Abstract: Provided are an infrared optical imaging camera lens and an imaging device. The lens includes sequentially along an optical axis, from an object side to an imaging side: a stop, a first lens having positive focal power, a second lens having positive focal power, a third lens having negative focal power, and an optical filter. An object-side surface of the first lens is a convex surface, and an image-side surface of the first lens is a concave surface. An object-side surface of the second lens is a concave surface, and an image-side surface of the second lens is a convex surface. An object-side surface of the third lens is a convex surface in a region near the optical axis, and an image-side surface of the third lens is a concave surface in the region near the optical axis.

Abstract: The imaging lens consists of, in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a positive refractive power, and a third lens group. During focusing, only the second lens group moves. The second lens group includes at least four lenses. The imaging lens satisfies predetermined conditional expressions.

Abstract: An optical lens system includes, in order from the object side to the image side: a stop, a first lens with positive refractive power, a second lens with positive refractive power, a third lens with negative refractive power, wherein a distance from an image-side surface of the third lens to an image plane along an optical axis is BFL, a distance from an object-side surface of the first lens to the image plane along the optical axis is TL, following condition is satisfied: 0.38<BFL/TL<0.58. Such arrangements can meet the requirement of miniaturization under the condition of longer back focal length.

Abstract: The present disclosure provides an optical imaging lens assembly including, sequentially from an object side to an image side along an optical axis, a first lens having positive refractive power; a second lens having positive refractive power and a convex object-side surface; and a third lens having negative refractive power. A distance TTL along the optical axis from an object-side surface of the first lens to an imaging plane of the optical imaging lens assembly and half of a diagonal length ImgH of an effective pixel area on the imaging plane satisfy 2.0<TTL/ImgH<2.5.

Abstract: The present application discloses a camera lens assembly, the camera lens assembly, from an object side to an image side, sequentially including a first lens group and a second lens group, wherein the first lens group includes a first lens and a second lens; the second lens group includes at least a third lens; a filter is provided between the second lens group and the image side; and a radius of curvature of an object side surface of the first lens R1 and a radius of curvature of an image side surface of the first lens R2 satisfy: 0.5<R1/R2<1. The camera lens assembly according to the present application includes two sets of lens groups and the filter, and has characteristics of a low temperature sensitivity, a high image quality and miniaturization.

Abstract: An imaging lens includes first, second, and third lens elements arranged in sequence from an object side to an image side along an optical axis. Each lens element has an object-side surface and an image-side surface. The image-side surface of the first lens element has a concave portion in a vicinity of the optical axis and a convex portion in a vicinity of a periphery. The image-side surface of the second lens element has a convex portion in a vicinity of the optical axis and a concave portion in a vicinity of a periphery. The third lens element has negative refracting power. The object-side surface of the third lens element has a concave portion in a vicinity of a periphery. A mobile device is also provided.

Abstract: Provided is a microscope objective lens that sufficiently corrects on-axis and off-axis chromatic aberrations and that has a long working distance. A microscope objective lens OL includes, in order from an object side, a first lens group G1 with positive refractive power and a second lens group G2 with negative refractive power. The first lens group G1 of the microscope objective lens OL includes a diffractive optical element GD including a diffractive optical surface D, and the diffractive optical element GD is arranged at a position closer to the image than a section where a diameter of a light flux passing through the first lens group G1 is the largest.

Abstract: A microscope objective lens includes, in order from an object side, a first lens group having positive refractive power, a second lens group having positive refractive power, and a third lens group having negative refractive power, and is configured such that the first lens group includes, on the most object side, a positive meniscus lens whose concave surface is directed to the object side, such that the second lens group includes a diffractive optical element having positive refractive power, and such that the diffractive optical element is arranged at a position closer to the image than a portion at which the diameter of a light flux passing through the first lens group and the second lens group is the largest.

