Using an iPhone app to replace a $1000 spectrometer?

Believe it or not, there's a quick, easy, and inexpensive way to take a color temperature reading off an 18% gray card using an iPhone app called ProCam ($4.99). You should be able to do this with a white card as well, but I use a gray card for both white balance and exposure. This is especially useful for those shooting with a camera like the Sony PXW-FS7 in Cine EI mode which doesn’t currently offer custom white balance. I just happened to stumble upon this one day when using ProCam to shoot stills with my iPhone. Simply open the app camera, point it at a gray card or white card (filling the screen), and note the color temperature in "K." That's it. It's pretty accurate when comparing it to the custom white balance measurements taken on the FS7.

You can see this video and more on my Vimeo channel at www.vimeo.com/martinlisius