Tuesday, May 24, 2011

White balance with Canon DSLRs — not as easy as video

White balance with Canon DSLRs — not as easy as video: "

A couple of my colleagues at Northern Arizona University’s School of Communication noted how difficult it is to do manual white balance with the Canon DSLRs some of our students are using.

All I can say: Not as easy as video cameras. The Canon presets have worked pretty well for all the projects I’ve shot, but I’m using a Canon 5D Mark II where I dial in the color temperature I want. Beginning students may no what color temperature to use or just rely on presets — especially when they have to go through the steps I outline below. Or some may just want to use the simplicity of video cameras. Whatever camera you choose to shoot with, manual white balance is an important step not to neglect.

And if it’s more difficult with a DSLR, then you have to decide if it’s worth the extra effort. For me and many of my students who have purchased their own DSLRs, we realize one thing: The image quality, baby, the image quality. But knowing how to color balance is part of mastering the image quality.

Why do we even bother with adjusting color temperature in the first place? Why not just set the camera to automatic. If you’re controlling your image professionally, then you need to use the manual settings so it doesn’t do things you don’t want it to be doing.

Our eyes balance white automatically. A camera’s sensor isn’t as smart as us and it doesn’t have the multitasking capabilities of our minds. So you need to tell the camera what kind of light it’s seeing so it can find true white. White indoors is different than white outdoors. See the chart below:Digital White Balance

Color temperature in degree Kelvins. This chart provides a list of different lamps and their corresponding color temps. (Image courtesy of Mapawatt.)

So if you’ve set your DSLR to an indoor light setting (~3700K), such as standard tungsten (a regular light bulb) and you go outdoors (~5500K), the white the camera saw indoors is now different and now has a bluish tint to it. If you’ve set your camera to daylight and you go indoors, the camera’s image now contains a warm yellow cast. See the images below.Canon DSLR

The top image contains the bluish tint of an indoor white balance setting used incorrectly outdoors. The bottom image is too yellow — the typical problem with an outdoor setting used incorrectly indoors. The center image is properly color balanced. Photos by Kurt Lancaster (courtesy of Focal Press).

And if you are shooting a scene with multiple light sources (such as a window and a room with fluorescent lighting), you need to tell the camera which one it should see. Is the window your key light? Then dial in the proper color temperature or set the custom white balance.

The best way to make sure you don’t make mistakes? Use custom white balance. The most precise way to make sure your whites are really white is to use a standard 18% grey card. With a video camera, you simply fill the lens with the grey card (or a white sheet of paper when you need something handy) and press the manual white balance button. Be sure you’re angling the card or sheet of paper so that it’s reflecting the light you’re balancing into the camera’s lens!

However, a Canon DSLR is more complicated than video cameras. They don’t have a point and shoot white balance mode. However, some of the cameras, such as the 60D, 7D, and 5D Mark II allow you to dial in the color temperature manually (you’ll need to know the color temperature of your light source, of course).Canon DSLRs

In this shot from the short, “The Last 3 Minutes“, the DP, Shane Hurlbut, ASC, dialed in the color temperature to 4700K in order to emphasize the warmth of the beach sunset. The Canon 60D, 7D, and 5D Mark II allow shooters to dial in color temperature in 100 degree increments.

However, until you gain the eye and experience of a professional photographer or cinematographer, it’s really good practice to manually set the white balance so as to avoid mistakes. Also, don’t rely on the “fix it in post” adage. DSLRs with their 8-bit color space don’t allow much room for error. As Shane Hurlbut, ASC, says, you need to get the image close, treating the DSLR like reversal film stock. Expose for the highlights and be sure to get the color temperature right. (See Hurlbut’s lecture from the Collision Conference, here; direct link to video segment about color balance, here.)

To white balance manually, follow the steps below to get the most accurate reading in the light conditions you’re shooting.

Manual settings of white balance for Canon DSLRs

  1. Take a photo of the white sheet or grey card, reflecting the light you want to balance from the card into your lens. Also, be sure it fills the lens, that it is in focus, and you have proper exposure (don’t blow it out or underexpose it).
  2. Turn your Mode Dial (top circle dial with images and letters on it) to manual camera mode (such as P). (This is necessary in order to access the Custom White Balance menu.)
  3. Press the menu button and wheel over to the second camera menu (the camera image with two dots beside it).
  4. Go down to Custom White Balance.
  5. The photo you took as your white balance reference will appear. Choose, OK. The camera has been properly white balanced. You now need to make sure the camera is using custom white balance in the presets.
  6. Press the menu button to exit the menu.
  7. Switch the Mode Dial back to the video mode.
  8. Press the Q button (or white balance button) and move down to the white balance menu where you can rotate through the white balance settings: Auto, Daylight, Shade, Cloudy, Tungsten light, White fluorescent light, Flash, and Custom. Select Custom. The camera is now properly white balanced.

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