Hans Seeger, Militaerische Fernglaeser und Fernrohre, 2.3.4 - I, Pages 83-101 Germany. The first Military field glasses and 'Basismodelle' in the first and second World War. Carl Zeiss developed in 1893 in Jena the first prism field glass, in the form still used today, and also produced the first official German military prism field glass. In the beginning part of this chapter a Zeiss circular was cited, wherein the official introduction of the Zeiss Military Field glasses in 1896 was noted. Models from that time are shown in figure 46a. The designations O.D.F. 95 and D.F. 95 are an indication of the fact that in 1895 military models by Zeiss had already been delivered or at least undergone trial. According to both popular opinion and the literature, the first Zeiss military model was the D.F. 95 with 8 times magnification and bent prism housing lids, and there is also an opinion that this construction form was chosen to distinguish these military models from the civilian ones. Is this true? As in many cases about which this book reports, the answer is given more by the surviving field glasses in collections, than by the literature. The only (?) document which extensively informs us about the first Zeiss military models is the article ' The First Fieldglasses' in the Zeiss internal magazine of Oct.1941. The author Michaelis reports about the 'Ancient History' of the Zeiss military field glasses: 'After the field glass was rendered usable, efforts were made to interest the military in these new glasses, which were probably without success for some time. Only by the cooperation of the Artillery Test Comission (A.P.K.) was the instrument suitable for army purposes created. The D.F. 95 8x (Doppelfernrohr 1895) and the O.D.F. 6x (Offiziers Doppelfernrohr) were created. To distinguish the military from the civilian glasses, the D.F. 95 received convex prism housing covers; and in addition the hinge could be fixed by a friction brake, although in use this could not always prevent a change of position of the hinge when riding and when on the ammunition box, and so was soon replaced by a cog wheel brake. The civilian glasses had an adjustable detent device to facilitate the return to a previously used ocular distance..... The hard rubber eye cups were not graduated at first, and so the oculars had to be adjusted with each use, along with the inter-ocular distance adjusted to match the interpupillary distance, which was rather cumbersome. The first progress may be observed when the eyecups received an arbitrary so called ‘finding graduation’. The designated adjustment had to be remembered, because the glass, as something novel, went from hand to hand. The A.P.K. also demanded a ‘value graduation’ on the eyecups, and an interocular distance scale on the cover screwed to the axis. The cover could be secured by screws against unintended loosening. That is how the diopter graduation was born. [page 84] The A.P.K. demanded further improvements: At that time, each prism housing had 13 screwholes that could allow dust and humidity to enter. First the ‘rain cover’ was invented, which prevented the wetting of the oculars.... Then the bearing surfaces of the covers and the hinge were caulked with varnish....another bad influence of the tropical air made itself known: The leather cover of the housings shrank, even loosened, and the exposed metal (A - Metall) became dust. Consequently a complete reconstruction becomes necessary, to do justice to the new requirement of the A.P.K to obtain watertight instruments. Hinge and body became one. The screwed on hinge was dropped. The covers received an projecting rim and the oculars and objectives were bedded in a waxlike grease. With this, and by the pressing of the covers with caulking onto the body clad in hard rubber, a complete watertightness was achieved. When glasses were delivered to the military, some were submerged into water for a lengthy time as a test. If there was only one glass that showed the slightest trace of humidity in its interior, the entire order was tested the same way.' [end Michaelis] These last sentences refer to the improved Zeiss models like the ‘Marineglas’ 6 x 30, which is described later. The improved method for watertightness described by Michaelis created another advantage: The objectives were 'swimming in grease, so to speak', and were placed in the housing free of stress and watertight. By these methods the deformation of the objective ‘screw coil’ [cell] could not be transferred to the objective itself, and this freedeom from stress enhanced the quality of the image. Before we talk about the Zeiss military 'Original Model' [Urmodelle], another quote shall make clear the emphasis that was put on military optics at the time; a quote that also proves that in the previous centuries common experimentation had not gone completely out of fashion: 'With tenacious perseverance, Jakob Heckel attempted to completely fulfill all requirements and wishes of the military. We older Zeiss people still see him in our minds, clad in a thin mechanic’s blouse, at work in his ice cold cubicle, the window wide open in minus 10 degree celsius, to force the best image from the the objectives of the 20 power ‘scissor telescope’. His eagerness seemed to make him unaffected by the cold, though his body did not seem to show any warming, insulating layer of fat. But everybody connected with production was affected by his diligence, starting with the plug makers in the foundry, up to the last refining hand of Max Ottes, who indefatigably exchanged objectives until the image was good, and he had fished out the