Binoculars Carl Zeiss Jena Telact 8x (1)

Magnification: 8x
Aperture (objective diameter): 24 mm
Field of view: 6.6°
Exit pupil diameter: 3 mm
Visible field of view (eyepiece FOV): 52.8°
The closest focusing distance: 5.8 m
Width: 14.8 cm
Height: 12 cm
Weight: 570 g
Production date: 1914.

   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) 
   Telact is a new design fine model with perfect optical features, 8x magnification and a 24mm lens. It’s a civilian model; similar military models are marked as D.F.8x, D.F.8x24 and D.F.95 n/A.
   The binocular’s “civilian” application is also 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. Telact was produced in 3 versions with various design changes until 1915:
   1st version: in which the cap of frame lens and the lower prismatic cover were made as a single part (since 1907) and the eyepiece case had the “transverse” knurling (see photo)
   2nd version: with the two-ring type lens frames (starting from 1908 and up to the beginning of 1914);
   3rd version: with the rounded lens covers (starting from 1914) 
   This device belongs to later, 3rd version, with rounded lens covers. The covers possess grooves intended to minimize spurious flares. The eyepieces base diameter is equal to 24.5 mm and the width of upper prismatic cover is 50 mm (see photo). The eyepieces possess the diopter scale and the diagonal knurling (the binocular’s previous version had the transverse knurling, see photo). The binoculars case height (including upper prismatic cover) is equal to 77 mm.  
   There are inscriptions “Carl Zeiss Jena” on the left prism cover. There is also an inscription “Telact 368962 8x” 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.
   The binocular’s coffer has peculiarities specific to that period (see Hans T.Seeger. Zeiss Handfernlaser 1919-1946, Modelle-Merkmale-Mythos, pp. 607-627), namely, the design of self-tightening side belt fasteners, carrying handle on the top cover, the top cover fastening to coffer’s case, specific rivets (see photo). The upper cover is of the “seamless” design. 
   The binocular’s serial number is “368962” and it was released as a 700 pieces batch in 1914. 
   A very early model in Telact 8x design, but with the Feldstecher 8 Fach marking, which is characterized by rare eye cup shape and narrower neck strap loops, can be checked by the following link:
   Another early model, belonging to the 1st version of lens frame (see above) can be checked here:
   In 1909/10, the Telactem 8x binoculars model with central focusing was released:
   In 1912 the Telact 8x binoculars were replaced by the Turact 8x model (this binocular was produced in parallel with Telact). It has become much lighter and smaller than its predecessor, but worse in optical characteristics.