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.

Abstract: A magnetic head has a core body for defining a magnetic path, a pair of magnetic thin films deposited on a pair of opposing surfaces of the core body, a gap member deposited between the pair of opposing surfaces to define a magnetic gap, and a bonding member such as a glass disposed between the pair of magnetic thin films, thereby bonding the magnetic thin films. The angle between the surface on which the magnetic thin film is deposited and one side surface of the core body is made greater than in conventional magnetic heads. The bonding member directly bonds the pair of opposing surfaces of the core body to each other and not through the magnetic thin films.

Abstract: A magnetic head comprises a pair of magnetic core half parts abutted to each other and having magnetic alloy films on both abutted surfaces, a magnetic gap material composed of laminated films formed on the abutted surface of at least one of the pair of magnetic core half parts, and welding glass welding the pair of magnetic core half parts. The laminated films are composed of an SiO.sub.2 film and a Cr.sub.2 O.sub.3 film located in sequence from the magnetic core half part side. The laminated films serve to protect the magnetic alloy film from an erosion due to the welding glass. The Cr.sub.2 O.sub.3 film ofers excellent wettability by the welding glass, thereby improving the strength of the magnetic head.

Abstract: A magnetic head comprises a magnetic head element constituted of a core composed of a material of high permeability, a case for the magnetic head element, the magnetic head element being fixed into said case with a fixing material which comprises a plurality of epoxy resins having different number of epoxy groups from each other.