I have searched here and there and the maximum distance that is offered is no more than 15 Meters and that too is with the OEM's drive electronics (like Polaroid),...

Hallo Babar,

the reason that Polaroid's style distance measuring is limited to about 15 meters, has not to do with lack of ultrasonic methode for longer distances, but only with the properties of a normal photo camera. It makes no sense to distinguish longer distances than 15 meters. At your camera there's the symbol 'infinity' for those distances.

If early reflections from surroundings make no trouble I would try ultrasonic methode first.

Kai