A zoom lens includes, in order from an object side to an image side, a first lens unit having a positive refractive power, a plurality of zooming lens units configured to move along an optical axis in zooming and including a lens unit having a negative refractive power, and a final lens unit having a positive refractive power. A distance between each pair of adjacent lens units changes in zooming. The first lens unit includes, in order from the object side to the image side, a first subunit having a negative refractive power, a second subunit having a negative refractive power, and at least one subsequent subunit, a distance between each pair of adjacent subunits changing for focusing. The second subunit is configured to move along the optical axis for focusing. A predetermined condition is satisfied.

A zoom optical system comprises, in order from an object: a front lens group (GFS) having a positive refractive power; an M1 lens group (GM1) having a negative refractive power; an M2 lens group (GM2) having a positive refractive power; an RN lens group (GRN) having a negative refractive power; and a subsequent lens group (GRS). Upon zooming, the distance between the front lens group (GFS) and the M1 lens group (GM1) changes, the distance between the M1 lens group (GM1) and the M2 lens group (GM2) changes, and the distance between the M2 lens group (GM2) and the RN lens group (GRN) changes. Upon focusing from an infinite distant object to a short distant object, the RN lens group (GRN) moves.

A zoom lens includes, from an object side a first lens unit (a positive refractive power) configured not to move for zooming, two or more intermediate lens units configured to move in zooming, and a rear lens unit (a positive refractive power), wherein an interval between each pair of adjacent lens units changes in zooming, the first lens unit includes, from the object side, a first lens subunit (a negative refractive power) configured not to move for focusing, a second lens subunit (a positive refractive power) configured to move for focusing, and a third lens subunit (a positive refractive power), the zoom lens satisfies specific inequalities concerning a focal length of the first lens unit, a length on an optical axis from a last surface to a rear principal point of the first lens unit, and a focal length of the zoom lens at a telephoto end.

Provided is a zoom lens including a plurality of lens units, in which an interval between each pair of adjacent lens units is changed during zooming. The plurality of lens units consist of, in order from an object side to an image side: a first lens unit having a positive refractive power; a second lens unit having a negative refractive power; a third lens unit having a negative refractive power; and a rear lens group including at least one lens unit. An interval between the second lens unit and the third lens unit becomes larger at a telephoto end than at a wide angle end. The third lens unit is moved during focusing. Focal lengths of the second lens unit and the third lens unit, a focal length of the zoom lens at the wide angle end, and a back focus at the wide angle end are appropriately set.

The zoom lens consists of, in order from an object side, a first lens group having a positive power, a second lens group having a negative power, a third lens group having a negative power, a stop, a fourth lens group having a positive power, and a fifth lens group having a positive power. During zooming, the first lens group and the fifth lens group remain stationary, and the other lens groups and the stop move. The most image side positive lens is disposed to be closest to the image side in the first lens group. The following conditional expression relating to a partial dispersion ratio gF1p of the most image side positive lens between the g line and the F line and an Abbe number 1p is satisfied:

0.6376<gF1p+0.00171p<0.7.

A zoom lens includes lens units whose interval between adjacent units is changed during zooming, wherein the lens units consist of, in order from an object side, a positive first unit, an negative intermediate lens group including a unit, a positive (n1)-th unit, and a positive n-th unit, wherein the first unit moves during zooming, wherein an interval between the (n1)-th and n-th units is smaller at telephoto end than at wide angle end, wherein the n-th unit includes positive lenses LPL made of a material having proper Abbe number, wherein the n-th lens unit includes a positive lens LPH arranged on the image side of the lenses LPL and made of a material having proper refractive index and wherein a distance between lens surfaces on the most-object side and on the most-image side of the n-th lens unit, and back focus at the wide angle end are properly set.

In an optical system (ZL) capable of imaging in a plurality of object side media (for instance, air and water) whose refractive indexes are different from each other, the optical system is composed of, in order from an object, a front lens group (G1) whose position in an optical axis fixed, and a rear lens group (for instance, G2 to G4), and the rear lens group comprises at least two moving lens groups (for instance, G2 and G3), and at least two moving lens groups in the rear lens group are moved along the optical axis upon changing between object side media.

A zoom lens including in order from an object side: a positive first unit configured not to move for zooming; a negative second unit configured to move to the image side for zooming to a telephoto end; and a relay lens unit configured not to move for zooming, wherein the first unit consists of five lenses including, in order from the object side, a negative lens, a positive lens, a positive lens, a positive lens and a positive lens, or six lenses including, in order from the object side, a positive lens, a negative lens, a positive lens, a positive lens, a positive lens and a positive lens, and a refractive index of the negative lens in the first unit, an Abbe number of the negative lens, a focal length of the negative lens, and a focal length of the first lens unit are appropriately set.

In an optical system (ZL) capable of imaging in a plurality of object side media (for instance, air and water) whose refractive indexes are different from each other, the optical system is composed of, in order from an object, a front lens group (G1) whose position in an optical axis fixed, and a rear lens group (for instance, G2 to G4), and the rear lens group comprises at least two moving lens groups (for instance, G2 and G3), and at least two moving lens groups in the rear lens group are moved along the optical axis upon changing between object side media.

A zoom lens includes a front lens group having a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, an aperture stop, and a rear lens group having a plurality of lens units. The first lens unit is fixed at the time of zooming, the first lens unit includes a first lens subunit having a negative refractive power, which is fixed at the time of focusing and a second lens subunit having a positive refractive power, which moves at the time of focusing. The second lens subunit is arranged at a position adjacent to the first lens subunit on the image side thereof, and the rear lens group includes a lens unit moving in a direction of an optical axis so that an imaging magnification at a telephoto end is larger than an imaging magnification at a wide-angle end.