Abstract: There is provided a lens module, including: a first lens having positive refractive power, an object-sided surface thereof being convex; a second lens having negative refractive power, an image-sided surface thereof being concave; a third lens having positive refractive power; a fourth lens having negative refractive power, an image-sided surface thereof being convex; and a fifth lens having negative refractive power, an image-sided surface thereof being concave, wherein the fourth lens satisfies Conditional Expression 1, [Conditional Expression 1] f ? ? 4 f < - 3.0 where f is an overall focal distance of an optical system and f4 is a focal distance of the fourth lens.

Abstract: An imaging lens is constituted of, in order from an object side to an image side, a first lens element having a positive refractive power and having a convex surface toward the object side; a second lens element of a meniscus shape having a negative refractive power and having a concave surface toward an image side; a third lens element having a positive refractive power and having a convex surface toward the image side; a fourth lens element of a meniscus shape having a negative refractive power and having a convex surface toward the image side; and a fifth lens element of a meniscus shape and having a concave surface toward the image side.

Abstract: This invention provides an imaging lens system including, in order from an object side to an image side: a first lens with positive refractive power having a convex object-side surface; a second lens with negative refractive power; a third lens having a concave image-side surface; a fourth lens with positive refractive power; a fifth lens with negative refractive power having a concave image-side surface, at least one surface thereof having at least one inflection point; and an aperture stop disposed between an imaged object and the third lens. The on-axis spacing between the first lens and second lens is T12, the focal length of the imaging lens system is f, and they satisfy the relation: 0.5<(T12/f)×100<15.

Abstract: This invention provides an imaging lens system including, in order from an object side to an image side: a first lens with positive refractive power having a convex object-side surface; a second lens with negative refractive power; a third lens having a concave image-side surface; a fourth lens with positive refractive power; a fifth lens with negative refractive power having a concave image-side surface, at least one surface thereof having at least one inflection point; and an aperture stop disposed between an imaged object and the third lens. The on-axis spacing between the first lens and second lens is T12, the focal length of the imaging lens system is f, and they satisfy the relation: 0.5<(T12/f)×100<15.

Abstract: An image capturing lens which substantially consists of five lenses, composed of a first lens having a positive refractive power with the object side surface being formed in a convex shape toward the object side, a second lens having a negative refractive power, a third lens having a positive refractive power, a fourth lens having a negative refractive power with the object side surface being formed in a concave shape toward the object side, and a fifth lens having a negative refractive power with a region in which the negative refractive power is gradually reduced outwardly in a radial direction from the optical axis, arranged in this order from the object side, and satisfies predetermined conditional expressions.

Abstract: Provided is an image pickup lens that forms an image on an image pickup element with light from a subject. In the image pickup lens, a lens that is disposed on an image pickup element side is fixed in position, and a focusing lens group having a plurality of lenses including a lens closest to the subject is moved in an optical axis direction, thereby performing focusing.

Abstract: Providing for a fixed focus optical system exhibiting extended depth of field is provided herein. By way of example, a compact and fast optical system that yields an asymmetric modulation transfer function (MTF) is disclosed. In some aspects, the asymmetric MTF results in extended depth of field for near field objects. Such a response can be particularly beneficial for small handheld cameras or camera modules having high resolution. According to some disclosed aspects, the resolution can be about 8 mega pixels. Additionally, the optical system can comprise four lenses in one aspect and five lenses in another, while remaining below about 5.3 mm total track length (TTL) for the respective systems. In at least one application, the disclosed optical systems can be employed for a high resolution compact camera, for instance in conjunction with an electronic computing device, communication device, display device, surveillance equipment, or the like.

Abstract: A photographing lens and a photographing apparatus including the photographing lens. The photographing lens includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens that are arranged sequentially from an object side. The first lens has a concave surface toward the object side and has a positive refractive power, and the second lens is formed with a meniscus shape having a concave surface toward an image side and has a negative refractive power.

