Abstract: The invention provides a zoom optical system comprising at least three lens groups and designed to implement zooming by varying a separation between the respective lens groups. The zoom optical system includes, on an image plane side with respect to a stop, a lens group comprising a plurality of lenses and having positive refracting power throughout. The lens group having positive refracting power includes an air double-convex positive lens in it.

Abstract: An optical system including five lens units having, in order from the object side, positive, negative, positive, negative, positive refracting powers respectively. The distances between the lens units change during zooming. The first and third lens units are located closer to the object side at the telephoto end than at the wide angle end of the zoom range. The first lens unit includes a negative lens, a first positive lens, and a second positive lens. The second lens unit includes a plurality of negative lenses and at least one positive lens. The third lens unit includes a plurality of positive lenses and at least one negative lens. The fourth and fifth lens units each include two lenses or less. The refractive indices of the at least one negative lens in the first lens unit, the at least one positive lens in the second lens unit, and the at least one negative lens in the third lens unit are not lower than 1.9. The optical system satisfies a certain condition.

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, an aperture stop, a third lens group G3 having a positive refractive power, and a fourth lens group G4 having a negative refractive power, and in which, at the time of zooming, air distances between lens groups are variable, and an air lens nearest to an image side in the third lens group G3 has a shape of a convex lens, the fourth lens group G4 includes one lens component, and is movable even at the time of focusing, and satisfies the following conditional expressions 0.5<(R4F+R4R)/(R4F?R4R)<8.0 ??(1) ?12.0<(R4LAF+R4LAR)/(R4LAF?R4LAR)<?2.

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: 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: A zoom lens and an image pickup apparatus are disclosed. The zoom lens includes, in order from an object side to an image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, and a fifth lens group having a positive refractive power. The fifth lens group includes a fixed group having a negative refractive power, and a movable group having a positive refractive power and being movable in a direction substantially orthogonal to the optical axis. The image formed on an image surface is movable in a direction substantially orthogonal to the optical axis by moving the movable group of the fifth lens group in the direction substantially orthogonal to the optical axis. The fifth lens group is satisfied predetermined conditions.

Abstract: The invention is directed to inner-focusing zoom lenses that include multi groups of lens pieces, namely, the first lens group or the leading lens group of positive refractivity, the second lens group of negative refractivity, and the remaining trailing groups of positive refractivity, as a whole. At least one group of positive refractivity among the trailing groups includes two or more negative lens pieces, at least one of which is connected on its surface to another lens piece to form a duplicated composite lens so that the junction between two of them functions to diverge incident beams. Assuming now that a sum of the refractivities of all the junctions of the composite lenses can be expressed as ??=?|(N1?N2)/R| where N1 and N2 are refractivities that substances before and after the junction of the composite lenses respectively have, R is a radius of curvature of the junction, ft is a focal length of the comprehensive lens optics of the zoom lens at the telephoto end.

Abstract: A compact wide-angle zoom lens and an image pickup device having the same. The zoom lens includes a first lens group having a negative refractive power and a second lens group having a positive refractive power in an order from an object side to an image side, performs zooming by varying a distance between the first and second lens groups, and performs focusing by using a first lens closest to the object side in the second lens group.

Abstract: A zoom lens includes a first lens unit with a negative refractive power, a second lens unit with a positive refractive power, and a third lens unit with a positive refractive power in order from the object side to the image side. The first lens unit includes a negative lens and a positive lens. When the curvature radius of the object side surface and that of the image side surface of the negative lens are respectively defined as R11 and R12 and the curvature radius of the object side surface and that of the image side surface of the positive lens are respectively defined as R21 and R22, the following conditional expression is satisfied: ?5.6<(R12+R21)/(R12?R21)<?4.7 and 1.5<(R11+R22)/(R11?R22)<2.3.

Abstract: In a zoom lens ZL1 having a plurality of lens groups G1 to G2 which are disposed in order from an object, where a refractive index average value of the lens components which constitute the zoom lens ZL1 is defined as ndav and a refractive index average value of the lens components which constitute the first lens group G1 which is disposed to closest to the object among the plurality of lens groups G1 to G2 is defined as ndGlav, the zoom lens ZL1 is constituted to satisfy the conditional expression ndav?1.80 and to satisfy the conditional expression ndGlav?1.85.

