Abstract: A zoom lens includes a first lens group having positive refractive power, a second lens group having negative refractive power, and a rear group. The second lens group consists of a second sub-first lens group having positive or negative power, and a second sub-second lens group having negative power. The second sub-second lens group consists of, sequentially from the object side toward the image: a positive second-first lens component; a negative second-second lens component; and a negative second-third lens component. During zooming from a short focal length end to a long focal length end, a distance between the first lens group and the second lens group increases, and a distance between the second lens group and the rear group decreases. A part of the second lens group is movable in a direction perpendicular to an optical axis during correction of image blurring.

Abstract: A zoom lens includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a rear group, sequentially from an object side. Intervals between lens groups varies when changing magnification. A lens group having a highest negative refractive power among a lens group having a negative refractive power in the rear group is a focusing lens group GF configured to move toward an image side when focusing from infinity to a close range. A lens group GFF having a positive refractive power and arranged adjacent to an object side of the focusing lens group GF among a lens group having a positive refractive power included in the rear group includes a positive lens component L1 positioned on a most image side, which includes a positive lens L1P having a refractive index NdL1P, and a conditional expression (1) 1.85<NdL1P is satisfied.

Abstract: A zoom lens includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a rear group, sequentially from an object side. Intervals between lens groups varies when changing magnification. A lens group having a highest negative refractive power among a lens group having a negative refractive power in the rear group is a focusing lens group GF configured to move toward an image side when focusing from infinity to a close range. A lens group GFF having a positive refractive power and arranged adjacent to an object side of the focusing lens group GF among a lens group having a positive refractive power included in the rear group includes a positive lens component L1 positioned on a most image side, which includes a positive lens L1P having a refractive index NdL1P, and a conditional expression (1) 1.85<NdL1P is satisfied.

Abstract: A zoom lens system includes a first lens group; a second lens group; and a subsequent lens group arranged in that order from the object side. The second lens group consists of a second lens group-a, a second lens group-b, and a second lens group-c arranged in that order from the object side. A distance between the first lens group and the second lens group increases and a distance between the second lens group and the subsequent lens group decreases during a change in magnification from a short focal length end to a long focal length end. During a change in focus from infinity to a short distance, the second lens group-b is movable to the image side, and a distance between the second lens group-a and the second lens group-b and a distance between the second lens group-b and the second lens group-c are changeable.

Abstract: A zoom lens satisfies Conditional Expression (1) as follows: ?20<Twt/Twm<1,??(1) Twt is a moving amount of the second lens group during zooming from the short focal-length end to the long focal-length end, a moving amount to the object side being indicated by a positive sign, a moving amount to an image side being indicated by a negative sign, and Twm is a moving amount of the second lens group during zooming from the short focal-length end to an intermediate focal length, a moving amount to the image side being indicated by a negative sign, the intermediate focal length being expressed by fm=(fw·ft)1/2, where fw is a focal length of a whole system at the short focal-length end, and ft is a focal length of the whole system at the long focal-length end.

Abstract: A zoom lens system includes a first lens group; a second lens group; and a subsequent lens group arranged in that order from the object side. The second lens group consists of a second lens group-a, a second lens group-b, and a second lens group-c arranged in that order from the object side. A distance between the first lens group and the second lens group increases and a distance between the second lens group and the subsequent lens group decreases during a change in magnification from a short focal length end to a long focal length end. During a change in focus from infinity to a short distance, the second lens group-b is movable to the image side, and a distance between the second lens group-a and the second lens group-b and a distance between the second lens group-b and the second lens group-c are changeable.

Abstract: A zoom lens system includes a first lens group having positive refractive power; a second lens group having negative refractive power; and a rear group, the first lens group, arranged in that order from an object side. The second lens group includes a second lens group-a having negative refractive power and a second lens group-b having negative refractive power arranged in that order from the object side. During a change in a focus from a short focal length end to a long focal length end to change a magnification power, a distance between the first lens group and the second lens group-a increases, a distance between the second lens group-a and the second lens group-b is changeable or stationary, and a distance between the second lens group-b and the rear lens group decreases.

Abstract: A zoom lens includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a rear group, sequentially from an object side. Intervals between lens groups varies when changing magnification. A lens group having a highest negative refractive power among a lens group having a negative refractive power in the rear group is a focusing lens group GF configured to move toward an image side when focusing from infinity to a close range. A lens group GFF having a positive refractive power and arranged adjacent to an object side of the focusing lens group GF among a lens group having a positive refractive power included in the rear group includes a positive lens component L1 positioned on a most image side, which includes a positive lens L1P having a refractive index NdL1P, and a conditional expression (1) 1.85<NdL1P is satisfied.

Abstract: A zoom lens includes a first lens group having positive refractive power, a second lens group having negative refractive power, and a rear group. The second lens group consists of a second sub-first lens group having positive or negative power, and a second sub-second lens group having negative power. The second sub-second lens group consists of, sequentially from the object side toward the image: a positive second-first lens component; a negative second-second lens component; and a negative second-third lens component. During zooming from a short focal length end to a long focal length end, a distance between the first lens group and the second lens group increases, and a distance between the second lens group and the rear group decreases. A part of the second lens group is movable in a direction perpendicular to an optical axis during correction of image blurring.

Abstract: A zoom lens system includes a first lens group; a second lens group; and a subsequent lens group arranged in that order from the object side. The second lens group consists of a second lens group-a, a second lens group-b, and a second lens group-c arranged in that order from the object side. A distance between the first lens group and the second lens group increases and a distance between the second lens group and the subsequent lens group decreases during a change in magnification from a short focal length end to a long focal length end. During a change in focus from infinity to a short distance, the second lens group-b is movable to the image side, and a distance between the second lens group-a and the second lens group-b and a distance between the second lens group-b and the second lens group-c are changeable.

