Binoculars Carl Zeiss Jena Telactem 8x

Magnification: 8x
Aperture (objective diameter): 24 mm
Field of view: 6.6°
Visible field of view (eyepiece): 52,8°
Outlet pupil diameter: 3 mm
The closest focusing distance: 6.4 m
Width: 16 cm
Height: 12 cm
Weight: 650 g
Production date: 1912.

   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.
   Telactem 8x binoculars were produced from 1909/1910 and up to 1914 in two versions: with the two-ring type lens frames (1909/1910-1913) and with the rounded lens covers (1913-1914) .
   As well as its split-focus analogue (namely, Telact 8x), this binocular is characterized by excellent optical characteristics among similar-level devices.
   The binocular “civilian” use is proved by the central focus mechanism (military models were never produced with it) and the central hinge clamp’s (fastener’s) small diameter (see photo), which has a hole for a knob (included to binoculars delivery kit). Focus wheel has an extremely rare perpendicular knurling. There is an interpupillary distance scale on the upper hinge disc. The diopter scale is still missing on the central focus flywheel (the earliest series did not have it, the scale appeared later). The right eyepiece has its own focusing mechanism with a diopter scale.
   This device belongs to an early version with the two-ring type binocular frame. The eyepieces’ grooves (knurling) are located along the binocular optical axis. The width of the upper prismatic cover is 49 mm; the binoculars height from the lower cut of lens frames to upper prismatic cover is equal to 80 mm. The prism covers are fixed to binoculars case with the help of three screws. The eyepieces base diameter is equal to 24 mm.
   There are inscriptions "Carl Zeiss Jena" on the left prism cover. There is also an inscription "Telactem 278684 8x " on the right prism cover. The inscription is made in block letters against the background of Carl Zeiss Tessar photo lens schematic image.
   The binocular is well-equipped, including the hinge fixing knob (which is a big rarity), binocular belts and the coffer.
    The rare feature of this "civilian" binocular consists in the presence of a military rangefinder "grid" (see photo). In addition, this binocular’s case has features peculiar to the models of that period (see Hans T. Seeger. Zeiss Handfernlaser 1919-1946, Modelle-Merkmale-Mythos, pp. 607-627), however, it possesses features of the "military" coffer (wide belt loop). There are two versions for explaining this fact: the device was either equipped with the "grid" and the military coffer later, during the First World War or it was originally manufactured in such form.
   The binocular’s serial number is 278684 and it was released as a 400 pieces batch in 1912.
   The split-focus analogue of this binocular with similar features, namely Telact 8x, is available by the following link -