Abstract: An image amplifying tube system for a day and night combined use in an observation equipment includes an image amplifying tube assembly mounted on the daytime periscope of the naked-eye sighting device, in which the image amplifying tube assembly swerves from the optical path during the daytime sighting and moves into the optical path during the nighttime sighting. Consecutively, the image amplifying tube is positioned at a specific focusing distance on the optical path by a vertical and horizontal moving mechanism. In this way, it may be possible to use the periscope both in the daytime and in the nighttime.