Patent ID: 6542312
Filing Date: 2003-04-01
Classification: G02B

Abstract:
A zoom lens, comprising:a first lens group having positive refracting power and fixed with respect to an image plane; a second lens group having negative refracting power and varying power, wherein the power is varied by moving along an optical axis; a third lens group having positive refracting power and fixed with respect to the image plane; and a fourth lens group having positive refracting power and moving along an optical axis so as to keep the image plane varied by movement of the second lens group and an object at a predetermined position from a reference surface; wherein the first, second, third, and fourth lens groups are disposed from the object side to the image plane side in this order, the second lens group comprises at least one aspherical surface, the third lens group comprises three lenses including a first positive lens, a second positive lens and a negative lens disposed from the object side in this order and comprises at least one aspherical surface, the fourth lens group comprises a positive lens with said positive lens including at least one aspherical surface, and the zoom lens has a zoom ratio of at least about 14 times.