Abstract: A telephoto zoom lens include a first, a second, a third and a fourth lens groups sequentially arranged along an optical axis and from an object side to an image side. The refractive powers of the four lens groups are positive, negative, positive and positive, respectively. The first lens group is fixed at a first predetermined position. The second lens group is movable along the optical axis depending on the variation of the magnifying power of the zoom lens. The third lens group is fixed at a second predetermined position. The fourth lens group is movable along the optical axis to keep an image plane generated by the zoom lens to project accurately onto an image sensor. Hence, the first and the third lens groups are in resting state, and the second and the fourth lens groups are movable during zoom-in or zoom-out operation of the zoom lens.

Abstract: A zoom lens includes in order from an object 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, and a fourth lens unit having a positive refractive power, and at the time of zooming, the first lens unit moves, and the zoom lens satisfies the following conditional expressions (1-1a), (1-2a), and (1-3a). 0.43<(?2T/?2W)/(?3T/?3W)<0.68??(1-1a) 0.4<(?1G/f1)/(?4G/f4)<2.3??(1-2a) 2.1<f3/fW<4.

Abstract: A zoom lens includes a first lens unit of a positive refractive power, a second lens unit of a negative refractive power, a third lens unit of a positive refractive power, and a fourth lens unit of a positive refractive power, wherein the first lens unit does not move for zooming, at least the second and fourth lens units are moved during zooming, the first lens unit includes at least one positive lens, and an Abbe number and a relative partial dispersion of a material of the positive lens, an average refractive index of materials of negative lenses included in the second lens unit, a movement amount of the second lens unit for zooming from a wide-angle end to a telephoto end, a focal length of the second lens unit, and a focal length of the entire zoom lens at the telephoto end are appropriately set.

Abstract: A zoom lens includes, in order from an object side toward 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, and a fourth lens unit having a positive refractive power. The second lens unit, the third lens unit, and the fourth lens unit are moved during zooming. A position of the third lens unit at a telephoto end is closer to the object side than a position of the third lens unit at a wide-angle end. The focal length of the zoom lens at the wide-angle end, the difference in the position of the second lens unit on an optical axis between that at the wide-angle end and that at the telephoto end, and the focal length of the second lens unit are set appropriately.

Abstract: A zoom lens includes a first lens group, a second lens group, an aperture, a third lens group, a fourth lens group, a fifth lens group, and an image surface in order along an optical axis from an object side to an image side. The first lens group has positive refractive power, and includes three lenses. The second lens group has negative refractive power, and includes fourth lenses. The third lens group has positive refractive power, and includes two lenses. The fourth lens group has positive refractive power, and includes five lenses. The fifth lens group has positive refractive power, and includes two lenses. Therefore, the zoom lens has a small size and high zoom ratio.

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: 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: 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 includes in order from an object side: 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 positive refractive power which moves during zooming; and a fourth lens unit having a positive refractive power which does not move for zooming, the third lens unit moving to an image side and then to the object side for zooming from a wide angle end to a telephoto end, in which a focal length (f1) of the first lens unit, a focal length (f2) of the second lens unit, a focal length (f3) of the third lens unit, and a lateral magnification (?3w) of the third lens unit at the wide angle end when a ray enters from infinity are appropriately set.

Abstract: A zoom lens includes a first lens group having a positive refractive power, and a second lens group having a negative refractive power, an aperture stop, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power arranged in order from an object side, the third lens group having a first positive lens, a second positive lens, and a negative lens, and a third positive lens in order from the object side. When zooming from short to long focal end, the zoom lens is moved so that the interval between the first and second lens groups increases, that between the second and third lens groups decreases, that between the third and fourth lens groups increases, and the first and third lens groups are positioned closer to the object at the long focal end than the short focal end.

Abstract: The present invention has, in order from an object, 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; and a fourth lens group (G4) having positive refractive power, wherein zooming is performed by changing an air gap between the lens groups, the fourth lens group (G4) includes, in order from the object, a lens component (La) having positive or negative refractive power, a positive lens component (Lb), and a positive lens component (Lc) having a convex surface facing the object, and the following conditional expression is satisfied: 0.00<(Rc2?Rc1)/(Rc2+Rc1)<1.

Abstract: The present invention has, in order from an object: 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; and a fourth lens group (G4) having positive refractive power, wherein zooming is performed by changing an air gap between the lens groups, the fourth lens group (G4) includes, in order from the object, a first positive lens component (La), a second positive lens component (Lb) having a convex surface facing the object, and a negative lens component (Lc), and the following conditional expression is satisfied: 0.00<(Rb2?Rb1)/(Rb2+Rb1)<1.00, where Rb2 denotes a radius of curvature of an image side surface of the second positive lens component (Lb) which constitutes the fourth lens group (G4), and Rb1 denotes a radius of curvature of an object side surface of the second positive lens component (Lb) which constitutes the fourth lens group (G4).

