| 摘要 |
PROBLEM TO BE SOLVED: To obtain a stable photographic image by making small-sized a lens system and its driving system by a variable power optical system which comprises four positive, negative, positive, and positive groups while having the 3rd group composed of a positive (3a)th group, a negative (3b)th group, and a (3c)th group, and corrects a blur of the photographic image by using the (3b)th group, and excellently correcting various aberrations. SOLUTION: A positive 1st lens group G<SB>1</SB>which is fixed during power variation and focusing, a negative 2nd lens group G<SB>2</SB>having a power varying function, a positive 3rd lens group G<SB>3</SB>, and a 4th lens group G<SB>4</SB>having a function of correcting image plane variation due to power variation and a focusing function are arranged in order from an object side. The 3rd lens group G<SB>3</SB>is constituted by arranging a positive (3a)th lens group (7th lens L<SB>7</SB>), a negative (3b)th lens group (8th lens L<SB>8</SB>), and a (3c)th lens group (9th lens L<SB>9</SB>), and the (3b)th lens group (8th lens L<SB>8</SB>) is moved orthogonally to an optical axis X to correct blur of a photographic image accompanying vibration of the variable power optical system. COPYRIGHT: (C)2005,JPO&NCIPI
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