Abstract: A zoom lens includes a positive first lens group, which is fixed during changing magnification and during focusing, a negative second lens group, which is moved during changing magnification, a positive third lens group, which is fixed during changing magnification and during focusing, a positive fourth lens group, which is moved during changing magnification and during focusing, and a negative fifth lens group, which is moved during changing magnification, which are in this order from an object side. A lens group constituting the first lens group consists of a negative front group and a positive rear group in this order from the object side. The second lens group consists of four lenses of a negative lens, a positive lens, a negative lens, and a positive lens or a negative lens arranged in this order from the object side.

Abstract: An optical element incorporated into an imaging optical system, comprising: an effective diameter area that allows effective light flux contributing to imaging to pass, a non-effective diameter area that surrounds the effective diameter area; and an outer peripheral face that surrounds the non-effective diameter area. The effective diameter area, the non-effective diameter area and the outer peripheral face are centered on an imaging optical axis. At least a thickness-direction part of the outer peripheral face or a circumferential part thereof is a non-parallel face having an inclination to an imaging optical axis. A light incident from a face of an object side, reflected on a face of an image-plane side to the outer peripheral face and reflected on the outer peripheral face is not incident to an image plane.

Abstract: A zoom lens includes a negative first lens-group, a positive second lens-group, and a positive third lens-group, sequentially arranged from the object side. The focal length magnification of the zoom lens is changeable by changing a distance between the lens-groups. The first lens-group is composed of a negative first lens, the image side of which is concave, and a positive second lens that is an aspheric plastic lens. The second lens-group is composed of a cemented lens and a meniscus-form fifth lens having a convex surface facing the object side. The cemented lens is composed of a double-convex-form positive third lens and a double-concave-form negative fourth lens. The third lens-group is composed of a positive sixth lens, which is a single lens. Formula (1) about focal length fG2 of the second lens-group and focal length fw of the entire system at wide end is satisfied: 1.10<fG2/fw<1.33??(1).

Abstract: An imaging device with a short length and small aberration is provided. A total length D of an image-forming optical system is less than 3.6 mm. A maximum incidence angle of a principle ray on an image forming plane exceeds 33°. Conditions f/fL<?1.50 or f/fL<?0.9, and D/f<1.10 are satisfied where f denotes a focal length of the entire image-forming optical system and fL denotes a focal length of a last lens.

Abstract: A zoom lens includes a negative first lens-group, a positive second lens-group, and a positive third lens-group, sequentially arranged from the object side. The focal length magnification of the zoom lens is changeable by changing a distance between the lens-groups. The first lens-group is composed of a negative first lens, the image side of which is concave, and a positive second lens that is an aspheric plastic lens. The second lens-group is composed of a cemented lens and a meniscus-form fifth lens having a convex surface facing the object side. The cemented lens is composed of a double-convex-form positive third lens and a double-concave-form negative fourth lens. The third lens-group is composed of a positive sixth lens, which is a single lens. Formula (1) about focal length fG2 of the second lens-group and focal length fw of the entire system at wide end is satisfied: 1.10<fG2/fw<1.33??(1).

Abstract: The evaluating apparatus evaluates a restoration-premised lens which is employed in an image forming system that converts an optical image into an electronic image and then enforces a restoration processing on the electronic image in order to obtain a sharp image, is actually manufactured based on such design as premised on the restoration processing. The evaluating apparatus includes an evaluating corrective optical system, measuring section and evaluating section. The evaluating corrective optical system, when it is combined with a lens manufactured just as designed, forms a sharp optical image. The measuring section measures the optical characteristics of a composite optical system provided by combining together the evaluating corrective optical system and the manufactured lens. The evaluating section evaluates the manufactured lens according to measured results provided by measuring section.

Abstract: An optical element incorporated into an imaging optical system, comprising: an effective diameter area that allows effective light flux contributing to imaging to pass, a non-effective diameter area that surrounds the effective diameter area; and an outer peripheral face that surrounds the non-effective diameter area. The effective diameter area, the non-effective diameter area and the outer peripheral face are centered on an imaging optical axis. At least a thickness-direction part of the outer peripheral face or a circumferential part thereof is a non-parallel face having an inclination to an imaging optical axis. A light incident from a face of an object side, reflected on a face of an image-plane side to the outer peripheral face and reflected on the outer peripheral face is not incident to an image plane.