Abstract: A lens barrel including a telescopic cylinder configured to be accommodated within a fixed frame; a plurality of lens groups configured to be retained in the telescopic cylinder; a lens driving device configured to drive the plurality of lens groups along a longitudinal axis of the telescopic cylinder between a collapsed position in which at least one portion of the plurality of lens groups is stored in the fixed frame and an extended position in which the at least one portion of the plurality of lens groups is extended out of the fixed frame; and a retractable lens group configured to be retracted into the fixed frame through an opening in a wall of the fixed frame when the telescopic cylinder is in the extended position.

Abstract: A zoom lens comprises in order from an object side a first lens unit having a positive refractive power. The first lens unit consist one positive lens. The zoom lens satisfies the following conditional expressions (1) and (2). Fno(W)<2.7??(1) 3.1<ft/fw where, Fno(W) denotes an F-number of the zoom lens at a wide angle end, ft denotes a focal length at a telephoto end of the overall zoom lens system, and fw denotes a focal length at the wide angle end of the overall zoom lens system.

Abstract: A zoom lens includes, sequentially from an object side, a first lens group having a positive refractive power; a second lens group having negative refractive power; a third lens group having a positive refractive power; and a fourth lens group having a positive refractive power. The third lens group includes, sequentially from the object side, a front group having a positive refractive power and a rear group having a negative refractive power. Zoom is performed by moving the second lens group and the third lens group in a direction along an optical axis, and by integrally moving the front group and the rear group in a direction along the optical axis. Focusing is preformed by moving the front group in a direction along the 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; and a fourth lens group having a positive refractive power. Zoom is performed by moving the second and the third lens groups in a direction along an optical axis. The fourth lens group consists of, sequentially from the object side, a front group having a positive refractive power, an intermediate group configured by a cemented lens formed by a positive lens and a negative lens and having an overall refractive power that is negative, and a rear group having a positive refractive power. Blur is corrected by moving the intermediate group in a direction that is substantially orthogonal to the optical axis.

Abstract: A zoom lens system includes first through fourth lens groups. Upon zooming from the short to long focal length extremities, the second and third lens groups move while the distance between the first and second lens groups increases, and the distance between the second and third lens groups decreases. The fourth lens group includes a positive lens element having a convex surface on the object side; a cemented lens having a positive lens element and a negative lens element; a biconvex positive lens element, and a negative meniscus lens element having a convex surface on the image side. The following condition (1) is satisfied: 1.6<f1/f4<3.0??(1), wherein f1 and f4 designate the focal lengths of the first and fourth lens groups, respectively.

Abstract: A remote communication apparatus for receiving the image of a remote user captured by an imaging device to show the image to another user includes a zoom controller for controlling a zoom ratio defining the angle of view of the imaging device, and an estimator for estimating a distance between the imaging device and the remote user on the basis of the zoom ratio of the imaging device.

Abstract: A zoom lens includes first and second lens units having positive and negative refractive powers, an aperture stop, and third and fourth lens units having positive and negative refractive powers in order from an object side to an image side. During zooming from a wide angle end to a telephoto end, the first lens unit remains fixed, and the second and fourth lens units move. The first lens unit includes negative, positive, negative, positive, and positive lenses in order from the object side to the image side, the third and fourth lens units include two or more lenses. Focal lengths of the first and third lens units and of the entire system at the wide angle end, the thickness of the first lens unit on an optical axis, and the distance between principal points between the first and the second lens units at a wide angle end are appropriately set.

Abstract: A zoom lens, including in order from an object side to an image side: a first lens unit; a second lens unit; a third lens unit; and a fourth lens unit, in which the second lens unit includes four lenses as a whole, in which a first lens and a second lens are disposed successively in order from the object side to the image side, and the following conditional expressions are satisfied: 7.8<f1/|f2|<12.0; 1.20<f21/f2<1.63; and 0.04<O12/D2<0.15, where f1 represents a focal length of the first lens unit, f2 represents a focal length of the second lens unit, f21 represents a focal length of the first lens, O12 represents a distance from a lens surface vertex of the first lens on the object side to an object side principal point position of the second lens unit, and D2 represents a thickness of the second lens unit on an optical axis.

