This is a Zeiss (blc) 8x60 U Boat commanders binocular, the attached page from Dr. Stephan Rohan's book provides the size weight, etc information on the set, there is also an example made by Emil Busch (Optische Industrie, Rathenow) coded CXN but it is in collecting terms a rare set and is not often see. (Optically on a par with this set). This binocular hits all the notes to a collector of binoculars and as a WW2 Collectible as it was only issued to U Boat crews and will only ever be seen with these simple markings code and issue/ batch number anything else is an add on. ( A few years ago a set appeared on eBay with an alternative focusing mechanism and was stated to be an experimental model, not a word about it. It was either a "clever" fake or simply something a " clever" previous owner had done but it was not as described.) Dr. Hans Seeger in his "Grey Book" showed an example that had a very stylish but utterly fake eagle impressed on it, again an example of a valuable set being defaced. This set is heavy my partner asked me one day " Could you not have found a heavier set to bring with you?", something of a Rhetorical question. The body is cast aluminum, the set is heavily painted ( a textured and smooth finished sets are encountered, but only one batch of textured sets was made)#. It is completely waterproofed, the lens are " cold coated" and focusing is by means of a screw head which turns a worm screw within the ocular tower so the set can be "set" for the user's eyes, lifted to the eye and you get an instant focus. This is useful as the set would have been difficult for prolonged use on a moving bridge. The bakelite rain guard is often missing, often referred to as a "Benutzer" ( this is molded on the guard) but this simply means "user". Desiccating cells are located on the back of the prism housings in line with the "ocular towers", a special tool allows for these to be unscrewed, the contain a substance which allows moisture to be absorbed from the interior of the sets so fogging up is prevented. Desiccant - Wikipedia The set balances well, returning an excellent wide field of view along with an excellent image but it is heavy and when you have it around your neck for half an hour you do become aware of it and notice it when you take it off. the eye cup flip open to reveal two huge oculars which drink in light via the 80mm front lens and provide a pin-sharp image and if you use them in this fashion you get a little extra by way of "field of view" eg another degree or two left and right of the centre, it is noticeable. Photographic images of the set, well they are a little rare but they do exist, in works published in the 1980s and previous - the set was often misidentified or described simply as " an unknown or as a yet unknown binocular" - the "Bender" set on "Uniforms and Traditions of the Kriegsmarine" ( Volume 3) does so. In the Uk you occasionally find these sets for sale covered in a thick black paint - both these sets were so found, I decided to remove the paint and underneath found the period WW2 green almost completely intact apart from some minor wear. Some folks say "black" sets were issued and perhaps so but with a better finish, IMO a think crude finish indicates one which went on post-war and to make the set " ready " for post-1945 selling in a civilian market. (This commonly happened for the huge number of sets Ross, Zeiss Barr and Stroud which were sold of in the late 1940's- early 50's.) Should you by one, well I never intended to buy two. Occasionally and rarely one finds a line " right down the middle of the field of view, this allowed the set to be used as a UZO, the two cased sets - how they might arrive to a U Boat going on patrol the larger case has anti spray hood and a large heavy "swan neck" to mount it, the smaller case is still rare but seem more often. (I have one but it is a reproduction, the "real "McCoy" just too much money for me).
A set being used by "Helmut" and a comparison between the "fat 8x60 ( top) and the "slim" 8x60 ( bottom) , you will see the "old man" in Das Boat using this set when they attack the convoy, he removes it from around his neck just before the deranged Johan arrives in the control room and in the "Gibraltar" scene. The first shot of a U Boat skipper with an 8x60 around his neck from "U Boot im Focus". The next photo source escapes me at present but from a book I have. (This and the one below probably from one of Luc Braeuer's books.) One of the post-war sales from Frank's of Glasgow - £55 for an 8x60 or £25 for a UDF, a lot at the time but if I had a "tardis". Kurt Petersen, U-541 on his surrender at Gibraltar in May 1945. A photo which was a delight to get.
Rich, very few sets suitable for use as a surface sight produced my two are standard 8x60's, a friend in Antwerp has an example of the same batch as mine.