Abstract: A zoom lens system wherein a positive lens unit located closest to an object side is fixed with respect to an image surface in zooming, a negative lens unit, among lens units located on an image side relative to an aperture diaphragm, is a focusing lens unit which moves along an optical axis in focusing, and the conditions: ?1.8<fn/fW<?0.3 and 0.1<T1/fW<1.5 (fn: a composite focal length of the negative lens unit, T1: an axial thickness of the positive lens unit located closest to the object side, fW: a focal length of the entire system at a wide-angle limit) are satisfied.

Abstract: A zoom lens includes a first lens unit, a second lens unit, a third lens unit and a fourth lens unit that includes a 41 lens group and a 42 lens group. The 41 lens group includes a 411 lens group and a 412 lens group. A lens surface on a most image side of the 411 lens unit has a shape convex to the image side and a lens surface on the most object side of the 412 lens unit has a shape concave to the object side. A curvature radius r411 of the lens surface on the most image side of the 411 lens unit, a curvature radius r412 of the lens surface on the most object side of the 412 lens unit, and lateral magnification ?3w of the third lens unit at a wide-angle end are respectively appropriately set.

Abstract: In a zoom lens including a positive first lens unit, negative second lens unit, positive third lens unit, and positive fourth lens unit, the fourth lens unit includes a 41 lens group, a 42 lens group, and a 43 lens group. the lateral magnification of the third lens unit at a wide-angle end when an infinite object is focused, the focal length of the fourth lens unit, the lens configuration length of the fourth lens unit, the air interval between the 41 and 42 lens groups, the air interval between the 42 and 43 lens groups, the focal length of the 42 lens group, the average values of the Abbe constants and partial dispersion ratios of positive lens of the 42 lens group, the average values of the Abbe constants and partial dispersion ratios of negative lenses of the 42 lens group, and the like are appropriately set.

Abstract: A zoom lens, including, in order from object side to image side: a positive first lens unit which does not move during zooming; a negative second lens unit for zooming; a positive third lens unit for zooming; a negative fourth lens unit which moves during zooming; and a positive fifth lens unit which does not move during zooming, in which: 0.6<|?3F|<1.0, ?4.0<f4/f3<?1.0, and 20<L2w/L3w<300 are satisfied, where ?3F is a lateral magnification of the third lens unit at a position at which a lateral magnification of the second lens unit becomes ?1; f3 and f4 are respectively focal lengths of the third and fourth lens units; L2w is a gap between the second and third lens units at a wide angle end; and L3w is a gap between the third and fourth lens units at the wide angle end.

Abstract: In a variable magnification optical system, 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, arranged in order from the object side, in which magnification is changed by moving the second lens group and focusing is performed by moving the fourth lens group, the first lens group includes a positive lens and a positive cemented lens, arranged in order from the object side, the third lens group includes an aperture stop on the most object side, the fourth lens group includes a positive lens, a negative lens, and a positive lens, arranged in order from the object side, with at least one surface being an aspherical surface, and the system satisfies given conditional expressions.

Abstract: A positive first lens group that is fixed during magnification change, a negative second lens group that is movable during magnification change, a positive third lens group that is movable during magnification change, a positive fourth lens group that is movable during magnification change, and a positive fifth lens group that is fixed during magnification change are arranged in this order from the enlargement side. The system is telecentric at the reduction side. Conditional expression (1) is satisfied: L/Im?<15.0??(1), where L is a distance along the optical axis from the most enlargement-side lens surface to the most reduction-side lens surface when the projection distance is infinity, and Im? is a maximum effective image circle diameter at the reduction side.

Abstract: A zoom lens includes a positive first lens group fixed during zooming, a negative second lens moved to the image side upon zooming from the wide angle end to the telephoto end, a negative third lens group for image plane correction during zooming, and a positive fourth lens group fixed during zooming. The first lens group is composed of a negative first lens group front group, a positive first lens group middle group, and a positive first lens group rear group, disposed in order from the object side. The first lens group front group is composed of two negative lenses and one positive lens, disposed in order from the object side. Focusing is performed by moving only the first lens group middle group in an optical axis direction. The zoom lens satisfies a predetermined conditional expression.

