Abstract: Provided are a zoom lens device and a method for controlling the device, capable of reducing astigmatism regardless of the position of the zoom lens. In accordance with a zoom command, a lens constituting a zoom optical system is moved in the direction of the optical axis (step 81). The position of the moved lens is detected (step 82), and an amount of rotation corresponding to the detected position of the moved lens is read from a table that is stored (step 83). The lens is rotated by the read amount of rotation (step 84). As a result of the rotation of the lens, astigmatism in the zoom optical system is reduced.

Abstract: A zoom lens consists of, in order from the object side, a positive first lens group that is fixed during magnification change, at least three movable lens groups that are moved during magnification change, and a positive end lens group that is disposed at the most image side and is fixed during magnification change. The at least three movable lens groups include, in order from the object side, a positive lens group, a negative lens group, and a negative lens group. The first lens group includes at least two negative lenses, where the most object-side negative lens has a meniscus shape with the convex surface toward the object side, and a first-n lens, which is at least one negative lens of the rest of the negative lenses of the first lens group, satisfies given condition expressions (1) and (2).

Abstract: A zoom lens consists of, in order from the object side, a positive first lens group that is fixed during magnification change, at least two movable lens groups that are moved during magnification change, and a positive end lens group that is disposed at the most image side and is fixed during magnification change. The first lens group consists of, in order from the object side, a negative first-a lens group that is fixed during focusing, a positive first-b lens group that is moved during focusing, and a positive first-c lens group. The first-a lens group includes at least two negative lenses, where the most object-side negative lens has a meniscus shape with the convex surface toward the object side, and a first-n lens, which is at least one negative lens of the rest of the negative lenses of the first-a lens group, satisfies given condition expressions (1) to (3).

Abstract: A zoom lens includes: a first lens group having a positive refractive power which is fixed while changing magnification; two or more movable lens groups that move independently from each other while changing magnification; and a final lens group having a positive refractive power which is fixed while changing magnification, provided in this order from an object side. The zoom lens satisfying Conditional Formula (1) below: 1.30<h/(Yimg·tan ?)<2.37??(1).

Abstract: Provided are a zoom lens device and a method for controlling the device, capable of reducing astigmatism regardless of the position of the zoom lens. In accordance with a zoom command, a lens constituting a zoom optical system is moved in the direction of the optical axis (step 81). The position of the moved lens is detected (step 82), and an amount of rotation corresponding to the detected position of the moved lens is read from a table that is stored (step 83). The lens is rotated by the read amount of rotation (step 84). As a result of the rotation of the lens, astigmatism in the zoom optical system is reduced.

Abstract: A zoom lens consists of, in order from the object side, a positive first lens group that is fixed during magnification change, at least two movable lens groups that are moved during magnification change, and a positive end lens group that is disposed at the most image side and is fixed during magnification change. The first lens group consists of, in order from the object side, a negative first-a lens group that is fixed during focusing, a positive first-b lens group that is moved during focusing, and a positive first-c lens group. The first-a lens group includes at least two negative lenses, where the most object-side negative lens has a meniscus shape with the convex surface toward the object side, and a first-n lens, which is at least one negative lens of the rest of the negative lenses of the first-a lens group, satisfies given condition expressions (1) to (3).

Abstract: A zoom lens consists of, in order from the object side, a positive first lens group that is fixed during magnification change, at least three movable lens groups that are moved during magnification change, and a positive end lens group that is disposed at the most image side and is fixed during magnification change. The at least three movable lens groups include, in order from the object side, a positive lens group, a negative lens group, and a negative lens group. The first lens group includes at least two negative lenses, where the most object-side negative lens has a meniscus shape with the convex surface toward the object side, and a first-n lens, which is at least one negative lens of the rest of the negative lenses of the first lens group, satisfies given condition expressions (1) and (2).

Abstract: A zoom lens includes: a first lens group having a positive refractive power which is fixed while changing magnification; a second lens group constituted by two or more magnification changing groups; an aperture stop; and a third lens group having a positive refractive power which is fixed while changing magnification, provided in this order from an object side. The magnification changing groups respectively move along an optical axis while changing magnification from a wide angle end to a telephoto end. The zoom lens satisfies the following conditional formula: u?/u<0.5??(1) wherein u is the angle of inclination of a paraxial chief ray of light that enters the lens surface most toward the object side within the first lens group, and u? is the angle of inclination of the paraxial chief ray of light that exits the lens surface most toward an image side within the first lens group.

