Abstract: An imaging lens system for forming an optical image of an object on a light receiving surface of a solid-state image sensor, comprising, in order from an object side, an aperture diaphragm, and three lens elements, i.e., a first lens element which is a bi-aspherical lens having a positive optical power and a convex surface on an image side, a second lens element having a negative optical power and being a bi-aspherical meniscus lens whose object side has a concave shape, and a third lens element having a positive optical power and being a bi-aspherical meniscus lens whose object side has a convex shape.

Abstract: An optical lens system for taking image comprises three lens elements with refractive power, from the object side to the image side: a first lens element with positive refractive power having a convex object-side surface and a convex image-side surface, and the object-side surface being aspheric; a plastic second lens element with negative refractive power having a concave object-side surface and a convex image-side surface, and the front and image-side surfaces thereof being aspheric; a plastic third lens element with positive refractive power having a convex object-side surface and a concave image-side surface, the front and image-side surfaces thereof being aspheric; wherein an aperture stop is located between the first and second lens elements. By such arrangements, it can reduce the volume and sensitivity of the optical lens system, and furthermore can obtain higher resolution.

Abstract: A zoom lens system includes, in order from an object side, a first lens unit G1 having a positive refracting power, a second lens unit G2 having a negative refracting power, a third lens unit G3 having a positive refracting power, and a fourth lens unit G4 having a positive refracting power, and at the time of zooming from a wide angle end to a telephoto end, a space between the lens units changes, and the first lens unit includes two lenses namely, a negative lens and a positive lens, and satisfies the following conditional expression ?0.75<SF1p<?0.1??(1) where, SF1p is defined as SF1p=(R1pf+R1pr)/(R1pf?R1pr), when R1pf is a paraxial radius of curvature of a surface on the object side, of the positive lens in the first lens unit, and R1pr is a paraxial radius of curvature of a surface on an image side, of the positive lens in the first lens unit.

Abstract: An optical lens system for taking image, from object side along the optical axis comprises an aperture stop, a first lens element, a second lens element, and a third lens element. The first lens element is a positive meniscus lens element with its convex surface facing the object side. The second lens element is a negative meniscus lens element with its convex surface facing the image side. The third lens element is a positive meniscus lens element with its convex surface facing the object side. The three lens elements are made of plastic, and both surfaces of each lens element are aspheric. The focal length of the optical lens system is f, the focal lens of the first lens element is f1, the focal length of the second lens system is f2, and they satisfy the relations: 0.7<f1/f<0.9 and ?0.35<f2/f<?1.2.

Abstract: An optical system includes at least one of a movable lens unit movable in an optical axis direction and a fixed lens unit that is not movable in the optical axis direction. The at least one lens unit includes a plurality of refractive optical elements. The refractive optical elements are made of resin and have focal lengths of the same sign. When ?i is a refractive power, with respect to d-line, of the ith refractive optical element from an object side, ?G is a refractive power of a negative lens in the lens unit including the refractive optical elements, and ?a is an average refractive power, with respect to d-line, of the refractive optical elements, ?i, ?G, and ?a are adequately set.

Abstract: The object is to obtain an imaging lens system having an entire lens system downsized, being excellent in portability, and being compatible with a large number of pixels by which a favorable image quality is provided. Provided is an imaging lens system for forming an optical image of an object on a light receiving surface of a solid-state image sensor, comprising, in order from an object side, an aperture diaphragm (100), a first lens element (101) having a positive optical power and a convex surface on an image side, a second lens element (102) having a negative optical power and being a meniscus lens whose object side has a concave shape, and a third lens element (103) having a positive optical power and being a meniscus lens whose object side has a convex shape, in which the following conditional expressions are satisfied: 1.9<|fd/f2d|<3.5 0.9<|fd/f3d|<2.0 ?2.5<(r201+r202)/(r201?r202)<?1.4 ?1.7<(r301+r302)/(r301?r302)<?1.0.

Abstract: There is provided an imaging lens including a first lens having a positive refracting power, a second lens having a concave surface on an object side and having a negative refracting power, and a third lens having a positive refractive power and a meniscus shape having a convex surface on the object side and at a vicinity of an optical axis, in order from the object side. The imaging lens satisfies conditional equations below. f designates a focal length of the total system, f1 designates a focal length of the first lens, D2 designates an interval between the first lens and a second lens on an optical axis, ?123 designates an average of Abbe numbers of the first lens, the second lens and the third lens, and ?2 designates the Abbe number of the second lens. 0.7<f1/f<1.3??(1) 0.25<D2/f<0.

