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Zoom lens system

A zoom lens and lens group technology, applied in the field of zoom lens system, can solve the problems of large amount of movement and insufficient autofocus focusing speed

Inactive Publication Date: 2006-09-27
NIKON CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] However, in each of the embodiments disclosed in Japanese Patent Application Laid-Open No. 6-51202, the amount of movement of the focus lens required for focusing is still large, so the focusing speed of autofocus is insufficient

Method used

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Embodiment Construction

[0067] Embodiments according to the present invention are explained in detail below with reference to the drawings.

[0068] A zoom lens system according to an embodiment of the present invention is composed of, in order from an object: a first lens group having positive refractive power; a second lens group having negative refractive power; and a third lens group having positive refractive power. When the state of the lens group position is changed from the wide-angle end state to the telephoto end state, at least the first lens group and the third lens group are moved so that the distance between the first lens group and the second lens group increases, and the second lens group The distance between the second lens group and the third lens group is reduced. The first lens group is composed of the following in order from the object: a front lens group G1a, which has positive refractive power; and a rear lens group G1b, which has positive refractive power. The front lens grou...

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Abstract

Providing a zoom lens system that satisfies making the focusing lens light and reducing a moving amount for focusing, simultaneously. The zoom lens system includes a first lens group having positive power, a second lens group having negative power and a third lens group having positive power. When zooming from a wide-angle end state to a telephoto end state, at least the first and third lens groups are moved such that a distance between the first and second lens groups increases, and a distance between the second and third lens groups decreases. The first lens group is composed of a front lens group with positive power having at least one negative lens and at least one positive lens, and a rear lens group with positive power having one positive lens. Focusing from infinity to a close object is carried out by moving only the rear lens group to the object.

Description

[0001] The disclosures of the following prior applications are hereby incorporated by reference: [0002] Japanese Patent Application No. 2005-084117 filed March 23, 2005. technical field [0003] This invention relates to zoom lens systems suitable for use in single-lens reflex cameras. Background technique [0004] In the focusing method of the zoom lens system, there has been a widely used method: most of the object side lens group, which is the first lens group, is elongated. In this method, there is an advantage that the amount of movement for focusing does not depend on the zoom position and is determined by the distance to the object, so it is effective for simplifying the focusing mechanism. However, a plurality of lenses have to be moved for focusing, and the weight of the focusing lens group tends to become heavy, so it becomes difficult to make the focusing speed of autofocus faster. In order to solve this problem, a method has been proposed in which the first l...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G02B9/14G02B15/14
CPCG02B15/173G02B27/646G02B15/143105
Inventor 芝山敦史
Owner NIKON CORP
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