Zoom lens system

• US 6,771,430 B2
• Filed: 09/17/2002
• Issued: 08/03/2004
• Est. Priority Date: 09/28/2001
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Obama, Akihiko
• Primary Examiner(s): Schwartz, Jordan M.
• Application Number:
  US10/244,424
• Publication Number:
  US 20030072088A1
• Time in Patent Office: 686 Days
• Field of Search: 359/680-682, 359/676, 359/683, 359/687-688, 359/690-691, 359/738-740
• US Class Current: 359/682
• CPC Class Codes: G02B 15/143507 arranged -++
• CPC Class Codes: G02B 15/177 having a negative front lens or group of lenses

Abstract

According to one aspect of the present invention, a zoom lens system includes, in order from an object along an optical axis, a first lens group having negative refractive power, and a second lens group having positive refractive power. A distance between the first lens group and the second lens group decreases when the state of lens group positions varies from a wide-angle end state to a telephoto end state. The second lens group is composed of, in order from the object, a first lens having positive refractive power, a first cemented lens having negative refractive power, and a second cemented lens having positive refractive power. The first cemented lens in the second lens group is constructed by a positive lens cemented with a negative lens. The second cemented lens in the second lens group is constructed by a negative lens cemented with a positive lens.

Claims

1. A zoom lens system comprising, in order from an object along an optical axis;

a first lens group having negative refractive power; and

a second lens group having positive refractive power;

a fixed stop being arranged between the first lens group and the second lens group;

a distance between the first lens group and the second lens group decreasing when the state of lens group positions varies from a wide-angle end state to a telephoto end state;

when the state of lens group positions varies from the wide-angle end state to a certain intermediate focal length state, a distance between the first lens group and the fixed stop decreasing as the fixed stop is moved with the second lens group in a body; and

when the state of lens group positions varies from the certain intermediate focal length state to the telephoto end state, a distance between the second lens group and the fixed stop decreasing as the fixed stop as moved with the first lens group in a body.

2. The zoom lens system according to claim 1, wherein the second lens group has an aperture stop;

and

wherein the following conditional expressions are satisfied;

3. The zoom lens system according to claim 2, further comprising a third lens group having positive refractive power located to the image side of the second lens group, wherein the third lens group is substantially fixed relative to the image plane when the state of lens group positions varies from the wide-angle end state to the telephoto end state.

4. The zoom lens system according to claim 1, further comprising a third lens group having positive refractive power located to an image side of the second lens group, wherein the third lens group is substantially fixed relative to the image plane when the state of lens group positions, varies from the wide-angle end state to the telephoto end state.