Abstract: A zoom lens system having at least five lens units, each lens unit being composed of at least one lens element, the zoom lens system, in order from an object side to an image side, comprising: a positive first lens unit; and a negative second lens unit, and in order from the image side to the object side, comprising: a positive lens unit ?; a negative lens unit ?; and a positive lens unit ?, wherein the first lens unit is composed of only optical elements having optical power, and in zooming from a wide-angle limit to a telephoto limit, at least the positive first lens unit is fixed with respect to an image surface, the positive lens unit ? moves with respect to the image surface separately from an aperture diaphragm, and the negative lens unit ? moves to the object side.

Abstract: A zoom lens includes: a first lens group having a negative power; and a second lens group having a positive power, in this order from an object side. The first lens group includes a first lens having a negative power and a second lens having a positive power. The zoom lens satisfies conditional formulae 1.6<|f1|/fw<2.5 (1); 1.6<f2/fw<2.4 (2); 0.32<d2/fw<0.60 (3); 2.5<ft/fw<4.5 (4); 1.56<nd2<1.66 (5); and ?d2<33 (6), when f1: the focal length of the first lens group, f2: the focal length of the second lens group, fw: the focal length of the entire system at the wide angle end, d2: the distance between the first and second lenses along an optical axis, ft: the focal length of the entire system at the telephoto end, nd2: the refractive index of the second lens at the d line, and ?d2: the Abbe's number of the second lens at the d line.

Abstract: The zoom lens includes a front unit including a first positive lens unit and a second positive or negative lens unit, a reflective mirror and a rear unit including two or more lens units. During zooming, the reflective mirror is not moved, and the first lens unit and at least two lens units of the rear unit are moved. When the zoom lens is retracted into a body of an image pickup apparatus, at least one of rotation of the reflective mirror such that a normal line thereto is brought closer to parallel to an optical axis of the rear unit and axial movement thereof in a direction of the optical axis of the rear unit is performed. The front unit is moved into a space formed by the at least one of the rotation and the axial movement. Conditions of 10.5<ft/|fn|<30.0 and 0.80<(Lf?L)/Lm<1.30 are satisfied.

Abstract: A zoom lens includes, in order from the object side, a positive first lens unit which does not move for zooming or focusing, a negative second lens unit which moves during zooming, a positive third lens unit which moves during zooming, a negative fourth lens unit which moves during zooming and focusing, and a positive fifth lens unit which does not move for zooming or focusing. An aperture stop which does not move for zooming or focusing is arranged adjacent to the fourth lens unit. The focal lengths of the second, third, and fourth lens units, a zoom ratio of the zoom lens at infinity focus, the lateral magnification of the third lens unit at the wide angle end and the telephoto end at infinity focus, the lateral magnifications of the fourth and fifth lens units at the telephoto end at infinity focus are appropriately set.

Abstract: The zoom lens includes at least, 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 negative refractive power; and a fifth lens group G5 having negative refractive power. In the zoom lens, focusing from infinity to a proximity of object is achieved by movement of just fourth lens group toward an image focusing side and is characterized in Satisfaction of expressions below: [Expression 1] 2.1<?rt<3.5??(1) ?1.80<?2t<?0.94??(2) where “?rt” is composite lateral magnification at a telephoto end of lens groups locating closer to the image focusing side than the third lens group at infinity focusing, and “?2t” is lateral magnification at a telephoto end of the second lens group at infinity focusing.

Abstract: An imaging lens includes: a positive first lens group; a positive second lens group which moves while focusing; and a third lens group. The first lens group includes a positive lens having a convex surface with a radius of curvature having a small absolute value toward the image side, a positive biconvex lens, a negative lens having a concave surface with a radius of curvature having a small absolute value toward the object side, and a positive lens having a convex surface with a radius of curvature having a small absolute value toward the object side, in this order from the object side. The second lens group includes a positive lens having a convex surface with a radius of curvature having a small absolute value toward the object side. The third lens group includes two positive lenses and one negative lens. The imaging lens satisfies a predetermined conditional formula.

