Define your subject with a 'shallow' depth of field.

Depth of field, or dof, is the area of sharpness, front to back, in an image.

For this theme, we are looking for 'shallow' depth of field. Which simply means that we want to isolate the subject.

The larger the aperture (small "f" number) the shallower the depth of field.

Check out the "Depth of Field" articles in our files section on Yahoo.