Abstract: An image pickup lens includes a first lens having a positive refractive power with a convex surface facing the object side, a second lens having a negative refractive power with a concave surface facing an image side, a third lens of a meniscus shape having a convex surface facing the object side, a fourth lens of a meniscus shape having a positive refractive power with a convex surface facing the image side, and a fifth lens having a negative refractive power with a concave surface facing the image side, wherein the both surfaces of the fifth lens have an aspherical shape, and the curvature radius of the fourth lens satisfies conditional expression (13) below: 1.4<r7/r8<3.0??(13) where r7 is the curvature radius of the object-side surface of the fourth lens, and r8 is the curvature radius of the image-side surface of the fourth lens.

Abstract: An image pickup optical system of the present invention comprises, in order from an object side, a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, a fourth lens having a positive refractive power, a fifth lens having a negative refractive power, which is formed into a meniscus shape facing its concave surface toward the object side, and an aperture located on the most object side. Thus, there can be provided an image pickup optical system and an image pickup apparatus having the same, in which the maximum effective lens aperture is small and various aberrations are corrected properly.

Abstract: Disclosed herein is an imaging lens suitable for a camera module using a high resolution imaging sensor, decreasing a flare phenomenon and reducing the sensitivity. The imaging lens comprises, in order from the object side, a first lens having positive (+) refractive force; a second lens having negative (?) refractive force; a third lens having positive (+) refractive force; a fourth lens having positive (+) refractive force; and a fifth lens having negative (?) refractive force, wherein an object side plane of the third lens is convexly formed.

Abstract: There is provided a lens module, including: a first lens having positive refractive power, an object-sided surface thereof being convex; a second lens having negative refractive power, an image-sided surface thereof being concave; a third lens having positive refractive power; a fourth lens having negative refractive power, an image-sided surface thereof being convex; and a fifth lens having negative refractive power, an image-sided surface thereof being concave, wherein the fourth lens satisfies Conditional Expression 1, f ? ? 4 f < - 3.0 [ Conditional ? ? Expression ? ? 1 ] where f is an overall focal distance of an optical system and f4 is a focal distance of the fourth lens.

Abstract: An image capturing optical system includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element and a fifth lens element. The first lens element with positive refractive power has a convex object-side surface. The second lens element with negative refractive power has a concave object-side surface and a convex image-side surface. The third lens element has refractive power, wherein the surfaces of the third lens element are aspheric. The fourth lens element has positive refractive power, wherein the surfaces of the fourth lens element are aspheric. The fifth lens element with refractive power is made of plastic material, and has a concave image-side surface, wherein the surfaces of the fifth lens element are aspheric, and the fifth lens element has inflection points formed on at least one of the surfaces thereof.

Abstract: An optical lens assembly for imaging pickup, sequentially arranged from an object side to an image side, comprising: a first lens element, a second lens element, a third lens element, a fourth lens element and a fifth lens element. The first lens element with positive refractive power has a convex object-side surface. The second lens element has negative refractive power. The third lens element with refractive power has bi-aspheric surfaces. The fourth lens element with positive refractive power has a concave object-side surface and a convex image-side surface and both being aspheric. The fifth lens element with negative refractive power has a concave image-side surface, bi-aspheric surfaces and at least one inflection point. Therefore, the optical lens assembly for imaging pickup satisfies conditions related to shorten the total length and to reduce the sensitivity for use in compact cameras and mobile phones with camera functionalities.

Abstract: An image pickup lens includes a first lens having a positive refractive power with a convex surface facing the object side, a second lens having a negative refractive power with a concave surface facing an image side, a third lens having a negative refractive power with both surfaces formed from aspheric surface, a fourth lens of a meniscus shape having a positive refractive power with a convex surface facing the image side, and a fifth lens of a meniscus shape having a negative refractive power with a concave surface facing the image side, wherein the curvature radius of the fourth lens satisfies conditional expression (13) below: 1.4<r7/r8<3.0??(13) where r7 is the curvature radius of the object-side surface of the fourth lens, and r8 is the curvature radius of the image-side surface of the fourth lens.

