This is a list of serial numbers, observed in collections and recorded from sources online, of German 7×50 binoculars manufactured mostly from 1943 to 1945, marked U.D.F. — Unterseebootdoppelfernrohr (U-boat surface targeting binoculars) — equipment of the Unterseebootwaffe (U-boat Service, Submarine Service) of the German Kriegsmarine (Navy) during the Second World War.
Surface action on the open bridge of U-373, a Type VIIC boat out of La Pallice, France in April 1942. Tracking a surface target with the U.D.F. (Unterseebootdoppelfernrohr, U-boat surface targeting binoculars) mounted on the U.Z.O. (Überseebootrzieloptik, U-boat surface targeting optics) column at the center of the open bridge. As part of the U.Z.O., the U.D.F. transmitted surface target bearings to the Torpedo-Vorhaltrechner (Torpedo data computer) to constantly generate updated torpedo fire control solutions.
When U-boats were submerged, targeting data for torpedo attacks were received from the attack periscope. When U-boats were conducting torpedo attacks on the surface, targeting data were received from the U.D.F. Unterseebootdoppelfernrohr (U-boat surface targeting binoculars).
Linked to the target bearing transmitter, the U.D.F. were mounted on a permanent pedestal at the center of the U-boat open bridge on top of the conning tower.
The U.D.F. were an integral part of the U.Z.O. (Überseebootzieloptik, U-boat surface targeting optics) used to track and conduct torpedo attacks on surface targets. The U.D.F. constantly transmitted surface target bearings to the Torpedo-Vorhaltrechner (Torpedo data computer), generating constantly updated torpedo fire control solutions.
The Torpedo-Vorhaltrechner (Torpedo data computer) was a Siemens-made electro-mechanical deflection calculator in the U-boat conning tower that transmitted attack coordinates into the gyrocompass steering mechanism of torpedoes in their tubes.
The aiming device (UZO, attack periscope, or sky periscope) used during the attack was selected (connecting the proper target bearing transmitter with the computer) by means of one of the two rotary switches located at the aiming subsystem control box that was installed in the control room, under the chart table.
The main part of the U-boat fire control system was the Torpedo-Vorhaltrechner (torpedo data computer) designed and manufactured by Siemens. It was located in the conning tower on the starboard side between the helmsman’s station and the attack periscope. The computer solved the torpedo triangle, and calculated the gyro angle and the torpedo spread angle. Active tracking of surface targets with the U.D.F. automatically provided target bearings to the the target data computer (target bearing could also be set manually in an emergency). Target speed, angle on the bow, torpedo speed, and target length were set manually using hand-wheels on the target data computer.
The U.D.F. were deployed when the U-boat was surfaced to launch torpedoes at surface targets. The rotatable U.D.F. were mounted on a permanent pedestal (bridge aiming column with target bearing transmitter) on the open U-boat bridge. A bearing ring marked in degrees on the pedestal provided direct bearing readings on surface targets, and a mechanical link to the U-boat Vorhaltrechner (analogue attack computer) in the commander’s battle station directly below the bridge generated fire control solutions.
A reticle within the right prism, in the form of a single black vertical line in daylight or a single white vertical line at night (illuminated by luminous paint), always aligned exactly on the target bearing.
Although not much larger than the standard 7×50 Dienstglas (overall length 20 cms, 7.87 inches), U.D.F. are built of massively strong, heavy cast bronze construction, and weigh approximately 6 kgs (13.23 lbs). Designed to resist the crushing water pressure of deep ocean depths, U.D.F. were guaranteed watertight to a depth of at least 100 meters (328 feet). Although watertight, the U.D.F. would only be mounted after coming to the surface, then before submerging, taken back inside. In case of a sudden emergency dive, the U.D.F. could be left behind on the conning tower.
Focus was fixed at the factory, and is not adjustable. A lever on the right prism housing was marked Hell (light) and Dunkel (dark) to set reticle illumination. In daylight, the knob is put in the Hell position, and the reticle is visible as a black vertical line. At night, the knob is put in the Dunkel position, and the reticle is visible as a white vertical line, illuminated by luminous paint. At the back is a bending bar for adjusting the eye position. U.D.F. have flip up rubber rear lens shields with side extensions to block light shining in from the sides. They are also equipped with small holes to drain condensation.
