Patent ID: 8760770

Claim:
A zoom lens comprising: a first lens group having positive refracting power; a second lens group having negative refracting power; a third lens group having positive refracting power; a fourth lens group having positive refracting power; and a fifth lens group having positive refracting power arranged in this order from an object side toward an image side, wherein when the zoom lens undergoes zooming operation from a wide-angle end toward a telescopic end, the first lens group moves away from the second lens group toward an object to be imaged, the third lens group approaches the second lens group toward the object, and the fourth lens group approaches the third lens group toward the object, the third lens group is formed of at least two lenses and at least one air separation formed therebetween, the zoom lens satisfies the following conditional expression (1) 4.5<100× D ( T, 2−3)/ fW< 15 (1), and the third lens group satisfies the following conditional expression (2) 2.0< d (3,air)/ D ( T, 2−3) (2) where D(T, 2−3) represents the distance along an optical axis between the surface in the second lens group that is closest to an image to be formed and the surface in the third lens group that is closest to the object to be imaged in the telescopic-end zoom position, and fW represents the focal length of the entire optical system in the wide-angle-end zoom position, and where d(3, air) represents the largest of air separations in the optical axis direction present in the third lens group.