Binoculars Carl Zeiss Jena D.F.6х24 (1)

   In 1906-1907, Carl Zeiss radically changed the construction and the design of his binoculars (both “civilian” and military ones). Optical characteristics were significantly improved for the new devices (field of view and the lenses diameter were increased, while optical aberrations were reduced), and the devices’ construction was also changed: the central hinge and the “ears” for the neck strap were not attached to the binocular with the help of screws any more - they became the whole part with it instaed, an eccentric lens alignment system appeared and the design of its frame changed, prism covers spanned the binocular body and they were lubricated with a special compound at the joints with the purpose of tightness improvement. In addition, the prisms inside the binocular were no longer pressed by prismatic covers, but they were fixed with special flat springs, which increased the device reliability significantly.
   The new version of military binocular D.F.6х (its old version is available by the following link: https://binocollection.com/ru/catalog/binokl-carl-zeiss-jena-df6x.html) appeared a little bit earlier than its “civil twin” – namely Telex binocular - https://binocollection.com/ru/catalog/binokl-carl-zeiss-jena-telex-6x.html, around the end of 1906. This device became the most popular military binocular of the First World War and its release stopped in the 30s of the last century, before the Second World War. Around 1916-1917, the “D.F.6x” label was changed by “D.F.6x24”. There are several major modifications of this model:
   1st version: 6x21 - the one, where the lens frame and the lower prismatic cover are made as one component (starting from 1906/1907) and having the eyepieces case with the “transverse” knurling (see photo). Nearly 6,000 specimens were produced with such design option.
   2nd version: 6x21 - the one with double-ring type lens frames (starting from 1908/1909);
   3rd version: 6x24 - the one with double-ring type lens frames (starting from 1911/1912) https://binocollection.com/catalog/binoculars-carl-zeiss-jena-df6x-4.html;
   4th version: 6x24 - the one with rounded objective covers (starting from 1913).
   The presented binoculars belong to the last, 4th option (rounded objective covers). Its extremely interesting feature is the high serial number 2334978, which indicates a rather late production date - 1947. However, the device has all the signs of an earlier origin:
   - diagonal knurling on the body of the eyepieces;
   - prism covers are attached to the body of the binoculars with one screw;
   - the material of the prism covers and eyepiece housings is zinc alloy;
   - rounded lens caps.
   - the presence of a lock (clamp) of the central hinge.
   These features are typical for Carl Zeiss Jena binoculars from 1917-1918. This discrepancy can be explained by two versions:
   - the binoculars were made in 1947 from components produced much earlier (in 1917-1918);
   - the binoculars were produced in 1917-1918, but in 1947 they were repaired (restored) and given a corresponding (new) serial number. The second version is more plausible. The design features of the binoculars are identical to this device https://binocollection.com/catalog/binoculars-carl-zeiss-jena-df6x24.html.
   The binocular’s “military" application is also proved by the large diameter of the central hinge clamp (lock) (see photo). The interpupillary distances scale is indicated on the upper hinge disk. The eyepieces have a diopter scale for acutance adjustment. The upper prismatic cover width is 45.5 mm; the binocular height from lens frames’ lower cut to upper prismatic cover is equal to 69.3 mm. The eyepieces base diameter is equal to 20.5 mm.
   There are inscriptions “Carl Zeiss Jenna” on the left prism cover. There is also an inscription “D.F.6x 2334978” on the right prism cover. The inscription is made in block letters (early models had an inscription in italics until 1904) on the background of Carl Zeiss Tessar photo lens schematic image. The prism covers, the upper hinge disc and the eyepieces’ bodies are made of zinc alloy (Germany felt shortage of non-ferrous metals at the end of the war: those parts were made of brass earlier). The prism covers are attached to a binocular carcass with the help of one screw (previously, three screws were used).
   The previous version of this model without zinc alloy application in the construction and with the marking “6x” is available by the following link:  https://binocollection.com/ru/catalog/binokl-carl-zeiss-jena-df6x-3.html