Abstract: A variable magnification optical system includes, in order from the object side along the optical path, a first group that has a positive power, a second group that has a positive power, a third group that has a negative power, a stop, a fourth group that has a positive power, and a fifth group that has a positive power. The first group includes two mirrors. An intermediate image is formed in the optical path between the first group and the second group. The second group, the third group, and the fourth group are refractive optical systems. During changing magnification, the two mirrors of the first group, the second group, the stop, and the fifth group are immovable, the third group moves to the image side, and the fourth group moves to the object side.

Abstract: The zoom lens consists of, in order from an object side, a positive first lens group, a negative second lens group, a positive third lens group, a stop, and a negative fourth lens group. During zooming, the second and third lens groups move. The fourth lens group consists of, in order from the object side, a fourth A lens group, a negative fourth B lens group moving during image blur correction, a positive fourth C lens group, and a negative fourth D lens group moving during focusing, and a positive fourth E lens group. The zoom lens satisfies predetermined conditional expressions.

Abstract: The zoom lens consists of, in order from an object side, a positive first lens group, a negative second lens group, a negative third lens group, and a positive fourth lens group. During zooming from a wide-angle end to a telephoto end, the second lens group moves to an image side, and the third lens group moves to the image side after moving to the object side. The fourth lens group consists of, in order from the object side, a positive fourth A lens group, a negative fourth B lens group moving during image blur correction, a positive fourth C lens group, a fourth D lens group moving during focusing, and a fourth E lens group having a refractive power with a sign different from that of a refractive power of the fourth D lens group.

Abstract: The imaging lens includes at least one negative lens that satisfies predetermined Conditional Expressions (1) to (3) indicating conditions in which dispersion is relatively low and refractive index is high while having a negative rate of change of the refractive index. A positive lens having a largest Abbe number at the d line among positive lenses included in the imaging lens satisfies predetermined Conditional Expressions (4) and (5).

Abstract: The zoom lens consists of, in order from an object side, a positive first lens group, a negative second lens group, a negative third lens group, and a positive fourth lens group. During zooming from a wide-angle end to a telephoto end, the second lens group moves to an image side, and the third lens group moves to the image side after moving to the object side. The fourth lens group consists of, in order from the object side, a positive fourth A lens group, a negative fourth B lens group moving during image blur correction, a positive fourth C lens group, a fourth D lens group moving during focusing, and a fourth E lens group having a refractive power with a sign different from that of a refractive power of the fourth D lens group.

Abstract: The zoom lens consists of, in order from an object side, a positive first lens group, a negative second lens group, a positive third lens group, a stop, and a negative fourth lens group. During zooming, the second and third lens groups move. The fourth lens group consists of, in order from the object side, a fourth A lens group, a negative fourth B lens group moving during image blur correction, a positive fourth C lens group, and a negative fourth D lens group moving during focusing, and a positive fourth E lens group. The zoom lens satisfies predetermined conditional expressions.

Abstract: The zoom lens includes, in order from an object side, a positive first lens group G1, a negative second lens group G2, a positive third lens group G3, a diaphragm, and a fourth lens group G4. During zooming, only the second lens group G2 and the third lens group G3 move. The first lens group G1 includes, in order from the object side, a cemented lens that is formed by cementing a positive lens and a negative meniscus lens convex toward the object side, a positive lens, and a negative lens. A conditional expression (1): ?0.8<f1a/f1b<0 is satisfied, where f1a is a composite focal length of the first to third lenses from the object side of the first lens group G1, and f1b is a focal length of the fourth lens.

Abstract: The imaging lens includes at least one negative lens that satisfies predetermined Conditional Expressions (1) to (3) indicating conditions in which dispersion is relatively low and refractive index is high while having a negative rate of change of the refractive index. A positive lens having a largest Abbe number at the d line among positive lenses included in the imaging lens satisfies predetermined Conditional Expressions (4) and (5).

Abstract: The zoom lens consists of, in order from the object side, a first lens group that has positive refractive power, a second lens group that has a negative refractive power, a third lens group that has a positive refractive power, a stop, and a fourth lens group that has a positive refractive power. During zooming, the second lens group and the third lens group move, and the other lens groups and the stop remain stationary. The second lens group consists of, in order from the object side, a second A lens group that has a cemented lens at a position closest to the image side, consists of three or less lenses, and has a negative refractive power, a second B lens group that consists of one or more negative single lenses, and a second C lens group that consists of a cemented lens and has a negative refractive power.

Abstract: The zoom lens consists of, in order from the object side, a first lens group that has positive refractive power, a second lens group that has a negative refractive power, a third lens group that has a positive refractive power, a stop, and a fourth lens group that has a positive refractive power. During zooming, the second lens group and the third lens group move, and the other lens groups and the stop remain stationary. The second lens group consists of, in order from the object side, a second A lens group that has a cemented lens at a position closest to the image side, consists of three or less lenses, and has a negative refractive power, a second B lens group that consists of one or more negative single lenses, and a second C lens group that consists of a cemented lens and has a negative refractive power.

Abstract: A variable magnification optical system includes, in order from the object side: a positive first lens group, which is fixed when changing magnification; a negative second lens group that moves from the object side to the image side when changing magnification from the wide angle end to the telephoto end; and a rearward lens group having a positive refractive power throughout the entire variable magnification range that includes at least one lens group that moves when changing magnification. The first lens group includes, in order from the object side, a positive first lens group front group, a positive first lens group middle group, and a first lens group rear group constituted by a negative lens. The first lens group front group and first lens group middle group include cemented lenses formed by cementing a negative lens and a positive lens, provided in this order from the object side, together.

