(© Ian Plant) We all love to capture colorful skies at sunrise and sunset, but there is a color that often goes overlooked by most photographers: blue. This is because our eyes (actually, our brains) don’t always perceive the blue color cast that exists when the sky is covered with clouds. Especially during twilight, more blue light is passing through the clouds than other colors, although human brains tend to do a bit of “automatic white balance correction,” ignoring the blue light that is present in the scene. If your camera is set to automatic white balance, it is likely that it too will try to remove the blue. By setting your white balance to the Daylight preset (or cooler), you can capture the blues as they really are, even if the eye doesn't quite perceive it that way. When shooting raw format, you don’t need to set the white balance before you take the shot—you can set the white balance when you process the raw file on your computer, without any loss of image quality. To learn more about how white balance works, see my posts Understandng and Selecting the Best White Balance and 5 Examples of Creative White Balance.
This image, taken in Torres del Paine National Park in Chilean Patagonia, was made at twilight during a cloudy evening. I wouldn't have taken the shot if it were merely uniform overcast, but since the clouds had distinct texture, I knew that during a long exposure they would streak across the image frame—and since the clouds were heading towards me, they would appear to radiate diagonally. Still conditions allowed me to capture a near-perfect reflection of the scene in Lago Pehoé. I used a three-stop neutral density filter to achieve a two-minute exposure.
About the image: "The Blue Hour"—Lago Pehoé, Torres del Paine National Park, Chile. Canon EOS 5D Mark III Digital Camera, Tamron SP 24-70mm f/2.8 DI VC USD Lens for Canon Cameras, ISO 200, f/16, 2 minutes.