When is white not really white? When it’s headed toward an unprepared camera sensor. Understanding white balance and the colour difference between light sources is critical to getting the best look from your camera, which also makes it a crucial part of cinematography where everything in the frame needs to look perfect.

Different light sources produce different colour temperatures

A stroll through your neighbourhood at night can reveal some important differences in colour temperature among artificial light sources. As your eyes adjust to the dark, observe the different colours of light around you. Those little solar lights in the garden seem to be bluer. The light coming from the house fixtures looks more orange. That kitchen window seems almost green. Those street lights look almost pink. Your brain tells you, though, that each of them is white light.

Science tells us that light is a vast spectrum that ranges from what we see into the invisible — infrared and ultraviolet light. In between is the entire rainbow of colours, graded by colour temperature on the Kelvin scale.

On this scale, incandescent or tungsten light sits at about 3200 kelvin (or 3200 K for short). Sunlight varies as it travels across the sky but is placed generally at 5600 K. At dawn and dusk, it’s actually warmer, or more reddish. This means, counterintuitively, that it has a lower color temperature. On an overcast day, daylight has a higher color temperature, leading us to perceive it as cooler, or bluer.

• Higher color temperature = “cooler,” bluer light
• Lower color temperature = “warmer,” redder light

While your brain automatically corrects for these differences in color temperature, your camera does not.

Your camera simply records the color that enters the lens. Yes, digital cameras have an automatic white balance setting, but if your location has multiple light sources, you might get some strange results. It’s during these times that you learn the hard way that you can’t always “fix it in post.”

Getting the white balance right

The first step is learning how your camera white balances. For a typical digital camera, there will be a setting in your menu or a separate button. In DSLRs and mirrorless cameras, white balancing can be a little more complicated. Check your user’s manual for the details.

Next, you will need to find something that is white or at least neutral, like a piece of paper, and place it in front of your camera. The key is to make sure your white is being lit by the main light source. Don’t turn your camera onto a white wall, for example, that is not getting the same light as your subject.

 

THE KEY IS TO MAKE SURE YOUR WHITE IS BEING LIT BY THE MAIN LIGHT SOURCE.

It’s a good idea to experiment with your camera in different situations. You need to be comfortable with white balancing and know what results you will get. Try going into a kitchen and shooting a subject in the following conditions:

1. Turn off all the lights and open all the window covers around noon. White balance the camera and record a few seconds.
2. Try it again at dusk.
3. Turn on an overhead light fixture or two and try it again.
4. Close all the curtains, or wait until dark, and use all the available lights.

When you’re done, playback your video and note the differences.

Some expert advice

We interviewed John Turner, the Technical Services Manager for KLAS-TV in Las Vegas, Nevada. He attended the USC School of Cinematographic Arts and has been in broadcast television since 1985. He has done production in all types of situations, from wars and natural disasters to court cases and presidential inaugurations.

John tells us his most challenging lighting situations are theatres.

“Typically speaking, stage lighting burns me every time. Stage lighting can be a combination of all temperatures combined in one scene. So what will you set as the primary temperature?”

Most stage lights are tungsten, but not all of them. Some theatres may have spotlights that are HMI (Hydrargyrum medium-arc iodide). These are the same temperature as daylight. You may also find newer LED lights that can be changed to cover much of the spectrum. In addition, theatrical lighting can also be coloured using thin, heat resistant plastic called gels. All of this can play havoc with digital cameras.

So what does Turner recommend in a theatre?

“Balancing and balancing often will need to occur as temps will most certainly change.”

The Right Look

John Turner tells us that ultimately white balance is going to be based on the “look” that you want to achieve. “Ask yourself what is important with this image? What am I trying to say? This will help you know what is most important about lighting.”

He tells us that in journalism, the choices may be different than in cinematography. “News photographers tend to want to keep their photography as pure and as natural as possible. ‘Keep it pure’ means going with what you have and adding nothing artificial. So, what is the object you are shooting and what is the prevailing temperature.”

Look carefully at what you are focusing on and notice what light is hitting the subject. What is the most dominant light source?

Let’s say that you’re shooting in an office with a giant picture window on your subject’s side. There are also fluorescent lights overhead and a tungsten desk lamp. The dominant light source is probably the big window. Try turning off the overhead lights and the desk lamp if that is possible and white balance off the daylight from the window.