A zoom lens L0 consists of a first lens unit L1 having negative refractive power, a middle group Lm including one or more lens units, and a last lens unit having positive refractive power. The first lens unit L1 includes a first negative lens, a second negative lens, and a third negative lens that are arranged sequentially in an order from an object side to an image side. The number of negative lenses included in the first lens unit L1 is four or less. The middle group Lm includes a plurality of cemented lenses each having a cemented surface that is convex toward the object side, and includes a lens element Ln that is disposed closest to the image side among lens elements having negative refractive power included in the middle group Lm. The zoom lens L0 satisfies a predetermined inequality.

A variable magnification projection optical system includes, in order from an enlargement side: a first lens group having negative refractive power; a second lens group having negative refractive power; and a third lens group having positive refractive power. During zooming, the first lens group is fixed, and the second lens group and the third lens group move. The second lens group includes a plurality of lenses each having positive refractive power. All lenses each having positive refractive power in the first lens group and the second lens group are made of a glass material having a transmittance greater than 0.98 per thickness of 10 mm with respect to light having a wavelength of 440 nm.

An imaging lens consisting of, in order from an object side to an image side: a first lens group; a second lens group that has a positive refractive power; and a third lens group that has a negative refractive power, wherein the first lens group includes, successively in order from a position closest to the object side to the image side, two negative lenses and a positive lens, the second lens group includes a positive lens and a negative lens, during focusing from an object at infinity to a closest object, the first lens group remains stationary with respect to an image plane, and the second lens group moves along an optical axis, and assuming that a focal length of the first lens group is f1, and a focal length of the second lens group is f2, Conditional Expression (1) is satisfied: −0.5<f2/f1<0.5 (1).

An imaging lens consisting of, in order from an object side to an image side: a first lens group; a second lens group that has a positive refractive power; and a third lens group that has a negative refractive power, wherein the first lens group includes, successively in order from a position closest to the object side to the image side, two negative lenses and a positive lens, the second lens group includes a positive lens and a negative lens, during focusing from an object at infinity to a closest object, the first lens group remains stationary with respect to an image plane, and the second lens group moves along an optical axis, and assuming that a focal length of the first lens group is f1, and a focal length of the second lens group is f2, Conditional Expression (1) is satisfied: 0.5<f2/f1<0.5 (1).

An imaging lens consisting of, in order from an object side to an image side: a first lens group; a second lens group that has a positive refractive power; and a third lens group that has a negative refractive power, wherein the first lens group includes, successively in order from a position closest to the object side to the image side, two negative lenses and a positive lens, the second lens group includes a positive lens and a negative lens, during focusing from an object at infinity to a closest object, the first lens group remains stationary with respect to an image plane, and the second lens group moves along an optical axis, and assuming that a focal length of the first lens group is f1, and a focal length of the second lens group is f2, Conditional Expression (1) is satisfied: ?0.5<f2/f1<0.5 (1).

A zoom lens includes, in order from an object side to an image side: a negative first lens unit; a negative second lens unit; and a positive third lens unit, in which the first lens unit is not moved for zooming, the second lens unit and the third lens unit are moved during zooming, and an interval between each pair of adjacent lens units is changed during zooming, in which the first lens unit includes at least two negative lenses, and a focal length of the first lens unit, a focal length of the zoom lens at a wide angle end, a focal length of the zoom lens at a telephoto end, an interval on an optical axis between the first lens unit and the second lens unit at the wide angle end, and a back focus at the wide angle end are appropriately set.

An optical system SL installed in a single-lens reflex camera includes, in order from an object side, a first lens group G1, a second lens group G2 having negative refractive power, and a third lens group G3 having positive refractive power. The second lens group G2 is disposed movably in a direction including a component perpendicular to an optical axis, and a given conditional expression is satisfied, thereby providing an optical system having excellent optical performance with excellent vibration reduction performance, an optical apparatus equipped with the optical system, and a method for manufacturing the optical system.

A variable magnification projection optical system includes, in order from an enlargement side: a first lens group having negative refractive power; a second lens group having negative refractive power; and a third lens group having positive refractive power. During zooming, the first lens group is fixed, and the second lens group and the third lens group move. The second lens group includes a plurality of lenses each having positive refractive power. All lenses each having positive refractive power in the first lens group and the second lens group are made of a glass material having a transmittance greater than 0.98 per thickness of 10 mm with respect to light having a wavelength of 440 nm.

An imaging lens consisting of, in order from an object side to an image side: a first lens group; a second lens group that has a positive refractive power; and a third lens group that has a negative refractive power, wherein the first lens group includes, successively in order from a position closest to the object side to the image side, two negative lenses and a positive lens, the second lens group includes a positive lens and a negative lens, during focusing from an object at infinity to a closest object, the first lens group remains stationary with respect to an image plane, and the second lens group moves along an optical axis, and assuming that a focal length of the first lens group is f1, and a focal length of the second lens group is f2, Conditional Expression (1) is satisfied: 0.5<f2/f1<0.5 (1).