Colour temperature
Colour temperature can be quantified using a scale marked in degrees Kelvin. Lighting can vary in colour temperature between 2,000 degrees Kelvin (warm) and 9,500 degrees Kelvin (cold); the scale is derived from the fact that the light emitted by heated objects produces a spectrum, which changes as the temperature increases. Low-temperature lighting is progressively warmer (more red/yellow), while high-temperature lighting grows progressively colder (more blue), and this change is what the white balance control on a digital camera is designed to compensate for. You can either leave the white balance set to automatic, and hope for the best, or choose a manual preset to match the conditions. Some high-end digital cameras quote white balance values in degrees Kelvin, but most use named presets corresponding to specific conditions, such as Daylight, Tungsten and Shade. Our chart illustrates the variations in colour temperature that you might encounter for a range of subjects and shooting situations.  | | Sunrise/sunset - The light changes rapidly at sunset or dawn. With the sun this low on the horizon, the colour temperature
of the lighting could be as low as 2,400K, which gives sunsets their characteristic yellow/orange/red tones. |
|  | | Domestic tungsten - Domestic tungsten lighting has a strong yellow/orange cast, because its colour spectrum is shifted towards stronger wavelengths. It can be even lower than 3,200K, depending on the bulb type. |
|  | | Photo tungsten - Photographic tungsten lighting is cooler and more neutral than domestic tungsten lighting, but still much ‘warmer’ than daylight. It will produce a yellow cast, unless you adjust the camera’s white balance.3,400K |
|  | | Early morning/evening sun - The 4,000K temperature of the light climbs slowly during
the morning, and falls towards evening. Even with the sun well above the horizon, the light cast have a warm glow beloved by landscape photographers. |
|  | | Noon sun/flash - Noon sunlight produces neutral colours, and has the same colour temperate as some flash systems (flash may also produce a slightly cooler light). This neutral light isn’t always best for landscapes.5,500K |
|  | | Cloudy/overcast - The light from an overcast sky is slightly ‘cooler’
than that of direct sunlight, and you may want to use a warming filter when shooting, or adjust the white balance to counter this effect.6,000K |
|  | | Deep shade - Deep shade can produce cooler lighting still. The auto white balance on digital cameras will usually fail to correct sufficiently for this, leading to excessively cold-looking shots.6,500K |
|  | | Shade in daylight - Worst of all for making shots look ‘cold’ is open shade on a sunny day, because it’s the blue sky that’s providing all the illumination. Make sure
you select the Shade white balance setting to compensate.7,500K |
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