Original finish over the natural bronze construction is dark sea-blue enamel paint. The U.D.F. serial numbering system appears to be a special series for the Marine (Navy), or perhaps just for the Unterseebootdienst (Submarine Service, U-boat Service).
blc — Carl Zeiss, Militarabtailung, Jena, Thuringia, Deutschland |
|||||
| Serial Numbers
The serial numbers of U-boat U.D.F. conning tower fire control surface targeting binoculars appear to be a special series for the Marine (Navy). |
|||||
| S/N | Identifying Features | Year of Mfg | |||
U.D.F. with known serial numbers |
|||||
| s/n 112845
unit number 4 |
|
||||
| s/n 112853
unit number 19 |
|
||||
| s/n 171211
unit number 565 |
U.D.F. s/n 171211 – unit number 565 : U-boat conning tower fire control surface targeting binoculars : blc (Carl Zeiss / Jena) 7×50, light gray enamel painted bronze, hinged, flip up rubber lens fittings, left prism cover marked “T” (Transparentenbelag — coated lenses), over “blc” over “M” (Marine – Navy) and Reichsadler and “IV/1” (“IV/1” is the code of the Navy inspector at the Zeiss factory in Jena), right prism cover marked “U.D.F. 7×50” over “565” | blc : 171211 mfg. about 19xx
|
|||
| s/n 207083
unit number 1328 |
U.D.F. s/n unknown – unit number 1328 : U-boat conning tower fire control surface targeting binoculars : blc (Carl Zeiss / Jena) 7×50, light gray enamel painted bronze, hinged flip up rubber lens fittings, left prism cover marked “T” (Transparentenbelag — coated lenses), over “blc” over “M” (Marine – Navy) and Reichsadler and “IV/1” (“IV/1” is the code of the Navy inspector at the Zeiss factory in Jena), right prism cover marked “U.D.F. 7×50” over “1328” | blc : 207083 mfg. about 19xx
|
|||
| s/n 242710
unit number 1889 |
|
blc : 242710 mfg. about 19xx
|
|||
| s/n 242812 | U.D.F. s/n 242812 : U-boat conning tower fire control surface targeting binoculars : blc (Carl Zeiss / Jena) 7×50, light gray enamel painted bronze, hinged, flip up rubber lens fittings, left prism cover marked “U.D.F. 7×50” over “242812” over “blc”, right prism cover blank | blc : 242812 mfg. about 19xx
|
|||
| s/n 255796
unit number 2093 |
|
blc : 255796 mfg. about 19xx
|
|||
| s/n 295025 |
|
blc : 295025 mfg. about 19xx
|
|||
| s/n 295109 | U.D.F. s/n 295109 : U-boat conning tower fire control surface targeting binoculars : blc (Carl Zeiss / Jena) 7×50, light gray enamel painted bronze, hinged, flip up rubber lens fittings, hinged, flip up bronze sights on right lens barrel, lens shades and hinged, flip up, front covers on both lens barrels, left prism cover marked “U.D.F. 7×50” over “295109” over “blc”, right prism cover blank | blc : 295109 mfg. about 19xx
|
|||
| s/n 295123 | U.D.F. s/n 295123 : U-boat conning tower fire control surface targeting binoculars : blc (Carl Zeiss / Jena) 7×50, originally light gray enamel painted bronze, now unpainted bronze, hinged, flip up rubber lens fittings, left prism cover marked “U.D.F. 7×50” over “295123” over “blc”, right prism cover blank | blc : 295123 mfg. about 19xx
|
|||
| s/n 295129 | U.D.F. s/n 295129 : U-boat conning tower fire control surface targeting binoculars : blc (Carl Zeiss / Jena) 7×50, light gray enamel painted bronze, hinged, flip up rubber lens fittings, left prism cover marked “U.D.F. 7×50” over “295129” over “blc”, right prism cover blank | blc : 295129 mfg. about 19xx
|
|||
| s/n 316120 | U.D.F. s/n 316120 : U-boat conning tower fire control surface targeting binoculars : blc (Carl Zeiss / Jena) 7×50, light gray enamel painted bronze, hinged, flip up rubber lens fittings, left prism cover marked “U.D.F. 7×50” over “316120” over “blc”, right prism cover blank | blc : 316120 mfg. about 19xx
