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10 x 80 multicoated cxn Flak 45˚



History of multicoating

The binocular was produced near the end of the second war. 
Following by Dr Stephen Rohan research, we can learn that in 1936 Carl Zeiss made a discovery of using a vapor coating on the surface of the component lenses of the binocular.
But we have, in our collection 8 x 60H binocular from September 1935 with original coating.

The official German statement was from 1936, but a few was done before.
The coating reduced the amount of light lost in the binocular because of light reflection from the surfaces of the glass elements.
Dr S. Rohan says:  “The first coating materials were very soft, and easily damaged therefore, they were generally applied only to the interior of the binocular lenses” (look at the literature list - poss.). 

Martin C. Cohen in his article: “Carl Zeiss – A History of a Most Respected Name in Optics” says:

“Another noteworthy milestone was on November 1, 1935 when by then a staff at Zeiss (Aleksander Smakula) developed and then patented antireflective (T - Transparenz) coatings thereby improving light transmission dramatically over uncoated lenses in binoculars to over 80 per cent,...” *)

Aleksander Smakula worked at ‘The Carl Zeiss AG company’, in Jena from 1934.

In the same period over antireflection coatings had worked two scientists: Katherine Burr Blodgett and Irving Langmuir.  They developed organic antireflection coatings.

Katherine Blodgett was working, as first women, for General Electric Laboratory in Schenectady, New York, were was Dr Irving Langmuir working as well.  Both scientists were working on mono molecular coatings design (mono layer - a single closely packed layer of atoms, molecules or cells), to cover surfaces of water, metal or glass. These coatings were oily.

Katherine Blodgett discovered a way, how to spread these mono molecular onto glass or metal.  She used a barium stearate (also known as Barium Salt of Stearic Acid) film to cover glass with 44 layers, which made the glass more than 99% transmitting, creating an ‘unseen’ glass.   

This kind of coating was named as Langmuir-Blodgett.

Inspired with soap bubbles, Katherine Blodgett invented the colour gauge. She noticed that the different thickness of the soap bubbles gives new colors.  She worked out a glass rules to show different colors corresponding to the thickness.

Katherine Blodgett was the first woman to earn a Ph.D. degree, in physics from Cambridge University, in 1926.

At 5th November 1940 Dr Blodgett issued three US. Patents: “Film structure and method of preparation”; “Reduction of Surface Reflection”; “Low-Reflectance Glass”. **) 

It seems that the Aleksander Smakula method of multicoating was the best. Presumably, the temperature and vacuums applied during the coating process has given stronger coatings of the lenses.     

Additionally, the surfaces of the lenses are degreased and antireflection coating applied by magnesium fluoride. The prism plates are located in the nests of the evaporator tray. Application of the coating is done by vapor deposition of magnesium fluoride in a vacuum. The process consists of three stages lasting about 1 hour. The first phase is a heating chamber to 300 degrees Celsius. This is followed by ion cleaning. The third phase is a proper vapor deposition occurring in a high vacuum, of 10 to minus 5 Torr. ***)

The method described above was applied by PZO in 1970s and in Wetzlar in 2006. In Wetzlar the temperature was applied to 400 C.
Presumable the similar method was applied by Aleksander Smakula.
As Martin C. Cohen says: “By 1990, Zeiss Oberkochen improved the anti reflecting coatings to transmit more than 90 % of the light of the light entering a binocular (the T* designation). In 1988 ‘Phase Correction’ coatings were introduced on all Carl Zeiss Oberkochen roof prism binoculars to further improve resolution and contrast of roof prism”.
The improvement of the anti reflections coatings is very controversial.  Many sources pointed different percentages of development. 
Hensoldt in the factories catalogue from about 1963-1964 says: “E-coating eliminates every disturbing reflected image in the binocular and increases the light transmission extremely - about one third more than in uncoated glasses”.  In the Hartmann Wetzlar catalogue (1970) is pointed to 30 -35%.  When in Carl Zeiss Jena catalogue (1952) is told that a light transmission in Zeiss T optic is 80% against 60% for non coated binocular.   The catalogue of Carl Zeiss Oberkochen/Württ, also from 1952, opted for 50% improved of the light transmission.
We could conclude that parameters founded, before experiments were different in each factories and with different binoculars, presumably with a different elements of glasses.  In this way the results of trials are dissimilar.

