| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an imaging optical system which offers a small distance to an image sensor, reduced size, a small F-number, a reduced exit angle of light rays, good correction for various aberrations while shooting in a range from infinity to a short distance, and a view angle of approximately 40-60°.SOLUTION: An imaging optical system comprises, in order from an object side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, and a third lens group G3 having negative refractive power. When shifting focus from an object at infinity to an object at a short distance, the second lens group G2 moves toward the object side while the first lens group G1 and third lens group G3 are stationary relative to an image plane I. The first lens group G1 includes an aperture stop S and comprises prescribed lens groups, and the third lens group G3 comprises a prescribed lens groups. The imaging optical system satisfies predetermined conditional expressions.</p> |