last little speck of dust with a brush from the finished field glass.' As we have learned, the Zeiss models O.D.F. 95 and D.F. 95 were developed or built in 1895, as the names indicate. [page 85] The O.D.F. is a little bit smaller, with a magnification of 6 power, but straight prism housing covers as with the first civilian field glasses built from 1893-94 on. (See fig. 46a) Perhaps that is why the O.D.F. 95 is the first official military Zeiss prism glass and therefore the first German military prism glass. The idea that Jena was thinking of providing military officers with the 'officer-specific' O.D.F. is not erroneous. But we don’t want to speculate here. Note: the serial numbers of the early Zeiss models, etched into the bridge of the binocular models (see fig. 46a below), and adjacent to the ocular of the monoculars, do not necessarily indicate the age of the glass. It seems as if at that time in Jena, a new number sequence starting with 1, was given to each new model. There is no proof of that; and it seems as if the same number sequence was used for models with the same or very similar construction methods (for example, the O.D.F. 95 and the D.F. 6x) The name ‘Doppelfernrohr’ [double telescope] was used regularly by Zeiss from 1904 on. From a Zeiss Publication of 1904: The Army models of our field glasses have, according to the regulations of the Royal War ministry of January 15, 1904 (Army regulations, volume 38 no. 1) have the following specifications: Zeiss Doppelfernrohr 8x (8 power); abreviated name: D.F.8x Zeiss Doppelfernrohr 6x(6 power); abbreviated name: D.F. 6x Zeiss Doppelfernrohr 4x (4 power); abbreviated name: D.F. 4x Note: The D.F. 8x has almost the same construction as the D.F. 95, see fig. 46a, for example it has bent upper covers. D.F. 6x: see fig. 46a, D.F. 4x, see below, also fig. 46b (later model). The D.F. name is older, for the first Zeiss military field glasses were already named D.F., as for example the D.F. 95. In one of the first Zeiss brochures (Oct. 1894) it says in a headline: 'New Double Telescopes'. A brochure from Goerz reported on the D.F. 99: 'The instruments have received the official name: Doppel-Fernrohr Modell 1899'. On a laid in order form the abbreviation 'D.F. 99' can be found. In the first paragraph of this book the ‘Doppelfernrohr 74’ was mentioned. This name is found in an official paper, and probably originated in 1874, see fig. 7. It is probably the oldest example of a name using the concept of 'Double telescope' Around 1899 for the first time the name (Doppel-) Feldstecher [double ‘field piercer’] can be found in the Zeiss publications. In 1900, brochure T37 the binoculars are called 'Doppel-Feldstecher'. This name is used, along with 'Doppelfernrohr' and 'Feldstecher', until 1906. In the course of time, different ways of spelling emerged from the producers of German military optics: 'D. F.', 'D.F.', 'D.-F.' and 'DF'. Was the term D.F. originally used as an abbreviation for 'Dienst- Feldstecher' (Service field glass)? This statement was made internally by a Zeiss colleague, when at the beginning of the fifties in Oberkochen, they considered giving the name DF to the new civilian prism glasses being developed there. (R. Leinhos, personal communication). In Oberkochen, they avoided the name DF for the civilian. But since there is no proof that there is another reason for the neutral ‘Doppelfernrohr’ [double telescope], we shall not give any more speculations about D.F. (In East Germany the 'DF' name was used for some civilian models) In some models of the D.F. 95 is a feature that was realized in other military field glasses in a different way (for example in fig. 44), the possibility of securing the oculars to a fixed focus. This is missing from most of the surviving D.F. 95s, and a very early model with this device is shown in fig. 46a. Whether this is a glass from a special series, or the original version of the D.F. 95, is hard to say. Certain characteristics point to a very early construction, but the serial number (1093), indicates otherwise. This fixed focus device probably didn’t find approval, but we can definitely say that the D.F. 95 was the first prism field glass with the possibility of fixing the oculars, the predecessor of all 'fixed focus' models. Note: The D.F. 95 example in question was documented by Wilbert Engel, and shows once more that 'desk research' (the perusing of brochures or reading of company publications) does not suffice to obtain complete knowledge of early developments. The best documentation is the glasses themselves. Now to the O.D.F. 95, the Offizier-Doppelfernrohr 95 [officer’s double telescope], which was built with the D.F. 95, if not before. In 1902 the O.D.F. 95 was improved. In the Army regulations publication of July 16 1902 it says: 'Improvement of the Officer Binoculars 95 In the future, these binoculars will be delivered by Zeiss, Jena, with an improved ocular and enlarged field of view. Every one of these binoculars contains an eye cup for future use. There will not be a price raise.' [Page 86] This announcement was in regard to the 6 power Zeiss model with straight covers, comparable to fig. 46a, middle left. This model looks rather modern and its form looks, like its predecessor the O.D.F. 95, quite a bit like the first 'civilian' Zeiss field glasses A little later the name ‘Offizier-Doppelfernrohr’ was dropped. The Army regulation announcement from January 1904 contains, among other things: 'the Double Telescope with 6 times magnification is the model formerly called the Officer Double Telescope, but with larger f.o.v. and increased