Abstract: A zoom lens substantially consists of, in order from the object side: a first lens group that has a positive refractive power and is fixed during magnification change; a second lens group that has a negative refractive power and is moved along the optical axis during magnification change; a third lens group that has a negative refractive power and corrects for fluctuation of the image plane along with magnification change; and a fourth lens group that has a positive refractive power and is fixed during magnification change. Focusing of an object at a distance between infinity and a predetermined distance is achieved by moving a first-group second lens sub-group, which is a part of the first lens group, along the optical axis, and focusing of an object at a closer distance than the predetermined distance is achieved by moving the third lens group along the optical axis.

Abstract: A zoom lens includes first, second, third, and fourth lens groups respectively having positive, negative, negative, and positive powers. The first lens group includes an 11 lens group having a negative power, which is fixed during focusing operations, a lens group having a positive power, which moves during focusing operations, and a lens group having a positive power, which is fixed during focusing operations. The 11 lens group includes two negative meniscus lenses having concave surfaces toward an image side, and a cemented lens constituted by a biconcave lens toward an object side and a biconvex lens toward the image side. A distance D4 between the second meniscus lens and the cemented lens and the focal distance f1 of the first lens group satisfy the relationship: 0.60<D4/f1<2.0. Thereby, variations in angles of view while changing magnification are suppressed, sufficient reductions in size and weight, and high performance are achieved.

Abstract: A zoom lens includes first, second, third, and fourth lens groups respectively having positive, negative, negative, and positive powers. The first lens group includes a first lens subgroup having a negative power, which is fixed while focusing, a second lens subgroup having a positive power, which moves while focusing, and a third lens subgroup having a positive power, which is fixed while focusing. The second lens subgroup includes a positive lens having a surface having a radius of curvature with a smaller absolute value toward the image side; and a cemented lens constituted by a negative lens toward the object side and a positive lens toward the image side, cemented together at a joint surface having a convex surface toward the object side. The focal distance f12 of the second lens subgroup and the focal length fw of the entire system at the wide angle end satisfy the relationship: 3.0<f12/fw<20.0.

Abstract: A zoom lens includes: a first lens group having a positive refractive power which is fixed while changing magnification; two or more movable lens groups that move independently from each other while changing magnification; and a final lens group having a positive refractive power which is fixed while changing magnification, provided in this order from an object side. The zoom lens satisfying Conditional Formula (1) below: 1.30<h/(Yimg·tan ?)<2.

Abstract: A zoom lens includes: a first lens group having a positive refractive power which is fixed while changing magnification; a second lens group constituted by two or more magnification changing groups; an aperture stop; and a third lens group having a positive refractive power which is fixed while changing magnification, provided in this order from an object side. The magnification changing groups respectively move along an optical axis while changing magnification from a wide angle end to a telephoto end. The zoom lens satisfies the following conditional formula: u?/u<0.5??(1) wherein u is the angle of inclination of a paraxial chief ray of light that enters the lens surface most toward the object side within the first lens group, and u? is the angle of inclination of the paraxial chief ray of light that exits the lens surface most toward an image side within the first lens group.

Abstract: A zoom lens includes first, second, third, and fourth lens groups respectively having positive, negative, negative, and positive powers. The first lens group includes an 11 lens group having a negative power, which is fixed while focusing, a 12 lens group having a positive power, which moves while focusing, and a 13 lens group having a positive power, which is fixed while focusing. The 12 lens group includes a positive lens having a surface having a radius of curvature with a smaller absolute value toward the image side; and a cemented lens constituted by a negative lens toward the object side and a positive lens toward the image side, cemented together at a joint surface having a convex surface toward the object side. The focal distance f12 of the 12 lens group and the focal length fw of the entire system at the wide angle end satisfy the relationship: 3.0<f12/fw<20.0.