Abstract: In a three-group zoom lens having negative power, positive power, and positive power in order from an object side, a first lens group is built from a first negative lens and a second positive biconvex lens which is formed from a plastic material and which has at least one aspherical surface; a second lens group G2 is built from a positive, a negative cemented lens and a fifth lens L5 assuming a meniscus shape; and a third lens group is built from a sixth lens L6 which is a positive single lens. The zoom lens fulfills conditional expressions provided below: 3.2<fg2/fw??(1) 26<?1??2<30??(2) D1/fw<0.75??(3) (fg2: a focal length of the second lens, fw: a focal length of an entire system achieved at a wide-angle end, ?1: Abbe number of the first lens, ?2: Abbe number of the second lens, and D1: Axial distance from a lens surface most closely positioned to the object side to a lens surface most closely positioned to an image side in the first lens group).

Abstract: The evaluating apparatus evaluates a restoration-premised lens which is employed in an image forming system that converts an optical image into an electronic image and then enforces a restoration processing on the electronic image in order to obtain a sharp image, is actually manufactured based on such design as premised on the restoration processing. The evaluating apparatus includes an evaluating corrective optical system, measuring section and evaluating section. The evaluating corrective optical system, when it is combined with a lens manufactured just as designed, forms a sharp optical image. The measuring section measures the optical characteristics of a composite optical system provided by combining together the evaluating corrective optical system and the manufactured lens. The evaluating section evaluates the manufactured lens according to measured results provided by measuring section.

Abstract: In a three-group zoom lens having negative power, positive power, and positive power in order from an object side, a first lens group is built from a first negative lens and a second positive biconvex lens which is formed from a plastic material and which has at least one aspherical surface; a second lens group G2 is built from a positive, a negative cemented lens and a fifth lens L5 assuming a meniscus shape; and a third lens group is built from a sixth lens L6 which is a positive single lens. The zoom lens fulfills conditional expressions provided below: 3.2<fg2/fw ??(1) 26<?1??2<30 ??(2) D1/fw<0.75 ??(3) (fg2: a focal length of the second lens, fw: a focal length of an entire system achieved at a wide-angle end, ?1: Abbe number of the first lens, ?2: Abbe number of the second lens, and D1: Axial distance from a lens surface most closely positioned to the object side to a lens surface most closely positioned to an image side in the first lens group).

Abstract: A three lens group zoom lens is provided and includes three lens groups of negative, positive, and positive in this order from an object side and varies a magnification by changing distances among respective lens groups. A first group includes, in order from the object side, a negative lens in a meniscus shape directing a convex surface on the object side, a negative lens in a meniscus shape directing a convex surface on the object side, and a positive lens in a meniscus shape directing a convex surface on the object side. A second group includes, in order from the object side, a cemented lens including a bi-convex lens and a bi-concave lens, and a lens in a meniscus shape directing a concave surface on the object side. A third group includes a positive lens. Each of the first group and the second group includes an aspherical surface.

Abstract: A three-group zoom lens includes five lens components and six lens elements. The first lens group from the object side has negative refractive power and both the second lens group, which includes a stop, and the third lens group from the object side have positive refractive powers. The first and second lens groups each include an aspheric surface. During zooming, the first lens group moves nearer the second lens group while the second lens group moves farther from the third lens group. The third lens group moves toward the object side when focusing from an object at infinity to a nearby object. The three lens groups have particular lens element constructions, and lens elements of the second and third lens groups satisfy certain conditions related to their focal lengths, Abbe numbers, and the focal length of the zoom lens.

Abstract: A three lens group zoom lens is provided and includes three lens groups of negative, positive, and positive in this order from an object side and varies a magnification by changing distances among respective lens groups. A first group includes, in order from the object side, a negative lens in a meniscus shape directing a convex surface on the object side, a negative lens in a meniscus shape directing a convex surface on the object side, and a positive lens in a meniscus shape directing a convex surface on the object side. A second group includes, in order from the object side, a cemented lens including a di-convex lens and a di-concave lens, and a lens in a meniscus shape directing a concave surface on the object side. A third group includes a positive lens. Each of the first group and the second group includes an aspherical surface.

Abstract: A three-group zoom lens includes five lens components and six lens elements. The first lens group from the object side has negative refractive power and both the second lens group, which includes a stop, and the third lens group from the object side have positive refractive powers. The first and second lens groups each include an aspheric surface. During zooming, the first lens group moves nearer the second lens group while the second lens group moves farther from the third lens group. The third lens group moves toward the object side when focusing from an object at infinity to a nearby object. The three lens groups have particular lens element constructions, and lens elements of the second and third lens groups satisfy certain conditions related to their focal lengths, Abbe numbers, and the focal length of the zoom lens.