brightness.' According to the last mentioned citations, the name ‘Officer double telescope’ was only used until 1903 for Zeiss models. Some notes on the O.D.F. 95 (officer double telescope 95) and its successor, the D.F. 6x (from W. Engels, personal communication): The O.D.F. 95 shown in fig. 46, upper left, has the serial number 2307 and the Privat-Nr 2190 [owner’s number, inscribed at factory]. The exterior of this O.D.F. resembles the later D.F. 6x, also shown in fig. 46a. It has a similar tightening screw, but different eye cups. The depicted D.F. 6x is a very early model, indicated by the serial number of 3719. Between the O.D.F. 95 shown here, and a later D.F. 6x (not shown, serial number 8439, private number 5304), there are the following differences: f.o.v. of the O.D.F: 105m/1000 m, f.o.v. of the D.F. 6x: 120 m/1000m. The housing covers of the DF 6x are 4mm wider (51mm, compared to 47mm). The arrangement of the ocular lenses are different, with a larger ocular holder (20.5mm, compared to 17 mm diameter for the D.F.). The slide or ways of the wormdrive is fastened with 3 screws for the D.F., the O.D.F. has only 2. Weight: O.D.F. = 433 g, D.F. = 475 g. The D.F. has different eye cups and a 'modern' tightening screw. This screw is positioned toward the front so that its front surface lies in the plane of the objective rings, and the field glass consequently rests on three points. For both models, the same objective diameter (18mm) was used, so that it is not quite explicable what the 'increased brightness' means. We cannot exclude the possibility that they were already talking about the Zeiss D.F. 6 x 21, of which it is known that it was recommended officially in March 1907 for the Naval-infantry, but it was surely in production at an earlier date. Returning to the D.F. 95; in the form with the domed covers, the D.F. 95 (8 x 20) stayed alive for only a few years. In 1907 it was replaced by the D.F. 95 n/A with 8x24 designation, where n/A means ‘new issue’. The D.F. 95 n/A has straight covers and can hardly be distinguished from the civilian Zeiss 8 x 24 'Telact'. Other firms followed in those steps. 'Proven' and known designations were transferred to military glasses, which had diferent constructions than the original models. For example, for the Goerz Model D.F. 03 we find no less than 4 different executions (fig. 48), and also the name Marine Trieder was used by the same firm several different times, even for glasses of vastly different construction. The name D.F. 03 was taken up by other producers as well. From a newsletter of Carl Zeiss, Vienna, concerning the recommended Army field glass, the M.7 Z. in March 1908: 'With courteous reference to the ordinance of the imperial and royal war minister, dept. 5, no. 106, of 1908, we take the liberty to send the imperial and royal command a number of brochures and order forms for the Army fieldglass M.7 Z.' The M. 7 Z is a 6 x 21 model. One example carries the imprint ‘Carl Zeiss Vienna’, in the lens symbol; and on the right, ‘Army field glass M 7 Z 6 power’. It has covers of brass, hard rubber coating, and a reticle on the right. The Serial number 175637 is on the rim of the cover of the right side. (Personal communication from Thomas Mix.) Note: The M notation of the military Vienna and Gyoer models probably stood for 'Model', but usage is not completely uniform. Example: M 8 Z. 12 power (12 x 40, No 312426, collection Mix) M 8 Z 15x Doppelfernrohr (15 x 60), see fig 98 M 8/12 Z 15 power (15 x 60), see fig 98 M 9/13 Z 6 power (6 x 30, No. 313737) M 9/13 Z 6 power (6 x 30 Zeiss Karoly, Gyoer, No. 553537) Before we go the modern Zeiss field glasses, another look at the 4 power model. The above cited paper of 1904 mentions the Zeiss D.F. 4x. This field glass must have had, as did the other two models that have been discussed (D.F. 8x and D.F. 6x), a screwed on bridge and must have resembled the civilian 4 power Zeiss model (compare 'Feldstecher', fig. 34). Surviving examples of the first D.F. 4x are not known to the author. The model shown in fig. 46b is a later construction, recognizable by the integral cast bridge and the serial number, which indicates manufacture in 1912. This model, also named D.F. 4x, is probably a prototype, produced in very low numbers. We have more exact knowledge about the Zeiss field glasses for the Army and Navy which were mentioned in the contemporary newsletters. The separation of Army from Navy models in this book is arbitrary for many models. The listings in the Army handbook of 1913 - 1914, published by Carl Zeiss, Jena, give information about the field glasses available at that time, see chart 6. [on page 91] This excerpt shows that all models could be delivered either in black or field grey. [page 87] The 7x50 model is the 'Noctar'(not so called in the contemporary paper), see fig. 196, and not the 'Binoctar', compare fig. 225. Of all the models the author knows only examples of those marked D.F. Only in 1908, after the lapse of the Zeiss patents, could the most practical form for Porro I field glasses be adopted by all producers of military optics. For this reason alone they became more and more similar to each other. In Germany, where military agencies and the leading optical producers work closely with each other, there was a standardization of the basic models, which were produced in great numbers (6 x 24, 6 x 30, later also 7 x 50, 10 x 50) Another addition to the early German military field glasses was the reticle, probably used from the beginning and at first called 'thread plates' [Fadenplatten], from the use in the last century (and in Great