Abstract: This invention provides an imaging lens system, in order from an object side to an image side comprising: a first positive lens element having a convex object-side surface at a paraxial region and a convex image-side surface at the paraxial region; a plastic positive second lens element having a concave object-side surface at the paraxial region, a convex image-side surface at the paraxial region, and both of the object-side and image-side surfaces being aspheric; and a plastic negative third lens element having a concave object-side surface at the paraxial region, a concave at the paraxial region and convex at a peripheral region image-side surface, and both of the object-side and image-side surfaces being aspheric.

Abstract: An imaging lens includes: a first lens having positive refractive power; a second lens having positive refractive power; a third lens having negative refractive power; a fourth lens having positive refractive power; a fifth lens having positive refractive power; and a sixth lens having negative refractive power in vicinity of an optical axis and having positive refractive power in a peripheral portion. The first to sixth lenses are arranged in order from object plane.

Abstract: An image capturing lens assembly includes, in order from an object side to an image side, a first lens element, a second lens element and a third lens element. The first lens element with positive refractive power has a convex object-side surface and a convex image-side surface, wherein the surfaces of the first lens element are aspheric. The second lens element with positive refractive power has a concave object-side surface and a convex image-side surface, wherein the surfaces of the second lens element are aspheric. The third lens element with negative refractive power has a concave image-side surface in a paraxial region thereof, wherein the image-side surface of the third lens element has at least one convex shape in an off-axis region thereof, and the surfaces of the third lens element are aspheric. The image capturing lens assembly has a total of three lens elements with refractive power.

Abstract: An imaging lens SL comprising, in order from an object side: a first group G1 having positive refractive power; an aperture stop S; a second group G2 having positive refractive power; and a third group G3 having negative refractive power; upon focusing from infinity to a close object, the first group and the second group moving independently along an optical axis toward the object side, the first group including, in order from the object side, a front group having negative refractive power, and a rear group having positive refractive power, and the front group consisting of, in order from the object side, a positive lens and a negative lens, thereby providing an imaging lens capable of obtaining excellent optical performance upon focusing from infinity to a close object, with downsizing the optical system with a simple lens construction, an optical apparatus and a method for manufacturing the imaging lens.

Abstract: Embodiments relate to an image pickup lens including a first lens having both convex surfaces, a second lens in the form of a positive meniscus lens and a third lens in the form of a negative meniscus lens, the first lens to the third lens being arranged in sequence from an object side to an image side. The first lens to the third lens are formed of the same material.

Abstract: An imaging lens includes a first lens having positive refractive power; a second lens having positive refractive power; and a third lens having negative refractive power, arranged in the order from an object side to an image plane side. The first lens and the third lens respectively have an object-side surface and an image plane-side surface whose curvature radii are both positive. The second lens has an image plane-side surface whose a curvature radius is negative. In addition, when the first lens has refractive power P1, the second lens has refractive power P2, the third lens has refractive power P3, the curvature radius of the image plane-side surface of the second lens is R2r, and the curvature radius of the object-side surface of the third lens is R3f, the imaging lens satisfies specific conditional expressions.

Abstract: An image pickup lens includes, an aperture stop, a first meniscus lens having positive refractive power with a convex surface facing the object, a second lens having positive refractive power with a concave surface facing the object, a third lens having negative refractive power with a convex surface facing the object, the both surfaces of the third lens are aspheric and having at least one pole-change point, and following conditional expressions are satisfied: TTL<3.0??(1) 0.80<f1/f<0.93??(2) 0.35<bf/TTL<0.42??(3) 0.70<TTL/(2IH)<0.85??(4) where TTL: a length from the surface closest to the object to an image plane, f: a focal length of an overall optical system, f1: a focal length of the first lens, bf: a length from the image-side surface of the third lens to the image plane, and IH: a maximum image height.