Abstract: Disclosed herein is a zoom lens including a first lens group, a second lens group, a third lens group, a fourth lens group, and a fifth lens group. The zoom lens satisfies following conditional expressions (1) and (2), 0.03<H1?/f1<0.3??(1) 0.3<|f2|/?(fw·ft)<0.65??(2) where H1? is an interval from a vertex of a surface nearest to the image side in the first lens group to a principal point on the image side of the first lens group (? denotes the object side, and + denotes the image side), f1 is focal length of the first lens group, f2 is focal length of the second lens group, fw is focal length of an entire lens system at a wide-angle end, and ft is the focal length of the entire lens system at a telephoto end.

Abstract: A high zoom-ratio zoom lens system includes a positive first lens group, a negative second lens group, a positive third lens group, and a positive fourth lens group, in that order from the object side, wherein upon zooming from the short to the long focal length extremities, the first through fourth lens groups are moved along the optical axis direction, wherein an amount of movement of the first lens group is greater than that of the third lens group. The following conditions (1) and (2) are satisfied: 1.4<FT/F1<2.4??(1), and 5<M2T/M2W<10??(2), wherein FT designates the entire focal length at the long focal length extremity, F1 designates the focal length of the first lens group, and M2T and M2W designate the magnification of the second lens group with respect to an object at infinity at the long and short focal length extremities, respectively.

Abstract: A zoom lens system, in order from an object side to an image side, comprising a first lens unit of positive power, a second lens unit of negative power, a third lens unit of positive power, and a fourth lens unit of positive power, wherein in zooming, the first to the fourth lens units are moved along the optical axis such that the air spaces between the individual lens units should vary, so that magnification change is achieved, and wherein the conditions: ?0.60<M2/fG2<?0.07, ?W?30, and fT/fW?4.5 (M2 is an amount of axial movement of the second lens unit in zooming, fG2 is a composite focal length of the second lens unit, ?W is a half view angle at a wide-angle limit, and fT and fW are focal lengths of the entire system at a telephoto limit and at a wide-angle limit, respectively) are satisfied, an imaging device and a camera are provided.

Abstract: A zoom lens system includes a negative first lens group, a positive second lens group, and a positive third lens group. The second lens group includes a positive lens element, and two negative lens elements. The following conditions (1) and (2) are satisfied: 2.0<|VD1t?VD1w|/(ft/fw)<3.4 ??(1), and 0.89<|m2w/m3w|??(2), wherein VD1t and VD1w designate the distances, at the long and short focal length extremities, from the image-side surface of the lens element provided closest to the image side within the first lens group to the object-side surface of the positive lens element provided closest to the object side within the second lens group; ft and fw designate the entire focal length of the zoom lens system at the long and short focal length extremities; and m2w and m3w designate the lateral magnification of the second and third lens groups at the short focal length extremity when focused on an object at infinity.

Abstract: A zoom lens system includes, in order from an object side: a first lens group having positive refractive power; a second lens group having negative refractive power; a third lens group having positive refractive power; a fourth lens group having negative refractive power; and a fifth lens group having positive refractive power. Upon zooming from a wide-angle end state to a telephoto end state, a position of the first lens group is fixed. At least a portion of any one of the lens groups is moved in a direction including a component perpendicular to an optical axis, and a given conditional expression is satisfied, thereby providing a zoom lens system capable of excellently suppressing variation in aberrations upon zooming and upon correcting an image blur, an optical apparatus including the zoom lens system, and a method for manufacturing the zoom lens system.

Abstract: This invention provides a zoom lens assembly in order from an object side toward an image side including a first lens group with negative refractive power, a second lens group with positive refractive power and a third lens group with positive refractive power. The first lens group has only two lenses with refractive power from an object side toward an image side in order including a first lens with negative refractive power and a second lens with negative refractive power. The second lens group from an object side toward an image side in order includes an aperture stop, a third lens and a fourth lens. The third lens group includes a fifth lens. The number of the lens with refractive power in the zoom lens assembly is N, which satisfies the condition of 5?N?7, and the lens with refractive power in the zoom lens assembly includes at least three aspheric-surface lens.

