Binoculars Carl Zeiss Jena Silvamar 6x (3)

?Magnification: 6x
Aperture (objective  diameter): 30 mm
Field of view: 8.4° 
Exit pupil diameter: 5 mm
Visible  field  of view (eyepiece FOV): 50° 
The closest focusing distance: 4.1 m
Width: 16.7 cm
Height: 12 cm
Weight: 660 g
Production date: 1908.

   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)
   Silvamar is the first binocular model having 30 mm lenses. The device turned out to be very successful, characterized by high aperture, plasticity and wide field of view, and therefore it became the “champion” in terms of production time: Silvamar was produced from 1907 up to 1969 with various changes. It is a “civilian” model; similar military versions are marked as D.F.6x30 and Marineglas 6x(30).
   The “civilian” application of this model is proved by the central hinge fixture’s (clamp’s) small diameter (see photo), which has a hole for a knob (included to binoculars delivery kit), with the help of which the hinge could have been finally fixed depending on the observer’s interpupillary distance. The interpupillary distances scale is indicated on the upper hinge disk.
   This binocular is the first, rare design variant with the prism cover and lens barrel made in one piece (see photo). In this form, binoculars were produced for a short time from 1907 to 1909.
   This device possesses eyepieces of the so-called "1/3" design (see Hans T.Seeger.  Zeiss-Feldstecher, Handfernglaser von 1894-1919, Modelle-Merkmale-Mythos, p.117) with the base diameter equal to 24.5 mm and the top prism cover width equal to 52 mm (see photo). The eyepieces possess a diopter scale and a transverse knurling. The binoculars’ case height (including upper prism cover) is equal to 77.5 mm, the diameter of the front lens of the eyepiece is 13.5 mm.
   There are inscriptions “Carl Zeiss Jenna” on the left prism cover. There is also an inscription “Silvamar 150684 6x” on the right prism cover. The inscription is encrusted with the help of silver alloy and is made in block letters against the background of Carl Zeiss Tessar photo lens schematic image. Prism covers are attached to the housing with the help of three screws.   
   On the upper disk of the central hinge there is an engraving “Calderoni & Co Budapest”: the binoculars were sold in Budapest, in a shop owned by Stefano Calderoni (1794–1881), an Italian-speaking optician from Lombardy. This oldest firm was founded in 1819.


   The binoculars have the serial number "150684" and were made in 1908 in a batch of 100 pieces. 
   The binocular military analogues - Marineglas and D.F.6x30 models can be checked here:and here
   Later versions of Silvamar 6x(30) binoculars with other lens frames’, eyepieces’ and housings’ designs can be checked here
   The binocular model with central focusing, namely Silvarem 6x, was released in 1909