Britain even during WW II), of spider web threads in telescopes and binoculars. The reticle or cross hair in one half of the field glass changes its position [rotates] when the bridge is adjusted for different interpupillary distances. French and Italian field glasses therefore had a turnable reticle whose position in the field glass could be optimized for the user, and also allowed measuring across a perpendicular. [page 90] As far as the author knows, only rarely were there reticles that could be rotated from the outside in German military optics, (for example, the Zeiss D.F. 12x50, see paragraph 2.3.4.IIIa). This is probably because of very good reasons; such a construction is an unnecessary complication and also not watertight. Of course, companies in Germany were aware of these things. In the Army regulations of June 1906 it says: 'Double Telescopes of Zeiss in Jena. When ordering reticles for binoculars for private use, it is recommended to give the delivering firm (Zeiss Jena) the exact interpupillary distance. Only then can it be certain that the lines of the reticle are vertical.' Between 1895, the year of the first military prism field glass, and 1914, the start of the first world war, Zeiss was not the only company that was active in military optics, and important developments and interesting field glasses also came from other German firms. In the first place we have to name the company Goerz of Berlin, whose Galilean- model C 91 made Goerz a producer of German military optics even before Zeiss. By 1906, Goerz field glasses 'are officially introduced into the following countries: Germany, Russia, Austria, Hungary, England, Italy, Portugal, Japan, Switzerland, Sweden, Norway, Denmark, Holland, Rumania, Bulgaria, Greece, United States of North America' (text from a brochure). The first sample order for 10 ‘Trieder Binocles’ was executed in 1899 for the Prussian Army (Goerz Festschrift 1911, also the source of some of the following information). The Goerz D.F. 99 (fig. 47) was officially introduced in 1900, according to the order of the Royal Prussian War Minister. It is interesting that the buyer could have a ‘Privat-number’ engraved on the field glass by the producer. The D.F. 99 had a special kind of individual focus ocular, the so- called guide-bar [Geradfuehrung] ocular. Turning the ring moves the eye cup and lens up and down, but the ocular does not rotate. [helical focus] (Registered design no. 115394, 1899, 'Ocular focusing for prism binoculars, specified by the fact that the ocular travels in a straight line and is moved by a turnable slide-bar with cord and partitions.') *The helical focus is still used today, for example see fig. 82 and 120, but for reasons other than those of 90 years ago. The author cannot confirm if the following is valid: 'The ‘guide bar’ of the oculars was conceptualized, to avoid rotation of an ocular with several lenses. Early lenses which could not be ground so perfectly, could have changed the image [when rotated].' (personal communication of the author.) From the text of a brochure for the D.F. 99: Our prism binoculars of 7 power, which were introduced according to the Royal Prussian ordinance of January 1903 are, as made known in the order of the royal general command department, offered by us to members of the German Army and Navy for their own use, also at the discounted price, agreed upon by the department, of 95 Marks, if the order is made by the Military. The instruments are officially called: ‘Doppel-Fernrohr Modell 1899’, and are engraved as follows: ‘C.P. Goerz, Berlin’ on the left telescope tube and ‘D.F. P. no.’ (i.e. Double Telescope Model 1899 Private No.) *In a letter from Zeiss, Jena of June 1913, to the 'Mr Military Student, von Philipsborn, Main Cadet institution Berlin Lichterfelde', the reason for requiring order through the military is revealed. In the letter from Jena it says: 'We require this military approved order without exception from all gentlemen whose name is not listed in the officers list.' In later brochures, (circa 1906), the D.F. 99 is recommended for Artillery. In an article (German Officers’ News XI, 1907), it is reported that Goerz offers the double telescopes in 6, 7 and 8 power, and if desired with accessories (Telemeterplatte [distance measuring reticle], yellow filters, compass, etc.) The D.F. 03 was also a Goerz development. As the name says, it was mass produced in 1903 and 'by the order of the Royal Prussian War Department of July 20, 1905, officially introduced by the name D.F. 03'. See fig. 48. But even before that, this field glass had an official name. In the Army regulations of June 27, 1903 it can be read: 'War Department. Berlin. June 20, 1903. General War Dept. No 384/6. 03. A.2 Double Telescopes 1903 C.P. Goerz in Friedenau-Berlin offers the Doppelfernrohr 1903 with officer case (folding case) to members of the German Army and Navy for their own use, if the order and payment is executed by a military official, at the price of 75 marks, also payable in ten monthly payments if so desired. The Doppelfernrohre are tested before delivery by the rifle inspection commission. Signed: Sixt von Arnim [page 91] Soon the D.F. 03 New Model came on the market, see fig. 48, middle. The D.F. 03 was recommended for infantry and cavalry soldiers. It could be delivered in 6,7, and 8 times magnification. The Army regulations of July 24, 1905 contain important information about the D.F. 03. The War Ministry, General War Dept. under No. 904/6. 