Abstract: The optical system includes first (positive) and second (negative) lens units arranged in order from an object side to an image side, and an aperture stop disposed further on the image side than the second lens unit. The first lens unit includes at least one first optical element satisfying ?GH>0.0, ?dGH<39.5 and ndGH>1.70. The optical system satisfies 0.65<|?2/?1|<6.00 and 0.45<|??GH×?2/?12|<4.00. ?GH represents a refractive power of the first optical element when light-entrance and light-exit surfaces thereof are in contact with air, ?dGH and ndGH respectively represent an Abbe number and a refractive index of a material forming the first optical element for a d-line, ?1 and ?2 respectively represent the refractive powers of the first lens unit and the second lens unit, and ??GH represents a sum total of the refractive power ??GH of the at least one first optical element.

Abstract: A zoom lens and an image pickup apparatus are disclosed. The zoom lens includes, in order from an object side to an image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, and a fifth lens group having a positive refractive power. The fifth lens group includes a fixed group having a negative refractive power, and a movable group having a positive refractive power and being movable in a direction substantially orthogonal to the optical axis. The image formed on an image surface is movable in a direction substantially orthogonal to the optical axis by moving the movable group of the fifth lens group in the direction substantially orthogonal to the optical axis. The fifth lens group is satisfied predetermined conditions.

Abstract: This is addressed to provide a zoom lens which has a good optical performance for imaging device having a large number of pixels even with its simple construction, and which can also be small and thin in structure, and an imaging apparatus using the zoom lens. A zoom lens 1 is composed by arranging, in the following order from an object side, a first lens group GR1 having a weak refractive power, a second lens group GR2 having a negative refractive power, a third lens group GR3 having a positive refractive power, and a fourth lens group GR4 having a positive refractive power, and is configured to perform zooming by moving the second lens group and the third lens group. The first lens group is composed by arranging, in the order from an object side, a single lens G1 having a a negative refractive power, a prism G1 for folding an optical path, and a single lens G3 having a a positive refractive power.

Abstract: A zoom lens ZL installed in an electronic still camera 1 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. A distance between the first lens group G1 and the second lens group G2 varies upon zooming from a wide-angle end state to a telephoto end state. The second lens group G2 has a front lens group G2F and a rear lens group G2R, and the front lens group G2F is moved along the optical axis upon focusing on a close object, thereby providing a compact zoom lens having excellent optical performance, an optical apparatus equipped with the zoom lens, and a method for manufacturing the zoom lens.

Abstract: A variable-power optical system includes, in order from an object side thereof: a first lens group with a negative optical power; a second lens group with a positive optical power; and a third lens group with a negative optical power, where an interval between the first lens group and the second lens group decreases when a power of the variable-power optical system varies from a wide-angle end to a telephoto end. The first lens group comprises a negative lens and a positive lens. The second lens group consists of a positive lens and a negative lens, and includes at least one aspheric surface. The variable-power optical system satisfies the predetermined conditional expressions.

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

Abstract: A small-sized zoom lens having a high zooming rate and a high optical performance, the zoom lens including a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power, wherein an iris diaphragm is disposed between the second lens group and the third lens group.

Abstract: A zoom lens includes, sequentially from an object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group. During zooming from a wide angle position to a telephoto position, the interval between the first lens group and the second lens group increases, the interval between the second lens group and the third lens group decreases, and an interval between the third lens group and the fourth lens group varies. The fourth lens group includes, sequentially from the object side, a first sub-lens group having a positive refractive power, a second sub-lens group having a negative refractive power, and a third sub-lens group. The second sub-lens group of the fourth lens group is moved along an optical axis to perform focusing.

Abstract: A zoom lens includes, in order from an object side to an image side, a first lens unit of negative refractive power, a second lens unit of positive refractive power, and a third lens unit of positive refractive power. The zoom lens changes the distances between the lens units during zooming. The following condition is satisfied: 0.3<|f1/fT<0.5 2.3<|f1/fw<3.5, where f1 is a focal length of the first lens unit, fT is a focal length of the zoom lens at a telephoto end, and fw is a focal length of the zoom lens at a wide-angle end.

Abstract: A lens system and an image capturing device having the same include a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, and a fifth lens group being exchangeable with the third lens group.