Abstract: A zoom lens includes first, second, third, and fourth lens groups respectively having positive, negative, negative, and positive powers. The first lens group includes an 11 lens group having a negative power, which is fixed during focusing operations, a lens group having a positive power, which moves during focusing operations, and a lens group having a positive power, which is fixed during focusing operations. The 11 lens group includes two negative meniscus lenses having concave surfaces toward an image side, and a cemented lens constituted by a biconcave lens toward an object side and a biconvex lens toward the image side. A distance D4 between the second meniscus lens and the cemented lens and the focal distance f1 of the first lens group satisfy the relationship: 0.60<D4/f1<2.0. Thereby, variations in angles of view while changing magnification are suppressed, sufficient reductions in size and weight, and high performance are achieved.

Abstract: A zoom lens substantially consists of, in order from the object side: a first lens group that has a positive refractive power and is fixed during magnification change; a second lens group that has a negative refractive power and is moved along the optical axis during magnification change; a third lens group that has a negative refractive power and corrects for fluctuation of the image plane along with magnification change; and a fourth lens group that has a positive refractive power and is fixed during magnification change. Focusing of an object at a distance between infinity and a predetermined distance is achieved by moving a first-group second lens sub-group, which is a part of the first lens group, along the optical axis, and focusing of an object at a closer distance than the predetermined distance is achieved by moving the third lens group along the optical axis.

Abstract: A variable magnification optical system includes first-lens-group having negative refractive power, aperture stop, and second-lens-group having positive refractive power, arranged from the object-side. An aspheric lens, a central portion of the object-side surface of which is convex, is arranged on the most object-side of the second-lens-group. The object-side surface of the aspheric lens is formed in such a manner that positive power decreases from the central portion of the object-side surface of the aspheric lens toward the periphery thereof, or that an inflection point is present between the central portion and the periphery and positive power decreases as a distance from the central portion increases between the central portion and the inflection point, and negative power increases toward the periphery between the inflection point and the periphery. The aspheric surface satisfies the following formulas (1) and (2) about refractive index and Abbe number: Ne5<1.53??(1); and ?d5>75??(2).

Abstract: A variable magnification optical system includes first lens group having negative refractive-power, an aperture-stop and second lens group having positive refractive-power, arranged from the object-side. A negative lens having a concave surface facing the image-side is arranged on the most object side of the first lens group, and an aspheric lens having a concave surface facing the object-side and an aspheric surface facing the image-side is arranged on the most image side of the first lens group. A positive lens having a convex surface facing the image-side is arranged, on the object-side of the aspheric lens, immediately before the aspheric lens. The image-side surface of the aspheric lens at the most image side of the first lens group includes a portion having higher positive power on the outside of positions through which outermost rays of an axial beam pass, compared with the vicinity of the optical axis.

Abstract: A variable magnification optical system includes first-lens-group having negative refractive power, aperture stop, and second-lens-group having positive refractive power, arranged from the object-side. An aspheric lens, a central portion of the object-side surface of which is convex, is arranged on the most object-side of the second-lens-group. The object-side surface of the aspheric lens is formed in such a manner that positive power decreases from the central portion of the object-side surface of the aspheric lens toward the periphery thereof, or that an inflection point is present between the central portion and the periphery and positive power decreases as a distance from the central portion increases between the central portion and the inflection point, and negative power increases toward the periphery between the inflection point and the periphery. The aspheric surface satisfies the following formulas (1) and (2) about refractive index and Abbe number: Ne5<1.53??(1); and ?d5>75??(2).

Abstract: A variable magnification optical system includes first lens group having negative refractive-power, an aperture-stop and second lens group having positive refractive-power, arranged from the object-side. A negative lens having a concave surface facing the image-side is arranged on the most object side of the first lens group, and an aspheric lens having a concave surface facing the object-side and an aspheric surface facing the image-side is arranged on the most image side of the first lens group. A positive lens having a convex surface facing the image-side is arranged, on the object-side of the aspheric lens, immediately before the aspheric lens. The image-side surface of the aspheric lens at the most image side of the first lens group includes a portion having higher positive power on the outside of positions through which outermost rays of an axial beam pass, compared with the vicinity of the optical axis.