25mm Kellner eyepiece 1,25”

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.