Zoom Eyepieces - Notched Mount Tube

A: Small notches are machined into the mount tube of the zoom eyepiece in order to key the eyepiece in place within in the focuser.

This is to keep the eyepiece from rotating within the focuser tube whenever the zoom collar of the eyepiece is turned.

When placing the zoom eyepiece into the focuser, rotate the eyepiece until it is engaged in the detent /key in the focuser. (Once engaged, the eyepiece will no longer rotate freely); then simply lock the eyepiece in the focuser.