The German discovery was kept as a military secret, in the early years of WW II,  because of the military importance. During the war the harder coating process was developed. It allowed to applied antireflective coatings to the outer lens elements.  But the coating was still not as hard as that applied after the war. This information it is easy to confirm making a close examination, of the binocular objective. Unfortunately, many tiny scratches are visible.
The coating lenses were marked on the binoculars body with a capital letter “T”. We have not seen this mark on any 10 x 80 multicoated binoculars.

As Dr Blodgett described; the coating glass does not have colour. 
Let’s look, in short way, how lens coating works. In the most easy way, we could say that the reflections from the glass, and from the coating surface, cancelling each other.
Reflections, physicists described as reflected waives of light.  When a light wave strikes the glass surface, some of the ways bounce off as a reflection. The reflected ray has the same wave as the incident ray, only moving in the opposite direction. 
As a wave, the reflection can be cancelled out, when that other wave can be made to be equal frequency, direction and magnitude, and opposite phase.  The equal frequency has to obtain differently for all colours, visible in spectrum of light.

The production
The binocular was made by Emil Busch cxn and is no markings on the body to indicate it is a coated version.

Interesting is that the manufacture of multicoated binoculars were at least three groups of the serial numbers , mixed with  the  production serial numbers of  uncoated glasses 10 x 80, produced by Emil Busch.
The body of multicoated binoculars are, in majority, in German army tan colour.  It appears that it was produced in gray colour as well.
Fred König - the binoculars’ collector from Germany has sent the pictures from his collection. The body of the binocular is in original gray colour. It is the first binocular we have seen in this colour.

10x80cxn grey 10% for web

                                                           The picture of Fred König binocular

10x80cxn grey oculars  10% for web

                                                                  The picture of Fred König binocular

The binocular is unusual in other way. It has a deferent serial number as from a different serial group of the binoculars production. The number is - 77263.

10x80cxn grey 50% for web

                                                          The picture of Fred König binocular

The serial number of the binocular from our collection, in tan colour, is: 112574
The binocular was fully and professionally serviced by Terry Vacani.

10X80 multicoated-our (12) 40% rom web

                                                    The 10x80 multicoated in our collection

The other collectors sent us, serial production numbers of their multicoated binoculars, in tan colour:
The list of production numbers of the multicoated binoculars, which were sent to us:
-         101445;
-         101459;
-         101828;
-         101858;
-         112574; (from our collection)
-         121791;
-         77263; (gray colour);

Patrick multicoated 12% for web

                                                                The picture of Patrick Quentel binocular

Multicoated from email -James Wilkie 12% for web

                              The picture of James Wilkie binocular (sent by e-mail as a respond to this article)

10x80 from USA 60% for web

                The picture of John Coe, Hamilton, MT, USA binocular (sent by e-mail as a respond to this article)

The colour of coating is not every time the same, sometime it is orange-red, other time reddish-purple. The outside coating is easy to scratch and difficult to clean. 
10X80 multicoated-our (6);20% fpr web

10X80 multicoated-our (3);20% for web
                                            The binocular from our collection - serial production number: 112574

Patrick multicoated 10% for web
                                                            The picture of Patrick Quentel binocular

Multicoated from email 13% for web

                                The picture of James Wilkie binocular (sent by e-mail as a respond to this article)

All glasses are coated, inside and outside surfaces.  All filters are coated from both sides. Only one element is not coated, it is reticule. The filters selector knob and the eye width control knob always made from brown Bakelite. 

