PURPOSE: To excellently correct the parallax of a finder by fitting an accessory provided with a half mirror surface, total-reflecting mirror surface, and prescribed fitting means to a front lens barrel section by means of a positioning means.

CONSTITUTION: A half mirror surface 4a which reflects part of the luminous flux made incident on a photographing lens 7, to the sides of the photographing lens 7, total-reflecting mirror surface 5a which guides to luminous flux reflected by the mirror surface 4a to an optical element 17 provided in the vicinity of the photographing lens, and a removable fitting means 3a which is fitted to part of a lens barrel 6 of the photographing lens are provided. When zooming of the photographing lens is performed by moving the lens barrel 6 forward or backward along the optical axis, the magnification of a finder system is changed in such a way that an intermediate lens 18 is moved along with the lens barrel 6 and an object lens 17 is moved along the optical axis together with the 1st mirror frame 10 as the zooming of the photographing lens is performed. Therefore, the parallax of the finder can be corrected effectively over the entire zooming range.