Abstract: An imaging lens includes: a first lens group having a positive refractive power which is fixed during focusing operations; a second lens group having a positive refractive power which moves during focusing operations; and a third lens group which is fixed during focusing operations. The first lens group includes a 1a lens group having a positive refractive power, an aperture stop, and a 1b lens group having a positive refractive power. The 1a lens group includes a positive lens, a negative meniscus lens, a negative meniscus lens, a positive meniscus lens, a negative lens, a positive lens, a negative lens, and a cemented lens formed by a positive lens and a negative lens.

Abstract: A zoom lens including, in order from object side to image side: a first positive lens unit which does not move for zooming; a second negative lens unit which moves during zooming; a third positive lens unit which moves during zooming; a fourth lens unit which moves during zooming; and a fifth positive lens unit which does not move for zooming. The second unit passes through a point at which magnification of the second unit becomes ?1 during zooming from wide-angle end to telephoto end, and ?1<?34<?0.3, and 4.0<|m2/m3|<15 are satisfied where ?34 represents a magnification of a combined unit including the third and fourth units at a zoom position fz at which the magnification of the second unit becomes ?1, and m2 and m3 respectively represent displacements of the second and third units on optical axis at the zoom position fz with reference to the wide-angle end.

Abstract: There is provided a zoom lens including, in order from an object side to an image side, a first lens group having negative refractive power, a second lens group having positive refractive power, a third lens group having positive refractive power, and a fourth lens group having positive refractive power. In zooming from a wide-angle end to a telescopic end, the first lens group moves to the object side in a manner that a distance toward the second lens group shortens, and a distance between the third lens group and the fourth lens group lengthens. The third lens group includes a single lens or a single cemented lens.

Abstract: A zoom lens includes, in order from an object side to an image side: a positive first lens unit; a negative second lens unit; a positive third lens unit; and a positive fourth lens unit, wherein the first lens unit includes a positive first lens subunit, which does not move for focusing, a positive second lens subunit, which moves during the focus adjustment, and a positive third lens subunit, which does not move for focusing; and focal lengths of the first lens unit, the second lens unit, the third lens unit, a magnification of the third lens unit U3 at a wide angle end, focal lengths of the first lens subunit, the second lens subunit appropriately satisfy certain relations.

Abstract: An optical system for imaging an object on an image acquisition unit has a variable focal length for zooming. The optical system has precisely three lens units from the object in the direction of an image acquisition unit, namely a first lens unit, a second lens unit, and a third lens unit. The second lens unit and the third lens unit are movably situated along an optical axis of the optical system for a change of the focal length. The first lens unit includes a first lens group and a second lens group. The first lens group of the first lens unit is fixedly situated on the optical axis of the optical system. The second lens group of the first lens unit is movably situated along the optical axis of the optical system for focusing. The second lens group includes at least two lenses.

Abstract: A zoom lens includes first to third lens units having positive, negative, and positive refractive power, respectively, and a rear lens group having positive refractive power. An aperture stop is arranged between a lens surface of the second lens unit closest to the image side and a lens surface of the third lens unit closest to the image side. The third lens unit includes first and second positive lenses each including an aspheric surface, and a negative lens. In the third lens unit, a refractive index of the first positive lens, and an Abbe number and relative partial dispersion of the second positive lens are appropriately set.

Abstract: A zoom lens system has, in order from the enlargement side, a first lens group that remains stationary during zooming and that has a negative optical power and a plurality of lens groups that move during zooming. The first lens group includes three lens groups each having a negative optical power, namely a 1a-th lens group, a 1b-th lens group, and a 1c-th lens group. The 1a-th lens group remains stationary during focusing and includes at least one positive lens element. The 1b-th lens group moves toward the reduction side during focusing from infinity to a close distance. The 1c-th lens group moves toward the enlargement side during focusing from infinity to a close distance.

