Abstract: This invention prevents a degradation in image quality resulting from undesirable reflected light and undesirable transmitted light generated near the ridgeline of the edge portion of an optical element including an aperture blade or an ND filter. The aperture edge of the aperture blade cooperates with the aperture edge of another aperture blade to form an almost rhombic aperture. A small saw-toothed and non-periodic uneven portions having various sizes are formed along two, front and rear ridgelines of the aperture edge and along those of the ND filter. When incident light beams strike the aperture edge of the aperture blade or the edge of ND filter, the uneven portions formed at the ridgeline reflect them in various directions.

Abstract: This invention prevents a degradation in image quality resulting from undesirable reflected light and undesirable transmitted light generated near the ridgeline of the edge portion of an optical element including an aperture blade or an ND filter. The aperture edge of the aperture blade cooperates with the aperture edge of another aperture blade to form an almost rhombic aperture. A small saw-toothed and non-periodic uneven portions having various sizes are formed along two, front and rear ridgelines of the aperture edge and along those of the ND filter. When incident light beams strike the aperture edge of the aperture blade or the edge of ND filter, the uneven portions formed at the ridgeline reflect them in various directions.

Abstract: A plurality of darkness distributions having a predetermined relationship with a darkness distribution for ND-filtering transmission light at the position of an aperture blade in an aperture device are formed on an original. The original is photographed on a film by a camera, and after the film is developed, the film is molded to obtain a plurality of ND filters.