05 A. 2.from Berlin, July 20, 1905: 'Doppelfernrohre 03. To achieve an even greater capacity for resistance in the double telescope 03 the folllowing changes were made on the sample: Housing and prism seat are now made in one piece; the places where the covers lie upon the housings are caulked with a cement; the Ocular screw is tightly connected to the dioptre ring with another screw; instead of the two thin arms that connect the two telescope halves, larger pieces are substituted; the rain protecting cover has a longer shape and a metal rim; the carrying strap is fastened so that it presses the rain protecting cover against the eyecups from above. The Doppelfernrohre 03 must not be dismantled by the troops any longer. [page93] Cleaning of the glasses is limited to the wiping of the outer ocular and objective surfaces. The keys that have been delivered for dismantling the glasses are to be given to the rifle testing commission for destruction. From now on, glasses which are sent to Goerz for repair are being waterproofed at the factory without cost, by sealing them with a cement- like agent at the cover rims, and the ocular screw is screwed onto the dioptre ring. The carrying case for the new model Doppelfernrohre 03 can be used for the old glasses without problem, as well as the old case for the new glass. The difference between the two cases consists only of the improved fastening of the lining, using rivets. Graf von Schmettow' The D.F. 03 in fig. 48 upper right, has the following features which are very seldom found: Except for the bridge, the prism housings and other parts are like the later model with increased distance between objectives. The bridge is cast as one piece with the housing, and there is no increased distance between objectives. After the expiration of the Zeiss patent, Goerz needed only to change the casting form and could then, from 1908 on, build the '03' with increased distance between objectives, a logical improvement. After 1908, the other German producers also made service glasses with increased distance between objectives, and some of these later 03 models are shown in fig. 49. The Goerz D.F. 03 of fig. 48, upper right, has an unusual arrangement for collimation, which is accomplished by moving the prisms and was patented by Goerz on November 29, 1907 (German Patent No. 201 653). To adjust, the cover screws are removed, and through the threaded opening, using a thin screwdriver, the adjusting screws can be reached. The cover doesn’t have to be removed. Turning the screws causes the prism to move, working over little blocks (little pressure blocks). This method of collimation is known as the Goerz adjustment or ‘little pressure block’ adjustment and was also used by Goerz in other models. Note: In German military hand held field glasses, after the invention of collimation using an eccentric cell for the objective (first decade of the 20th century), and after the Goerz adjustment, only these two collimation processes were allowed. To this day, the eccentric cell for collimation is a sign of high quality glasses. There was also a Goerz 8 x 26 model in the construction form shown in fig. 48 upper right. The only known example has the name: 'Trieder Armee Binocle' and the serial no. 142935, see text for fig. 48 (collection Engel). In 1908, Goerz introduced two modern-appearing Goerz Army Trieder models as the 'new model 1908', see fig. 50. They used the Zeiss design, with increased distance between objectives, providing heightened plasticity.* (*Today, we wouldn’t consider this description for the early Goerz Army Models as being very accurate. It says that these Army field glasses, without increased distance between objectives, provide 'Excellent perception of depth distances.' Until 1908, the superior design was patented by Zeiss, with increased distance between objectives and therefore better image plasticity.) 'The Army Trieder 1908 was introduced according to the regulations of the War Ministry of November 24, 1908, no. 569.11.08.A4.' (from a Goerz brochure). The dates and numbers of both models: f.o.v. ( m/1000m) Weight in case (g) 6x24 122.5 965 8x26 112 1110 In the Festschrift of 1911, it is noted that: 'the optical firm C.P. Goerz was the sole purveyor of prism double telescopes for the entire Prussian Infantry from 1903 to 1908.' Goerz also delivered U Boat periscopes; but in the above mentioned Festschrift the Navy is less discussed, and hardly mentioned (or rather not at all) in connection with handheld glasses. The use of the Fernglas 03 can be learned from the Army regulations of September 22, 1917: 'Field glasses for machine-gun troops: In the future, for every machine-gun 08 there is only 1 Fernglas 03 mandated. Excess field glasses now in use must be returned....' Another specification of the early Goerz military models must be mentioned: The rotating ocular setting, which is shown in fig 75 and 77. In civilian models this 'invention' is not to be found, and it vanished from the Goerz military models after a few years. In the Pernox brochure (1904) is found: 'The eye piece is independent of the cord ring, and freely rotates, so that after one adjustment for focus, carrying of the glass on its strap does not cause an unintentional shift from rubbing against clothing. [page94] As a supplement, we shall introduce here a military accessory produced by Goerz which is now forgotten, and can be seen in fig. 51: the ‘Goerz distance estimator for Goerz Marineglas 6x (E. 83a)’. It works by shifting the image in a section of the field. After attaching the distance estimator, a disk is visible, which occupies half the field of view. The image in the disk is laterally shifted in relation to the original image in the field glass, and the extent of the shift is controlled from the outside. There is a definite analog to the telemeters, which use either a reticle with a double thread or a shifting of the image produced by double refraction in calcite plates. Compare fig. 33 to 37. From the directions for use for the Goerz distance estimator: 1. Assembly: Put the device on the binocular and fix horizontally if the height of the object is known, fix vertically if the length of the object is known. 