Binoculars Carl Zeiss Jena Teletur 6x15

Magnification: 6x
Aperture (objective diameter): 15 mm
Field of view: 7.1°
Visible field of view (eyepiece): 40°
Outlet pupil diameter: 2.5 mm
The closest focusing distance: 1.7 m
Width: 8.6 cm
Height: 6.5 cm
Weight: 215 g
Production date: 1920.

   Binoculars with central focusing appeared on the market in the middle of the 19th century. Carl Zeiss engineers were not in a hurry with such devices’ production, since they considered them less reliable and protected from dust and dirt. First prototypes of these binoculars were produced in Jena back in 1907, but only in 1909/1910 Carl Zeiss was forced to begin mass production of the devices of such design under the competitors’ pressure and because of the demand. First models of central-focus binoculars appeared in T136 catalog in 1910–those were Teletur 6x15, Telexem 6x21, Telactem 8x24 and Silvarem 6x30. Subsequently, all civilian Carl Zeiss binoculars with central focusing had an “...em” ending in their designations.
   Carl Zeiss Teletur 6x15 binoculars have many features that make them unique:
   - in 1910 it was the smallest prismatic binoculars;
   - a complex design (focusing with objective lenses), which was not reproduced by any competitor of Carl Zeiss;
   - the first binoculars for tourists with high magnification and small size;
   - one of the first Carl Zeiss binoculars with a central focus. The binoculars did not have a "twin" with separate focusing for use in the army.
   This very interesting "baby" was produced from 1910 to 1927-28. Carl Zeiss deliberately sacrificed binocular plasticity (the effect of volume, which depends on the distance between the objective lenses) to increase the compactness of the device. This binocular was intended for those people for whom small size and minimum weight were important: for tourists, for people watching sports competitions, etc.
   In total, two modifications of Teletur 6x15 were released: with an eyepiece field of view of 40 degrees. (until 1921) and a field of view of 50 degrees. (until 1927-28). Accordingly, the design of the eyepieces was changed (the diameter of the "eye" lens increased from 10.2 mm to 12.5 mm).
   This device belongs to the first iteration (with an eyepiece field of view of 40 degrees). Grooves (knurling) on ??the body of the eyepieces are parallel to the optical axis of the binoculars. On the upper disk of the hinge of the binoculars, a scale of interpupillary distances is applied. The right eyepiece has its own focusing mechanism with a diopter scale. The lens barrels are designed with grooved bushings to reduce side flare.
   The width of the top prism cover is 35.5 mm, the height of the binoculars from the lower cut of the lens mounts (at the maximum focusing distance) to the top prism cover is 41 mm. The prism covers are attached to the body with three screws. The diameter of the base of the eyepieces is 16 mm.
   Inscriptions on the left prism cover "Carl Zeiss". On the right prism cover - " Teletur 1095598 6x15". The inscription is applied in block letters with silver solder against the background of a schematic image of a Carl Zeiss Tessar photographic lens.
   The storage case for these binoculars has features typical for that period (see Hans T.Seeger. Zeiss Handfernlaser 1919-1946, Modelle-Merkmale-Mythos, p.607-627) with characteristic rivets and an embossed "Carl Zeiss Jenna" logo.
   The serial number of the device is 1095598, it was made in 1920 in a batch of 300 pieces.