Abstract: A zoom lens system comprising, in order from an object side: a first lens unit comprising two lens components; and a second lens unit comprising one lens component, during zooming, a space between the first lens unit and the second lens unit changing, the first lens unit and the second lens unit having aspherical surfaces, at least one aspherical surface of the first lens unit satisfying the following condition: R1/h1<1.35, wherein R1 denotes a paraxial radius of curvature of the at least one aspherical surface, and h1 denotes a length from a first intersection between a chief ray reaching a point of maximum image height on an image surface and the at least one aspherical surface to an optical axis in the wide-angle end at a time when the chief ray enters the zoom lens system with an angle of incidence equal to or larger than 36 degrees and passes through the at least one aspherical surface.

Abstract: A zoom lens system comprising, in order from an object side: a first lens unit comprising two lens components; and a second lens unit comprising one lens component, during zooming, a space between the first lens unit and the second lens unit changing, the first lens unit and the second lens unit having aspherical surfaces, at least one aspherical surface of the first lens unit satisfying the following condition: R1/hl 1.35, wherein R1 denotes a paraxial radius of curvature of the at least one aspherical surface, and hi denotes a length from a first intersection between a chief ray reaching a point of maximum image height on an image surface and the at least one aspherical surface to an optical axis in the wide-angle end at a time when the chief ray enters the zoom lens system with an angle of incidence equal to or larger than 36 degrees.

Abstract: An observation optical system has an entrance surface, a reflecting surface, and an exit surface. At least one of these surfaces is configured as a free-formed surface, to which a volume holographic optical element (HOE) is closely adhered. The observation optical system satisfies the following conditions: ?0.20<?x/Px<0.30 ?0.20<?y/Py<0.20 where ?x is the power of only the HOE in an x direction at the point of intersection of an axial principal ray with the surface of the HOE, ?y is the power of only the HOE in a y direction (parallel to the direction of decentration) at the point of intersection of the axial principal ray with the surface of the HOE, Px is the power of the whole of the observation optical system in the x direction, and Py is the power of the whole of the observation optical system in the y direction.

Abstract: An imaging optical system includes, in order from an object side, a first lens having positive refracting power, a concave surface of which is directed toward the object side, a third lens having positive refracting power, a convex surface of which is directed toward an image side and a fourth lens having negative refracting power, wherein the second lens and the third lens are cemented together. Having such a configuration, an angle made by the incident light and the exiting light to the cemented lens can be kept small, and accordingly, the generation of aberrations at the refracting surface and performance change of lenses when these are in a relative decentering position can be suppressed.

Abstract: A zoom lens system comprising, in order from an object side, a first lens unit having a negative refractive power, a second lens unit having a positive refractive power and a third lens unit having a positive refractive power, wherein during zooming from a wide-angle end to a telephoto end, a space between the first lens unit and the second lens unit narrows, at least the second unit move only toward the object side, and the third lens unit G3 is constituted of one positive lens.

Abstract: A three-unit zoom lens system comprising, in order from an object side, a first lens unit having a negative refractive power; a second lens unit having a positive refractive power; and a third lens unit having a positive or negative refractive power, wherein during magnification change from a wide-angle end to a telephoto end, a space between the first lens unit and the second lens unit narrows, the second lens unit and the third lens unit move toward the only object side, and a space between the second lens unit and the third lens unit changes during a focusing operation.

Abstract: The invention relates to a zoom lens wherein the total of lens components is reduced as much as possible and image-formation capability is enhanced far more stably over the entire zoom range, so that a lot more thickness reductions are achievable upon received at a lens mount, and an electronic imaging system that incorporates it. The electronic imaging system of the invention comprises a zoom lens having a plurality of lens groups G1 and G2 with a variable space between adjacent lens groups during zooming or focusing, wherein the lens group G1 nearest to the object side of the zoom lens comprises two components consisting of a negative lens component and a positive lens component, each having an aspheric surface, and an electronic image pickup device located on an image side of the zoom lens. Image data obtained by taking an image is processed to produce image data with shape changes as an output. The zoom lens satisfies condition (1) that defines the degree of barrel distortion at a zoom wide-angle end.