2. Focusing: When the focusing screw is set on infinity, an unchanged image is given. The screw is turned until the known heights, (the upper level of a chimney or waterline), and the known lengths, (bow to stern), are adjacent to or above each other in the ocular, and at that point the distance can be read. 3. Reading the distance:.The intersection of the distance indicator on the glass disk, and the height or length indicator on the cone drum, give the distance. (The function is explained rather laboriously as follows) The instrument...consists mainly of a conical metal housing, in which two rotatable circular glass wedges are housed. 7. These glass wedges extend halfway into an opening for viewing, in the flattened part of the housing, closed by 2 glass disks. 8. Under a protective glass, which has regular partitions (divisions of distance), there is a rotatable cone with divisions of length and known sizes at the point of view. 9. The glass wedges and the cones are connected to each other with a cog wheel. They are manipulated by the focusing screw. The light that passes through the opening and also through the glass wedges, is deflected according to the rotation, and the length divisions are passed in front of the distance partitions. Another interesting detail in regards to the often mentioned competition between Goerz and Zeiss is that from 1907 through 1908, it was not Zeiss that was the more prolific producer of field glasses. In a brochure of December, 1907, Goerz announced: 'The total number of prism double telescopes fabricated by us is over 130,000'. Not until some months later can Zeiss announce (February 1908 advertisement to the military): '...since the beginning of our field glass production, that is in about 14 years, to date we have sold over 130,000, and at a steadily increasing pace.' In the years before the first World War all optical firms which produced field glasses had a booming business. In a company newsletter (75 Years of Spindler and Hoyer, Dr G. Meinhard, Spindler & Hoyer KG, Goettingen 1973) it says: 'Germany began to carry out the last major increase of the Army before the first World War. Thousands and thousands of active officers needed field glasses, and the reserve officers were required to buy glasses with their own money. By the way, that led to the situation where the German reserve and militia officers had in many cases better field glasses than the active officers.' Among all military field glasses, from all areas, after the end of the first World War, the 6 x 30 service glass became predominant, in both the Navy and the Army. This model remained the Army’s most used binocular for decades. The Army regulations H.Dv. 448/1 (1927 and 1940 in the same words), say about this model: 'As a standard double telescope for all branches of the Army of the Reich, the double telescope 6 x 30 with normal reticle, is introduced. This is a D. F. with 6 times magnification, an entrance pupil of 30 mm, and a field of view of 150m at 1000m distance.' In terms of its importance and the quantities produced, the D.F. 6 x 30 played a major role after the end of W.W. I, and later became the most important binocular. Next to the 6 x 30 is the D.F. 10 x 50 of the army. Some examples: In the Army Regulations of November 29, 1919, after the end of the First World War, an inventory was ordered of the quantity of optical instruments in the infantry, because of new regulations on equipping the troops with optical instruments. Of the hand held field glasses, only the Fernglaeser 03, 08, 6 x 30, and 10 x 50 are mentioned. In a news flyer of March 1939, regarding the height calibrations of the reticle, only the double telescopes 6 x 30 and 10 x 50 are mentioned. The same is true for the Army technical regulation news of June 1944, concerning the carrying strap for the Doppelfernrohre 6 x 30 and 10 x 50. The construction form of the common D.F. 6 x 30 corresponds to the equally common Zeiss Silvamar. Fig. 53 shows several 6 x 30s. There are only minor differences. Fig 52 is a facsimile print of the Army regulations H.Dv. 448/1. This is for the D.F. 6 x 30; the markings used there are mostly used in this book. [page 95] With the 'Basismodell' 6x30, we find many developments in the course of time, which can be found in later field glass models: the models with brass housing covers were originally produced in expensive versions; and leather or hard rubber covers were transformed during the first World War in Germany into cheap materials. Zinc replaced the brass of the housing covers. Leather vanished as a covering material, often replaced by a cover of black lacquered cardboard or just lacquer. For further details in this connection, see note in 4.3.1. In the thirties, nearly all metal parts of the service glasses were made of aluminium, to save precious brass and to reduce the weight at the same time. This statement is not true for all countries, but for the great majority of German field glasses. However, at least until the beginning of the war, German military outfits could order models with some brass parts. Two other measures led to further weight reduction: In Germany field glasses with 'Elektron' metal housings were built, (the corresponding civilian Zeiss field glasses were called 'Featherweight'). The material itself was reduced and the weight of these models, of the same construction form and classification, was reduced. (see Seeger, 'Feldstecher', page 80). From 1940-41, service glasses in Germany were not marked with the manufacturer’s imprint, but instead with the so- called production imprint, consisting of three lower case letters (see paragraph 2.3.4.