Patent ID: 7535653
Filing Date: 2009-05-19
Classification: G02B

Abstract:
1. A zoom lens, comprising: a first group optical system having a negative focal length; a second group optical system having a positive focal length and including at least two positive lenses and at least one negative lens in which one of the two positive lenses is disposed nearest to an object side in the second group optical system; a third group optical system having a positive focal length, the first group optical system, the second group optical system and the third group optical system being arranged in this order from the object side to an image side; and an aperture stop configured to move together with the second group optical system and disposed on the object side of the second group optical system, a change in magnification being carried out by decreasing a space between the first group optical system and the second group optical system when the change in magnification is carried out from a short focal length end to a long focal length end, wherein the following formulae are satisfied: in which Nn represents a refractive index of a lens with a highest refractive index in the at least one negative lens of the second group optical system, and νn represents an Abbe number of the lens with the highest refractive index in the at least one negative lens of the second group optical system.