Binoculars Carl Zeiss Jena Silvarem 6x30 (1)

   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.
   The Silvarem 6x (30) binoculars turned out to be very successful in design and optical characteristics and was produced from 1909 to 1969.
   The presented specimen refers to the fifth version of this model (was produced since 1920/21 (?)) and it has the following features:
   - the binocular design is characterized by long carcass and short lens frames (the first version of this model had another design, with short carcass and long lens frames of the double-ring type with leather coating);
   - the lens caps are made with rounded edges (the previous version of this model had grooves on the caps for spurious flares minimization);
   - the prism covers are made of aluminum alloy (in previous versions they were made of zinc alloy and earlier - of brass) and they are fastened with the help of one screw (in older versions three screws were used);
   - there is a diopter scale on the central focusing wheel (the first version of this model did not have it);
   - the central focusing ocular bridge shoulders again have thickenings in the places of attachment to the central hinge (they were flat and of the same thickness in previous version of this model) and they are made of aluminum alloy - see photo;
   - the eyepieces front lens’s diameter is equal to 11.5 mm, the binocular’s field of view is equal to 8.5° (these values were respectively equal to 12.7 mm and 8.4° for the first version of this model);
   - the eyepieces are with longitudinal knurling (the previous version had a diagonal knurling);
   - the serial number is located on the central hinge front disk (there is no central hinge clamp/fastener) - see photo

   Silvarem 6x30 was produced in this design but with some small modifications until 1969.
   The binocular’s “civilian” application is proved by the central focusing mechanism. The interpupillary distances scale is indicated on the upper hinge disk. The right eyepiece has its own focusing mechanism with a diopter scale.
   The base diameter of this device’s eyepieces is equal to 24.5 mm and the top prismatic cap width is equal to 52 mm (see photo). The binocular’s case height (including the upper prism cover) is equal to 77 mm; the binocular’s height without lens frame is equal to 66 mm. The binocular’s weigh decreased from 665 g to 600 g compared with previous version.
There are inscriptions “Carl Zeiss Jenna” on the left prism cover. There is also an inscription “Silvarem 6x30” on the right prism cover. The inscription is made in block letters on the background of Carl Zeiss Tessar photo lens schematic image.
   The device’s serial number is “1564157” and it is located on the front hinge disc. The binocular was manufactured in 1930 as a 600 pieces batch.
   Previous Silvarem 6x model options can be checked by the following link: https://binocollection.com/catalog/binoculars-carl-zeiss-jena-silvarem-6x.html,  https://binocollection.com/catalog/binoculars-carl-zeiss-jena-silvarem-6x-1.html and https://binocollection.com/catalog/binoculars-carl-zeiss-silvarem-6x30.html
   The Silvamar 6x binocular model with a similar design but with separate focusing can be checked by the following link: https://binocollection.com/catalog/binoculars-carl-zeiss-jena-silvamar-6x30-military.html