If the camera's angle were always the same, an optimal viewing distance could be easily calculated. However, the camera's horizontal angle varies as the focal length of its lens changes. If the camera's sensor has fixed dimensions, a shorter focal length (wide angle) lens captures a wider angle of view, requiring the viewer to sit closer to the screen. Conversely, a longer focal length (telephoto) lens captures a narrower angle of view, demanding a more distant viewer position.