Abstract: A single-focal-length imaging lens system achieves focusing by, while keeping first and third lens groups stationary relative to the image plane, moving a second lens group along the optical axis. The second lens group includes a positive lens element. The third lens group includes an aspherically shaped lens element having an inflection point at a position other than the intersection with the optical axis. The first and second air lenses formed by the intervals between the first and second and between the second and third lens groups have negative and positive refractive powers respectively. The conditional formula 0?|Fi1/Fi2|?|Fm1/Fm2|?10 is fulfilled (Fi1 and Fi2 representing the focal lengths of the first and second air lenses, respectively, when focusing on the infinite object distance; Fm1 and Fm2 representing the focal lengths of the first and second air lenses, respectively, when focusing on the closest object distance).

Abstract: A wide-angle lens system includes, in an order from an object side toward an image surface side: a first lens group having positive or negative refractive power; a second lens group having positive refractive power; and a third lens group having negative refractive power. When an object position changes from an infinite distance to a nearest distance, the first and third lens groups are fixed, and the second lens group moves along an optical axis to perform focusing.

Abstract: 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 and convexly formed at an object side surface; a second lens having positive (+) refractive power and concavely formed at an object side surface; and a third lens having negative (?) refractive power, wherein the imaging lens meets a conditional expression of 1.6<ND3<1.7, where ND3 is a refractive index of the third lens.

Abstract: A photographing lens assembly includes, in order from an object side to an image side, a first lens element, a second lens element and a third lens element. The first lens element with positive refractive power has an object-side surface being concave at a paraxial region thereof and an image-side surface being convex at a paraxial region thereof. The second lens element has positive refractive power. The third lens element with negative refractive power made of plastic material, and has an image-side surface being concave at a paraxial region thereof and being convex at a peripheral region thereof, wherein an object-side surface and the image-side surface of the third lens element are aspheric.

Abstract: An optical image capturing lens system includes, in order from an object side to an image side, a first lens element, a second lens element and a third lens element. The first lens element with positive refractive power has an object-side surface being convex at a paraxial region. The second lens element with positive refractive power is made of plastic material, and has an object-side surface being convex at a paraxial region and an image-side surface being concave at a paraxial region, wherein the surfaces of the second lens element are aspheric. The third lens element with negative refractive power is made of plastic material, and has an object-side surface being concave or planar at a paraxial region and an image-side surface being concave at a paraxial region and being convex at a peripheral region, wherein the surfaces of the third lens element are aspheric.

Abstract: A single focal length lens system comprising: at least a front lens unit having positive or negative power, and being fixed in focusing; a focusing lens unit having positive power, and moving along an optical axis in focusing; and a rear lens unit having negative power, and being fixed in focusing, wherein the focusing lens unit includes: a cemented lens of a negative lens and a positive lens; and a positive single lens located on the image side relative to the cemented lens and having an aspheric surface, the rear lens unit is composed of one single lens, and the condition: ?0.5<fW/fGR<?0.1 (fW, fGR: focal lengths of the entire single focal length lens system, the rear lens unit) is satisfied.

Abstract: An imaging lens includes: a movable lens group configured to travel to allow the imaging lens to come into focus; and a rearmost lens group arranged at a most-image-sided fixed position, and having negative refractive power. Following conditional expression is satisfied, ?2<ft/fr<?0.45??(1) where ft is a total focal length of the imaging lens in a condition that the imaging lens is in focus on an object at infinite, and fr is a focal length of the rearmost lens group.

Abstract: A small-size wide angle lens substantially consists of a first lens group having positive refractive power, a stop, a second lens group having positive refractive power, and a third lens group having negative refractive power, which are arranged in this order from the object side. Each of the first lens group, the second lens group and the third lens group includes a negative lens and a positive lens. Further, at least one of the second lens group and the third lens group includes an aspheric surface. Further, the small-size wide angle lens satisfies predetermined formulas.