Abstract: A zoom lens system comprises a first lens unit having a positive refractive power, a second lens unit having a negative refractive power and a third lens unit having a positive refractive power, and during zooming from a wide-angle end to a telephoto end, a space between a first lens unit and a second lens unit and a space between the second lens unit and a third lens unit are changed, the space between the first lens unit and the second lens unit is enlarged in the telephoto end as compared with the wide-angle end, and the space between the second lens unit and the third lens unit is narrowed in the telephoto end as compared with the wide-angle end.

Abstract: The present invention is a compact lens system for use as a wide-field photographic objective with small format digital image sensors having a pixel dimension less than 0.010 mm. The f-number of the lens system is 2.9740, and the effective focal length of the system is 3.85 mm. The full angular field of view of the lens system is 61 degrees, and the chief ray incidence angles on the image plane are less than 18 degrees. The system comprises three plastic lenses, each having two aspheric surfaces. At least one of the aspheric surfaces in the system is coated with a multilayer infrared cut-off filter for blocking infrared wavelengths from the image sensors. The lens system has a reduced sensitivity to manufacturing tolerances, particularly lateral misalignment of optical elements and surfaces.

Abstract: An optical system includes at least one of a movable lens unit movable in an optical axis direction and a fixed lens unit that is not movable in the optical axis direction. The at least one lens unit includes a plurality of refractive optical elements. The refractive optical elements are made of resin and have focal lengths of the same sign. When ?i is a refractive power, with respect to d-line, of the ith refractive optical element from an object side, ?G is a refractive power of a negative lens in the lens unit including the refractive optical elements, and ?a is an average refractive power, with respect to d-line, of the refractive optical elements, ?i, ?G, and ?a are adequately set.

Abstract: An optical lens system for taking image comprises three lens elements with refractive power, from the object side to the image side: a first positive lens element having a convex surface on the object side and a concave surface on the image side, and at least one of the object side and image-side surfaces being aspheric; a negative plastic second lens element having a concave surface on the object side and a convex surface on the image side, and the object-side and image-side surfaces thereof being aspheric; a positive plastic third lens element having a convex surface on the object side and a concave surface on the image side, the object-side and image-side surfaces thereof being aspheric; and an aperture stop located in front of the first lens element for controlling brightness of the optical lens system. A focal length of the second lens element is f2, a focal length of the optical lens system is f, and they satisfy the relation: 0.1<|f/f2|<0.74.

Abstract: A lens unit according to the present invention is capable of varying power for forming an image onto an image pickup element. The lens unit includes: a plurality of lens groups, a diaphragm, and a shutter. In the plurality of lens groups, a distance between a k-th lens group counting from an object side and a (k+1)-th lens group arranged at an image side of the k-th lens group changes for varying power. The diaphragm is arranged between a position at an image side of the k-th lens group and a lens surface facing the object side of a lens closest to the image in the (k+1)-th lens group. The shutter is provided with an aperture in a noncircular shape and fulfills the predetermined conditional formulas.

Abstract: The invention relates to a zoom lens in which tweaks to the mode of movement of lens groups and the first lens group contribute more to making sure the desired zoom ratio and optical performances and ensuring that the whole length of the zoom lens is kept short while carrying it around. The zoom lens comprises a positive first lens group G1, a negative second lens group G2 and a positive third lens group G3, and includes an aperture stop S located between the second G2 and the third lens group G3. Upon zooming from the wide-angle end to the telephoto end, the first lens group G1 moves in unison, and the second lens group G2 moves in unison. The first G1 and the second lens group G2 are positioned nearer to the object side at the telephoto end than at the wide-angle end, with an increasing spacing between the first G1 and the second lens group G2 and a decreasing spacing between the second G2 and the third lens group G3.