-VI). Models which were produced towards the end of the war, occasionally had neither the company name nor the code imprint, see fig. 53. That is also an indication of wartime production, where unnecessary finishing measures were often (but not always) omitted. During WWII, a black lacquer replaced the cover material on field glass housings for the German models. The particular consistency was achieved by adding cork meal. [page 98] At the war’s end, even black pigments were hard to get, and a sandcolored lacquer was used for some optics and other equipment (even vehicles). This was originally planned for the Africa Corps and received the name: 'standard camouflage paint Europe'. But, this color is not the rule for optics; since, except for some military Dialyte 6 x 30 military glasses (fig. 63), and ‘Winkelfernrohre’ [‘angle telescopes’, trench binoculars] (fig. 122), the author doesn’t know of any sand colored military field glasses. Note: Some military collectors think all army equipment used in the Africa campaign had the 'standard camouflage paint'. That is probably true for the vehicles used in Africa, but false when we are talking about things like optics. In pictures from the Africa campaign, field glasses are visible that had the usual black color. (Lothar Esch, personal communication) The black ‘tar color’ with added corkmeal proved to be advantageous and was also produced after the war. Thus, the lacqer on the 8 x 60 of the RZA 5b in Oberkochen was made with corkmeal, see fig. 249. Some further details on the accessories of the German Army 'Grundmodelle' [basic model]: The Army regulation news of August 1934 says under 'binocular 6 x 30': 'The carrying case for the 6 x 30 delivered by Zeiss is to be changed in the following ways: a) Cloth cover for the holding blocks instead of leather. b) holding blocks to be fastened to the case by wooden screws. c) Artificial leather cover to be removed from the lid and a new leather cover to be glued in...' These regulations can help when pinpointing the age of Zeiss field glass cases. The following news from the 'General Army news' of Oct. 7, 1939 is important because it contains serial numbers and indirectly points to the introduction of bakelite field glass cases: 'Binocular 6 x 30 Cases The 6 x 30 binoculars of G. Rodenstock, Munich, up to production number 203501 of M. Hensoldt and Sons, Wetzlar, to production number 383621 and Oigee, Berlin-Schoeneberg to production number 21651 are possibly to be stored in the case for the binocular 6 x 30 made of leather, since they can only with difficulty be stored in the cases of bakelite. O.K.H. (BdE), Sept. 26, 1939. 79 - ln 4 (IIIb).' The regulations of Sept. 1942, are known to collectors and allow them to maintain the authenticity of their field glass cases when they lack the case carrying strap: 'Binoculars 6 x 30 and 8 x 30... 1. In the future only 50% of the binoculars 6 x 30 and 8 x 30 are to be equipped with carrying straps. 2. Army and Army Reserve shall receive only D.F. 6 x 30 and D.F. 8 x 30 without carrying strap as replacements until further notice.. Carrying straps which are missing according to 1. have to be specially requested.' Concerning the field glass strap, the Army Regulations from June 15, 1944 report: 'Binoculars 6 x 30 and 10 x 50 Binocular carrying strap The carrying straps for binoculars DF 6 x 30 and 10 x 50 are provided with 5 button holes from now on, so that they can be adjusted. The binocular carrying straps at hand can be changed by the armourer according to the enclosed drawing. O.K.H. (Ch H Ruest, BdE), April 26, 1944. 79 - ln 4 (Slc)' *Concerning the problem of a translation of the inscription, the following (Leslie Andrew, personal communication): The owner of a very similar 8 x 30, inscribed in Arabic or Persian, with identical crown symbol, but with an enlarged Zeiss symbol (see fig. 76, right bottom), wrote to (1) Zeiss in Jena, (2) an expert in oriental languages, and (3) a well known Museum, asking for information. From the answers (all from the 1980s): [text in English] Doubtlessly the last cited expert came to the correct conclusion, and if he had known that the firm of Nedinsco in Venlo was a member of the Zeiss conglomerate (see paragraph 2.3.5.), he could have said exactly what was meant by the inscription. An optics expert would have come to the same conclusion, without knowledge of Persian, because of the Zeiss Venlo inscription. [page 100] The drawing , not shown here, shows the ends of a carrying strap which had as usual, 2 of these button holes on one end and 6 on the other side, so there are 4 more button holes than the old version had. A group of 6 x 30 service glasses is shown in fig. 53. These models have every right to be shown here, when one considers the frequency and the quantity of their use. The Busch 'Bakelitglas' is related to the Busch model 'Heda', in regards to the material from which it is made. The 'Heda' is a civilian Galilean model with plastic housing, produced from 1933. In contrast to the 'Heda', the 'Bakelitglas' is not a cheap model; it is of good optical