Abstract: A three-piece optical lens system comprises, in order from the object side to the image side: a first lens element with a positive refractive power having a convex object-side surface, one of the object-side surface and an image-side surface being aspheric; a stop, a second lens element with a positive refractive power having a concave object-side surface, one of the object-side surface and an image-side surface being aspheric; a third lens element with a negative refractive power having a concave image-side surface, one of an object-side surface and the image-side surface being aspheric. A refractive index of the third lens element is N3, an Abbe number of the third lens element is V3, and they satisfy the relations: N3>1.57; V3<40. Such arrangements can reduce the volume of the three-piece optical lens system and improve the image quality of the periphery of the image.

Abstract: A lens system includes a first, a second and a third lenses, and an image plane. The lens system satisfies the formulae: FB/TTL>0.30; G1R2/F1>19.54; and D1/D2<1.62. FB denotes a distance between a nearest point of an image-side surface of the third lens relative to the image plane and the image plane, TTL denotes the total track length of the lens system, G1R2 denotes the curvature radius of the vertex of an image-side surface of the first lens, F1 denotes the focal length of the first lens. D1 denotes an orthogonal distance between a farthest point of an image-side surface of the second lens relative to an optical axis of the lens system and a central point of the image-side surface of the second lens, along a direction substantially perpendicular to the optical axis. D2 denotes an orthogonal distance between the farthest point and the central point along the optical axis.

Abstract: An imaging optical system has, in order from an object side to an image side, a first lens group, an aperture stop, a second lens group and a third lens group. A first lens, in said third lens group, is movable along an optical axis thereby implementing focusing from a focusing-on-infinity state to a focusing-on-a-near-distance state, with satisfaction of: |f(2+3)g/f1g|<1??(1) ?6.0<(R3gr+R3gf)/(R3gr?R3gf)<3.5??(2) where f(2+3)g is the combined focal length of the second lens group and the third lens group upon focusing on infinity; f1g is the focal length of the first lens group; R3gr is the axial radius of curvature of the surface of the most image side of a negative lens component of the third lens group; and R3gf is the axial radius of curvature of the surface of the most object side of said lens component of the third lens group.

Abstract: The present invention provides an imaging lens composed of three lenses that can be made compact (downsized, thinned), allows a reduction in cost and can be made compatible with a high pixel imaging element having a megapixel or more incorporated in a small mobile product such as a mobile phone. The imaging lens 6 includes, in order from the object side to the image surface side: an aperture stop 4; a first lens 1 having positive refractive power whose lens surface facing the image surface side is provided with a diffractive optical element; a second lens 2 composed of a meniscus lens having positive refractive power whose lens surface facing the image surface side is convex; a third lens 3 having negative refractive power.

Abstract: A micro-lens module including a plurality of lens groups is provided. The lens groups are disposed between an object side and an image side, wherein at least one lens group in the lens groups is composed by a complex lens. The complex lens includes a plurality of lenses, the lenses are adhered to each other, and an index of at least one lens in the lenses is different from indexes of the other lens in the lenses. The provided micro-lens module has an improved imaging quality and a miniaturized size while considering a manufacturing convenience.

Abstract: A lens system includes, from an object-side to an image-side, a first lens with positive refractive power, an aperture stop, a second lens with positive refractive power, a third lens with negative refractive power, a color filter, and an image plane. The first lens includes a first surface facing the object-side and a second surface facing the image-side. The second lens includes a third surface facing the object-side and a fourth surface facing the image-side. The imaging lens satisfies the following conditions: 0.26<R1/F1<0.35; and ?0.65<R2/F2<?0.35. Wherein: R1 is a radius of curvature of the first surface; R2 is a radius of curvature of the second surface; F1 is a focal length of the first lens; F2 is a focal length of the second lens.

Abstract: An image pickup apparatus having a simple configuration and being capable of performing switching between an image pickup mode based on a light field photography technique and a normal high-resolution image pickup mode is provided. The image pickup apparatus includes an image pickup lens 11, a microlens array section 12 where light passing through the image pickup lens 11 enters, and an image pickup device 13 sensing light emitted from the microlens array section 12, and the focal length of each of microlenses constituting the microlens array section 12 is variable in response to an applied voltage.