Abstract: An image capture lens includes, in order and from a side of an object, a first positive lens having a convex surface facing the object, an aperture diaphragm, a second negative lens having a convex surface facing an image, a third positive lens having a concave surface facing the image, and an IR cut filter. The three lenses, aperture diaphragm, and IR cut filter are formed of resin materials, all the lens surfaces except for the IR cut filter are aspheric, and Conditional Equations (A0) to (A2) are satisfied. (A0) 0.3<f/f1<1.5, (A1) ?9<f/|f2|×100 <?0.9, and (A2) 0.3<D2/D3<0.5, where f: focal distance of the whole system, f1: focal distance of the first lens, f2: focal distance of the second lens, D2: distance from the first lens to aperture diaphragm, and D3: distance from aperture diaphragm to the second lens.

Abstract: An optical system which corrects an intensity distribution of incident light to a flat intensity distribution includes: a first lens group which includes at least one lens and has a positive refracting power; a second lens group which includes at least one lens and has a negative refracting power, the second lens group being positioned behind the first lens group in a direction of the incident light; and a third lens group which includes at least one lens and has a positive refracting power, the third lens group being positioned behind the second lens group in the direction of the incident light. In the optical system, the incident light is collimated, and the intensity distribution of the incident light is corrected to the flat intensity distribution by spherical aberrations of the first lens group, the second lens group and the third lens group.

Abstract: A compact image pickup lens includes, in order from an object side to an image side, a first lens element G1 of positive refractive power, a second lens element G2 of positive refractive power, and a third lens element G3 of negative refractive power. The first lens element has a meniscus shape with its convex surface L1 on the object side. The second lens element also has a meniscus shape but with its convex surface L4 on the image side. Each of the first, second and third lens elements has at least one aspheric surface. An aperture STO is further positioned in front of the second lens element. The image pickup lens satisfies the following conditions: 0.85?(v1/v2)?1.15 and 0.85?(v2/v3)?1.25, where v1 is the Abbe number at the d-line (587.5618 nm) of the first lens element, v2 is the Abbe number at the d-line (587.5618 nm) of the second lens element, and v3 is the Abbe number at the d-line (587.5618 nm) of the third lens element.

Abstract: An optical lens system for taking image comprises three lens elements with refractive power, from the object side to the image side: a first positive lens element having a convex front surface and a concave rear surface, and the front surface being aspheric; a negative plastic second lens element having a concave front surface and a convex rear surface, and the front and rear surfaces thereof being aspheric; a positive plastic third lens element having a convex front surface and a concave rear surface, the front and rear surfaces thereof being aspheric; and an aperture stop located between the first and second lens elements for controlling brightness of the optical system. The focal length of the first lens element is f1, the focal length of the optical lens system is f, and they satisfy the relations: f/f1<0.9.

Abstract: There is provided a subminiature imaging optical system utilizing only three sheets of lenses having positive, negative and positive refractive powers, respectively. The subminiature imaging optical system comprising, sequentially from an object side: a first lens having a meniscus shape with a convex object-side surface, the first lens having at least one apherical surface and positive refractive power; a second lens having a meniscus shape with a convex image-side surface, the second lens having at least one spherical surface and negative refractive power; and a third lens having both surfaces formed of an aspherical surface and having positive refractive power.

Abstract: An image pickup lens is disclosed, comprising three lenses characterized in that the lenses comprise a first lens L1 having a convex surface facing a subject side and positive refracting power, an aperture S, a second lens L2 having a convex surface facing an image side and negative refracting power, and a third lens L3 having a concave surface facing the image side and positive refracting power which are disposed sequentially from the subject side as well, all the lens surfaces are composed of aspheric surfaces and the following conditional formulas (A0) and (A1) are satisfied. f/f2<?0.9 ??(A0) 2<|R21?R22|/|R21+R22|<5 ??(A1) With this arrangement, there is provided a compact and less expensive image pickup lens having a good optical performance and used to a solid image pickup device and an image pickup device using the image pickup lens.

Abstract: The purpose is to provide a large-aperture-ratio internal focusing telephoto lens applicable to a wider photographing area by equipping a vibration reduction function capable to satisfactorily correct a camera shake and the like with securing superb optical performance. The large-aperture-ratio internal focusing telephoto lens includes, in order from an object, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, and a third lens group G3 having positive refractive power. The second lens group G2 is moved along an optical axis upon changing focus from infinity to a close-range object. The first lens group G1 has at least two cemented lenses and satisfies a given conditional expression. Either one of the cemented lens satisfies a given conditional expression.

