Colour temperature and light

In addition to having bright and dark qualities, light has a colour spectrum which is measured using Kelvin degrees of temperature. This can be affected by a number of factors: time of day, type of lighting, altitude. (Stick with me here, it gets easier.)

If you used to shoot a lot of film you probably remember taking pictures indoors under ordinary tungsten lighting conditions without a flash. Inevitably, the images had a yellow or orange tone unless you used a film specifically designed for tungsten light.

That is because tungsten light has a lower colour temperature than daylight. The lower the colour temperature, the more yellow/orange (warmer) the light. Daylight has a higher (cooler) colour temperature and has more blue in it.

Uncorrected fluorescent light has a greenish cast to it. To make it all the more interesting, fluorescent lights are different from manufacturer to manufacturer and even within a brand.

That’s why your office friends have sallow looking complexions and women always complain about the light in stores’ dressing rooms. If the light is awful, it makes one LOOK awful. It can also make you feel awful.

On a lighting design Web site the glossary says, “colour temperature is a simplified way to characterize the spectral properties of a light source. ( Low colour temperature implies warmer (more yellow/red) light while high colour temperature implies a colder (more blue) light. Daylight has a rather low colour temperature near dawn, and a higher one during the day.”

It also has a warmer temperature in the late afternoon. I wait for that warm glow the hour or so before sunset for landscape photos or to add a visual effect when shooting fashion models.

The Golden Hour is how that last hour is often described.

Light at high altitudes is very blue and many photographers using some sort of warming filter to add colour to a cold scene. Check your menu and see if you have colour filters in your digital camera.

But what is white balance

Even entry-level digital cameras have a method to correct colour temperature variations — white balance or WB for short. The camera looks around and determines what white is supposed to look like. (Aren’t computers wonderful?)

Most of the time, but not all of the time, auto white balance works for us. But if you are unhappy about the colour of your image, many cameras allow you to set a white balance. There are settings you can choose in your menu or on a mode wheel, or you can take a picture of an object that is white which tells the camera “this is white” and voila! custom WB. (Remember back a few lessons ago I mentioned “read the manual”. This is where it comes in handy.)

If you change your WB to shoot indoors under tungsten or fluorescent lighting, be sure to change it back to auto or daylight when you head outdoors or your pics will have a funny magenta or really blue cast to them.

That’s because the camera adds magenta to fluorescent lighting to correct for the green or it adds blue to correct for the orange of tungsten light.

Messing up white balance

You might ask how do I know these little things. Well, I was photographing cops surrounding a bad guy’s apartment one day — an outside-bright-sunlight-kinda day and forgot to change the setting from the tungsten setting from a previous assignment to daylight — oh dear, magenta pictures.

Those cops had funny skin tones, the sky was mostly purple and it was very hard to correct the colour mistake. We used to do this with filters but now we can do it in camera. (Did I mention how wonderful computers are?!)

White balance effects

There are times when you want a specific colour to your images. Lovely special effects can be created when you set the camera on indoor tungsten light and shoot outdoors. It all turns an almost magical blue. Breathe on the lens and instant hazy blue effects. How cool is that! Instant Twilight Zone.

Yes, you can do that with a point and shoot too, as long as you hold the shutter button down halfway to keep it in focus. So sometimes that blue is cool and sometimes it is not.

Exercise: Set your camera on daylight white balance, shoot a series of images inside and outside, without flash. Now set it on tungsten, usually the little light bulb icon in your menu lighting settings or on the mode wheel, shoot the same series indoors and out. Compare the images to see how it all comes together. Be sure to set it back if you have changed it from your normal setting.

“The quality of colour is directly related to the quantity of light falling on the subject.” — Me