Terrestrial telescope with digital camera

摘要

A terrestrial telescope with digital camera has an imaging optical system having a group of objective lenses and an imaging element disposed at a position at which an optical image is formed by the group of objective lenses. An observation optical system is provided for observing the optical image transmitted by the group of objective lenses. An optical element is inserted into the optical axis so as to be retractable from the optical axis during imaging. The optical element has a transmission surface having a single-eccentric toroidal configuration with different curvatures in vertical and horizontal planes of the optical element for correcting the position on the imaging element at which the optical image is formed so that the position on the imaging element at which the optical image is formed remains substantially unchanged regardless of whether the optical element is inserted into or retracted from the optical axis of the group of objective lenses.