Panzer Beobachtungs Fernrohr
There are two known versions of this sort of periscope. The difference lies in the diameter of lenses. 70 mm on the Pz.B.F.2 and 50 mm for the Pz.B.F.5. A larger lens brings more light, which is better for night vision. The headrest of the “5” controls a little flap which closes the light thoughput. In this way no light is shining outside through the head when there is no head in front of the lenses. The headrest of the “2” is fixed. The total weight also differs. The “2” is more ruggedised and so 14 kg heavier, which is important for balancing the counterweight in the cupola as the periscopes can move up and down. Both optics have a detachable mirror head which stuck out of the cupola during observations. Two breaking plates controlled the damage caused by direct fire. These plates would brake easily so only the head was lost. The scopes mainbody could be refitted with a spare head, which was supplied in the transport case. The “5” had the provision to keep the inside of the tube under higher pressure, so moist from the outside would have no effect.
This is the “2”. Note the large oculairs and the snap mechanisme for changing the mirrorhead. The scale on the right picture shows the vertical angle of the mirror which is controlled by the wheel left on the photo left. These periscopes are for army artillery observation, so the scale is in thousands (Strich).
The mirror control system and the airpressure valve is visible next to the red screw.
Breakingplate. Left as on the optic, right shows the incision which weakens the plate at the proper place.