Provided is a zoom lens including, 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 positive refractive power; a fourth lens unit having a negative refractive power; a fifth lens unit having a positive refractive power; a sixth lens unit having a negative refractive power; a seventh lens unit having a positive refractive power; and an eighth lens unit having a negative refractive power, in which an interval between each pair of adjacent lens units is changed for zooming.

A zoom lens includes, in order from an object side, a first lens group that is positive, a second lens group that is negative, a third lens group that is positive, and a fourth lens group that is positive. During zooming from a wide angle end to a telephoto end, at least the first lens group and the third lens group are fixed and an interval on an optical axis of an adjacent lens group relative thereto is changed. In the zoom lens, the fourth lens group includes at least one positive lens and satisfies a predetermined conditional expression. In addition, an imaging device includes the zoom lens and an image sensor.

A zoom lens includes, in order from an object side, a first lens group that is positive, a second lens group that is negative, a third lens group that is positive, and a fourth lens group that is positive. During zooming from a wide angle end to a telephoto end, at least the first lens group and the third lens group are fixed and an interval on an optical axis of an adjacent lens group relative thereto is changed. In the zoom lens, the fourth lens group includes at least one positive lens and satisfies a predetermined conditional expression. In addition, an imaging device includes the zoom lens and an image sensor.

A zoom optical system according to an embodiment of the present invention includes a first lens group, a second lens group, a third lens group, and a fourth lens group which are sequentially arranged in a direction from a subject side to an image side, wherein the second lens group and the third lens group are movable, and an effective focal length (EFL) in a telephoto mode is defined by an expression below.

[00001]$11.5<\frac{{\mathrm{EFL}}_{\mathrm{tele}}}{H_{\mathrm{imageD}}}<12.5$

Here, EFL.sub.tele is the EFL of the zoom optical system in the telephoto mode, and tele H.sub.imageD is a half value of a diagonal length of a pixel area of an image sensor.

A zoom lens includes, in order from an object side to an image side, a first lens unit having a negative refractive power, and a rear group having a positive refractive power as a whole including at least one lens unit. During zooming from a wide-angle end to a telephoto end, a distance between adjacent lens units changes. The first lens unit includes at least three negative single lenses, and a predetermined condition is satisfied.

A zoom lens includes, in order from an object side to an image side, a first lens unit having a negative refractive power, and a rear group having a positive refractive power as a whole including at least one lens unit. During zooming from a wide-angle end to a telephoto end, a distance between adjacent lens units changes. The first lens unit includes at least three negative single lenses, and a predetermined condition is satisfied.

A zoom optical system (ZL) comprises, in order from an object: a first lens group (G1) having a positive refractive power; a second lens group (G2) having a negative refractive power; a third lens group (G3) having a positive refractive power; and a subsequent lens group (GR), wherein upon zooming, a distance between the first lens group (G1) and the second lens group (G2) changes, a distance between the second lens group (G2) and the third lens group (G3) changes, and a distance between the third lens group (G3) and the subsequent lens group (GR) changes, the subsequent lens group (GR) comprises a focusing lens group that moves upon focusing, and following conditional expressions are satisfied, 3.70<f1/(−f2)<5.00, 3.20<f1/f3<5.00, where f1: a focal length of the first lens group (G1), f2: a focal length of the second lens group (G2), and f3: a focal length of the third lens group (G3).

A zoom optical system (ZL) comprises, in order from an object: a first lens group (G1) having a positive refractive power; a second lens group (G2) having a negative refractive power; a third lens group (G3) having a positive refractive power; and a subsequent lens group (GR), wherein upon zooming, a distance between the first lens group (G1) and the second lens group (G2) changes, a distance between the second lens group (G2) and the third lens group (G3) changes, and a distance between the third lens group (G3) and the subsequent lens group (GR) changes, the subsequent lens group (GR) comprises a focusing lens group that moves upon focusing, and following conditional expressions are satisfied, 3.70<f1/(−f2)<5.00, 3.20<f1/f3<5.00, where f1: a focal length of the first lens group (G1), f2: a focal length of the second lens group (G2), and f3: a focal length of the third lens group (G3).

The invention relates to an optical zoom device (1) Optical zoom device (1), comprising a first lens assembly (2), and a second lens assembly (3) following the first lens assembly (2) in the direction of an optical axis (A) of the optical zoom device (1) so that light (L) can pass through the first lens assembly (2) and thereafter through the second lens assembly when travelling along the optical axis (A), wherein said lens assemblies each comprise a focus-adjustable lens (31, 32) as well as an electropermanent magnet (107, 207) or a shape memory alloy (120, 220) for actuating the respective lens (31, 32).

The invention relates to an optical zoom device (1) Optical zoom device (1), comprising a first lens assembly (2), and a second lens assembly (3) following the first lens assembly (2) in the direction of an optical axis (A) of the optical zoom device (1) so that light (L) can pass through the first lens assembly (2) and thereafter through the second lens assembly when travelling along the optical axis (A), wherein said lens assemblies each comprise a focus-adjustable lens (31, 32) as well as an electropermanent magnet (107, 207) or a shape memory alloy (120, 220) for actuating the respective lens (31, 32).