[Aktungbby]

Originally Posted by Catfish

Once more the observation perisope down in the control room, we were wondering why there are two oculars.. anyone?

From your own site: http://www.tvre.org/en/aiming-with-the-periscope

In the control room of the U 995 (located in the Laboe type VIIC U-Boat converted to museum-ship) is installed the type ASR C/13 (Angriff-Sehrohr) periscope. This is post-war periscope designed by Zeiss, based on the war-time type ASR C/6 periscope, which was designed for type XXIII U-Boats. This periscope consisted of the ocular box of type NLSR C/9 night periscope and periscope head of the type StaS C/2 attack periscope. The ocular box of the type NLSR C/9 night periscope was fitted with additional optical system (kind of telescope), which made possible reading of the bearing while looking through the periscope. The bearing scale was visible in the upper part of the view field. This optical system consisted of prisms and lens, and transmitted the view of the bearing scale through the slit in the periscope collar to the ocular box interior. Type ASR C/13 periscope which can be seen in the U 995 control room comes most likely from the U-Hai or U-Hecht (ex U 2365 and U 2367 respectively) and was installed on U 995 in the time when (most likely) she was converted to the museum-ship (during her service in the Royal Norwegian Navy as KMN Kaura, in the control room was installed the original type NLSR C/9 periscope).
The ocular box of the type ASR C/13 periscope is simplified version of the type NLSR C/9 periscope ocular box. It is slightly smaller, however the layout of the oculars, knobs and levers is the same. The ocular box is not fitted with the optical system for showing the bearing scale in the view field (the system was probably abandoned to make the manufacture simpler, faster and cheaper). The current periscope bearing is indicated by indication line, engraved on the periscope tube. It points the current bearing at the fixed azimuth circle. That's why type ASR C/9 periscope is fitted with only one azimuth circle, with 180° mark directed toward to the bow (please note, that azimuth circle in the U 995 control room is not properly set relative to the U-Boat longitudinal line). Over the fixed azimuth circle, the deflection angle ring is located, which is used in the same way as in case of previously described periscopes.

Backside view The cross-section of the type NLSR C/9 periscope ocular box (the optical system for transmitting bearing scale is visible)