| 摘要 |
PROBLEM TO BE SOLVED: To provide a zoom lens adequate to any device using a high resolution imaging device. SOLUTION: This zoom lens is constituted of four lens groups G1, G2, G3, and G4 which are positive, negative, negative and positive, respectively, in this order from an object side. The focal length of the entire system at a wide angle end is defined as fW, and the focal lengths of the first, the second and the third lens groups are defined as f1, f2, and f3, respectively, and condition expressions (1) 0.05<fW/f1<0.25, (2) 0.2<|fW/f2|<0.7, and (3) 0.15<|fW/f3|<0.45 are satisfied. The four lens groups are constituted of only spherical lens. The second lens group G2 is constituted of two lenses, and the fourth lens group G1 is constituted of at least three lenses including one negative lens. In the case of zooming, the first and the fourth lens groups G1 and G4 are fixed the group G2 is moved in the optical axis direction so that power variation is attained, and the group G3 is moved in the optical axis direction so that the image surface shift due to the power variation is compensated.
|
