DESCRIPTION: This 'Improved Aplanatic Loupe' with a Magnification of 6 power, is signed in German:

'Verbess. Aplan. Lupe, Vergr.=6' and on the opposite side:
'Carl Zeiss Jena.'

The abbreviations stand for the German words: verbesserte (improved), aplanatic, and Vergrößerung(magnification).
The original turned wooden case ('Wooden Capsule' in the catalog of 1902) is signed on its top in gold lettering:'Lupe, Vergr. 6.'
All the signatures are in script. The form is a cylinder without a handle. The instrument is made of chrome or rhodium-plated brass with the ends made of blackened brass and knurled. As is mentioned in the catalog (entry shown here), the instrument produces a flat field from edge to edge, but for proper use, it must be held close to the eye. The fact that a flat object that is being viewed is in focus from edge to edge is what makes this instrument 'aplanatic' which means free of spherical aberration. This instrument does offer fine flat images from edge to edge.

HISTORY OF THIS LOUPE

'Steinheil' aplanatic loupes, invented by Steinheil in 1864, were offered by Zeiss in the late 19th century. The instrument pictured here is the 'Improved Aplanatic.' 'Improved Aplanatic loupes' were offered as early as 1891 and, according to the 1891 catalog, supplied in a wooden 'capsule' as pictured above. In addition to the 6X 'improved aplanatic', a 10X was also offered. An attachable small metal handle was also offered, and is shown in the illustration immediately above and to the right. The handle was offered as an optional accessory in some of the catalog entries of various years.