Abstract: The imaging optical system of the invention is built up of, in order from its object side, the first lens group G1 having positive refracting power, the stop S, the second lens group G2 having positive refracting power, and the third lens group G3 having negative refracting power. The first lens group G1 comprises a cemented lens consisting of the first lens L1 and the second lens L2. The second lens group G2 comprises the third lens L3. The third lens group G3 comprises the fourth lens L4. The second lens L3 has an object-side surface that is concave on its object side both on and off the optical axis, and an image-side surface being an aspheric surface that is convex on its object side on the optical axis and has one or more off-axis inflection points.

Abstract: The imaging lens includes, in order from the object side, a first lens having positive refractive power, a second lens having positive refractive power, and a third lens having negative refractive power. The first lens is provided with a substrate portion which is a parallel plate, and a lens portion formed of a material having a refractive index different from that of the substrate portion on at least one of the object-side surface or the image-side surface of the substrate portion, and the second lens is a single lens and satisfies the following conditional expression: 1<f2/f<20, wherein f2 represents the focal length of the second lens and f represents the focal length of the entire imaging lens system.

Abstract: An optical system includes, in order from an object side: a first lens group G1 having negative refractive power; and a second lens group G2 having positive refractive power; upon zooming from a wide-angle end state W to a telephoto end state T, a distance between the first lens group G1 and the second lens group G2 varying, and the second lens group G2 moving, and the second lens group G2 including a focusing lens group Gf that carries out focusing from an infinity object to a close object, and a decentering lens group Gs that is movable in a direction having a component perpendicular to an optical axis, thereby providing an optical system capable of establishing both of internal focusing and a decentering lens group with obtaining compactness and excellent optical performance, an optical apparatus equipped with the optical system, and a method for manufacturing the optical system.

Abstract: A projection optical system for magnifying an image on a primary imaging plane onto a secondary imaging plane includes a first optical system for forming an intermediate image and a second optical system including a concave reflecting surface disposed between the intermediate image and the secondary plane. The first optical system includes first and second groups respectively having negative and positive power, an aperture, and a third group having positive power from the intermediate image. The surfaces of the first and second optical systems have rotational symmetry about a light axis. A ray traveling from the center of the primary plane to the center of the secondary plane intersects the light axis, is reflected off the reflecting surface, intersects the light axis again, and reaches the secondary plane. The following conditions are satisfied: 0.5<?1/?2<3, 1<AST/ASS<5,|AST|/L12<1, and ?3<K_rel.

Abstract: A wide angle optical system is formed by, in order from the object side, an aperture stop, a first lens with positive refracting power, a second lens with negative refracting power, and a third lens. Both surfaces of the third lens are an aspherical surface in which refracting power varies in accordance with distance from the optical axis in such a way that the both surfaces have a convex shape facing toward the object side in the vicinity of the optical axis and have a concave shape facing toward the object side in the vicinity of the outer circumference, and the following conditions (1) and (2) are satisfied: 0.1<d5/d6<0.65??(1) ?0.04<f/f3<0.04??(2) where d5 is a space distance between the second and third lenses on the optical axis, d6 is the thickness of the third lens on the optical axis, f is a focal length of the whole of the wide optical system, and f3 is a focal length of the third lens.

Abstract: The present disclosure relates to a wide angle lens system. The wide angle lens system includes, in order from the object side to the image side thereof, a first lens of positive refraction power, a second lens of positive refraction power, and a third lens of negative refraction power. The wide angle lens system satisfies the following condition: 0.45<f/TTL<0.75; and 1.4<f1/f<2.4. Wherein, TTL is a distance from a surface of the first lens facing the object side of the wide angle lens system to an image plane, f is a focal length of the wide angle lens system, and f1 is a focal length of the first lens.

