This shot was taken during a seminar at my studio a last month ago with Rick Ferro. It was raining outside and we had promise as part of the class to do some available light shooting. So we placed the subject next to the window in the lobby.
Window light is one of the most beautiful (and cheapest) types of light a photographer can use.
Where do you think soft boxes came from? Photographers trying emulate this beautiful quality of light in the studio. The easiest way to understand window light is to think of the windows as a very fixed soft box. Therefore, the size of the window will affect the quality of light just like the size of the soft box in the studio will affect the quality of light on the subject. The larger the window, the softer the light.
The biggest difference between window light and a soft box is in the studio you can move the soft box in relation to the subject to achieve the quality of light and the lighting pattern you want. When working with window light you will have to move the subject in relation to the window. For the image below, we positioned the subject to achieve a short lighting pattern on her face and used a silver reflector as the fill (see set shot).
I love shooting wide open whenever possible and shot this one with my Canon 85mm set at f2. This allowed the limited depth of field and takes the viewers attention away from the rather blah background.
Main light: Window
Fill: Silver reflector
Canon 5D Mark II
Lens: Canon 85mm
1/500 sec @ f1.2