Patent ID: 9013802
Filing Date: 2015-04-21
Classification: G02B

Abstract:
1. A zoom lens comprising, in order from an object side in an optical axis: a first lens group having a positive refractive power; a second lens group having a negative refractive power; a third lens group having a negative refractive power; a fourth lens group having a positive refractive power; a fifth lens group having a positive refractive power; and an aperture stop arranged between the third lens group and the fourth lens group, an interval between the first lens group and the second lens group being increased, an interval between the second lens group and the third lens group being increased, an interval between the third lens group and the fourth lens group being decreased, and an interval between the fourth lens group and the fifth lens group being decreased when changing a magnification from a wide-angle end to a telephoto end, the third lens group including one negative lens made of a negative meniscus lens having a concave surface on the object side, and focusing being performed by moving the third lens group in an optical axis direction, wherein a curvature radius of an object side surface of the third lens group, R31, a curvature radius of an image side surface of the third lens group, R32, a focal length of the third lens group, F3, a synthesis focal length of the second and third lens groups at the wide-angle end, F23w, a synthesis focal length of the second and third lens groups at the telephoto end, F23t, a focal length at the wide-angle end, Fw, a focal length at the telephoto end, Ft, and √(Fw×Ft), Fm satisfy the following conditions (1), (2), (3):