| 摘要 |
A zoom lens substantially consists of, in order from the object side: a first lens group that has a positive refractive power and is fixed during magnification change; a second lens group that has a negative refractive power and is moved along the optical axis during magnification change; a third lens group that has a negative refractive power and corrects for fluctuation of the image plane along with magnification change; and a fourth lens group that has a positive refractive power and is fixed during magnification change. Focusing of an object at a distance between infinity and a predetermined distance is achieved by moving a first-group second lens sub-group, which is a part of the first lens group, along the optical axis, and focusing of an object at a closer distance than the predetermined distance is achieved by moving the third lens group along the optical axis. |
