| 摘要 |
PROBLEM TO BE SOLVED: To provide a lens system achieving a high magnification in a range of approximately 25x to 30x and a reduction in the size (total length) of the lens system to have a telephoto ratio of approximately 0.7.SOLUTION: A zoom lens system includes a positive first lens group, a negative second lens group, a positive third lens group, a negative fourth lens group, and a positive fifth lens group arranged in order from the object side. When zooming from the wide angle end to the telephoto end, the distance between the first lens group and the second lens group is widened and the distance between the second lens group and the third lens group is narrowed. The lens system satisfies the following conditional expressions (1), (2). (1) 0.30<f1/ft<0.43, (2) 7.0<M2t/M2w<17.0; where f1 represents a focal length of the first lens group, ft represents a focal length of the entire lens system at the long focal length end, M2w represents a lateral magnification of the second lens group at the short focal length end when focused at infinity, and M2t represents a lateral magnification of the second lens group at the long focal length end when focused at infinity. |
