Not all window light photography is the same. There are many different ways to use the skill.
Here are a few examples of just how photographers use window light to create professional portraits.
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When one thinks about window light photography this is a typical image to be displayed. The two-thirds view has the camera out further into the room.
Window light is not always used for the typical portrait. One can achieve a very realistic look with a very limited amount of equipement.
The standard of time. The Full Face Rembrandt Lighting. Also very usefully with a two thirds full face pose.
A classic in it's own right. The split full to two thirds. Just a little more light and you have a two thirds full. A reflector could totally change the look and feel of this image.
Normaly I try not to include the window in a widow light portrait. However. There are times when the window plays a huge roll in making the image. Some of the best light for photographing little childeren is windown light.