Abstract: An imaging lens SL comprising, in order from an object side: a first group G1 having positive refractive power; an aperture stop S; a second group G2 having positive refractive power; and a third group G3 having negative refractive power; upon focusing from infinity to a close object, the first group and the second group moving independently along an optical axis toward the object side, the first group including, in order from the object side, a front group having negative refractive power, and a rear group having positive refractive power, and the front group consisting of, in order from the object side, a positive lens and a negative lens, thereby providing an imaging lens capable of obtaining excellent optical performance upon focusing from infinity to a close object, with downsizing the optical system with a simple lens construction, an optical apparatus and a method for manufacturing the imaging lens.

Abstract: A zoom eyepiece lens system EL includes, in order from an eyepoint EP side: a first lens group G1 having positive refractive power; a second lens group G2 having positive refractive power; and a third lens group G3 having negative refractive power. Upon zooming from a low magnification end state to a high magnification end state, the second lens group G2 and the third lens group G3 move along an optical axis in opposite directions with each other. The second lens group G2 includes, in order from the eyepoint EP side, a first lens L3 having negative refractive power, a second lens L4 having positive refractive power, and a third lens L5 having positive refractive power. At least one aspherical surface is formed on the third lens L5.

Abstract: The present disclosure relates to a wide angle lens system. The wide angle lens system includes, in order from the object side to the image side thereof, a first lens of positive refraction power, a second lens of positive refraction power, and a third lens of negative refraction power. The wide angle lens system satisfies the following condition: 0.45<f/TTL<0.75; and 1.4<f1/f<2.4. Wherein, TTL is a distance from a surface of the first lens facing the object side of the wide angle lens system to an image plane, f is a focal length of the wide angle lens system, and f1 is a focal length of the first lens.

Abstract: An imaging lens of which various aberrations are corrected well, optical length is short, and back focus is sufficiently secured, is provided. The imaging lens is formed of a first lens L1, an aperture stop S, a second lens L2 and a third lens L3, arranged in this sequence from the object side to the image side. The first lens L1 is a meniscus lens having a positive refractive power, of which convex surface faces the object side, the second lens L2 is a meniscus lens having a positive or negative refractive power, of which convex surface faces the image side, and the third lens L3 is a meniscus lens having a negative refractive power, of which convex surface faces the object side. The Abbe number ? of the second lens L2 is a value in a 50.0 to 60.0 range.

Abstract: An immersion microscope objective lens of the present invention has: in order from an object, a first lens group G1 having positive refractive power and having a cemented lens of a plano convex lens having a plane facing the object and a meniscus lens having a concave surface facing the object, and a single meniscus lens having a convex surface facing the object; a second lens group having positive refractive power and having a plurality of cemented lenses; and a third lens group having negative refractive power and having a cemented meniscus lens having a concave surface facing an image, and a cemented meniscus lens having a concave surface facing the object. And the following conditional expressions 0.12<d0/f<0.25, 0.04<?Ct(p)??Ct(n)<0.09 and ?0.03<?hg(p)??hg(n)<0.00 are satisfied.

Abstract: An immersion type microscope objective lens OL includes, in order from a cover plate C side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, and a third lens group G3 having negative refractive power. The first lens group G1 includes at least one cemented lens. The second lens group G2 includes at least two achromatic lenses. The third lens group G3 includes, in order from the object side, an achromatic lens CL31 having a strong concave surface facing an image side, and an achromatic lens CL32 having a strong concave surface facing the object side.

Abstract: A scanning objective lens for scanning on an observation target with light emitted from an exit end face of an optical fiber moving on a curved plane formed to be convex on an objective lens side, including first and second lens groups each having a positive power, wherein the first lens group and the second lens group are arranged in this order from the optical fiber's exit end face side, and the scanning objective lens satisfies conditions: 0.60<f1/f2<1.25??(1); and 0.95<|R1a/R1b|<2.50??(2) when f1 denotes a focal length of the first lens group, f2 denotes a focal length of the second lens group, R1a denotes a curvature radius in the first lens group nearest to the exit end face of the optical fiber, and R1b denotes a curvature radius of a lens surface in the first lens group nearest to the observation target.

