The family of angles in photography
In photography, the family of angles is another useful means of working out where to position your light for a given shot.
The simplest way to think about them is to begin with the angle of view of your camera (also known as the field of view, or more simply, the camera angle).
Your camera’s angle of view is finite because it has vertical and horizontal outer extents. Put simply, just as we can only see what’s in front of us with our eyes, we can only see so much through our camera.
The angle of view is dictated by the size of your camera’s sensor, as well as by focal length, which is itself dictated by your choice of lens.
In the illustration below, the angle of view is delineated by two black lines extending from the camera to the subject. These lines strike the surface at a certain angle of incidence, relative to the normal (dotted lines), and bounce back off it at an equal angle of reflection.
Those ‘reflected’ lines extend back away from the surface, creating a ‘family of angles’ – effectively, a combination of the angles of incidence and the angles of reflection.