Auto-internal-focussing telescope with focussing motor lens drive, for installation in e.g. automatic levelling appts.

摘要

The telescope includes an objective lens (11), a focussing lens (12), a horizontal compensation system (13), an image plane (14) and an eyepiece (15) to observe the image in the image plane. The position of the focussing lens may be adjusted according to the distance of the observed object. The telescope also contains an optical beam-splitter (18) in the optical path between the objective lens (11) and the image plane (14) to produce a virtual equivalent (14A) of the image plane, which is used by the auto-focussing control circuit (20) to output a control signal to the focussing drive (30) and motor (12b).