Binoculars Carl Zeiss Jena Telact 8x

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: 1907.

   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 “civilian” use is proved by the central hinge clamp’s (fastener’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. There is an interpupillary distance scale on the upper hinge disc. 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 end of 1914);
   3th version: with the rounded lens covers (from 1913 to 1915)
   This device (1st version) 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 50 mm (see photo). The eyepieces possess a diopter scale and a transverse knurling. The binoculars’ case height (including upper prism cover) is equal to 66 mm.
   There are inscriptions “Carl Zeiss Jena” on the left prism cover. There is also an inscription “Telact 155284 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 serial number is “155284” and it was released as a 1000 pieces batch in 1908.
   An early model having the Telact 8x design and the Feldstecher 8 Fach marking with the eyecups’ rare shape and narrower loops for a neck strap is available by the following link:
   Late model with the rounded lens covers:
   In 1909/10, the binoculars model with central focusing, named Telactem 8x, was released. It is available by the following link:
   In 1912 the Telact 8x binoculars were replaced by the Turact 8x model (the latter named binoculars were produced simultaneously with Telact). It became lighter and smaller than its predecessor, but worse in optical characteristics.