Color Temperature
Light is measured in kelvins (K). Neutral light is produced at 5000K, which is the equivalent to the light on a bright, sunny day. The color temperatures produced by other sources of light are as follows:
1000-2000K — Candlelight2500-3500K — Tungsten light (normal incandescent household bulb)3000-4000K — Sunrise/sunset (clear skies)4000-5000K — Fluorescent light5000-5500K — Electronic flash5000-6500K — Daylight (clear skies with the sun overhead)6500-8000K — Overcast skies (moderate)9000-10000K — Heavily overcast skies and shade
Why Color Temperature Is Important
You can see the way color balance affects photographs in photos taken under light from incandescent light bulbs, for example. These bulbs give a warm, yellow to orange light that is pleasing to the eye but doesn’t work well on camera. Look at old family snapshots from the days of film, and you’ll notice that most of them taken without a flash have an overall yellow hue. This is because most color films were balanced for daylight and, without special filters or printing, the images could not be adjusted to remove that yellow cast. In the age of digital photography, things have changed. Most digital cameras, even those on phones, have a built-in auto color balance mode. It attempts to adjust and compensate for the various color temperatures in an image to bring the entire tone back to a neutral setting that is similar to what the human eye sees. The camera corrects color temperature by measuring the white areas (the neutral tones) of the image. For example, if a white object has a yellow tone from tungsten light, the camera adjusts the color temperature to make it a truer white by adding to the blue channels. As great as technology is, cameras still have problems adjusting white balance properly. That’s why understanding how to use the various white balance modes available on a DSLR is so important.
White Balance Modes
DSLR cameras typically include a variety of white balance modes that allow you to adjust the color balance as needed. The symbols used for each are relatively standard and universal among DSLRs. Check your camera manual to familiarize yourself with the symbols. Some of these modes are more advanced than others and might require extra study and practice. Others modes are the presets for common lighting conditions that adjust the color balance based on the average color temperatures given in the chart above. The goal of each is to neutralize the color temperature back to daylight. Common presents include:
Auto White Balance (AWB) has advanced greatly in reliability, and it should set the color temperature correctly in all but the most complicated lighting situations.Daylight/sunny (symbol: a sun with light rays) is used in common lighting conditions and is equivalent to what most color films used.Cloudy (symbol: clouds) can be used on an overcast day to warm up the color tone.Shade (symbol: house with diagonal lines stretching to the ground) is similar to the cloudy preset and can be used to fine-tune the color balance when the cloudy setting doesn’t get it quite right.Flash (symbol: jagged arrow pointing down) is designed to add warmth when you use a flash.Tungsten (symbol: household lightbulb with light rays) can be used indoors under incandescent light when the AWB has not removed the yellow or orange cast completely.Fluorescent (symbol: horizontal line resembling a fluorescent tube with light rays) is useful under fluorescent light when the AWB doesn’t remove the blue or green cast completely.
Advanced White Balance Modes
Custom white balance (symbol: two triangles on their sides with a square in the middle) allows you to set your own white balance using a gray card that has a reading of 18 percent gray, the midpoint between true black and true white. Professional photographers often use this method when perfect color is essential.Kelvin (symbol: K in a rectangle) allows you to set the color temperature at will, giving a precise result. It is useful when you know the color temperature of the light source and allows for finely tuned incremental changes.
How to Set a Custom White Balance
Setting the custom white balance is easy, and if you’re a serious photographer, it’s a practice well worth learning. After a while, the process becomes second nature, and the control over color is worth the effort. You need a white or gray card, which you can find online or at a camera store. These cards are perfectly neutral in color and give you the most accurate color balance reading. In the absence of a white card, choose the brightest piece of white paper you can find, and make any fine-tuned adjustments with the Kelvin setting. To set custom white balance:
Final Tips for Using White Balance
As stated above, you can rely on AWB most of the time. This is particularly true when you’re using an external light source (such as a flash gun) because the neutral light it emits usually cancels out any color casts. Some subjects can cause a problem for AWB, though—in particular, settings with a natural abundance of warm or cool tones. The camera can misinterpret these subjects as casting a color over an image, and the AWB tries to adjust accordingly. For example, with a subject that has an overabundance of warmth (red or yellow tones), the camera may cast a bluish tinge over the image in an attempt to balance this out. All this does is leave your photo with a strange color cast. Mixed lighting (a combination of artificial and natural light) can be confusing for AWB, too. In general, it’s best to set the white balance for the ambient lighting manually, which gives everything lit by the ambient light a warm tone. Warm tones tend to be more attractive to the eye than sterile cool tones.
