Abstract: A multi-facet lens member for use in an optical device such as a conventional camera or a video camera, comprising: (a) a multi-facet optical lens having at least four optical surfaces arranged in at least two pairs, each pair of the optical surfaces being adapted to provide a predetermined effective focal length in a light path; and (b) a rotational member for rotating the multi-facet optical lens so as to position a desired pair of the optical surfaces in the light path and provide a desired effective focal length for the optical device. The multi-facet optical lens member can be used alone or in conjunction with other conventional optical lens to obtain optimum effect. In an example embodiment of a fouri-facet lens member, one arrangement of the optical surfaces provides an effective focal length of 25 mm, thus representing a wide-angle lens. By a simple 90 degrees rotation of the lens member, an effective length of 90 mm can be obtained, thus representing a telephoto lens, from the same optical device.