VARIABLE POWER OPTICAL SYSTEM, IMAGING DEVICE, METHOD OF VARYING MAGNIFICATION OF VARIABLE POWER OPTICAL SYSTEM

WIPO Patent Application WO/2008/010563

A1

A variable power optical system having a high ratio of magnification variation and excellent optical performance, an imaging device, and a method of varying the magnification of a variable power optical system. The variable power optical system has, in the mentioned order from the object side, a first lens group (G1) having negative refractive power, a second lens group (G2) having positive refractive power, a third lens group (G3) having negative refractive power, and a fourth lens group (G4) having positive refractive power. The variable power optical system also has an aperture stop (S) provided between the second lens group (G2) and the fourth lens group (G4). When the magnification is varied from a wide-angle end state (W) to a tele end state (T), each lens group moves such that the distance between the second lens group (G2) and the third lens group (G3) increases and the distance between the third lens group (G3) and the fourth lens group (G4) decreases, and such that the aperture stop (S) moves together with the third lens group (G3). The variable power optical system satisfies a predetermined conditional formula.

SHIBATA SATORU (JP)
SUZUKI TAKESHI (JP)
YAMAMOTO HIROSHI (JP)

PCT/JP2007/064300

January 24, 2008

July 12, 2007

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NIKON CORP (JP)
SHIBATA SATORU (JP)
SUZUKI TAKESHI (JP)
YAMAMOTO HIROSHI (JP)

G02B15/20; G02B13/18

JP2006113573A	2006-04-27
JPH09113808A	1997-05-02
JPH11174329A	1999-07-02
JP2001183585A	2001-07-06
JP2004061910A	2004-02-26
JPH11174329A	1999-07-02
US20050013015A1	2005-01-20

See also references of EP 2045639A4

INOUE, Yoshio (1-4 Nihonbashi,3-chome, Chuo-k, Tokyo 27, JP)

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