An optical system for alternative or simultaneous direction of light from two scenes to the eye of a viewer comprising (a) a first lens having a first focal length; (b) a second lens having a second focal length, the first and second lenses being positioned aside one another in front of one of the eyes of the viewer, such that a single light beam from any of the scenes passes only through one of the first and second lenses; and (c) an optical arrangement for directing incident light originating from the first scene and passing through the first lens into the eye of the viewer, and at the same time, for directing incident light originating from the second scene and passing through the second lens into the eye of the viewer, the optical arrangement being positioned between the first and second lenses and the eye of the viewer.