Election counts in the city where I work are special occasions, and I'm expected to photograph all but the most minor of them. The count is held in a ballroom in the Senior Center, a large room with a tan floor, red and cream-colored walls, green furniture, and bright incandescent lighting on dimmer switches. Getting the white balance right is a challenge, with almost every picture requiring individual attention.
At the count on Tuesday evening some of my pictures showed my other camera lying on a table with the City's 70-200mm f/2.8L IS II lens mounted. I discovered, more or less by accident, that the lens's color is a very good neutral grey and could often be used to set the white balance using the "click white balance" feature of Digital Photo Professional. I don't know whether Canon intended it that way, but it goes to show that one never knows to what uses one's equipment may be able to be put. 
