Patent ID: 8498051
Filing Date: 2013-07-30
Classification: G02B

Abstract:
1. A zoom lens system comprising, in order from an object along an optical axis a first lens group having positive refractive power; a second lens group having negative refractive power; a third lens group having positive refractive power; and an additional lens group being disposed to the most image side, the additional lens group having positive refractive power and including, in order from the object, a front group and a rear group having positive refractive power, a distance along the optical axis between the front group and the rear group being fixed upon zooming, focusing on the object being carried out by moving the rear group along the optical axis, the front group being fixed with respect to an image plane during focusing, and the following conditional expression being satisfied: where D denotes a distance along the optical axis between the most image side surface of the front group and the most object side surface of the rear group upon focusing on infinity, and fNb denotes a focal length of the rear group.