Description

Kellner eyepiece 25mm 1,25″ 

Kellner
eyepiece is an improved version of the Ramsden eyepiece. Instead of a
single eyepiece lens, an achromatic double lens was used, which
significantly reduced chromatic aberration. The first lens is
biconvex or plano-convex. In order to minimise chromatic aberration
and blurring on the edge of the visual field, the lens is fitted to
the focal plane of the objective.

Clear
and bright images are characteristic for the long focal-length
Kellner eyepieces. Use of three eyepieces enables getting a
reasonably good field of view of 40-50 degrees.