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: An imaging lens substantially consists of, in order from an object side, five lenses of a first lens that has a positive refractive power and has a meniscus shape which is convex toward the object side, a second lens that has a biconcave shape, a third lens that has a meniscus shape which is convex toward an image side, a fourth lens that has a positive refractive power, and a fifth lens that has a negative refractive power and has at least one inflection point on an image side surface. Further, the imaging lens satisfies a predetermined conditional expression.

Abstract: An imaging lens substantially consists of, in order from an object side, five lenses of a first lens that has a positive refractive power and has a meniscus shape which is concave toward an image side, a second lens that has a negative refractive power and has a meniscus shape which is concave toward the image side, a third lens that has a negative refractive power and is concave toward the object side, a fourth lens that has a positive refractive power and has a meniscus shape which is convex toward the image side, and a fifth lens that has a biconcave shape and has an aspheric shape which has at least one extreme point on an image side surface. Further, the imaging lens satisfies predetermined conditional expressions.

Abstract: A zoom lens includes, in order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power and a third lens group having a positive refractive power, wherein, during magnification change from the wide-angle end to the telephoto end, at least the first lens group and the second lens group are moved along the optical axis such that the interval between the first lens group and the second lens group is decreased and the interval between the second lens group and the third lens group is increased. The second lens group includes, in order from the object side, a positive lens, a cemented lens formed by a positive lens and a negative lens, a positive lens and a negative lens. The zoom lens satisfies given conditional expressions.

Abstract: An imaging lens substantially consists of, in order from an object side, five lenses of a first lens that has a positive refractive power and is convex toward the object side, a second lens that has a negative refractive power, a third lens, a fourth lens that has a positive refractive power, and a fifth lens that has a negative refractive power and has an object side surface and an image side surface which have aspheric shapes. Further, the imaging lens satisfies predetermined conditional expressions.

Abstract: An imaging lens substantially consists of, in order from an object side, five lenses of a first lens that has a positive refractive power and has a meniscus shape which is convex toward the object side, a second lens that has a negative refractive power, a third lens that has a negative refractive power, a fourth lens that has a positive refractive power, and a fifth lens that has a negative refractive power and has an object side surface and an image side surface which have aspheric shapes. Further, the imaging lens satisfies predetermined conditional expressions.

Abstract: An imaging lens substantially consists of, in order from an object side, five lenses of a first lens that has a positive refractive power and has a meniscus shape which is convex toward the object side, a second lens that has a biconcave shape, a third lens that has a meniscus shape which is convex toward the object side, a fourth lens that has a meniscus shape which is convex toward the image side; and a fifth lens that has a negative refractive power and has at least one inflection point on an image side surface. Further, the following conditional expression (1) is satisfied. 1.

Abstract: An imaging lens substantially consists of, in order from an object side, five lenses of a first lens that has a positive refractive power and has a meniscus shape which is convex toward the object side, a second lens that has a negative refractive power, a third lens that has a negative refractive power, a fourth lens that has a positive refractive power, and a fifth lens that has a negative refractive power and has an aspheric shape of which an image side surface has an extreme point. Further, the imaging lens satisfies a predetermined conditional expression.

Abstract: An imaging lens substantially consists of, in order from an object side, five lenses of a first lens that has a positive refractive power and has a meniscus shape which is convex toward the object side, a second lens that has a negative refractive power and has a meniscus shape which is concave toward the object side, a third lens that has a meniscus shape which is convex toward the image side, a fourth lens that has a positive refractive power and is convex toward the object side, and a fifth lens that has a negative refractive power and has at least one inflection point on an image side surface.

Abstract: An imaging lens substantially consists of, in order from an object side, five lenses of a first lens that has a positive refractive power and has a meniscus shape which is convex toward the object side, a second lens that has a negative refractive power and has a meniscus shape which is concave toward an image side, a third lens that has a meniscus shape which is convex toward the image side, a fourth lens that has a positive refractive power, and a fifth lens that has a negative refractive power and has at least one inflection point on an image side surface. Further, the imaging lens satisfies predetermined conditional expressions.