Abstract: A single focus lens is provided and includes: in order from an object side of the single focus lens, a first lens having positive power and having a convex surface on the object side; a second lens of a negative meniscus lens and having a concave surface of the object side on its paraxial axis; and a third lens of an aspherical lens having a convex surface on the object side on its paraxial axis. The single focus lens satisfies conditions specified in the specification.

Abstract: An optical system for taking image comprises three lens elements with refractive power, from the object side to the image side: a first positive lens element having a convex front surface and a concave rear surface, and the front surface being aspheric; a negative plastic second lens element having a concave front surface and a convex rear surface, and the front and rear surfaces thereof being aspheric; a positive plastic third lens element having a convex front surface and a concave rear surface, the front and rear surfaces thereof being aspheric; and an aperture stop located between the first and second lens elements for controlling brightness of the optical system. The focal length of the first lens element is f1, a focal length of the second lens element is f2, a focal length of the optical system is f, and they satisfy the relations: f/f1>0.95, |f/f2|>0.34.

Abstract: An imaging lens (100) comprising, arranged sequentially from the object side, a positive-meniscus first lens (1) with its convex plane facing the object side, a negative-power-meniscus second lens (2), and a positive-power third lens (3), the second and third lenses (2, 3) functioning as correction lenses. The first lens (1) has a strong power, and both the second and third lenses (2, 3) are aspherical on opposite planes. When the synthetic focal distance of the imaging lens is f, the focal distance of the first lens f1, the distance from the incident surface on the object side to the imaging surface of the first lens (1) ?d, and the Abbe number of the second lens ?d2, the following conditional expressions are satisfied. 0.50<f1/f<1.5 (1) 0.50<?d/f<1.5 (2) 50>?d2 (3). Accordingly, a small, low-cost imaging lens capable of high-quality imaging can be realized.

Abstract: An object is to provide an imaging lens system which can achieve reduction of the size and weight while maintaining the high optical performance. The imaging lens system of the present invention comprises, in order form an object side to an imaging surface side: a first lens having a positive power with its convex surface facing the object side; a second lens in a meniscus shape having a positive power with its concave surface facing the object side; and a third lens functioning as a correction lens, wherein the imaging lens system satisfies following expressions: 0.25<r1/f<0.50, and ?0.27<r3/f<?0.19 (where, r1: a radius of center curvature of the surface (first face) of the first lens on the object side, r3: a radius of center curvature of the surface (first face) of the second lens on the object side, f: a focal distance of an entire lens system).

Abstract: An optical system includes a first optical element and a second optical element on at least one of an enlargement side and a reduction side relative to a point P at which a light axis and a paraxial chief ray intersect. Each of the first optical element and second optical element is composed of a solid material having a refractive light incident surface and a refractive light emergent surface. The optical system satisfies the following conditional expressions: ??gF1>0.0272, ??gF2<?0.0278, and f1×f2<0 where ??gF1 and ??gF2 denote anomalous partial dispersion values of the first and second optical elements for the g-line and F-line, respectively, and f1 and f2 denote focal lengths of the first and second optical elements, respectively, when the light incident surfaces and the light emergent surfaces of the first and second optical elements are in contact with air.

Abstract: An image-forming lens set includes a first lens, a second lens, an aperture and a third lens arranged orderly from an objective side toward an image side in sequence. The first lens is made of plastic material and has a positive diopter and two opposite surfaces including a convex surface facing the image side. The second lens is made of plastic material and has a negative diopter and two opposite surfaces including a concave surface facing the image side. The third plastic lens is made of plastic material and has a positive diopter and two opposite surfaces including a convex surface facing the image side.

Abstract: A wide angle lens includes, in order from an object side, a first positive convex lens element, a second concavo-convex negative lens element, and a third lens element. The first lens element is made of an optical glass and defines a first convex aspheric surface on the object side and a second plane aspheric surface. The second lens element is made of an optical plastic and defines a third concave aspheric surface on the object side and a fourth convex aspheric surface. The third lens element is made of an optical plastic and defines a fifth high-aperture size convex aspheric surface on the object side and a sixth wave-shaped aspheric surface. Each of the lens elements is symmetrically disposed about an optical axis of the lens. The lens is compact and capable of covering total field angle of up to about 70 degrees.