Abstract: The image forming optical system comprises in order from an object side, a first lens having positive refracting power and a concave surface directed toward an object side, a second lens having double convex surfaces, an aperture stop, a third lens which is meniscus lens having negative refracting power and a convex surface directed toward an image side, and a fourth lens having positive refracting power. Each surface at an object side and at an image side of the fourth lens is formed an aspherical surface having radius of curvature which decreases toward a circumferential portion, and the following condition is satisfied: 0.05<?m/?p<0.90?2.0<r1f/f<?0.1 where ?m represents the power of the fourth lens at the position of the maximum light height, ?p is the power of the fourth lens at the position of the praxis, r1f is the radius of curvature of the first lens at the object side, and f is the focal length of the image forming optical system as a whole system.

Abstract: A zoom lens system comprising, in order from an object side: a first lens unit comprising two lens components; and a second lens unit comprising one lens component, during zooming, a space between the first lens unit and the second lens unit changing, the first lens unit and the second lens unit having aspherical surfaces, at least one aspherical surface of the first lens unit satisfying the following condition: R1/h1<1.35, wherein R1 denotes a paraxial radius of curvature of the at least one aspherical surface, and h1 denotes a length from a first intersection between a chief ray reaching a point of maximum image height on an image surface and the at least one aspherical surface to an optical axis in the wide-angle end at a time when the chief ray enters the zoom Lens system with an angle of incidence equal to or larger than 36 degrees and passes through the at least one aspherical surface.

Abstract: An optical system includes in order from an object side, a negative lens having a concave surface directed toward an object side, an aperture stop, a double convex lens, a negative meniscus lens having a convex surface directed toward an image side, and a positive lens. A surface at the object side of the fourth positive lens is constituted with an aspherical surface, a radius of curvature which decreases from a center portion toward a circumferential portion and a surface at the image side of the positive lens an aspherical surface, radius of curvature of which increases from the center portion toward the circumferential portion and the following condition is satisfied: 0.05<?m/?p<0.80 where m represents the power of the positive lens at the position of the maximum light height and p represents the power of the positive lens at the position the praxis.

Abstract: The image forming optical system includes, in order from the object side, a meniscus, a first lens having positive refracting power with a convex surface directed toward the object side, an aperture stop, a meniscus, a second lens having negative refracting power with a concave surface directed toward the object side, a third lens having positive refracting power with a convex surface directed toward the image side, and a biconvex, fourth lens having positive refracting power. The fourth lens has at least one aspherical surface and satisfies the condition: 1.0<?m/?p<50.0 where ?m and ?p represent power of the fourth lens at a position of the maximum light height and at the paraxial position, respectively. Also, the following condition is satisfied: 0.3<f1/f<2.0 where f1 and f represent the focal lengths of the first lens and of the entire image forming optical system, respectively.

Abstract: An imaging optical system comprises, in order from an object side a first lens having positive refracting power, a second lens having negative refracting power, a concave surface of which is directed toward the object side, a third lens having positive refracting power, a convex surface of which is directed toward an image side and a fourth lens having negative refracting power, wherein the second lens and the third lens are cemented. By such constitution, an angle made by the incident light and the exiting light to the cemented lens can be kept small, and accordingly, the generation of aberrations at the refracting surface and performance change of lenses when these are in a relative decentering position can be suppressed to the utmost.

Abstract: An imaging optical system that includes, in order from an object side, a first lens having positive refracting power, a concave surface of which is directed toward the object side, a third lens having positive refracting power, a convex surface of which is directed toward an image side and a fourth lens having negative refracting power, wherein the second lens and the third lens are cemented together. Having such a configuration, an angle made by the incident light and the existing light to the cemented lens can be kept small, and accordingly, the generation of aberrations at the refracting surface and performance change of lenses when these are in a relative decentering position can be suppressed.

