| 摘要 |
PURPOSE:To provide the zoom lens which is compact and maintains high performance although the aperture ratio is about 2.8 as to a zoom lens which has a wide field angle of 74 deg. or larger in maximum field angle. CONSTITUTION:The zoom lens has a 1st negative group (L1), a 2nd positive group (L2), a 3rd negative group (L3), and a 4th positive group (L4) in order from an object side and is varied in the overall power while an image plane position is held constant by moving the 1st, 2nd, and 4th groups in the direction of the optical axis so that the air interval between the 1st and 2nd groups and the air interval between the 3rd and 4th group decrease and the air interval between the 2nd group and 3rd group increases at the time of zooming from the short-focus side to a long-focus side; and the 1st group is equipped with a 1st negative lens, a 2nd positive lens, a 3rd negative lens, and a 4th lens block which has at least one negative lens and is negative on the whole. |