Abstract: A telephoto lens system includes a first lens group having a positive refractive power, and comprising at least three positive lenses and one negative lens; a second lens group having a negative refractive power, and which moves along an optical axis to perform a focusing operation; a third lens group having a positive refractive power, and comprising a cemented lens in which a positive lens having a convex surface toward the object side and a positive lens having a convex surface toward the image side are bonded to each other, a bi-convex positive lens, and a negative lens having a concave surface toward the object side, and the first through third lens groups are disposed sequentially from the object side to the image side.

Abstract: A taking lens system comprises a frontmost lens unit, a rearmost lens unit, and a plurality of lens units arranged between the frontmost lens unit and the rearmost lens unit. One of the plurality of lens units is a first focusing lens unit. During focusing from an infinite object distance to a close object distance, only the first focusing lens unit moves toward the image side in a first shooting mode, and at least two lens units in the taking lens system move in a second shooting mode. In the state in which the taking lens system is focused on an object at infinity, the positions of the first focusing lens unit and at least one lens unit in the taking lens system in the first shooting mode are different from those in the second shooting mode. The taking lens system satisfies the condition Mn1>Mn2.

Abstract: The present invention is directed to providing a large aperture telephotographing zoom lens that employs an inner-focusing system to enable quick focusing and avoid a great aberration when the zoom lens renders the close object in focus. The zoom lens comprises at least five groups of lens pieces arranged in series, namely, the foremost or first lens group of positive refractivity positioned the closest to the object, the succeeding second lens group of negative refractivity, the third lens group of negative refractivity, the fourth lens group of positive refractivity, and the rearmost or fifth lens group of positive refractivity. During varying the magnification for zooming in a transition from the wide-angle end to the telephoto end, all the lens pieces of the second, third, and fourth lens groups are moved toward the image plane, and the third lens group alone is displaced for focusing.

Abstract: A zoom lens includes a negative lens unit having a negative refractive power and a positive lens unit having a positive refractive power arranged in order from an object side to an image side. For focusing from infinity to a closest distance, the negative lens unit moves towards the image side and the positive lens unit moves towards the object side. Predetermined mathematical conditions are satisfied to obtain high optical performance over the entire focusing range.

Abstract: A zoom lens substantially consists of a positive first lens group, a negative second lens group, a positive third lens group, and a positive fourth lens group in this order from the object side, wherein the distance between the first lens group and the second lens group increases and the distance between the second lens group and the third lens group decreases, and the distance between the third lens group and the fourth lens group decreases while changing magnification. The fourth lens group substantially consists of a positive fourth-a lens group composed of a biconvex-shape lens, a negative meniscus-shape lens, and a biconvex-shape lens and a negative fourth-b lens group composed of a positive meniscus-shape lens and a biconcave-shape lens in this order from the object side, and only the fourth-b lens group is moved toward the image side while focusing.

Abstract: A zoom lens includes, in order from the object side to the image plane side, first to fifth lens units having positive, negative, positive, negative and positive refractive powers. At least the second lens unit and the fourth lens unit move during zooming such that at the telephoto end, in comparison with the wide angle end, the interval between the first lens unit and the second lens unit increases, the interval between the second lens unit and the third lens unit decreases, the interval between the third lens unit and the fourth lens unit changes, and the interval between the fourth lens unit and the fifth lens unit increases, and the fifth lens unit does not move. The zoom lens further includes a reflection unit for bending a light path, between the fourth lens unit and the fifth lens unit.

Abstract: Provided is a zoom lens system 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 negative refractive power sequentially from an object side to an image side, wherein a zooming operation is performed by moving the second lens group and the fourth lens group.

Abstract: A zoom lens includes, in order from an object side along an optical axis, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a negative refractive power, a fourth lens group having a positive refractive power, and a fifth lens group having a positive refractive power, wherein with a change in a magnification from a wide-angle end to a telephoto end, an interval between the first lens group and the second lens group is increased, the interval between the second lens group and the third lens group is changed, the interval between the third lens group and the fourth lens group is decreased, the interval between the fourth lens group and the fifth lens group is decreased, and focusing is performed by the third lens group.

