This short video tutorial shows how you can shift the color balance of sunlight to create a blue background that looks like moonlight.
I wanted a night time look to this 20′s scene. Shooting later was not an option. This was a way to give a night time look to the sunlight streaming in the window. This technique can be applied to all types of photography. I saw a wedding photographer using this technique by putting a small amount of warm gel on his strobe which allowed him to let the background behind the bride and groom go slightly blue. This adds depth and interest. I have used it in corporate portraiture to create a cool background out of what was a boring scene. The blue becomes a unifying layer that pulls a background together into one element.
(via The Slanted Lens via NSOP)