Abstract: A zoom lens comprises a first lens unit G1 having a positive refractive power, a second lens unit G2 having a negative refractive power, and a plurality of lens units G3 and G4. Zooming from a wide angle end to a telephoto end is carried out by changing a distance between the lens units. One of the first lens unit G1 and the second lens unit G2 has, or both the first lens unit G1 and the second lens unit G2 have a specific arrangement.

Abstract: A high-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. Upon zooming from the short focal length extremity to the long focal length extremity, the first through fourth lens groups move along the optical axis of the zoom lens system while increasing the distance between the first and second lens groups, and decreasing the distance between the second and third lens groups. The following conditions are satisfied: 0.9<f3/f4<1.3 and ?3.85<f123t/f4<?3.04 wherein f3 designates the focal length of the third lens group, f4 designates the focal length of the fourth lens group, and f123t designates the combined focal length of the first, second and third lens groups when an object at infinity is in an in-focus state at the long focal length extremity.

Abstract: A 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 the first lens group, the second lens group, the third lens group, and the fourth lens group are sequentially arranged in the order from an object side to an image surface side, while zooming from a wide-angle position to a telephoto position, the first lens group is moved in such a way that the distance between the first lens group and the second lens group is widened, the second lens group is moved along a trajectory convex toward the image surface side, the third lens group is moved from the image surface side to the object side, and the fourth lens group is moved along a trajectory convex toward the object side, and the zoom lens satisfies the following inequalities: vd1ave>68.2, and Nd1ave>1.

Abstract: A zoom lens includes 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, and a fourth lens unit having a positive refractive power in order from an object side to an image side. The second and fourth lens units move during zooming, and the first and third lens units do not move for zooming. A focal length fw of the entire zoom lens at a wide-angle end, a focal length ft of the entire zoom lens at a telephoto end, a focal length f1 of the first lens unit, a focal length f2 of the second lens unit, and a focal length f4 of the fourth lens unit are appropriately set.

Abstract: Providing a zoom lens system being compact and simple having excellent optical performance suitable for an optical apparatus with a limited space for a zoom lens, and capable of shifting an image, and an optical apparatus equipped therewith. The system includes, in order from an object: a first group having positive power and an optical path bending element; a second group having negative power; a third group having positive power; and a fourth group having positive power. Upon zooming from a wide-angle end to a telephoto end, the first and third groups are fixed relative to an image plane, the second group and the fourth group are moved along the optical axis, an image on the image plane can be shifted by shifting the third group or a portion thereof substantially perpendicularly to the optical axis. The first group includes at least one negative lens, and satisfies a given condition.

Abstract: A zoom lens includes a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having positive refractive power, and a fourth lens unit having positive refractive power. During zooming from a wide-angle end to a telephoto end, each lens unit moves so that a distance between the first lens unit and the second lens unit increases, and a distance between the second lens unit and the third lens unit decreases. Each of the first lens unit, the second lens unit, and the third lens unit consists of a single positive lens and a single negative lens, and the fourth lens unit consists of a single positive lens. Focal lengths of the entire zoom lens at the wide-angle end and the telephoto end and focal lengths of the first lens unit and the second lens unit are appropriately set.

Abstract: Providing a zoom lens system having a high zoom ratio being compact with high optical performance. The system includes, in order from an object along an optical axis, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, at least one lens group having positive refractive power, and an n-th lens group GN being disposed to the most image side. The n-th lens group GN with positive refractive power includes, in order from the object, a front group GNa and a rear group GNb having positive refractive power. Focusing on an object is carried out by moving the rear group GNb along the optical axis, and a given conditional expression is satisfied.

Abstract: The present invention is a variable power zoom lens that is suitable to APS-format single-lens reflex cameras. The zoom lens has 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, and the fourth lens group G4 of positive refractivity disposed in sequence from a position closer to the object to photograph toward the image plane. The third lens group G3 has a front lens subset G3F of positive refractivity and a back lens subset G3B, and the back lens subset G3B alone is moved orthogonal to the optical axis to correct a blur of an image on the image plane caused by a shake of photographer's hands.

Abstract: A zoom lens and an image pickup device including the same. 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. The first through fourth lens groups are sequentially arranged from an object side. The second lens group includes a lens formed of a material having a low refractive index.

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 side to an image side and an aperture stop disposed between the second and third lens groups. When changing the magnification of the zoom lens from a short focal end to a long focal end, an interval between the first and second lens groups increases, an interval between the second and third lens groups decreases, and an interval between the third and fourth lens groups increases. The first and third lens groups are moved so as to be positioned at object side positions at the long focal end relative to positions at the short focal end. The third lens group has two positive lenses. Predetermined conditions of the positive lenses of the third lens group are satisfied.