Abstract: A zoom lens includes, in order from the object side, a negative first lens group, a positive second lens group and a positive third lens group, wherein, during magnification change from the wide-angle end to the telephoto end, at least the first and second lens groups are moved such that the interval between the first and second lens groups decreases and the interval between the second and third lens groups increases. The first lens group includes a negative meniscus first-group first lens with a convex object-side surface, a negative meniscus first-group second lens with a convex object-side surface, and a positive first-group third lens with a convex object-side surface, and the second lens group includes a positive lens, a cemented lens formed by a positive lens and a negative lens, a positive lens and a negative lens, in order from the object side. The zoom lens satisfies given conditional expressions.

Abstract: A zoom lens includes: a first lens group having a negative refractive power; and a second lens group having a positive refractive power, provided in this order from an object side. Magnification is changed by moving the first lens group and the second lens group. The first lens group includes a first lens having a negative refractive power, a second lens having a positive refractive power, a third lens having a negative refractive power, and a fourth lens having a positive refractive power, provided in this order from the object side. The zoom lens satisfies the following conditional formulae, when fw is the focal length of the entire system at the wide angle end, f1 is the focal length of the first lens group, and f2 is the focal length of the second lens group: 0.00<fw/f2<0.43??(1-5) 0.56<|f1/f2|<2.00??(2-4).

Abstract: In a zoom lens in which a first lens group having a negative refractive power and a second lens group having a positive refractive power are disposed in order from the object side and zooming is performed by moving the first lens group and the second lens group, the first lens group is formed of a first lens having a negative refractive power, a second lens having a positive refractive power, a third lens having a negative refractive power, and a fourth lens having a positive refractive power, disposed in order from the object side. Then, when the focal length of the first lens group is taken as f1 and the focal length of the second lens group is taken as f2, the zoom lens is configured to satisfy a conditional expression give below: 0.00<|f1/f2|<1.04??(1-4).

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: In order from the object side, a first lens having positive power with a convex observation-side surface, a second lens having negative power and a meniscus shape with a concave object-side surface, and a third lens having positive power with an observation-side surface having a smaller radius of curvature than that of an object-side surface are provided. The first, second and third lenses are single lenses. The conditional expressions (1): 0.9<f1/f3<5.0, (2): 10.0<TL<17.0 and (3): 15.0<f<25.0 are satisfied at the same time, where f1 is a focal length of the first lens, f3 is a focal length of the third lens, f is a focal length of the entire system, and TL is a distance along an optical axis from an object-side lens surface of the first lens to the observation-side lens surface of the third lens.

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: An imaging lens substantially includes five lenses, constituted by: a first lens having a positive refractive power; a second lens having a negative refractive power; a third lens having a positive refractive power and a convex surface that faces an object side; a fourth lens having a negative refractive power and a meniscus shape with a concave surface that faces the object side; and a fifth lens having a positive refractive power, a meniscus shape with a convex surface that faces the object side, and at least one inflection point on the surface thereof toward an image side.

Abstract: An imaging lens substantially includes six lenses, constituted by: a first lens having a positive refractive power and a convex surface that faces an object side; a second lens having a negative refractive power; a third lens having a positive refractive power; a fourth lens having a positive refractive power; a fifth lens having a negative refractive power and a concave surface that faces the object side; and an aspherical sixth lens having a negative refractive power, the surface of which is concave toward an image side in the vicinity of an optical axis and convex toward the image side at the peripheral portion thereof. The imaging lens satisfies a predetermined conditional formula.

Abstract: A variable magnification optical system 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 an object side. The first lens-group and the third lens-group are fixed when magnification is changed from a wide-angle end to a telephoto end, and the magnification is changed from the wide-angle end to the telephoto end by moving the second lens-group toward an image side, and correction of an image plane and focusing, which have been necessitated by magnification change, are performed by moving the fourth lens-group. The first lens-group consists of two positive lenses and a negative lens in this order from the object side. The second lens-group consists of a negative 21st lens, a positive 22nd lens, a negative 23rd lens and a negative 24th lens in this order from the object side.