Abstract: A zoom lens system comprising a plurality of movable lens units which individually move along an optical axis at the time of zooming, wherein a lens unit located closest to an object side is fixed relative to an image surface at the time of zooming, at least two of the movable lens units are focusing lens units which move along the optical axis at the time of focusing in at least one zooming position, and the condition: 0.1<T1/fW<1.5 (T1: an axial thickness of the lens unit located closest to the object side, fW: a focal length of the entire system at a wide-angle limit) is satisfied; an interchangeable lens apparatus; and a camera system are provided.

Abstract: An embodiment of this invention provides a zoom lens, which comprises a plurality of lens groups in order from an object side to an image-forming side with positive, negative, positive, and positive refractive power respectively. The lens groups comprise a plurality of aspheric lenses and/or free form lenses and a plurality of plastic lenses. The zoom lens satisfies the following equation: DG/fw<3.5 and TTL/fw<15.5, wherein DG denotes the total summation of the thickness of each lens group, fw denotes the focal length of the zoom lens at the wide-angle end, and TTL denotes a total thickness of the zoom lens at the wide-angle end.

Abstract: A zoom lens system includes a negative first lens group, a positive second lens group, and a positive third lens group, in that order from the object side. The second lens group constitutes a focusing lens group. The following conditions (1) and (2) are satisfied: 0.4<|d12w/f1|<1.06??(1); and d12w<d23w??(2), wherein f1 designates the focal length of the first lens group, and d12w and d23w designate the air distances between the first and second lens groups, and the second and third lens groups respectively, at the short focal length extremity.

Abstract: A zoom lens includes a positive first lens group, which is fixed during changing magnification and during focusing, a negative second lens group, which is moved during changing magnification, a positive third lens group, which is fixed during changing magnification and during focusing, a positive fourth lens group, which is moved during changing magnification and during focusing, and a negative fifth lens group, which is moved during changing magnification, which are in this order from an object side. A lens group constituting the first lens group consists of a negative front group and a positive rear group in this order from the object side. The second lens group consists of four lenses of a negative lens, a positive lens, a negative lens, and a positive lens or a negative lens arranged in this order from the object side.

Abstract: A zoom lens includes, from the object side, a positionally-fixed first lens group having a positive refracting power, a second lens group having a negative refracting power and movable in an optical axis direction for zooming, a third lens group having a positive refracting power, and a fourth lens group movable in the optical axis direction. The first lens group includes a negative lens, a positive lens and another positive lens disposed in order from the object side and satisfies 15.0<ft/fw<31.0??(1) 7.0<f1/fw<13.0??(2) ?8.5<fL1/fw<?4.0??(3) where fw and ft are the focal lengths of the entire lens system in a wide angle end state and a telephoto end state, respectively, f1 is the focal length of the first lens group, and fL1 is the focal length of the negative lens of the first lens group.

Abstract: A zoom lens includes a lens unit Ln having negative refractive power including two or less lenses moving during focusing and zooming, a lens unit Lp1 having positive refractive power disposed adjacent to an object side thereof, and a lens unit Lp2 having positive refractive power disposed adjacent to an image side thereof. The lens units Lp1 and Lp2 move during zooming. A distance Tlw between a lens surface nearest to the object side in the entire zoom lens and an image plane at a wide-angle end, a distance Dnw between the lens surface nearest to the image side of the lens unit Ln and the image plane at the wide-angle end, a back focus bfw at the wide-angle end, and a maximum amount of movement Mnz during focusing of the lens unit Ln at a telephoto end are appropriately set.

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, an aperture stop, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, and fifth lens group. The zoom lens further satisfies given conditions.

Abstract: A zoom lens includes, in order from an object side to an image side, first to fifth lens units respectively having positive, negative, positive, negative, and positive refractive powers. During zooming from a wide-angle end to a telephoto end, each of the lens units moves in such a way that a distance between the first and second lens units increases, a distance between the second and third lens units decreases, a distance between the third and fourth lens units increases, and a distance between the fourth and fifth lens units increases. The distances D34w and D34t between the third and fourth lens units, the distances D45w and D45t between the fourth and fifth lens units, focal lengths fw and ft of the entire zoom lens, and focal lengths f1 and f4 of the first and fourth lens units are appropriately set.