Abstract: An image capture lens includes, in order and from a side of an object, a first positive lens having a convex surface facing the object, an aperture diaphragm, a second negative lens having a convex surface facing an image, a third positive lens having a concave surface facing the image, and an IR cut filter. The three lenses, aperture diaphragm, and IR cut filter are formed of resin materials, all the lens surfaces except for the IR cut filter are aspheric, and Conditional Equations (A0) to (A2) are satisfied. (A0) 0.3<f/f1<1.5, (A1) ?9<f/|f2|×100 <?0.9, and (A2) 0.3<D2/D3<0.5, where f: focal distance of the whole system, f1: focal distance of the first lens, f2: focal distance of the second lens, D2: distance from the first lens to aperture diaphragm, and D3: distance from aperture diaphragm to the second lens.

Abstract: A photographing optical system includes at least one of a positive lens and diffractive optical element being provided closer to an object side of the system than an intersection P of a light axis and paraxial chief ray, and a negative lens, provided closer to an image side than the intersection. The positive lens and the negative lens are formed of materials satisfying the following conditions when the maximum height of a paraxial marginal ray, passing through a lens surface, from the light axis at a location closer to the object side than the intersection is greater than a maximum height of the paraxial marginal ray, passing through a lens surface, from the light axis at a location closer to the image than the intersection: ?0.0015×?d+0.6425<?gF 60<?d where ?d is an Abbe number and ?gF is a partial dispersion ratio.

Abstract: It is to provide an imaging lens that can maintain telecentricity, sufficiently correct various aberrations, and acquire an excellent resolution, while being small and light. The imaging lens comprises, in order from an object side towards an image surface side, a first lens which is a biconvex lens, a diaphragm, a second lens which is a meniscus lens having a negative power whose convex surface faces the image surface side, and a third lens which is a meniscus lens having a positive power whose convex surface faces the object side, wherein conditions expressed by each of following expressions are to be satisfied: 0.7?f1/fl?1, ?6?f2/fl??2.8, and 3?f3/fl?10 (where, fl: focal distance of the entire lens system, f1: focal distance of the first lens, f2: focal distance of the second lens, and f3: focal distance of the third lens).

Abstract: Providing a zoom lens system that satisfies making the focusing lens light and reducing a moving amount for focusing, simultaneously. The zoom lens system includes a first lens group having positive power, a second lens group having negative power and a third lens group having positive power. When zooming from a wide-angle end state to a telephoto end state, at least the first and third lens groups are moved such that a distance between the first and second lens groups increases, and a distance between the second and third lens groups decreases. The first lens group is composed of a front lens group with positive power having at least one negative lens and at least one positive lens, and a rear lens group with positive power having one positive lens. Focusing from infinity to a close object is carried out by moving only the rear lens group to the object.

Abstract: In an imaging lens of the present invention, various types of aberration are corrected favorably, the optical length is short, and a sufficient back focus is secured. The imaging lens comprises an aperture diaphragm S1, a first lens L1, a second lens L2, and a third lens L3, and is constituted such that the aperture diaphragm, first lens, second lens, and third lens are arranged in succession from the object side toward the image side. The first lens has a positive refractive power and convex surfaces facing the object side and the image side. The second lens has a negative refractive power, a meniscus shape, and a convex surface facing the image side. The third lens L3 has a positive refractive power and convex surfaces facing the object side and the image side. Both surfaces of the first lens, both surfaces of the second lens, and both surfaces of the third lens L3 are aspherical.

Abstract: The invention relates to an image-formation optical system that meets both demands for high performance and compactness, and an imaging system that incorporates the same. The imaging system is built up of an image-formation optical system comprises, in order from its object side, an aperture stop S, a first positive single lens L1 wherein the absolute value of the axial radius curvature of its image side-surface is smaller than that of its object side-surface, a second negative single lens L2 wherein the absolute value of the axial radius curvature of its image side-surface is smaller than that of its object side-surface and a third positive single lens L3, three single lenses in all, and an image pickup device located on the image plane I of the image-formation optical system.

Abstract: An imaging lens comprises, in order from an object side: a first lens having a positive refractive power; a second lens having a negative refractive power whose concave surface faces to the object; and a third lens having a positive refractive power and having a meniscus form that has a convex surface, facing to the object, in a portion at and around an optical axis of the imaging lens; wherein the first, second and third lenses have at least one aspheric surface, and wherein the imaging lens satisfies conditional expressions given below: 0.7<f1/f<1.3??(1) 0.2<D2/f<0.6??(2) 0.3<|f2/f|<0.8??(3) 0.5<f3/f<0.8??(4) where f: a focal length of an overall system, f1: a focal length of the first lens, f2: a focal length of the second lens, f3: a focal length of the third lens, and D2: a spacing, on the optical axis, between the first lens and the second lens.

