Patent ID: 6839185
Filing Date: 2005-01-04
Classification: G02B

Abstract:
1. A zoom lens apparatus, comprising: a first optical lens group having a negative focal length arranged at a first position closest to a subject; a second optical lens group having a positive focal length arranged at a second position second closest to the subject; an aperture diaphragm which is disposed to a subject side of the second optical lens group closer to the subject in a manner such that the aperture diaphragm is movable integrally with the second optical lens group; and a third optical lens group, having a positive focal length arranged at a third position third closest to the subject, wherein the first optical lens group, the second optical lens group, and the third optical lens group move in such a way that a distance between the first optical lens group and the second optical lens group is gradually decreased and a distance between the second optical lens group and the third optical lens group is gradually increased when a scaling of the zoom lens system is changed from a short focal length edge to a long focal length edge, wherein the second optical lens group comprises a three-group and four-lens structure which comprises: wherein the zoom lens system satisfies an inequality condition 0.15<(N