|
|||
| s/n 317903 | U.D.F. s/n 317903 : U-boat conning tower fire control surface targeting binoculars : blc (Carl Zeiss / Jena) 7×50, light gray enamel painted bronze, hinged, flip up rubber lens fittings, hinged, flip up bronze sights on right lens barrel, lens shades and hinged, flip up, front covers on both lens barrels, left prism cover marked “U.D.F. 7×50” over “317903” over “blc”, right prism cover blank | blc : 317903 mfg. about 19xx
|
|||
| s/n 317940 | U.D.F. s/n 317940 : U-boat conning tower fire control surface targeting binoculars : blc (Carl Zeiss / Jena) 7×50, light gray enamel painted bronze, hinged, flip up rubber lens fittings, hinged, flip up bronze sights on right lens barrel, left prism cover marked “U.D.F. 7×50” over “317940” over “blc”, right prism cover blank | blc : 317940 mfg. about 19xx
|
|||
| s/n 317943
and s/n 317944 |
|
blc : 317943 blc : 317944 mfg. about 19xx
|
|||
| s/n 318090 | U.D.F. s/n 318090 : U-boat conning tower fire control surface targeting binoculars : blc (Carl Zeiss / Jena) 7×50, light gray enamel painted bronze, hinged, flip up rubber lens fittings, hinged, flip up bronze sights on right lens barrel, left prism cover marked “U.D.F. 7×50” over “318090” over “blc”, right prism cover blank | blc : 318090 mfg. about 19xx
|
|||
| s/n 345935 |
|
blc : 345935 mfg. about 19xx
|
|||
| s/n 345972 | U.D.F. s/n 345972 : U-boat conning tower fire control surface targeting binoculars : blc (Carl Zeiss / Jena) 7×50, light gray enamel painted bronze, hinged, flip up rubber lens fittings, hinged, flip up bronze sights on right lens barrel, lens shades and hinged, flip up, front covers on both lens barrels, left prism cover marked “U.D.F. 7×50” over “345972” over “blc”, right prism cover blank | blc : 345972 mfg. about 19xx
|
|||
| s/n 345976 | U.D.F. s/n 345976 : U-boat conning tower fire control surface targeting binoculars : blc (Carl Zeiss / Jena) 7×50, light gray enamel painted bronze, hinged, flip up rubber lens fittings, hinged, flip up bronze sights on right lens barrel, lens shades and hinged, flip up, front covers on both lens barrels, left prism cover marked “U.D.F. 7×50” over “345976” over “blc”, right prism cover blank | blc : 345976 mfg. about 19xx
|
|||
| s/n 346010 | U.D.F. s/n 346010 : U-boat conning tower fire control surface targeting binoculars : blc (Carl Zeiss / Jena) 7×50, originally dark sea blue enamel painted bronze, now light gray painted bronze, hinged, flip up rubber lens fittings, left prism cover marked “U.D.F. 7×50” over “346010” over “blc”, right prism cover blank | blc : 346010 mfg. about 19xx
|
|||
| s/n 346100 |
|
blc : 346100 mfg. about 19xx
|
|||
| s/n 346126 |
|
blc : 346126 mfg. about 19xx
|
|||
| s/n 346172 | U.D.F. s/n 346172 : U-boat conning tower fire control surface targeting binoculars : blc (Carl Zeiss / Jena) 7×50, light gray enamel painted bronze, hinged flip up rubber lens fittings, hinged, flip up bronze sights on right lens barrel, left prism cover marked “U.D.F. 7×50” over “346172” over “blc”, right prism cover blank | blc : 346172 mfg. about 19xx
|
|||
| s/n 346215 |
|
346215 | |||
U.D.F. with unknown serial numbers |
|||||
| U-310
s/n unknown unit number 2143 |
|
blc : s/n unknown mfg. about 19xx
|
|||
| U.D.F. — Unterwasserdoppelfernrohr (underwater binoculars) — are very rare. This one (U.D.F. 2143) belonged to U-310.
