| 摘要 |
PROBLEM TO BE SOLVED: To provide a variable power optical system having a variable power ratio of approximately two to three times and also having a small size and high accuracy, and to provide an imaging lens device having the variable power optical system, and digital equipment equipped with the imaging lens device. SOLUTION: The variable power optical system comprising a plurality of lens groups and varies a power by changing distances between the lens groups in the direction of its optical axis. The variable power optical system includes, in order from the object side, two or more lens groups whose optical power are negative and positive. Where an angle to a normal set in an image plane of the main light ray at a wide angle end and that at a telephoto end are represented byα<SB>W</SB>andα<SB>T</SB>respectively, the absolute value of a difference between them satisfies the following relation: 15°<¾α<SB>W</SB>-α<SB>T</SB>¾<30°. COPYRIGHT: (C)2006,JPO&NCIPI |
