Zoom lens unit and imaging apparatus incorporating the same

1. A zoom lens unit, comprising:

a zoom lens including a plurality of lens groups operable to move in an optical axis direction upon zooming from a wide angle end to a telephoto end,

a first lens group frame for supporting a first lens group positioned on the most object side of said zoom lens, and

a drive operable to move said first lens group frame in a vertical direction to said optical axis.

2. The zoom lens unit according to claim 1 , which satisfies the following condition (1):

0.0005 <|α/D|< 0.2  (1)

where α is a maximum distance between a point of connection of said optical axis with an image plane in an initial state of said first lens group before movement and a point of connection of said optical axis with said image plane in a decentered state of said first lens group after movement, and

D is a maximum image height at said image plane.

3. The zoom lens unit according to claim 1 , which satisfies the following condition (2):

0 <|AS|≦ 0.05  (2)

where AS is a quantity of change of field curvature of a meridional surface at a diagonal position.

4. The zoom lens unit according to claim 1 , wherein, given that a position of the first lens group in an initial state before movement is a first position, and a position of the first lens group in a decentered state after movement, where the first lens group is away from said initial state by a given distance in a direction vertical to said optical axis, is a second position, said first lens group frame moves to a third position symmetric with respect to the second position with said optical axis as center.

5. An imaging apparatus, comprising:

the zoom lens unit according to claim 1 ,

an imaging device that is located on an image side of said zoom lens unit and includes an imaging plane for receiving an image formed through said zoom lens unit, and

an imaging apparatus body including said imaging device disposed inside.