Abstract: An object is to provide an imaging lens system which can achieve reduction of the size and weight while maintaining the high optical performance. The imaging lens system of the present invention comprises, in order form an object side to an imaging surface side: a first lens having a positive power with its convex surface facing the object side; a second lens in a meniscus shape having a positive power with its concave surface facing the object side; and a third lens functioning as a correction lens, wherein the imaging lens system satisfies following expressions: 0.25<r1/f<0.50, and ?0.27<r3/f<?0.19 (where, r1: a radius of center curvature of the surface (first face) of the first lens on the object side, r3: a radius of center curvature of the surface (first face) of the second lens on the object side, f: a focal distance of an entire lens system).

Abstract: An imaging lens includes first to third lenses G1 to G3 arranged in order from a object side. The first lens has a biconvex shape in a vicinity of an optical axis Z1. The second lens has a concave surface facing a object side. The second lens has a negative refractive power. The third lens has a positive or negative refractive power and has a meniscus shape containing, in a vicinity of the optical axis, a convex surface facing the object side. The following conditional expression is satisfied: 0.7<f1/f<1.3 0.2<D2/f<0.5 where f denotes a focal length of the entire system of the imaging lens, f1 denotes a focal length of the first lens G1 and D2 denotes an interval on the optical axis Z1 between the first lens G1 and the second lens G2.

Abstract: Providing a compact zoom lens system having a high zoom ratio. The zoom lens system includes, in order from an object, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, and a third lens group G3 having positive refractive power. When a state of lens group positions varies from a wide-angle end state W to a telephoto end state T, at least the first lens group G1 and the third lens group G3 are moved along the optical axis to the object. Given conditional expressions are satisfied.

Abstract: An imaging lens is provided and includes: in order from an object side of the imaging lens, a first lens having a convex surface directed to the object side on an optical axis and having a positive power; an aperture diaphragm placed between a top position of an object-side surface of the first lens and a position of an image-side surface of the first lens on the optical axis; a second lens having a meniscus shape with a concave surface directed to the object side on the optical axis; and a third lens having a meniscus shape with a convex surface directed to the object side on the optical axis. Further, the imaging lens satisfies specific conditional expressions.

Abstract: It is to provide an imaging lens that can maintain telecentricity, sufficiently correct various aberrations, and acquire an excellent resolution, while being small and light. The imaging lens comprises, in order from an object side towards an image surface side, a first lens which is a biconvex lens, a diaphragm, a second lens which is a meniscus lens having a negative power whose convex surface faces the image surface side, and a third lens which is a meniscus lens having a positive power whose convex surface faces the object side, wherein conditions expressed by each of following expressions are to be satisfied: 0.7?f1/fl?1, ?6?f2/fl??2.8, and 3<f3/fl?10 (where, fl: focal distance of the entire lens system, f1: focal distance of the first lens, f2: focal distance of the second lens, and f3: focal distance of the third lens).

Abstract: A wideband, e.g., 550 nm to 940 nm, apochromatic lens system for use with an external aperture stop, includes first, second, and third optical groups having, in order, positive, negative, and positive powers. The first group includes four optical elements having, in order, negative, positive, negative, and positive powers. The second group includes one element of negative power; and the third group includes two elements each having positive power. In another embodiment for use with an internal stop, the system includes first, second, and third optical groups having, in order, positive, positive, and negative powers. The first group includes four optical elements having, in order, positive, negative, positive, and negative powers. The second group includes one element of positive power, and the third group includes one element of negative power. In either embodiment, all of the optical elements are formed from not more than three different types of glass material.

Abstract: An imaging lens (100) comprising, arranged sequentially from the object side, a positive-meniscus first lens (1) with its convex plane facing the object side, a negative-power-meniscus second lens (2), and a positive-power third lens (3), the second and third lenses (2, 3) functioning as correction lenses. The first lens (1) has a strong power, and both the second and third lenses (2, 3) are aspherical on opposite planes. When the synthetic focal distance of the imaging lens is f, the focal distance of the first lens f1, the distance from the incident surface on the object side to the imaging surface of the first lens (1) ?d, and the Abbe number of the second lens ?d2, the following conditional expressions are satisfied. 0.50<f1/f<1.5 (1) 0.50<?d/f<1.5 (2) 50>?d2 (3). Accordingly, a small, low-cost imaging lens capable of high-quality imaging can be realized.