Abstract: The invention relates to a zoom lens wherein the total of lens components is reduced as much as possible and image-formation capability is enhanced far more stably over the entire zoom range, so that a lot more thickness reductions are achievable upon received at a lens mount, and an electronic imaging system that incorporates it. The electronic imaging system of the invention comprises a zoom lens having a plurality of lens groups G1 and G2 with a variable space between adjacent lens groups during zooming or focusing, wherein the lens group G1 nearest to the object side of the zoom lens comprises two components consisting of a negative lens component and a positive lens component, each having an aspheric surface, and an electronic image pickup device located on an image side of the zoom lens. Image data obtained by taking an image is processed to produce image data with shape changes as an output. The zoom lens satisfies condition (1) that defines the degree of barrel distortion at a zoom wide-angle end.

Abstract: The image forming optical system of the present invention comprises, in order from an object side, a first lens which is meniscus lens having positive refracting power and a concave surface directed toward an object side, an aperture stop, a second lens having positive refracting power and a convex surface directed toward the object side, a third lens which is meniscus lens having negative refracting power and a convex surface directed toward an image side, and a fourth lens having positive refracting power.

Abstract: An image forming optical system comprises, in order from an object side, a first positive meniscus lens having a convex surface directed toward an object side, an aperture stop, a second positive meniscus lens having a convex surface directed toward the object side and a negative lens. At least one of surfaces of the negative lens is a spherical and the following condition is satisfied: ?2.0<?m/?p<0 ?2.0<(r1r+r2f)/(r1r?r2f)<1.0 where ?m represents the power of the negative lens at the position of the maximum light height and ?p represents the power of the negative lens at the position of the near axis, r1r represents the radius of curvature of the first lens at the image side and r2f is the radius of curvature of the second lens at the object side.

Abstract: An observation optical system has an entrance surface, a reflecting surface, and an exit surface. At least one of these surfaces is configured as a free-formed surface, to which a volume holographic optical element (HOE) is closely adhered. The observation optical system satisfies the following conditions: ?0.20<?x/Px<0.30 ?0.20<?y/Py<0.20 where ?x is the power of only the HOE in an x direction at the point of intersection of an axial principal ray with the surface of the HOE, ?y is the power of only the HOE in a y direction (parallel to the direction of decentration) at the point of intersection of the axial principal ray with the surface of the HOE, Px is the power of the whole of the observation optical system in the x direction, and Py is the power of the whole of the observation optical system in the y direction.

Abstract: A zooming optical system has at least one lens unit having a variable magnification function and at least one deformable reflecting surface having a compensator or focusing function. In this case, the zooming optical system satisfies the following conditions: 0?|øx/?|<0.5, 0?|øy/?|<0.5, where øx is power of an axis perpendicular to a direction of decentering of the deformable reflecting surface; øy is power of an axis in parallel with a direction of decentering of the deformable reflecting surface; and ? is power of the entire optical system.

Abstract: Lenses 1, 2, and 4 as an optical element having a power are cemented together in an optical axis direction. An optical filter 3 is sandwiched between the lenses 2 and 4. Optical elements neighboring each other are cemented together such that a positioning section which is disposed on a side surface of the optical element disposes an appropriate space in an optical axis direction and optical axes of optical elements align in a direction orthogonal to the optical axis. The cemented optical element arrays are cemented together and cut at a line in a cutting operation. By doing this, it is possible to manufacture a small image pickup lens unit, which can be used in an image pickup device, by mass-production and at a low cost.

Abstract: The image forming optical system comprises, in order from an object side, a first lens which is positive meniscus lens having a convex surface directed toward an object side, an aperture stop, a second lens which is positive meniscus lens having a convex surface directed toward an image side, a third lens which is positive meniscus lens having a convex surface directed toward an image side, and a fourth lens which is negative lens, wherein at least one of surfaces of the fourth lens is aspherical and the following condition is satisfied: ?2.0<?m/?p<0 where ?m represents the power of the fourth lens at the position of the maximum light height and ?p represents the power of the fourth lens at the position of the praxis. The third lens and the fourth lens are made of plastic material and the following condition is satisfied: 15.0<?3??4<40.0 where ?3 represents Abbe's number of the third lens and ?4 represents Abbe's number of the fourth lens.