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 zoom lens according to the present invention includes, in order from the object side to the image side, a first lens unit having a positive refracting power, a second lens unit having a negative refracting power, a third lens unit having a negative refracting power, and a fourth lens unit having a positive refracting power, wherein during zooming from the wide angle end to the telephoto end, the first lens unit, the second lens unit, the third lens unit, and the fourth lens unit move in such a way that they are located closer the object side at the telephoto end than at the wide angle end, the distance between the first lens unit and the second lens unit is larger at the telephoto end than at the wide angle end, the distance between the second lens unit and the third lens unit is larger at the telephoto end than at the wide angle end, and the distance between the third lens unit and the fourth lens unit is smaller at the telephoto end than at the wide angle end.

Abstract: A zoom lens includes a first lens group having a negative refractive power, a second lens group including a prism which has no refractive power and deflects an optical path, a third lens group that has a positive refractive power and is moved during zooming, a fourth lens group that has a negative refractive power and is moved during zooming, and a fifth lens group having a positive refractive power arranged in this order from an object side. A zoom group including the third positive lens group and the fourth negative lens group, not a fixed positive lens group, is provided on the rear side of the prism. The first lens group includes two negative lenses.

Abstract: A zoom lens includes, in order from object to image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power and movable during zooming, a third lens unit having a positive refractive power and including a positive lens element positioned nearest to an object-side end, and a fourth lens unit having a positive refractive power and movable during zooming. The second lens unit includes at least three negative lens elements arranged successively and independently along an optical axis and at least one positive lens element. The zoom lens satisfies specific numerical conditions defined for a focal length fw of the zoom lens at a wide-angle end, focal lengths f2 and f3 of the second and third lens units, and a focal length f31 of a positive lens element of the third lens unit nearest to the object-side end.

Abstract: A lens system includes, in order from an object side, a first lens group with positive refractive power, a second lens group with negative refractive power that moves during zooming, a third lens group with positive refractive power, and a fourth lens group with positive refractive power that moves during zooming and focusing adjustments. The first lens group includes a lens with positive refractive power and an Abbe number vd1x that satisfies a following condition (vd1x>80). The second lens group includes a lens with positive refractive power and an Abbe number vd2x and two lenses with negative refractive power and Abbe numbers vd2y and vd2z respectively, the Abbe numbers Vd2x, Vd2y and Vd2z satisfying following conditions (vd2x, vd2y, vd2z<23). The third lens group includes a plurality of lenses with positive refractive power, an average vd3a of the Abbe numbers of the plurality of lenses with positive refractive power satisfies a following condition (77.5<vd3a<82.

Abstract: A zoom lens includes a first negative lens group, a second negative lens group, a third positive lens group, an aperture diaphragm, and a fourth positive lens group arranged in this order from an object side. When power varies from a wide angle end to a telephoto end, the first and second lens groups are moved to an image surface along an optical axis and then moved to the object side. The third and fourth lens groups are moved to only the object side along the optical axis. The first lens group includes at least one aspheric lens, and the aspheric lens has an aspheric shape in which a positive refractive power is increased toward the periphery of the lens when a paraxial refractive power is positive and a negative refractive power is decreased toward the periphery of the lens when the paraxial refractive power is negative.

Abstract: In the zoom lens, the second lens group includes at least one surface that is an aspheric surface, and during changing magnification, the second lens group, the third lens group, and the fourth lens group are respectively capable of moving independently, with the position of the aperture moving along a convex trajectory on the optical axis from the image side to the object side during changing magnification. Through operation in this manner, the zoom lens of the invention is inexpensive and compact, and efficiently corrects various types of aberration. Thus, at a high magnification ratio of 5× or greater, the zoom lens of the invention affords a wide field exceeding approximately 78 degrees at the wide angle end, and affords a high performance compact zoom lens whose distortion is held to 3% or less.

Abstract: Provided is a zoom lens including, in order from an object side to an image side: a positive first lens unit without moving for zooming; a negative second lens unit moving during zooming; a negative third lens unit moving during zooming; a positive fourth lens unit moving during zooming; and a positive fifth lens unit without moving for zooming, in which the second lens unit moves to the image side during zooming from a wide angle end to a telephoto end, while the third lens unit moves along a locus convex toward the object side, and, when fw denotes a focal length of the entire system at the wide angle end, Z a zoom ratio, and fz a focal length of the entire system at a zoom position where the third lens unit is in the position closest to the object side, the following conditional expression is satisfied: fw×Z0.07<fz<fw×Z0.5.

