File:RKE Eyepiece David Rank.png

Summary
Diagram of the RKE eyepiece that was an adaptation of a Kellner eyepiece designed by Dr. David Rank for the Edmund Scientific Corporation, who marketed it throughout the late 1960s and early 1970s. This design provides slightly wider field of view than classic Kellner design.

Image created from Wikimedia Commons images each distributed under the GNU Free Documentation License.

Licensing:
{{{gfdl|migration=redundant}}