Zoom lens and imaging apparatus

1. A zoom lens, consisting of four lens groups, composed of a first lens group having a positive refractive power and being fixed during zooming, a second lens group having a negative refractive power and being moved during zooming, a third lens group having a positive refractive power and being moved during zooming to correct an image plane variation due to the zooming, and a fourth lens group having a positive refractive power and being fixed during zooming, in order from the object side, wherein:

a stop is disposed on the most object side in the fourth lens group;

the second lens group and the third lens group each pass through a point where the imaging magnification of each corresponding lens group is −1× at the same time during zooming from the wide angle end to the telephoto end; and

the second lens group includes at least two positive lenses and at least one negative lens, and when the d-line Abbe number and the partial dispersion ratio between the g-line and the F-line of one positive lens included in the second lens group are taken as νp and Pp respectively, the zoom lens satisfies conditional expressions (1) and (2) given below:

75.00<ν p   (1)

0.520< Pp< 0.550  (2)

where, νp and Pp are defined, when the refractive indices of the positive lens related to the conditional expressions (1) and (2) with respect to the g-line, the F-line, the d-line, and the C-line of the Fraunhofer lines are taken as Ng, NF, Nd, and NC respectively, as νp=(Nd−1)/(NF−NC) and Pp=(Ng−NF)/(NF−NC).

2. The zoom lens of claim 1 wherein the second lens group includes, on the most image side, a cemented lens in which three lenses of a positive lens, a negative lens, and a positive lens are cemented in order from the object side.

3. The zoom lens of claim 2 wherein the one positive lens in the second lens group that satisfies the conditional expressions (1) and (2) constitutes the cemented lens.

4. The zoom lens of claim 1 , wherein the second lens group includes a cemented lens on the most image side and satisfies a conditional expression (3) given below when the focal length of the cemented lens and the focal length of the second lens group are taken as f2cem and f2 respectively:

1.00<| f 2cem/ f 2|<44.00  (3).

5. The zoom lens of claim 1 , wherein both the first and second lenses from the object side in the second lens group are single lenses having a negative refractive power, and the object side surface of the most object side negative lens in the second lens group is aspherical.

6. The zoom lens of claim 1 , wherein:

the third lens group is composed of a third-a lens group having a positive refractive power and a third-b lens group having a positive refractive power, in order from the object side; and

the third-a lens group and the third-b lens group are moved independently during zooming from the wide angle end to the telephoto end.

7. The zoom lens of claim 1 , wherein the zoom lens satisfies a conditional expression (1′) given below:

80.00<ν p   (1′).

8. The zoom lens of claim 1 , wherein the zoom lens satisfies a conditional expression (2′) given below:

0.530< Pp< 0.540  (2′).

9. The zoom lens of claim 4 , wherein the zoom lens satisfies a conditional expression (3′) given below:

3.00<| f 2cem/ f 2|<42.00  (3′).

10. An imaging apparatus equipped with the zoom lens of claim 1 .