Abstract: A zoom lens system and an image pickup apparatus including the same are provided. The zoom lens system includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, and a fifth lens group having a positive refractive power, which are arranged in an order from an object side. When zooming is performed from a wide angle position to a telephoto position, the first lens group, the third lens group and the fifth lens group remain fixed and the second lens group and the fourth lens group move.

Abstract: The invention relates to a new mechanism for permitting a zoom lens to focus on a short distance subject by moving a focusing lens group in an amount that varies in an optical axis direction depending on a zooming position. The zoom lens comprises, in order from its object side, a positive first lens group, a negative second lens group and a positive third lens group. Zooming is implemented while the space between adjoining lens groups is varied, and focusing on a short distance subject is implemented by moving the negative second lens group in an amount that varies in the optical axis direction depending on a zooming position. The negative second lens group comprises a negative front unit G2F and a negative rear unit G2R. The space between the negative front unit G2F and the negative rear unit G2R is varied depending on a subject distance but that space remains constant wherever the zooming position lies.

Abstract: An object of the invention is to provide a projection lens capable of sufficiently correcting lateral chromatic aberration at both of the wide-angle end and the telephoto end, with an increased zoom ratio, a less number of lens elements, and less variation in telecentricity.

Abstract: A zoom lens includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power, which are disposed in order from an object along the optical axis, wherein the third lens group comprises: a pre-group, which has a first positive lens, a negative meniscus lens having a convex surface facing the object, a second positive lens, and which has a positive refractive power; and a negative meniscus lens having a convex surface facing the object, which are disposed in order from the object; at least one of three surfaces of an object side and image side lens surfaces of the first positive lens and an object side lens surface of the negative meniscus lens is aspherical; and at least one of three surfaces of an object side lens surface of the second positive lens, and an object side and image side lens surfaces of the negative meniscus lens is aspherical.

Abstract: A lens includes a front group including a plurality of lens groups; and a rear group that is provided on an image side of the front group and that includes a negative lens and a positive lens. The positive lens has a flat lens surface on its image side, and is tiltable about a spherical center of its object side lens surface that is convex on the object side. When a lens system is inclined, the positive lens is tilted in relation to the optical axis of the lens system based on: a focal length of the overall lens system; an angle of the optical axis of the lens system after being inclined in relation to the optical axis before being inclined; a distance between the image side lens surface of the positive lens and the image plane; and a refractive index of the positive lens.

Abstract: It is possible to use the magnification of an objective lens as is, substantially without changing the observation magnification, even when the working distance of the objective lens is changed. The invention provides a focus-adjusting unit disposed on an optical axis between an objective optical system that collects light from a specimen and an image-forming optical system that images the light collected by the objective optical system at a prescribed position, comprising a front optical system and a back optical system, sequentially disposed along the optical axis direction from a front side, with the objective optical system serving at the front side and the image-forming optical system at the back; and a lens driving part that relatively moves these optical systems in the optical axis direction, wherein the front optical system and the back optical system have refractive powers of different sign and focal lengths of substantially equal absolute value.

Abstract: Providing a high optical performance zoom lens system with realizing a high zoom ratio and compactness suitable for a highly integrated electronic imaging device. The system includes, in order from an object along an optical axis: a first group G1 having positive refractive power; a second group G2 having negative refractive power; a third group G3 having positive refractive power; a fourth group G4 having positive refractive power; and a fifth group G5 having negative refractive power. Upon zooming from a wide-angle end state W to a telephoto end state T, the second group G2 and the fourth group G4 are moved along the optical axis. The first group G1 includes, in order from the object along the optical axis, a front group G1f having negative refractive power, an optical-path-bending element P for bending an optical path, and a rear group G1r having positive refractive power. Given expression is satisfied.

Abstract: A zoom lens system includes a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power, wherein the first through third lens groups are arranged sequentially from an object side. When the zoom lens system is zoomed from a wide angle position to a telephoto position, an interval between the first lens group and the second lens group decreases and an interval between the second lens group and the third lens group increases. The first lens group comprises three lenses. An imaging apparatus includes the zoom lens system.