quality, and has specifications which cannot be found in other service glasses. There are eccentric steel inserts in the screwholes of the joint to preadjust the two halves (parallel positioning), and the two prisms in each side are different sizes for the changing direction of light in the housing (adjusting to the ray passage) [the cone of light from the objective requires a larger ‘first’ prism than the following prism], and finally an especially shock resistant mounting of the prisms. (*This design, with prisms of different height, was tried before, for example circa 1916 in the Voigtlaender Service Glass.) This unusual service glass was produced with the idea in mind, to produce a robust service glass without using expensive materials. Consequently, the glass consisted of 200 grams of bakelite, 140 grams of glass (lenses and prisms), and of 200 grams of steel and zinc or zinc alloy (Wilbert Engel, personal communication). The serial numbers of these 'Bakelitglaesern' which are known to the author, are between 407,000 and 426,000. This range of numbers includes the serial numbers of no other Bush models that are known (to the author). We can therefore suppose that perhaps 19,000 of these 'Bakelitglaesern' were manufactured. Before and during WW II, lens coatings were (probably) not put on the optics of the German 6 x 30 Service models, for the 'Grundmodell' [basic model] was probably not considered worthy of this expensive process. An exception was a later Zeiss 6 x 30 navy model (marked with an M. Terry Vacani, personal communication). Using special ‘gas mask oculars’, some of these 6 x 30s were used with gas masks, which was considered an important application, see fig. 55. Besides the 6 x 30 service glasses, the 8 x 30 models with the same exterior dimensions were already in use before the war, and even more during WW II. However, they did not match the distribution of the 6x30. Table 7: Binoculars which are shown in the three editions of the Army regulations (H.Dv.) 448 or mentioned there (notations of the author in parentheses) Binocular 6x30 (without mentioning a manufacturer, but the name 'Silvamar' is mentioned.) Binocular 10 x 50 of Zeiss (fig. 61) Binocular 10 x 50 of Leitz (fig. 59, bottom) Binocular 10 x 50 of Voigtlaender(fig. 59) Binocular 7 x 52.5 (without mentioning a manufacturer, fig. 94) Binocular 7 x 50 (Zeiss, Binoctar, fig. 222) Binocular 15 x 60 (Zeiss, fig. 98) Binocular for searchlight directional finder (Leitz 8 x 50, fig. 95) Scissor Binocular 14 Zeiss (S.F. 14 Z, fig. 114) Mentioned, but without pictures: Director telescope for median signal device (fig. 100) Director telescope for large signal device (6 power) The Zeiss export models with arabic or Persian markings and the larger 8 x 30 are unusual and interesting, see fig. 55. These glasses, some with markings from the third Reich, were mystifying until now, and their use and the reason for these unusual markings were only speculation. [page101] Research with witnesses from Jena (then still living), produced interesting facts; and the following is a citation from a personal communication from Guenther Siebrasse to the author. 'Already in the thirties, and continuing into the war, orders from foreign countries were accepted and delivered, depending on permission or refusal from Berlin. These field glasses were manufactured by Zeiss in Jena, for a government order from Persia. The inscriptions and accessories (ocular filter and case) for the glasses were manufactured according to Persian specifications. The glasses were supposed to be shipped during the war through Turkey to Persia. After Persia was occupied by allied troops (mainly Sovet), the shipments could no longer be made. Since, at that time, there was a serious lack of optical instruments, and shipment was considered impossible for some time, the glasses which were already manufactured, were given to the Navy. The Navy required an additional marking and an addition to the inscription on the case. This was done before delivery to the Navy by Zeiss.' The author knows of three models of this series, compare with chart 8. The serial numbers begin with 1990, and confirm that this series had at least 200 glasses. Probably more of these models were manufactured; these have the serial number on the rim of the upper right cover. These 8 x 30 models have a reticle with arabic numbers, they also have the eagle and M IV/1 and Artl. 5/6400 (fig. 55) After WW II, new 6 x 30 models were developed; and the service glass 6 x 30 is still the standard Army military glass. The Navy of most countries had begun using models with larger objectives (and increased brilliance) some decades earlier. These glasses also have the advantage of a larger exit pupil: When the ship rolls and weaves the observer doesn’t lose the object so easily. After the war, the Oberkochen Zeiss service glasses began using the tele-objective (air spaced achromat), to reduce length, volume and weight. The tele-objective was used in the fifties for civilian binoculars. (Seeger, 'Feldstecher', page 85, 88) Once more, back into the past: From the first World War to the time of the Second World War in Germany, along with the binoculars listed in H.Dv. 448, other special military binoculars were produced. Along with the better known service glasses, these optics were used for a long time, and it is not known in all cases when production began or ended. These field glasses will be mentioned in paragraph 2.3.4.-III, but before that. we will take a closer look at the official military glasses of the First World War, and the twenties, thirties, and forties. 13