Patent ID: 7933072
Filing Date: 2011-04-26
Classification: G02B

Abstract:
1. A zoom lens comprising, in order from an object side: a first lens group having a negative refractive power; a second lens group having a negative refractive power; a third lens group having a positive refractive power; a stop; and a fourth lens group having a positive refractive power; when power varies from a wide angle end to a telephoto end, the first lens group and the second lens group are moved to an image surface along an optical axis and then moved to the object side, the third lens group and the fourth lens group are moved to only the object side along the optical axis, the first lens group includes at least one aspheric lens, and the aspheric lens has an aspheric shape in which a positive refractive power is increased toward the periphery of the lens when a paraxial refractive power is positive and a negative refractive power is decreased toward the periphery of the lens when the paraxial refractive power is negative.