Abstract: An optical lens assembly for image taking, sequentially arranged from an object side to an image side, comprising: the first lens element with positive refractive power having a convex object-side surface; the second lens element with negative refractive power having a convex object-side surfaces and a concave image-side surface; the third lens element with positive refractive power having a convex image-side surface; the fourth lens element with refractive power having two aspheric optical surfaces; the fifth lens element with refractive power having a concave object-side surface and both aspheric optical surfaces; an image sensor disposed on an image plane and a stop provided for imaging a photographed object; specific relations being satisfied. Thereby, the optical lens assembly for image taking has good aberration correction, and can shorten the total length for use in compact cameras and mobile phones requiring high resolution.

Abstract: Disclosed is a low-cost, compact image pickup lens for a solid-state image pickup element. The image pickup lens includes, in the order from an object side, a first lens L1, which has a convex surface facing the object side on an optical axis and has a positive refractive power; a second lens L2, which has a concave surface facing an image side on the optical axis and has a negative refractive power; a third lens L3, which has a positive refractive power and has aspheric surfaces on the object side and the image side; a fourth lens L4, which has a convex surface facing the image side on the optical axis, has a positive refractive power, and has a meniscus shape; and a fifth lens L5, which has a concave surface facing the image side on the optical axis, has a negative refractive power, and has a meniscus shape.

Abstract: Provided is an imaging lens and a camera module, the device including in an orderly way from an object side, a first lens with positive (+) refractive power; a second lens with negative (?) refractive power; a third lens with negative (?) refractive power; a fourth lens with negative (?) refractive power; and a fifth lens with negative (?) refractive power, wherein the lens is concavely formed at an object side surface.

Abstract: An imaging lens system includes, from the object side, an aperture stop, a positive first lens convex to the object side, a negative second lens, a positive third lens convex to the object side, a positive meniscus fourth lens convex to the image side, and a negative biconcave fifth lens, and fulfills the conditional formulae 0.8<f/f1<1.30, 0.5<f4/f1<0.90, 0.6<d4/d3<2.0, and 0.80<R3_1/f<2.20, where f is the focal length of the entire imaging lens system, f1 and f4 are the focal lengths of the first and fourth lenses, d3 is the axial thickness of the second lens, d4 is the axial aerial distance between the second and third lenses, and R3_1 is the radius of curvature of the object-side surface of the third lens on the optical axis.

Abstract: An optical imaging lens assembly, sequentially arranged from an object side to an image side along an optical axis, comprising: the first lens element with positive refractive power having a convex object-side surface, the second lens element with negative refractive power having a convex object-side surface and a concave image-side surface, the third lens element with positive refractive power having a convex image-side surface, the fourth lens element with refractive power having both optical surfaces being aspheric, the fifth lens element with refractive power having a concave image-side surface and both optical surfaces being aspheric, wherein a stop and an image sensor disposed on an image plane are also provided. By such arrangements, the image pickup optical system satisfies conditions related to shorten the total length and to reduce the sensitivity for use in compact cameras and mobile phones with camera functionalities.

Abstract: It has conventionally been difficult to reduce the size of a fast lens system having an F number of about 1.4 to 2.4. In a lens system of the present invention, a positive lens element is disposed closest to an object side. A diaphragm is disposed in a widest air space in the lens system. The lens system of the present invention satisfies the following conditions: 0.05<L_1/L—TH<0.21 1.5<L—TH/Y<8 where L_1 is an interval from a lens surface located closest to the object side to a lens surface located on the object side relative to the diaphragm; L_TH is an interval from the lens surface located closest to the object side to a lens surface located closest to an image side; and Y is a maximum image height.

