Abstract: An imaging element (3) is disposed behind a group of objective lenses (1), and a retractable quick-return half-mirror (2) is disposed as an optical-path splitting means in the direction of an observation optical system between the group of objective lenses and the imaging element. Plane glass (9) for correcting an change in image-formation position caused by retraction of the quick-return half-mirror is inserted into the optical path of the imaging optical system in association with the retraction of the quick-return mirror from the optical axis of the imaging optical system. The quick-return half-mirror and the plane glass are respectively held at both ends of a mirror guide lever (8) of one rigid member to effect respective retractions and insertions. The quick-return half-mirror may be provided with an inclined plane for correcting an image-formation positional deviation in the optical axis crossing direction.

Abstract: A terrestrial telescope with digital camera includes objective lenses, an imaging element located downstream of the objective lenses, a retractable optical-path splitter between the objective lenses and the imaging element, and an optical system for observing an optical image divided from the optical path of the imaging optical system by the optical-path splitter. An optical element is inserted into the optical axis of the imaging optical system to correct for any change in the image-formation position when the optical-path splitter is retracted from the optical path of the imaging optical system during imaging.

Abstract: A terrestrial telescope with digital camera includes objective lenses, an imaging element located downstream of the objective lenses, a retractable optical-path-splitting means between the objective lenses and the imaging element, and an optical system for observing an optical image divided from the optical path of the imaging optical system by the optical-path-splitting means. An imaging position correction means is further provided which includes an optical element that is inserted into the optical axis of the imaging optical system to correct any change in the image-formation position when the optical-path-splitting means is retracted from the optical path of the imaging optical system during imaging.

Abstract: An ophthalmologic apparatus equipped with a projection optical system for projecting a laser beam spot image onto a prescribed point of an eye under examination has a zoom lens provided in the projection optical system for enabling the diameter of the projected spot image to be varied and some of the lenses of the zoom lens are made movable for enabling projection of a blurred spot image.