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 including a first sub-lens group having a positive refractive power, an iris, and a second sub-lens group having a positive refractive power; and a fourth lens group having a positive refractive power, wherein the first to fourth lens groups are sequentially arranged from an object side to an image side, the distance between each of the first through fourth lens groups changes when zooming, the surface of the lens closest to the image side in the first sub-lens group is concave, the lens closest to the object side in the second sub-lens group is a meniscus lens concave towards the object side, and the lens located closest to the object side in the third lens group is an aspheric lens.

Abstract: A zoom lens includes, in order from an object side, a positive first lens unit which does not move for zooming, a negative second lens unit which moves in an optical axis direction for zooming, a negative third lens unit which moves in the optical axis direction for zooming so as to correct image plane variation due to zooming, and a positive fourth lens unit which does not move for zooming. The fourth lens unit includes, in an order from the object side, a positive first sub lens unit and a positive second sub lens unit, which are separated by a largest air interval in the fourth lens unit. Abbe constants, partial dispersion ratios, and coefficients of the refractive index variation due to the temperature variation are appropriately set for lens materials forming the third lens unit, the first sub lens unit, and the second sub lens unit.

Abstract: A zoom lens system comprising a negative first lens unit, a positive second lens unit, a negative third lens unit, and a positive fourth lens unit, wherein the second lens unit is composed of an object-side second lens unit and an image-side second lens unit, the object-side second lens unit has positive optical power, an aperture diaphragm is located between the object-side second lens unit and the image-side second lens unit, and the conditions: ?0.5<f2O/f2I<1.0 and 0.12<d2O/fW<0.35 (f2O: a composite focal length of the object-side second lens unit, f2I: a composite focal length of the image-side second lens unit, d2O: an optical axial distance from a most object side lens surface of the object-side second lens unit to the aperture diaphragm, fW: a focal length of the entire system at a wide-angle limit) are satisfied.

Abstract: The lens driving apparatus moves a magnification-varying lens and moves a focus lens to compensate for image plane variation caused by movement of the magnification-varying lens. The apparatus includes a zoom operating member, a stepping motor, a zoom controller controlling drive of the stepping motor, a focus actuator moving the focus lens, a focus controller controlling drive of the focus actuator, a memory storing cam data to compensate for the image plane variation, and a zoom position detector. During a magnification variation operation, the zoom controller performs open-loop control of the drive of the stepping motor based on an operation amount of the zoom operating member, and the focus controller controls the drive of the focus actuator based on the actual position of the magnification-varying lens detected by the zoom position detector, and the cam data.

Abstract: An endoscope apparatus includes an objective optical system mounted at a distal end portion of an endoscope, which is inserted into a tube cavity, and configured to form an image of an object in the tube cavity, the objective optical system including a focusing lens movable in an optical axis direction, a solid-state image pickup device for color image pickup configured to pick up the image formed by the objective optical system, a color separation filter being arranged for each pixel in the solid-state image pickup device, a focus adjusting mechanism configured to move the focusing lens and automatically adjust the objective optical system to a focus position in a focused state, a moving range switching section configured to perform switching of a moving range of the focusing lens, a moving range limiting section configured to limit the moving range in association with the switching by the moving range switching section, and the like.

Abstract: A zoom lens and a photographing apparatus including the zoom lens are provided. The 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, all of which are arranged sequentially from an object side to an image side. The second lens group may include a first negative lens, a second negative lens, and a first positive lens. The second lens group may also satisfy 5.6?|fG2n2/fw|?10.0, where fG2n2 is a focal length of the second negative lens therein and fw is an overall focal length of the zoom lens at a wide-angle position.