Abstract: The present invention provides an imaging lens composed of three lenses that can be made compact (downsized, thinned), allows a reduction in cost and can be made compatible with a high pixel imaging element having a megapixel or more incorporated in a small mobile product such as a mobile phone. The imaging lens 6 includes, in order from the object side to the image surface side: an aperture stop 4; a first lens 1 having positive refractive power whose lens surface facing the image surface side is provided with a diffractive optical element; a second lens 2 composed of a meniscus lens having positive refractive power whose lens surface facing the image surface side is convex; a third lens 3 having negative refractive power.

Abstract: An imaging lens comprises, in order from an object side: an aperture stop; a first lens having a positive refractive power in a meniscus form having a convex surface facing toward the object; a second lens having a positive or negative refractive power in a meniscus form having a concave surface facing toward the object; and a third lens having a positive or negative refractive power in an aspheric form at both surfaces, wherein conditional expressions given below are satisfied: ?d1>50??(1) ?d3>50??(2) 0.7<f1/f<1.0??(3) ?0.9<f2/{f3·(45??d2)}<0.4??(4) where ?d1: Abbe number of the first lens, ?d2: Abbe number of the second lens, ?d3: Abbe number of the third lens, f: Focal length of an overall system, f1: focal length of the first lens, f2: focal length of the second lens, and f3: focal length of the third lens.

Abstract: An imaging module includes an imaging lens system and an image sensor. The imaging lens system includes a first lens, a second lens, and a third lens. The imaging module satisfies the formulae, 2.4<S1/D1<3.0, 0.3<R1/F<0.7, wherein S1 is the effective diameter of the first surface S1 of the first lens, D1 is the distance from the object side surface S1 to the image side surface S2 of the first lens along the optic axis, R1 is the radius of curvature of the object side surface S1 of the first lens, and F is the focal length of the imaging lens system.

Abstract: Providing a compact lens system having high optical performance over the entire focusing range from infinity to a close distance, an optical apparatus equipped therewith, a method for focusing the lens system, and a method for vibration reduction of the lens system. The lens system includes, in order from an object, a first lens group G1, a second lens group G2, and a third lens group G3. Combined refractive power of the first lens group G1 and the second lens group G2 is positive. The first lens group G1 and the second lens group G2 are movable to an object side for varying focusing from the object locating at infinity to the object locating at a close distance. Each lens group includes at least one positive lens and at least one negative lens. Given conditional expressions are satisfied.

Abstract: A lens system including: a first lens group having a positive refractive power; a second lens group having a positive refractive power; and a third lens group having a positive or negative refractive power, wherein the first lens group comprises four or less lenses, and the first through third lens groups are movable, independently, during focusing and have magnifications in a range from ?1 to 0.

Abstract: An objective lens OL includes, in order from an object, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a diffractive optical element GD forming a diffractive optical surface D thereon, and a third lens group G3 having negative refractive power. The first lens group G1 includes at least one cemented lens and the most object side surface thereof forms a concave surface facing the object. The second lens group G2 includes at least one cemented lens. The third lens group G3 includes at least one cemented negative lens. In the objective lens OL, a principal ray crosses an optical axis between the second lens group G2 and the third lens group G3, and in the diffractive optical element GD, the diffractive optical surface D is disposed in the vicinity of the position where the principal ray crosses the optical axis.

Abstract: An imaging lens system, in order from the object side to the image side thereof, includes a first lens with positive refractive power, a second lens with positive refractive power, a third lens with negative refractive power and an image sensing element. The imaging lens system satisfies the following formulas: L/TTL>1.23, and 0.3<G1R1/F1<0.4, where an active surface of the image sensing element is square and only includes effective pixels, and L is the length of one side of the active surface, image sensing element TTL is the distance along an optical axis thereof from the object-side lens surface of the first lens to an imaging plane of the image side, G1R1 is the radius of curvature of the object-side lens surface of the first lens, and F1 is the focal length of the first lens.