Patent ID: 8797656
Filing Date: 2014-08-05
Classification: G02B

Abstract:
1. A zoom lens, comprising: a first lens group having a positive refracting power and normally positioned at a fixed position; a second lens group having a negative refracting power and movable in the direction of an optical axis for zooming; a third lens group having a positive refracting power; and a fourth lens group movable in the direction of the optical axis for correction of a focal position by zooming and for focusing; the first, second, third and fourth lens groups being disposed in order from the object side to the image side; the first lens group comprising three lenses including a negative lens, a positive lens and another positive lens disposed in order from the object side to the image side and satisfying the following conditional expressions (1), (2) and (3) where fw is the focal length of the entire lens system in a wide angle end state, ft is the focal length of the entire lens system in a telephoto end state, f1 is the focal length of the first lens group, and fL1 is the focal length of the negative lens of the first lens group.