Abstract: A high-power zoom lens that achieves size and price reduction, and at the same time provides high-quality imaging. This lens includes at least four lens groups arranged along an optical axis, which are moveable along the axis in order to achieve changes in magnification. The first, third, and fourth lens groups have positive refractive powers, and the second group has a negative refractive power. The second lens group includes a negative meniscus lens arranged closest to the object, provided with a convex surface at the object side. A negative lens is arranged next to the negative meniscus lens, and a negative lens provided with a concave surface at the object side is arranged closest to the image. The fourth lens group includes at least two positive lenses and one negative lens.

Abstract: A variable magnification optical system substantially consists of a first lens-group having positive refractive-power, and which is fixed during magnification change, a second lens-group having negative refractive-power, a third lens-group having negative refractive-power, a fourth lens-group having negative refractive-power, an aperture stop, which is fixed during magnification change, and a fifth lens-group having positive refractive-power, and which is fixed during magnification change, in this order from an object-side along an optical-axis.

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, a fourth lens group having a positive refractive power, and a fifth lens group having a negative refractive power. The zoom lens satisfies given conditions to implement a compact, wide angle, large aperture ratio zoom lens having excellent optical performance and compatible with solid state image sensors capable of recording full high vision images.

Abstract: An inner focus lens, in order from an object side to an image side, comprising: a first lens unit having positive optical power; a second lens unit having negative optical power; and a third lens unit having positive optical power, wherein the second lens unit is moved along an optical axis so that focusing from an infinite-distance object side to a short-distance object side is achieved, the first lens unit includes a bi-convex air lens, and the following conditions: 0.65<|f2/f|<5.00 and 0.5<f23/f1<9.0 (f2: a focal length of the second lens unit, f and f23: a focal length of the entire system and a composite focal length of the second and third lens units in an infinity in-focus condition, f1: a focal length of the first lens unit) are satisfied; an interchangeable lens apparatus; and a camera system are provided.

Abstract: A zoom lens includes a first lens unit having a positive refractive power which does not move for zooming; a second lens unit having a negative refractive power which moves during zooming; a third lens unit having a negative refractive power which moves during zooming; a fourth lens unit having a positive refractive power which moves during zooming; and a fifth lens unit having a positive refractive power which does not move for zooming. Air intervals (L2w and L2t) between the second lens unit and the third lens unit at a wide-angle end and at a telephoto end, respectively, an air interval (L3w) between the third lens unit and the fourth lens unit at the wide-angle end, a focal length (f1) of the first lens unit, and a combined focal length (f23w) of the second lens unit and the third lens unit at the wide-angle end are appropriately set.

Abstract: A zoom lens system, in order from an object side to an image side, comprising a first lens unit having negative optical power, a second lens unit having positive optical power, a third lens unit having negative optical power, and a fourth lens unit having positive optical power, wherein the first lens unit moves along an optical axis, and the fourth lens unit is fixed relative to an image surface, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, and the condition: 0.8<|f1/fW|<1.4 (f1: a composite focal length of the first lens unit, fW: a focal length of the entire system at a wide-angle limit) is satisfied; an interchangeable lens apparatus; and a camera system are provided.

Abstract: A zoom lens includes, in order from the object side to the image side along its optical path, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power and including a prism reflecting member, a third lens unit having a positive refractive power, a fourth lens unit having a negative refractive power, and a fifth lens unit having a positive refractive power, wherein the distances between the lens units vary during zooming from the wide angle end to the telephoto end, the first lens unit and the third lens unit are located closer to the ray incidence side at the telephoto end than at the wide angle end, the position of the second lens unit is fixed during zooming from the wide angle end to the telephoto end.

Abstract: The 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 third lens unit having a positive refractive power, a fourth lens unit having a positive refractive power, and a fifth lens unit having a negative refractive power. During zooming, the second lens unit is not moved and the first, third and fifth lens units are moved. A distance between the first and second lens units at a telephoto end is larger than that at a wide-angle end, a distance between the second and third lens units at the telephoto end is smaller than that at the wide-angle end. A condition of 0.7<f3/f4<1.5 is satisfied where f3 represents a focal length of the third lens unit, and f4 represents a focal length of the fourth lens unit.