Abstract: The present invention is directed to provide an enhanced variable power zoom lens that has focusing lens optics reduced in weight so as to relieve of a load on a focusing drive system, and that has its anti-vibration lens optics reduced in both diameter and weight so as to relieve of a load on an anti-vibration drive system and downsize the same. The enhanced variable power zoom lens is adapted to have the foremost or first lens group G1 of positive refractivity, the second lens group G2 of negative refractivity, the third lens group G3 of positive refractivity, the fourth lens group G4 of negative refractivity, and the fifth lens group G5 of positive or negative refractivity arranged in sequence from a position closer to the object where the fourth lens group G4 serves as a focusing lens, and the third lens group G3 and the fifth lens group G5 together move on and along the same cam structure during zooming.

Abstract: Present embodiments provide for a mobile device and an optical imaging lens thereof. The optical imaging lens comprises five lens elements positioned in an order from an object side to an image side. Through controlling the convex or concave shape of the surfaces of the lens elements to allow the thickness of the second lens element and the sum of all air gaps between all five lens elements along the optical axis satisfying the relation: 0.20<T2<0.50 (mm) and 0.27<(T2/Gaa)<0.40, the optical imaging lens shows better optical characteristics and the total length of the optical imaging lens is shortened.

Abstract: The present invention provides an imaging lens assembly, comprising in order from an object side toward an image side, a first lens element with positive refractive power having a convex object-side surface, a second lens element with negative refractive power having a concave object-side surface and a convex image-side surface, a third lens element with positive refractive power having a concave object-side surface and a convex image-side surface, a fourth lens element with negative refractive power, a fifth lens element with positive refractive power, and an aperture stop positioned between an imaged object and the first lens element. The above lens arrangement shortens the total track length effectively, enabling a high performance imaging lens assembly with a wide field of view.

Abstract: A five-piece optical lens system is provided with, in order from the object side to the image side: a stop, a first lens element with a positive refractive power having a convex image-side surface, one of the object-side surface and an image-side surface being aspheric; a second lens element with a negative refractive power having a concave image-side surface, one of the object-side surface and an image-side surface being aspheric; a third lens element with a positive refractive power having a convex image-side surface, one of an object-side surface and the image-side surface being aspheric; a fourth lens element having a concave object-side surface, one of the object-side surface and an image-side surface being aspheric; a fifth lens element with a negative refractive power having a convex image-side surface, one of an object-side surface and the image-side surface being aspheric.

Abstract: An enhanced variable power zoom lens is lightweight in whole and in part, especially, having its focusing lens optics reduced in weight so as to relieve of a load on a focusing drive system, and having its anti-vibration lens optics reduced in both diameter and weight so as to relieve of a load on an anti-vibration drive system and downsize the same. The zoom lens has the foremost or first lens group of positive refractivity, the second lens group of negative refractivity, the third lens group of positive refractivity, the fourth lens group of negative refractivity, and the fifth lens group arranged in sequence from a position closer to the object. The fourth lens group moves toward the image plane for focusing on from the infinity to a proximity object while part of the third lens group moves orthogonal to the optical axis for shifting an image.

Abstract: An imaging lens is provided and includes: in order from the object side, a first lens having a positive refractive power; a second lens having a negative refractive power; a third lens having a concave surface on the image side near the optical axis and having a positive refractive power; a fourth lens having a positive refractive power near the optical axis; and a fifth lens having a negative refractive power near the optical axis. An image side surface of the fifth lens is concave near the optical axis and has a region where a negative power of the region decreases toward a periphery of the fifth lens as compared with a negative power near the optical axis.

Abstract: An imaging lens includes, in the order from an object side toward an image side: an aperture stop; a first lens having positive power and a concave image-side surface; a second lens having negative power and a concave object-side surface; a third lens having negative power; a fourth lens having positive power; and a fifth lens having negative power.

Abstract: A photographing optical lens system includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element and a fifth lens element. The first lens element with positive refractive power has a convex object-side surface. The second lens element has negative refractive power. The third lens element has refractive power. The fourth lens element with positive refractive power has a convex image-side surface. The fifth lens element with refractive power has a concave image-side surface, wherein an object-side surface and the image-side surface of the fifth lens element are aspheric, and the fifth lens element has at least one inflection point formed on at least one of the object-side surface and the image-side surface thereof.