As far as today, we now only five collectors, they have this binocular in their collection. This binocular is not a  rare binocular, but you can seldom find one with good coating on the outside of the objectives and eye lenses. In the past we have seen, in Belgium, four complete binoculars of this model in like new condition. The owner of this binoculars valued them highly.

The French collector Patrick Quentel, a big enthusiast of this model, says; it is a fantastic picture compared with the normal uncoated 10 x 80 45˚.



In general, during the WW II the 10x80 binoculars were used very often in the military actions, mostly were used for spotting enemy planes.  We can see many pictures of these binoculars, in German magazines.

In 1941 in Signal magazine, October edition, it was inserted the picture from Africa:



H20 October 1941p; 30% for web

                                                  The Signal magazine from our collection                          



In 1943, in Signal magazine was an article with a comparison to the W.W.I, and was pointed to the binocular 10 x 80, as a big development.
Under the picture, in French language, is information:
 “In 1943, such young men, and even younger ones, are drafted by the FLAK.
Against the terrorist attacks of the enemy, they thereby build up a defense front of utmost importance to the country.” – translated into English by Patrick Quentel.



Signal magazine No23 December 1943, in French,p.7; 30% for web
                       The Signal magazine – a French edition;1943, issue 23, p.7 (from our collection)

In the same year on the cover of Die Wehrmacht magazine is a picture of 10 x 80:

Die Wehrmacht ,Berlin, 8 December 1943;18%
                                             The ‘Die Wehrmacht’ magazine from our collection

Many other pictures of these binoculars, we can find in the Bundesarchiv and in German Signal magazine, not only on the covers. 

Sicili September 1943; 90% for web

          Sicily September 1943; on a tower.  Picture source: BArch, N 1603 Bild-258 Image/ Horst Grund**)

Seeing these pictures,  we can understand why multicoating experiments were applied for further improvement  binoculars’ performing.
It is easy to understand the issue of multicoating as a big advance in binoculars’ field. The image is a much brighter, because   the light transitions increased.  
In additional, the beneficiary of multicoated binocular is a brighter sharper picture with more contrast. A coating lens significantly reduced the reflected light.

Beside the multicoating subject, we would like to show you the next pictures.

We have just seen a monocular 10 x 80 version, produced by Emil Busch, but not multicoated:

10x80 monocular-Bassam (7);20% for web

                                                                    © Anna Vacani

10x80 monocular-Bassam (8); 20% for web

                   On the monocular is a visible description, as it is the monocular (designation next to 10x80)
                                                      ©Anna Vacani

The monocular Z.F. 10x80 (Zielfernrohr1 10x80) is one half of a 45 degree inclined ocular binocular which was used as a line of sight telescope for land target acquisition and fire direction in combination with the infamous 88 mm cannon Model numbers 18,36 and 37. All so far known have been manufactured by Emil Bush (code cxn) and none have had coated lenses.  The monocular was issued with a mounting bracket to fit the carriage of the 88mm cannon, a small head rest and an eye shield for the non used eye of the artillery spotter.
The pictures of the complete monocular we have received from the USA collector - John Coe:
10x80 monocular 60% (3)for web

                                                    The monocular of John Coe, serial number 123684

10x80 monocular 60% for web

                                                                  The monocular of John Coe

10x80 monocular 60% (4)for web

                                                                The monocular of John Coe

10x80 monocular 60% (2)for web

                                           The monocular of John Coe with  the eye shield for the non used eye

If any binocular enthusiast would like to add new information on this unusual multicoated binocular, it will be very welcome.

 ***) The Torr (symbol: Torr) is a non-SI unit of pressure with the ratio of 760 to 1 standard atmosphere, chosen to be roughly equal to the fluid pressure exerted by a millimeter of mercury, i.e., a pressure of 1 Torr is approximately equal to 1 mmHg. Note that the symbol is spelled exactly the same as the unit, but the symbol is capitalized, as is customary in metric units derived from names. It was named after Evangelista Torricelli, an Italian physicist and mathematician who discovered the principle of the barometer in 1644. Source of the information -






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