Abstract: Apparatus is disclosed for guiding a telescope during long-exposure astronomical photography. A reflecting prism or mirror is inserted into the peripheral portion of the optical field in front of the camera. The reflected light is observed through an eyepiece with cross-hairs, allowing the observer to focus the eyepiece on a particular guide star in the image field and adjust the telescope during the exposure to track the apparent motion of the object. The reflecting element is over half the diameter of the optical field in length, providing substantial improvement in light collection. The reflecting element may be rotationally adjusted around the optic axis for guide star selection. Further, the eyepiece position may be adjusted in a direction perpendicular to the eyepiece axis and in the plane of the optic axis, to provide for radial selection of the guide star in the optical field. A filter compartment behind the reflecting element is further provided.