Abstract: An imaging lens includes: an aperture stop; a biconvex first lens directing convex surfaces toward an object and an image; a second lens directing a convex surface toward the object near the optical axis and having negative refractive power; a biconvex third lens directing convex surfaces toward the object and the image near the optical axis; a fourth lens directing a concave surface toward the object near the optical axis and having positive refractive power; and a fifth lens directing a convex surface toward the object near the optical axis and having negative refractive power. The aperture stop and the first to fifth lenses are arranged in this order from the object side, and a conditional expression 1 being 0.50<f1/f<0.76 is satisfied, where f1 represents the focal length of the first lens and f represents the focal length of the entire imaging lens.

Abstract: An optical system for imaging pickup includes, sequentially arranged from an object side to an image side: the first lens element with positive refractive power having a convex image-side surface, the second lens element with refractive power having a concave image-side surface, the third lens element with refractive power, the fourth lens element with refractive power having both object-side and image-side surfaces being aspheric, and the fifth lens element with negative refractive power having a concave image-side surface, and both object-side and image-side surfaces being aspheric. By such arrangements, the optical system for imaging pickup satisfies conditions related to shorten the total length and to reduce the sensitivity for use in compact cameras and mobile phones with camera functionalities.

Abstract: An image lens, in the order from the object side to the image side thereof, includes a first lens including a first surface and a second surface, a second lens including a third surface and a fourth surface, a third lens including a fifth surface and a sixth surface, a fourth lens including a seventh surface and a eighth surface, a fifth lens including a ninth surface and a tenth surface, and an image plane. The image lens satisfies the following formulas: (1) D/TTL>0.94; (2) D/L>1.21; wherein D is the maximum image diameter of the image plane; TTL is a total length of the image lens, and L is a distance from an outmost edge of the tenth surface to an optical axis of the image lens along a direction perpendicular to the optical axis.

Abstract: The image pickup lens is composed of, in order from the object side, an aperture stop; a first lens with positive refractive power, including a convex surface facing the object side; a second lens with negative refractive power, including a concave surface facing an image side; a third lens with positive refractive power, including a convex surface facing the image side; a fourth lens with positive refractive power, having a meniscus shape including a convex surface facing the image side; and a fifth lens with negative refractive power, including a concave surface facing the image side. The image pickup lens satisfies conditional expressions relating to curvature radiuses of the object-side surface and the image-side surface of the fourth lens, a distance on an optical axis from the aperture stop to a focal point at the image side, and a focal length of the total system of the image pickup lens.

Abstract: This invention provides an imaging lens system including, in order from an object side to an image side: a first lens with positive refractive power having a convex object-side surface; a second lens with negative refractive power; a third lens having a concave image-side surface; a fourth lens with positive refractive power; a fifth lens with negative refractive power having a concave image-side surface, at least one surface thereof having at least one inflection point; and an aperture stop disposed between an imaged object and the third lens. The on-axis spacing between the first lens and second lens is T12, the focal length of the imaging lens system is f, and they satisfy the relation: 0.5<(T12/f)×100<15.

Abstract: An exemplary embodiment of the present invention relates to an imaging lens, the imaging lens including, in an ordered way from an object side, a first lens having positive (+) refractive power, a second lens having negative (?) refractive power, a third lens having negative (?) refractive power, a fourth lens having positive (+) refractive power, and a fifth lens having negative (?) refractive power, wherein the imaging lens meets a conditional expression of 0.8<?T/((FLD)X2)<1.2, where ?T is a distance from an object side surface of the first lens to an image-forming surface, and FLD is a distance from an optical axis to a maximum image height.

