Taking silhouettes is a fun way to create simple bold compositions and though most silhouettes are created outdoors against the sky, you can also create them indoors. I've shot many silhouettes of my cat, for example, sitting on the windowsill watching birds at the feeder. All I do is frame the cat and expose for the light outside.
You can also create some clever silhouettes in other indoor situations. I photographed this mother and child in front of a huge aquarium window at the Mystic Aquarium, for instance, just by hanging back and watching them as they waited for something interesting (a penguin in this case) to swim past. I shot several frames of them just standing there, but then the mother pointed at a penguin and I knew the gesture would make a more interesting shot.
The secret of a good silhouette is having a bright or colorful background (preferably both) and exposing for the background. Exposure isn't critical and you can always saturate the black shapes and the colors later in editing.
Friends in Beijing
9 hours ago