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Title:
ZOOM LENS
Document Type and Number:
Japanese Patent JPH0248624
Kind Code:
A
Abstract:
PURPOSE:To attain AF with high accuracy in the whole area of zooming by executing a focusing operation by a fourth lens component instead of a third lens component being a compensator. CONSTITUTION:The zoom lens is provided with a first lens component I which has positive refracting power and fixed in the course of zooming, a second lens component II which moves forward and backward on an optical axis at the time of zooming, and executes variable power, a third lens component III which has negative refracting power, moves forward and backward on the optical axis at the time of zooming and corrects the movement of an image point, a fourth lens component IV which has positive refracting power and executes focusing, and a fifth lens component V which has positive refracting power and fixed in the course of zooming. A tracking curve of a fourth lens component IV is constituted so as not to have an extreme value, therefore, both speed and acceleration of a fourth lens component IV at the time of zooming always go to the same direction, and a control of a lens driving system by AF is facilitated. Accordingly, AF can be attained with high accuracy in the whole area of zooming.

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Inventors:
SAKA MANAMI
TANAKA MASAMI
HATA KAZUYOSHI
AMADA MITSUHIRO
Application Number:
JP20155688A
Publication Date:
February 19, 1990
Filing Date:
August 11, 1988
Export Citation:
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Assignee:
MINOLTA CAMERA KK
International Classes:
G02B15/20; G02B15/22; (IPC1-7): G02B15/20; G02B15/22
Domestic Patent References:
JP2011012906A2011-01-20
JP2011012905A2011-01-20
JP2007032904A2007-02-08
JP2004352531A2004-12-16
JP2007248010A2007-09-27
JP2005197108A2005-07-21
JP2010257644A2010-11-11
JP2008045843A2008-02-28
JP2001248906A2001-09-14
Foreign References:
EP1770806A12007-04-04
EP1772682A22007-04-11
EP1798488A22007-06-20
EP1764562A12007-03-21
DE3311127A11984-10-11



 
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