Abstract: A zoom lens satisfies Conditional Expression (1) as follows: ?20<Twt/Twm<1,??(1) Twt is a moving amount of the second lens group during zooming from the short focal-length end to the long focal-length end, a moving amount to the object side being indicated by a positive sign, a moving amount to an image side being indicated by a negative sign, and Twm is a moving amount of the second lens group during zooming from the short focal-length end to an intermediate focal length, a moving amount to the image side being indicated by a negative sign, the intermediate focal length being expressed by fm=(fw·ft)1/2, where fw is a focal length of a whole system at the short focal-length end, and ft is a focal length of the whole system at the long focal-length end.

Abstract: A zoom lens system includes a first lens group having positive refractive power; a second lens group having negative refractive power; and a rear group, the first lens group, arranged in that order from an object side. The second lens group includes a second lens group-a having negative refractive power and a second lens group-b having negative refractive power arranged in that order from the object side. During a change in a focus from a short focal length end to a long focal length end to change a magnification power, a distance between the first lens group and the second lens group-a increases, a distance between the second lens group-a and the second lens group-b is changeable or stationary, and a distance between the second lens group-b and the rear lens group decreases.

Abstract: A zoom lens system includes a positive first lens group, a negative second lens group, a positive intermediate lens group, and a negative image-side lens group. Upon zooming from the short to long focal length extremities, a distance between the first and second lens groups increases, and a distance between the second and intermediate lens groups decreases. The image-side lens group consists of two lens elements. The following conditions are satisfied: ?6.0<f1/f2<?4.3, ?5.4<f1/fIMG<?3.9, and 0.3<D2/fw<3.0, f1, f2 and fIMG designate the focal lengths of the first, second and the image-side lens groups, respectively, D2 designates a distance between the second lens group and the intermediate lens group, at the short focal length extremity, fw designates the focal length of the zoom lens system at the short focal length extremity.

Abstract: A zoom lens system includes a positive first lens group, and a rear lens group behind the first lens group, in that order from the object side. The first lens group includes at least one positive single lens element, a negative meniscus lens element having a convex surface on the object side, and at least one positive lens element, in that order from the object side. A distance between the first lens group and the rear lens group increases upon zooming from the short to long focal length extremities. The following conditions (1) and (2) are satisfied: fG1/fn<?1.50??(1), and 65<?pave??(2), wherein fG1 designates the focal length of the first lens group, fn designates the focal length of the negative meniscus lens element, and ?pave designates the average value of the Abbe numbers with respect to the d-line of the positive lens elements.

Abstract: A zoom lens system includes a positive first lens group, a negative second lens group, a positive intermediate lens group, and a negative image-side lens group. Upon zooming from the short to long focal length extremities, a distance between the first and second lens groups increases, and a distance between the second and intermediate lens groups decreases. The image-side lens group consists of two lens elements. The following conditions are satisfied: ?6.0<f1/f2<?4.3, ?5.4<f1/fIMG<?3.9, and 0.3<D2/fw<3.0. f1, f2 and fIMG designate the focal lengths of the first, second and the image-side lens groups, respectively. D2 designates a distance between the second lens group and the intermediate lens group, at the short focal length extremity. fw designates the focal length of the zoom lens system at the short focal length extremity.

Abstract: A zoom lens system includes a positive first lens group, and a rear lens group behind the first lens group, in that order from the object side. The first lens group includes at least one positive single lens element, a negative meniscus lens element having a convex surface on the object side, and at least one positive lens element, in that order from the object side. A distance between the first lens group and the rear lens group increases upon zooming from the short to long focal length extremities. The following conditions (1) and (2) are satisfied: fG1/fn<?1.50??(1), and 65<?pave??(2), wherein fG1 designates the focal length of the first lens group, fn designates the focal length of the negative meniscus lens element, and ?pave designates the average value of the Abbe numbers with respect to the d-line of the positive lens elements.

Abstract: A zoom lens system includes a positive first lens group and a negative second lens group. The first lens group includes a cemented lens, a diffraction surface having a rotationally symmetric shape satisfying condition (1) formed on a cemented surface of the cemented lens, and condition (2) is satisfied: 130<|fD/RD|<10,000(fD>0)??(1), and 0.15<f1/fT<0.35??(2). fD designates the focal length of the diffraction surface; fD=?1/(2×P2×?0); P2 designates a secondary coefficient of an optical path difference function for calculating an optical path length addition amount of the diffraction surface, ?0 designates the d-line, RD designates the radius of curvature of the substrate surface having the diffraction surface and fT designates the focal lengths of the entire lens system at the long focal length extremity.

Abstract: The objective of the present invention is to provide a zoom lens system having an f-number of approximately 1.3 at the wide extremity, a half angle-of-view of 75 degrees, and a zoom ratio of approximately 3:1. The solution to this objective is to provide a zoom lens system including a first lens group, having a negative refractive power, a diaphragm, and a second lens group, having a positive refractive power, in that order from the object side; wherein the first lens group and the second lens group move in the optical axis direction so that the distance therebetween decreases upon zooming from the wide-angle extremity to the telephoto extremity.

Abstract: The objective of the present invention is to provide a zoom lens system having an f-number of approximately 1.3 at the wide extremity, a half angle-of-view of 75 degrees, and a zoom ratio of approximately 3:1.