Binoculars Carl Zeiss Jena D.F.6x30

   In 1907, Carl Zeiss radically changed the framework and the design of his binoculars, replacing "civilian" models Feldstecher 6 Fach by Telex, Feldstecher 8 Fach by Telact, Jagdglas by Silvamar and Feldstecher 12 Fach by Telefort. The new devices’ detailed characteristics were published in the 74-th volume of Carl Zeiss catalog in August 1907. The optical characteristics were significantly improved in new devices (the field of view and the objective diameter were increased, optical aberrations were decreased), and the devices’ design was also changed: the central hinge and the “lugs” for a neck strap were not attached to binocular with the help of screws any more, they became integral with it instead, an eccentric objective alignment system appeared and its frame design was also changed, the prism covers spanned the binoculars’ carcass, and they were lubricated with a special compound at the joint points in order to improve impermeability. Moreover, the prisms inside the binoculars were no longer pressed by prism covers – they were fixed with the help of special flat springs instead. It helped increasing the device’s reliability greatly. Actually, the binoculars have survived in such appearance up to present days (see Hans T.Seeger. Zeiss-Feldstecher, Handfernglaser von 1894-1919, Modelle-Merkmale-Mythos, pp.399-414)
   The D.F.6x30 model is the late military analogue of the Marineglas binocular https://binocollection.com/catalog/binocular-carl-zeiss-jena-marineglas-6x-3.html, with rounded objective covers, made of brass. It was produced from 1917/18.   The upper and lower prism covers are fixed to the carcass with the help of one screw. The prism covers’ width is equal to 52 mm (see photo). The binocular’s body height (including upper prism cover) is equal to 77 mm.
   The eyepieces’ base diameter is equal to 24.5 mm; the eyepieces’ front lens diameter is equal to 12 mm. In addition, the eyepieces have a diopter scale, a diagonal knurling and the one-piece-type design (previous versions of this model had the two-piece-type demountable design). The eyepiece is screwed into the binocular’s body and it presses the prism cover together with one screw. All the above mentioned binocular parts are made of zinc alloy (there was the non-ferrous metals shortage in Germany at the end of the World War I).
   The binocular’s “military" application is proved by the large diameter of the central hinge clamp (lock). It is made of steel (previously such clamps were made of brass).The interpupillary distances scale is indicated on the upper hinge disk.
   There are inscriptions “Carl Zeiss Jena” on the left prism cover. There is also an inscription “Dienstglas D.F.6x30 VIII 18. 997234” on the right prism cover. The inscription is made in block letters against the background of Carl Zeiss Tessar photo lens schematic image. There is information about the binocular’s previous owner on the front prism covers (it is also duplicated on the inner part of the case cover - see photo), a certain W.F.Chubb from Gloucester (England) - Gloucester, 25 Midland rd. There is also a stamp of the London Stereoscopic store (“London Stereoscopic”) on the inside part of the case cover. The binocular’s case has features not typical for Carl Zeiss Jena cases of that period, it was most likely made in England.
   The binocular’s serial number is "997234" and it was manufactured at the end of 1918 as a 1500 pieces batch.
   The D.F.6x30 model’s next version, which has minor differences, can be checked by the following link: https://binocollection.com/catalog/binocular-carl-zeiss-jena-df6x30-1.html
  The binocular’s "civilian" analogues – the Silvamar 6x models can be checked here: https://binocollection.com/catalog/germania/zeiss/grazhdanskie-binokli/silvamar-6x