Abstract: A remote communication apparatus for receiving the image of a remote user captured by an imaging device to show the image to another user includes a zoom controller for controlling a zoom ratio defining the angle of view of the imaging device, and an estimator for estimating a distance between the imaging device and the remote user on the basis of the zoom ratio of the imaging device.

Abstract: A zoom lens includes, in order from the object side to the 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, and a rear lens group including one or more lens units. During zooming, the first lens unit moves along a locus convex towards the image side, and the second lens unit and the third lens unit move such that an interval between the first lens unit and the second lens unit becomes larger at a telephoto end than at a wide-angle end and an interval between the second lens unit and the third lens unit becomes smaller at the telephoto end than at the wide-angle end. The third lens unit includes a positive lens and a negative lens.

Abstract: A zoom lens optical system includes a first lens unit having a positive refractive index, a second lens unit which is arranged behind the first lens unit and has a negative refractive index, a third lens unit which is arranged behind the second lens unit and has a positive refractive index, and a fourth lens unit which is arranged behind the third lens unit and has a positive refractive index. An aperture is arranged within the third lens unit to prevent reduction of shutter speed due to large diameter of the zoom lens optical system.

Abstract: A high-performance zoom lens system which is compact and has a wide view angle at a wide-angle limit and a high zooming ratio in a balanced manner, 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, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein the first lens unit is composed of at most two lens elements, the second lens unit is composed of two lens elements, the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and the conditions: ?W?36 and fT/fW>4.

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. During zooming from a wide-angle end to a telephoto end, the first lens unit moves with a locus convex toward the image side, and the third lens unit moves toward the object side. The first lens unit includes, in order from the object side to the image side, a negative first lens, a positive second lens, and a positive third lens. A distance (d12) between the first lens and the second lens, a focal length (fw) of the entire zoom lens at the wide-angle end, and a refractive index (Np) of a positive lens having the lowest refractive index among the refractive indices of materials of all positive lenses included in the first lens unit are appropriately set based on predetermined mathematical conditions.

Abstract: A zoom lens includes: a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group having positive refractive power, the first to fourth lens groups being arranged in order from an object side, in which zooming is performed through varying a distance between adjacent lens groups of the first to fourth lens groups, and the fourth lens group includes a first positive lens, a first negative meniscus lens, and a cemented lens which are arranged in order from the object side, the cemented lens being configured of a second negative meniscus lens with a convex surface facing the object side and a second positive lens.

Abstract: Disclosed herein is a zoom lens, including: a first lens group having a positive refracting power; a second lens group having a negative refracting power; a third lens group having a positive refracting power; and a fourth lens group having a positive refracting power; the first, second, third and fourth lens groups being disposed in order from the object side; the lens groups moving upon zooming from a wide angle end to a telephoto end of the zoom lens such that the distance between the first lens group and the second lens group increases while the distance between the second lens group and the third lens group decreases.

Abstract: A zoom lens comprises a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a rear group including at least two lens units and having a positive refractive power as a whole, in order from an object side to an image side. An interval of each of the lens units changes in a zoom operation, the rear group includes a lens unit R having a positive refractive power at the most image side, the lens unit R includes a lens having a concave surface at the image side and having an aspherical surface shape where a negative refractive power becomes stronger with increasing distance from an optical axis, and focal lengths f1, fR, and fw of the first lens unit, the lens unit R, and a whole system at a wide-angle end, respectively, are appropriately set.

Abstract: A zoom lens, in order from an object side to an image side, includes 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, and a fourth lens unit having a positive refractive power, the first lens unit is fixed and at least the second and fourth lens unit are moved during zooming, the third lens unit is configured by a cemented lens formed by cementing a negative lens having a meniscus shape convex towards the object side and a positive lens, the fourth lens unit is configured by a cemented lens formed by cementing a negative lens having a meniscus shape convex towards the object side and a positive lens, and focal lengths f3 and f4 of the third lens unit and the fourth lens unit are appropriately set.

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, in order from the object side, a first lens group having a positive refracting power and fixed in position, a second lens group having a negative refracting power and movable in a direction of an optical axis for zooming, a third lens group having a positive refracting power, and a fourth lens group movable in the direction of the optical axis. The first lens group includes three lenses including a negative lens, a positive lens and another positive lens disposed in order from the object side to the image side and satisfies 7.0<ft/fw<13.0 and??(1) 4.2<f1/fw<6.0??(2) 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, and f1 the focal length of the first lens group.