Abstract: A compact lens system includes, in succession from an object side to an image side, an aspheric first lens element (1) having a positive power, an aperture stop (4), an aspheric second lens element (2) having a negative power, and a third lens element (3) having a positive power. Both the first and second lens elements are meniscus lenses made of plastic, and the third lens element is a biconvex lens or a plano-convex lens made of glass. The first lens element has a convex surface (10) facing the object side and an opposite concave surface (11) facing the aperture stop. The second lens element has a concave surface (21) facing the aperture stop and an opposite convex surface (20) curved toward the image side. The surface (30) of the third lens element facing toward the image side has a radius of curvature larger than that of the other surface (31) facing the second lens element.

Abstract: A single focus lens comprises: a first lens of positive power having a convex-shaped surface on an object side; a second lens of a negative meniscus lens having, on the object side, a concave-shaped surface on its paraxial axis; and a third lens of an aspheric lens having, on the object side, a convex-shaped surface on its paraxial axis, in this order from the object side, wherein the single focus lens satisfies the predetermined conditions.

Abstract: An image capturing lens to capture an image of an object is provided with an aperture diaphragm having an aperture through which an image is captured; a first lens having a positive refracting power, wherein both surfaces of the first lens are shaped in a convex form; a second lens having a negative refracting power, wherein an object-side surface of the second lens is shaped a convex form; and a third lens which is a meniscus lens whose convex surface faces toward the object side; wherein the aperture diaphragm, the firs lens, the second lens and the third lens are aligned in this order from the object side.

Abstract: An imaging lens system including a first lens having a main positive power whose convex surface faces an object side, a second lens in a meniscus shape having a negative power whose convex surface faces an image surface side, and a third lens having a positive power whose convex surface faces the object side. The three lenses are disposed in order from the object side to the image surface side.

Abstract: A hybrid lens system includes, in order from an object side to an image side: a first positive lens, a second negative lens, and a third positive lens. The first lens is made of glass material. The second and second lenses are both made of plastic material and respectively have two aspheric surfaces. The hybrid lens system is capable of resisting scraping and providing high imaging quality.

Abstract: A lens assembly for an image sensor comprises an aperture, a first lens, a second lens and a third lens, which are arranged sequentially from the object side. The first lens is a planoconvex lens or a positive meniscus lens whose convex surface faces the object side; the second lens is a negative meniscus lens with a convex surface facing the image side and at least has an aspherical surface; and the third lens is a positive meniscus lens with a convex surface facing the object side and, at least, has an aspherical surface. The sensitivity of decentration and the aberration-correction effect of the whole lens assembly in accordance with the present invention can be effectively improved.

Abstract: A lens system has a plurality of lenses, a stop, and a diffractive surface, the entire lens system moves during focusing, and the lens system satisfies the condition of ??0.5, where ? is a maximum photographic magnification.

Abstract: A zoom optical system includes followings: a plurality of lens units for magnification, the plurality of lens unit for zooming including in order from a reduction conjugate side to a magnification conjugate side, a first lens unit having a positive optical power, a second lens unit having a negative optical power and a third lens unit having a positive optical power, wherein during zooming, respective intervals between the above described first, second and third lens unit vary, and across the entire zooming range, a magnification-side conjugate position with respect to a reduction-side conjugate position and a position of a pupil of the above described zoom optical system with respect to a reduction-side conjugate position are substantially immobile respectively.

Abstract: A third group of lenses is constructed by subsequently arranging those four lenses from an object side to an image side which include a positive lens, a cemented lens of a positive lens and a negative lens, and a positive lens, both of a surface of the third group of the lenses nearest to the object side and a surface of the third group of the lenses nearest to the image side are so aspheric that positive refractive power becomes gradually weaker as a location of the third group of the lenses departs from an optical axis; and a following conditional formula is satisfied: ?0.5<(Y? max/R34I)<0.0 where R34I is a curvature radius of the surface of the third group of the lenses nearest to the image side, and Y? max is a maximum image height.