A zoom lens system includes a first lens group having positive refractive power; a second lens group having negative refractive power; and a rear group, the first lens group, arranged in that order from an object side. The second lens group includes a second lens group-a having negative refractive power and a second lens group-b having negative refractive power arranged in that order from the object side. During a change in a focus from a short focal length end to a long focal length end to change a magnification power, a distance between the first lens group and the second lens group-a increases, a distance between the second lens group-a and the second lens group-b is changeable or stationary, and a distance between the second lens group-b and the rear lens group decreases.

A zoom lens system includes a first lens group having positive refractive power; a second lens group having negative refractive power; and a rear group, the first lens group, arranged in that order from an object side. The second lens group includes a second lens group-a having negative refractive power and a second lens group-b having negative refractive power arranged in that order from the object side. During a change in a focus from a short focal length end to a long focal length end to change a magnification power, a distance between the first lens group and the second lens group-a increases, a distance between the second lens group-a and the second lens group-b is changeable or stationary, and a distance between the second lens group-b and the rear lens group decreases.

A lens 1 has unevenness within an optical effective diameter D of an optical surface 2, an arithmetic mean roughness Ra within the optical effective diameter D of the optical surface 2 is 20 nm or more and 50 nm or less, and an average value of widths W of protrusion portions 3 of the unevenness on an average line C2 of a roughness curve C1 of the optical surface 2 is 1/200 or more and 1/50 or less of the optical effective diameter D of the optical surface 2. The lens 1 is suitably used as a lens that composes a zoom lens or an imaging lens.

Provided is a zoom lens including, in order from an object side to an image side, a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, and a rear lens group including a plurality of lens units. The zoom lens has a configuration in which an interval between each pair of adjacent lens units is changed for zooming. The first lens unit is configured to move for zooming. The rear lens group includes at least one lens unit having a negative refractive power. Further, a focal length of the first lens unit, a focal length of the second lens unit, a focal length of the zoom lens at the wide angle end, a total length of the zoom lens at the wide angle end, and a back focus at the wide angle end are each appropriately set.

Provided is a zoom lens including, in order from an object side to an image side, a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, and a rear lens group including a plurality of lens units. The zoom lens has a configuration in which an interval between each pair of adjacent lens units is changed for zooming. The first lens unit is configured to move for zooming. The rear lens group includes at least one lens unit having a negative refractive power. Further, a focal length of the first lens unit, a focal length of the second lens unit, a focal length of the zoom lens at the wide angle end, a total length of the zoom lens at the wide angle end, and a back focus at the wide angle end are each appropriately set.

A zoom lens includes, in order from an object side, a positive first unit, a negative second unit, a positive intermediate group consisting of one or two units and including a third unit located on a most object side, a negative unit, and a rear group consisting of one or two units including a positive unit located on a most object side. Conditional expressions are satisfied with respect to amounts of movement of the second and third units from a wide angle end to a telephoto end, a distance at the wide angle end from a most object side surface vertex in the first unit to a most object side surface vertex in the third unit, an Abbe number of a most object side lens in the first unit, a focal length of the second unit, and focal lengths at the wide angle end and at the telephoto end.

A zoom lens includes, in order from an object side, a positive first unit, a negative second unit, a positive intermediate group consisting of one or two units and including a third unit located on a most object side, a negative unit, and a rear group consisting of one or two units including a positive unit located on a most object side. Conditional expressions are satisfied with respect to amounts of movement of the second and third units from a wide angle end to a telephoto end, a distance at the wide angle end from a most object side surface vertex in the first unit to a most object side surface vertex in the third unit, an Abbe number of a most object side lens in the first unit, a focal length of the second unit, and focal lengths at the wide angle end and at the telephoto end.

A zoom lens includes a negative first lens group, a positive second lens group, and a subsequent lens group in order from an object side. A focusing lens group closer to an image side than the first lens group moves during focusing. The first lens group consists of a first-a lens group and a first-b lens group in order from the object side. Assuming that an average of refractive indices of the negative lenses of the first-a lens group is Nd1ave, a focal length of the focusing lens group is ff, and a focal length of the first lens group is f1, Conditional Expression (1) of 1.73<Nd1ave<1.95 and Conditional Expression (2) of 1<|ff/f1|<3 are satisfied.

A zoom lens includes a negative first lens group, a positive second lens group, and a subsequent lens group in order from an object side. A focusing lens group closer to an image side than the first lens group moves during focusing. The first lens group consists of a first-a lens group and a first-b lens group in order from the object side. Assuming that an average of refractive indices of the negative lenses of the first-a lens group is Nd1ave, a focal length of the focusing lens group is ff, and a focal length of the first lens group is f1, Conditional Expression (1) of 1.73<Nd1ave<1.95 and Conditional Expression (2) of 1<|ff/f1|<3 are satisfied.

A zoom optical system comprises, in order from an object: a first lens group (G1) having positive refractive power; a second lens group (G2) having negative refractive power; and a subsequent group (GR) including at least one lens group. Upon zooming, distances between the first lens group (G1) and the second lens group (G2) and between the second lens group (G2) and the subsequent group (GR) change. The subsequent group (GR) comprises a focusing group (Gfc) having negative refractive power for focusing. The first lens group (G1) comprises a 1-1st lens that has positive refractive power and is disposed closest to the object. A following conditional expression is satisfied:

0.20<f1/fR<0.85 where, f1 denotes a focal length of the first lens group, and fR denotes a focal length of a lens component, in the subsequent group, closest to an image surface.