magenta.
This knowledge of how colors interact allows you to correct improper color balances. For example, if an image is too red, adding some cyan (the opposite of red) can help to naturalize the color.
Software can also be used to adjust color intensity. Subtle use of imaging software can help to turn good photographs into great photographs.
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