Abstract: A zoom lens includes, in order from an object side to an image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a reflection unit including a reflection surface for bending an optical path, a third lens unit having a negative refractive power, a fourth lens unit having a positive refractive power, and a fifth lens unit having one of a positive refractive power and a negative refractive power. In the zoom lens, at least the second lens unit and the fourth lens unit move during zooming while the reflection unit remains stationary. In addition, a focal length of the first lens unit and respective focal lengths of the zoom lens at a wide-angle end and at a telephoto end are appropriately set.

Abstract: A zoom lens ZL installed in a single-lens reflex digital camera 1 and the like includes, in order from an object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, and a rear lens group GR having positive refractive power. The second lens group G2 includes at least one positive lens and a negative lens disposed adjacent to the object side of the positive lens having largest refractive power among the positive lenses. Each distance between lens groups varies upon zooming from a wide-angle end state and a telephoto end state. Thereby providing a zoom lens having excellent optical performance, an optical apparatus equipped the zoom lens, and a method for manufacturing the zoom lens.

Abstract: An inner-focusing zoom lens that includes multi groups of lens pieces, namely, the first lens group or the leading lens group of positive refractivity, the second lens group of negative refractivity, and the remaining trailing groups of positive refractivity, as a whole. At least one group of positive refractivity among the trailing groups includes two or more negative lens pieces, at least one of which is connected on its surface to another lens piece to form a duplicated composite lens so that the junction between two of them functions to diverge incident beams. Assuming now that a sum of the refractivities of all the junctions of the composite lenses can be expressed as ??=?|(N1?N2)/R| where N1 and N2 are refractivities that substances before and after the junction of the composite lenses respectively have, R is a radius of curvature of the junction, ft is a focal length of the comprehensive lens optics of the zoom lens at the telephoto end.

Abstract: A zoom lens includes, in order from an object side to an image side, a first lens unit of negative refractive power, a second lens unit of positive refractive power, and a third lens unit of positive refractive power. The zoom lens changes the distances between the lens units during zooming. The following condition is satisfied: 0.3<|f1 |/fT<0.5, where f1 is a focal length of the first lens unit, and fT is a focal length of the zoom lens at a telephoto end.

Abstract: Composing a zoom optical system ZL, in order from an object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having negative refractive power; and disposing each lens group with satisfying a given conditional expression (1); thereby providing a zoom optical system ZL capable of suppressing variation in aberrations upon zooming and carrying out excellent vibration reduction, an optical apparatus equipped therewith, and a method for manufacturing the zoom optical system.

Abstract: A zoom lens includes, in order from an object side to an image side, a first lens unit having a negative refractive power and a second lens unit having a positive refractive power. In the zoom lens, an interval between the first and second lens units becomes smaller at a telephoto end than at a wide-angle end during zooming. The first lens unit includes, in order from the object side to the image side, a first lens having a negative refractive power, a second lens having a negative refractive power, which is made of a plastic and has an aspheric lens surface, and a third lens unit having a positive refractive power. In the zoom lens, a refractive index and an Abbe number of the plastic (Nd, ?d), a focal length of the second lens (fn), and a focal length of the first lens unit (f1) are appropriately set.

Abstract: A zoom lens includes, in order from an object side thereof: a first lens group with a positive refractive power; a second lens group with a negative refractive power; a third lens group with a positive refractive power; a fourth lens group with a negative refractive power; and a fifth lens group with a positive refractive power. A power of the zoom lens is varied by changing intervals between neighboring lens groups in the first through fifth lens groups. The second lens group includes a cemented lens consisting of one positive lens and one negative lens, and the third lens group includes a cemented lens consisting of two positive lenses and one negative lens.

Abstract: A zoom lens includes a first optical system having a positive focal length, the first optical system, a second optical system having a negative focal length, a third optical system having a positive focal length, a fourth optical system having a negative focal length, and a fifth optical system having a positive focal length, which are arranged in order from an object side to an image side and an aperture stop provided at an object side of the third optical system. The following condition is satisfied: 0.5<(T23w/Y?)/(ft/fw)<1.0 where T23w is an interval between the second optical system and the third optical system at the short focus end, Y? is a maximum image height of the zoom lens, ft is a focal length of the zoom lens at the long focus end, and fw is a focal length of the zoom lens at the short focus end.