Abstract: An optical image lens system includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element and a fifth lens element. The first lens element with positive refractive power has a convex object-side surface. The second lens element with negative refractive power has a concave object-side surface and a convex image-side surface. The third lens element with negative refractive power has a concave image-side surface. The fourth lens element with refractive power has a concave object-side surface and a convex image-side surface, wherein the surfaces of the fourth lens element are aspheric. The fifth lens element with negative refractive power has a concave image-side surface, wherein the surfaces of the fifth lens element are aspheric, and the fifth lens element has inflection points formed on at least one of surface thereof.

Abstract: This invention provides an imaging lens system including, in order from an object side to an image side: a first lens with positive refractive power having a convex object-side surface; a second lens with negative refractive power; a third lens having a concave image-side surface; a fourth lens with positive refractive power; a fifth lens with negative refractive power having a concave image-side surface, at least one surface thereof having at least one inflection point; and an aperture stop disposed between an imaged object and the third lens. The on-axis spacing between the first lens and second lens is T12, the focal length of the imaging lens system is f, and they satisfy the relation: 0.5<(T12/f)×100<15.

Abstract: This invention provides an imaging lens system in order from an object side to an image side comprising five lens elements with refractive power: a first lens element with positive refractive power having a convex object-side surface; a second lens element with negative refractive power; a plastic third lens element having at least one of the object-side and image-side surfaces thereof being aspheric; a plastic fourth lens element having a concave image side surface, at least one of the object-side and image-side surfaces thereof being aspheric; and a plastic fifth lens element having a convex object side surface and a convex image-side surface, at least one of the object-side and image-side surfaces thereof being aspheric. By such arrangement, especially with the fourth lens element having the concave image side surface, the imaging lens system can correct peripheral rays while further improving the image resolution thereof.

Abstract: An imaging lens system includes a first lens group having a positive refractive power and a second lens group having a positive refractive power, the first lens group and the second lens group are sequentially arranged from an object side to an image surface. The first lens group includes a first lens having a positive refractive power, a second lens having a positive refractive power, and a third lens having a negative refractive power and having a concave surface toward the image surface, which are sequentially arranged from the object side to the image surface. The second lens group includes a cemented lens of a fourth lens that has a concave surface toward the object side and is a negative lens and a fifth lens that is a positive lens, which are sequentially arranged from the object to the image surface.

Abstract: The present invention ensures excellent optical characteristics corresponding with a high pixel imaging element while an imaging lens is miniaturized and has a larger aperture. The imaging lens includes, in order from an object side: a first lens having positive refractive power; a second lens in a meniscus shape including a concave surface facing an image side and having negative refractive power; a third lens having positive refractive power; a fourth lens in a meniscus shape including a concave surface facing the object side and having positive refractive power in the vicinity of an optical axis; and a fifth lens having negative refractive power in the vicinity of the optical axis and having positive refractive power in a peripheral section.

Abstract: The present invention provides an optical lens system comprising, in order from an object side to an image side: a first lens element with positive refractive power having a convex object-side surface; a second lens element with negative refractive power; a third lens element with positive refractive power having a convex object-side surface and a convex image-side surface; a fourth lens element; and a fifth lens element having a convex object-side surface and a concave image-side surface, the object-side and image-side surfaces thereof being aspheric and at least one inflection point being formed on the image-side surface. Such arrangement of optical elements can effectively minimize the size of the optical lens system, lower the sensitivity of the optical system, and obtain higher image resolution.

Abstract: Disclosed herein is an imaging lens suitable for a camera module using a high resolution imaging sensor, decreasing a flare phenomenon and reducing the sensitivity. The imaging lens comprises, in order from the object side, a first lens having positive (+) refractive force; a second lens having negative (?) refractive force; a third lens having positive (+) refractive force; a fourth lens having positive (+) refractive force; and a fifth lens having negative (?) refractive force, wherein an object side plane of the third lens is convexly formed.

Abstract: An image pickup lens has a configuration of five lenses whose aberrations are corrected favorably despite its compactness compared to a conventional type.

