JP2008046208A5 - - Google Patents

Claims (9)

In order from the object side to the image side, a first lens unit having a negative refractive power, a second lens unit having positive refractive power, a third lens unit having a negative refractive power and a fourth lens unit having a positive refractive power In a zoom lens in which each lens group moves on the optical axis so that the interval between the lens groups changes during zooming,
The second lens group includes, in order from the object side to the image side, a front group and a rear group having a positive refractive power with the widest air gap as a boundary, and the front group moves on the optical axis to focus. A zoom lens, comprising: a negative lens group, a positive lens, and a positive lens having a convex surface on the object side and a meniscus shape in order from the object side to the image side. When the radius of curvature of the surface closest to the object side of the second lens group is r21, and the focal length of the second lens group is f2,
1.0 <r21 / f2 <3.0
The zoom lens according to claim 1, wherein the following condition is satisfied. When the focal length of the second lens group is f2, and the focal length of the front group is f2a,
1.5 <f2a / f2 <2.5
The zoom lens according to claim 1, wherein the following condition is satisfied.   The zoom lens according to claim 1, wherein the negative lens included in the front group and the positive lens on the image side thereof are cemented. When i is the order of the lens groups counted from the object side, when the focal length of the i-th lens group is fi and the focal length of the entire system at the wide angle end is fw,
0.9 <| f1 | / fw <1.7
1.5 <f2 / fw <2.8
1.9 <| f3 | / fw <4.5
The zoom lens according to claim 1, wherein the following condition is satisfied.   6. The zoom lens according to claim 1, wherein the fourth lens group has an aspheric surface having a negative refractive power that increases as the distance from the optical axis increases.   7. The positive lens on the image side of the negative lens in the front group has a biconvex shape, and the most image side positive lens in the front group has a meniscus shape with a convex surface on the object side. Any one of the zoom lenses.   The zoom lens according to claim 1, wherein the zoom lens is an optical system for forming an image on a solid-state imaging device.   An imaging apparatus comprising: the zoom lens according to claim 1; and a solid-state imaging device that captures an image formed by the zoom lens.