an optical adapter for a light - wave rangefinder comprising a light emitting means for emitting a distance measuring light wave modulated by a predetermined modulation frequency , and a light receiving means for receiving a reflecting light wave reflecting from a target point to which the distance measuring light wave is directed , wherein a time delay between the distance measuring light wave and the reflecting light wave is utilized to determine the distance to the target point , the optical adapter comprising at least one photoconduction means for conducting distance measuring light wave and the reflecting light wave , and at least one single objective optical means for projecting the distance measuring light wave from the photoconduction means towards the target point , for condensing the reflecting light wave reflecting form the target point and for guiding the light wave to the photoconduction means .