Abstract: A variable magnification optical system includes, in order from the object side: a positive first lens group; a negative second lens group; a positive third lens group; a negative fourth lens group; and a positive fifth lens group. When changing magnification from the wide angle end to the telephoto end, the first and third lens groups are fixed with respect to an image formation plane, the second lens group moves toward the image side, the fourth lens group moves, and the distance between the fourth and fifth lens groups changes. A rearward lens group constituted by the third, fourth, and fifth lens groups has a positive refractive power throughout the variable magnification range. The transverse magnification ratio of the fourth lens group when focused on an object at infinity is negative throughout the variable magnification range.

Abstract: The zoom lens includes, in order from an object side, a positive first lens group G1, a negative second lens group G2, a positive third lens group G3, a diaphragm, and a fourth lens group G4. During zooming, only the second lens group G2 and the third lens group G3 move. The first lens group G1 includes, in order from the object side, a cemented lens that is formed by cementing a positive lens and a negative meniscus lens convex toward the object side, a positive lens, and a negative lens. A conditional expression (1): ?0.8<f1a/f1b<0 is satisfied, where f1a is a composite focal length of the first to third lenses from the object side of the first lens group G1, and f1b is a focal length of the fourth lens.

Abstract: A variable magnification optical system consists of a first lens-group having negative refractive-power, a stop and a second lens-group having positive refractive-power in this order from an object-side. The first lens-group includes an L11 negative meniscus lens, an L12 negative lens and a C11 cemented lens, in which a biconcave lens and a positive lens are cemented together in this order from the object-side, in this order from the object-side. The second lens-group includes an L21 positive lens that is arranged closest to the object-side and includes at least one aspheric surface, and an object-side surface of which is convex, and only two cemented lenses toward an image-side of the L21 positive lens, and each of which consists of a negative lens and a positive lens cemented together in this order from the object-side. The following conditional expressions (1) and (2) are satisfied: ?1.0<Rf11/Rf12<0.7??(1); and 55.0<?dave1??(2).

Abstract: An imaging lens consists of, in order from the object side, a front group, a stop, and a rear group, wherein the front group includes, in order from the most-object side, a positive first lens, a negative second lens, a negative third lens which are adjacently disposed, and further includes a final lens of the front group adjacent to the stop, with the surface toward the stop being convex toward the image side, the rear group includes, in order from the image side, two sets of cemented lenses having positive refractive powers, which are adjacently disposed, the object-side cemented lens of the two sets of cemented lenses is formed by cementing a positive lens and a negative meniscus lens together, and the image-side cemented lens is formed by cementing a negative meniscus lens and a positive lens together.

Abstract: An imaging lens consists of, disposed in order from the object side, a front group, a stop, and a rear group, wherein the front group includes, in order from the most-object side, a positive first lens, a negative second lens, and a negative third lens which are adjacently disposed, the rear group consists of two sets of cemented lenses having positive refractive powers and a positive single lens, the object-side cemented lens is formed by cementing, in order form the object side, a positive lens with a convex surface toward the image side and a negative meniscus lens together, the image-side cemented lens is formed by cementing, in order from the object side, a negative meniscus lens with a concave surface toward the image side and a positive lens together, and the image-side cemented lens is disposed at the most-image side of the rear group.

Abstract: A variable magnification optical system includes, in order from the object side: a positive first lens group, which is fixed when changing magnification; a negative second lens group that moves from the object side to the image side when changing magnification from the wide angle end to the telephoto end; and a rearward lens group having a positive refractive power throughout the entire variable magnification range that includes at least one lens group that moves when changing magnification. The first lens group includes, in order from the object side, a positive first lens group front group, a positive first lens group middle group, and a first lens group rear group constituted by a negative lens. The first lens group front group and first lens group middle group include cemented lenses formed by cementing a negative lens and a positive lens, provided in this order from the object side, together.

Abstract: A variable magnification optical system includes, in order from the object side: a positive first lens group; a negative second lens group; a positive third lens group; a negative fourth lens group; and a positive fifth lens group. When changing magnification from the wide angle end to the telephoto end, the first and third lens groups are fixed with respect to an image formation plane, the second lens group moves toward the image side, the fourth lens group moves, and the distance between the fourth and fifth lens groups changes. A rearward lens group constituted by the third, fourth, and fifth lens groups has a positive refractive power throughout the variable magnification range. The transverse magnification ratio of the fourth lens group when focused on an object at infinity is negative throughout the variable magnification range.

Abstract: An imaging lens includes: a first lens group; a stop; a positive second lens group; and a negative third lens group which is fixed while focusing, in order from the object side. The first lens group includes at least one positive lens, at least one cemented lens, and a negative meniscus lens having a concave surface toward the image side, in order from the object side. The second lens group includes a cemented lens formed by a biconcave lens and a biconvex lens and a biconvex lens, in order from the object side. The third lens group includes a negative meniscus lens having a convex surface toward the object side, a biconcave lens, and a biconvex lens, in order from the object side. The first lens group, the stop, and the second lens group move integrally along the optical axis to focus from an infinite to a finite distance.

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.