Abstract: A wide-angle image pickup lens having small F-value, high resolution, and small distortion is provided. The image pickup lens is configured from, in order from an object side to an image side, a first lens having a positive refractive power with a concave surface facing the object side, an aperture stop, a second lens having a negative refractive power with a concave surface facing the image side, a third lens having a positive refractive power, a fourth lens having a positive refractive power with a concave surface facing the object side, and a fifth lens having a negative refractive power with a concave surface facing the image side.

Abstract: This invention provides an optical image capturing lens system comprising: a first lens element with positive refractive power having a convex object-side surface; a second lens element; a third lens element; a fourth lens element; and a fifth lens element with negative refractive power, at least one of the object-side and image-side surfaces thereof being aspheric, and at least one inflection point is formed on at least one of the object-side and image-side surfaces thereof; wherein the system at least has one front stop and one rear stop; which are positioned between an imaged object and the third lens element as well as between the third lens element and the fifth lens element, respectively. By such arrangement, photosensitivity and total track length of the system can be reduced, and the aberration and astigmatism of the system can be effectively corrected. Moreover, the focusing performance thereof can be improved.

Abstract: A lens system is provided that comprises an enhanced depth of field based on a uniform or near uniform relative illumination via a lens with a large distortion. The distortion can be corrected with image processing equipment. The lens system can comprise an aperture stop and a group of lens, wherein there can be about five lenses in the group of lenses. The lens system is designed for relative illumination such that the light distribution over the lens system is substantially uniform.

Abstract: An image pickup optical system, sequentially arranged from an object side to an image side, comprises the first lens element with positive refractive power having a convex object-side surface, the second lens element with negative refractive power having a concave object-side surface and a convex image-side surface, the third lens element with refractive power, the fourth lens element with refractive power having a concave image-side surface, at least one of the surfaces being aspheric, the fifth lens element with refractive power having a concave image-side surface, at least one of the surfaces being aspheric and having at least one inflection point. Each of the five lens elements may be made of plastic with aspherical surfaces. The image pickup optical system satisfies conditions related to the reduction of the total length and the system sensitivity for use in compact cameras and mobile phone cameras functionalities.

Abstract: An imaging lens including: in order from an object side thereof, a first lens having a positive refractive power; a second lens formed in a meniscus shape having a negative refractive power with a concave surface faced to an image side; a third lens formed in a biconvex shape having a positive refractive power near an optical axis; a fourth lens formed in a meniscus shape having a positive refractive power with a concave surface faced to the object side near the optical axis; and a fifth lens having a negative refractive power near the optical axis and a positive refractive power in a peripheral portion, the imaging lens satisfying the following conditional expression (a), 3.0?f3/f4?30.0 (a) where f3 is a focal length of the third lens, and f4 is a focal length of the fourth lens.

Abstract: In an image forming optical system which includes in order from an object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, and a fourth lens group G4, and which includes maximum of five lens groups, and at the time of zooming from a wide angle end to a telephoto end, when a focal length of the overall image forming optical system is in a range of 1.2 fw to 1.8 fw, the first lens group G1 moves to be positioned more toward the object side than a position at the wide angle end, in a rectangular coordinate system in which, a horizontal axis is let to be ?d(LA) and a vertical axis is let to be nd(LA), when a straight line expressed by nd(LA)=a×?d(LA)+b(LA)(provided that a=?0.0267) is set, the image forming optical system satisfies a predetermined conditional expression.

Abstract: A compact low-cost imaging lens unit for a solid-state image sensor which corrects various aberrations adequately and produces a high-resolution high-definition image. The components of the unit are arranged from an object side to an image side in the following order: an aperture stop, a first lens with positive refractive power having a convex surface facing the object side, a second lens with negative refractive power having a convex surface facing the object side near an optical axis, a third lens with negative refractive power having a convex surface facing the object side near the optical axis, a fourth lens as a meniscus lens with positive refractive power having a convex surface facing the image side near the optical axis; and a fifth lens with negative refractive power having a concave surface facing the image side near the optical axis.