In this paper we study a passive optical ranging method based on several photometric measurements from the light radiated by an object and derive the range from these measurements. We discuss different techniques to obtain the profile of the interrogated object. The first technique uses two photometric measurements, while the other two use three photometric measurements. We evaluate these techniques in terms of noise and sensitivity. Preliminary experimental results indicating the feasibility of the method using CCD cameras and dual photo-detector set-ups are shown.