There are 3 posts on the roof of the late Jagdpanzer IV/70, (both V and A), Sturmtiger, Jagdpanther and probably other vehicles I'm forgetting, which were used to mount a EM 09 stereo rangefinder (Entfernungsmesser 0.9 metre Raumbild ) for use by the commander. The identification of theses objects, as well as this photo, can be seen on page 150 of Light Jagdpanzer, by Spielberger, Doyle and Jentz.
An EM 09 rangefinder. The tripod would be removed for mounting it to the vehicle;
Apparently these devices were difficult to operate. The user had to possess perfect 3-D vision in order for it to function properly, otherwise it was useless. After the actions at Sidi bou Zid, Major Lueder, commander of schwere Panzer-Abteilung 501, relayed some very open and frank opinions and observations about the EM 09 in the following letter dated 16 February 1943;
"Several EM 09 have recently arrived and the bulk of them are still in Italy. Trials have revealed that personnel must first be selected who possess stereoscopic vision, a difficulty that I realized only now. Special equipment is needed for such a test, which is available only at psychological testing stations. During the next few days I will let tests and selection occur at Flakgruppe Tunis using 4-meter rangefinders, because with these larger rangefinders one can at least approximately determine if the personnel grasp the fundamentals. I will then immediately let the chosen personnel begin training, instructed by my anti-aircraft platoon leader. Training must last several weeks, if one wants to achieve reasonable results. These are all suggestions from Flak personnel, who must know what they are talking about. A lot of time-consuming work is necessary be fore experience in the use of the EM 09 on the Tiger can be obtained."
These difficulties might help explain why we don't see photos of this device being used.