Abstract: A high-performance zoom lens system which is compact and has a wide view angle at a wide-angle limit and a high zooming ratio in a balanced manner, 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, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein the first lens unit is composed of at most two lens elements, the second lens unit is composed of two lens elements, the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and the conditions: fT/fW>6.

Abstract: A high-performance zoom lens system which is compact and has a wide view angle at a wide-angle limit and a high zooming ratio in a balanced manner, 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, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein the first lens unit is composed of at most two lens elements, the second lens unit is composed of two lens elements, the third lens unit is composed of three lens elements, and the condition: nd>1.75 (nd: a refractive index to the d-line of each lens element constituting the zoom lens system) is satisfied; an imaging device; and a camera are provided.

Abstract: Provided is a compact zoom lens with a high resolving power, a large aperture, and a high variable power. The zoom lens includes a positive first lens group, a moving negative second lens group, a stationary positive third lens group, and a moving positive fourth lens group. The first lens group includes a negative eleventh lens, a positive twelfth lens, and a positive thirteenth lens. The second lens group is composed of a negative twenty-first lens, a negative twenty-second lens, a positive twenty-third lens, and a negative twenty-fourth lens. The third lens group includes a positive thirty-first lens, a positive thirty-second lens, and a negative thirty-third lens. The fourth lens group is composed of a positive forty-first lens having one or more aspheric surfaces. The zoom lens satisfies the prescribed conditional expressions.

Abstract: A positive-negative-positive-positive four group zoom lens system capable of achieving about 30 times variable magnification, the positive-negative-positive-positive four group zoom lens system including, sequentially from an object side to an image 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; and a fourth lens group having positive refractive power, wherein the first lens group includes one negative lens, the second lens group includes one positive lens, the third lens group includes a positive lens, the fourth lens group includes at least one positive lens, and a first condition, 0.03<|f2/ft|<0.08, is satisfied, wherein f2 denotes a focal length of the second lens group and ft denotes a focal length of the zoom lens system in a telephoto position.

Abstract: Provided is a zoom lens for imaging an object on an imaging surface. The zoom lens includes, in the order from an object side to an image side thereof, a first lens group with positive refraction power, a second lens group with negative refraction power, a third lens group with positive refraction power, and a fourth lens group with positive refraction power. The first lens group includes a first surface. The zoom lens satisfies the formula: 0.15<|L3|/Lt<0.25, where L3 is a distance of the movement of the third lens group along an optical axis of the zoom lens when the zoom lens is switched between a wide-angle state and a telephoto state, and Lt is a distance from the first surface to the imaging surface.

Abstract: A zoom lens includes a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group having positive refractive power, the first, second, third, and fourth lens groups being arranged in order from an object side, and satisfies conditional expression (1) and conditional expression (2) below, (1) 0.95<|fw12|/fw<1.2 and (2) 140<f1/?t234<150, where, fw12 denotes a synthetic focal length of the first lens group and the second lens group at a wide-angle end, fw denotes a focal length of a whole lens system at the wide-angle end, f1 denotes the focal length of the first lens group, and ?t234 denotes the synthetic magnification of the second lens group, the third lens group, and the fourth lens group at a telephoto end.

Abstract: A zoom optical system includes, in order from its object side along its optical axis, a first lens group G1 having a positive refracting power, a second lens group G2 having a negative refracting power, a third lens group G3 having a positive refracting power, and a fourth lens group G4 having a positive refracting power, wherein at least one of the first, second, third and fourth lens groups G1, G2, G3, G4 comprises a front group having a positive refracting power including at least two lenses and a rear group having a negative refracting power, and during zooming from the wide angle end state W to the telephoto end state T, the distance between the front group and the rear group does not change, and during focusing onto an object, the front group moves along the optical axis.

Abstract: A zoom lens system including, in an order from an object to an image: a first lens group including at least one lens, and a refraction member for bending an optical axis, and having positive refractive power; a second lens group having negative refractive power; a third lens group; and a fourth lens group, wherein zooming is performed by changing at least one interval between the first through fourth lens groups.

Abstract: In a zoom lens having a plurality of lens groups which are disposed in that order from an object, a first lens group that is disposed to closest to the object among the plurality of lens groups has positive refractive power and comprises a light path bending element which bends the path of light and a plurality of lens components which are disposed closer to the object than the light path bending element; and, where the distance on the optical axis from the surface closest to the object in the first lens group to the surface closest to the object in the light path bending element is L1 and the distance on the optical axis of the light path bending element is Lp, the conditional expression L1/Lp<1.0 is satisfied.