The German submarine U-310 was a Type VIIC U-boat laid down January 30, 1942 at the Flender Werke yard at Lübeck as yard number 310, launched on January 3, 1943 and commissioned on February 24 under the command of Leutnant zur See Klaus Friedland. During her career, the U-boat sailed on six combat patrols, sinking two ships, before she surrendered in May 1945. U-310 was a member of seven wolfpacks. After the German surrender, there were 97 submarines in six Norwegian ports: With very few exceptions, these boats were transported to England, and there in late summer 1945, they were sunk. In the autumn 1945 , there was a commission settled by the Norwegian Government to see if some of the submarines still could be used. Among 15 boats, 4 were chosen that had potential for further sea service. Others were taken ashore and used for spare parts. U-310, U-926, U-995 and U-1202 were the ones chosen, and they were gathered together in Trondheim. In 1948, three out of four former German U-boats went into the Norwegian Navy. U-926 (KNM KYA) Inspection of the 4th sub, U-310, determined that the condition of the submarine was so poor that it was decided to cut it up for scrap. One of the workers took this binocular (U.D.F. 2143) from U-310. The U-310 had a record of two ships sunk. (Refer to “uboat.net” for the history of U-310). |
|||||
| U-534
s/n unknown unit number 1554 |
|
blc : s/n unknown mfg. about 19xx |
|||
| The German submarine U-534 is a Type IXC/40 U-boat built in 1942 in Hamburg-Finkenwerder by Deutsche Werft AG as yard number 352. She was launched on September 23, 1942 and commissioned on December 23, with Oberleutnant zur See Herbert Nollau in command.
U-534 is one of only four German World War II submarines in preserved condition remaining in the world, another being the Type IXC boat U-505 in Chicago’s Museum of Science and Industry. U-534 was used mainly for training duties, and during her service she sank no other ships. A Royal Air Force bomber sank her on May 5, 1945 in the Kattegat 20 kilometres northeast of the Danish island of Anholt. U-534 was salvaged in 1993 and since February 2009 has been on display in Birkenhead, England. |
|||||
| s/n unknown
unit number 4 |
U.D.F. s/n unknown – unit number 4 : U-boat conning tower fire control surface targeting binoculars : blc (Carl Zeiss / Jena) 7×50, light gray enamel painted bronze, hinged flip up rubber lens fittings, left prism cover marked “T” (Transparentenbelag — coated lenses) over “Carl Zeiss” over “Jena” logo over Reichsadler over “M”, right prism cover marked “U.D.F. 7×50” over “4” | blc : s/n unknown mfg. about 19xx |
|||
| s/n unknown
unit number 255 |
U.D.F. s/n unknown – unit number 255 : U-boat conning tower fire control surface targeting binoculars : blc (Carl Zeiss / Jena) 7×50, light gray enamel painted bronze, hinged flip up rubber lens fittings, left prism cover marked with “Carl Zeiss” over “Jena” logo, right prism cover marked “U.D.F. 7×50” over “255” | blc : s/n unknown mfg. about 19xx |
|||
| s/n unknown
unit number 1682 |
U.D.F. s/n unknown – unit number 1682 : U-boat conning tower fire control surface targeting binoculars : blc (Carl Zeiss / Jena) 7×50, light gray enamel painted bronze, hinged flip up rubber lens fittings, left prism cover marked “T” (Transparentenbelag — coated lenses) over “blc” over “M” and Reichsadler and “IV/1” (“IV/1” is the code of the Navy inspector at the Zeiss factory in Jena), right prism cover marked “U.D.F. 7×50” over “1682” | blc : s/n unknown mfg. about 19xx |
|||
| s/n unknown
unit number 1749 |
U.D.F. s/n unknown – unit number 1749 : U-boat conning tower fire control surface targeting binoculars : blc (Carl Zeiss / Jena) 7×50, light gray enamel painted bronze, hinged flip up rubber lens fittings, left prism cover marked “T” (Transparentenbelag — coated lenses) over “blc” over “M” and Reichsadler and “IV/1” (“IV/1” is the code of the Navy inspector at the Zeiss factory in Jena), right prism cover marked “U.D.F. 7×50” over “1749” | blc : s/n unknown mfg. about 19xx |
|||
