| 摘要 |
<p>A variable-power optical system in which the cross-section perpendicular to the imaging surface, parallel to the minor-axis direction of the imaging surface, and including the optical axis is a first cross-section, and the cross-section orthogonal to the first cross-section and including the optical axis is a second cross-section, the variable-power optical system having at least three groups having an anamorphic power in which the power differs between the first cross-section and the second cross-section, and of the groups having an anamorphic power, at least two groups are fixed groups that are fixed in position during power variation, at least one group is a moving group which moves during power variation, and the following conditions are satisfied: 0.6 < fw1/fw2 < 0.9, 0.6 < ft1/ft2 < 0.9, 1.03 < f1_g/f2_g < 1.50 (fw1, fw2: focal lengths on the first and second cross-sections at the wide-angle end; ft1, ft2: focal lengths on the first and second cross-sections at the telephoto end; f1_g, f2_g: focal lengths on the first and second cross-sections of any group having an anamorphic power).</p> |
