| 摘要 |
PROBLEM TO BE SOLVED: To provide a zoom lens which is sufficiently wide-angle with a half view angle of no less than 38 degrees at the wide angle end, and yet offers a magnification ratio of no less than 7x, an F-number of less than 3 at the wide angle end, a compact size, and resolving power compatible with image sensors with 10 to 15 million pixels.SOLUTION: A zoom lens includes a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, and a fourth lens group G4 having positive refractive power arranged in order from the object side. The first lens group G1 comprises a negative lens and a positive lens cemented together, and the second lens group G2 comprises a first negative lens, a second negative lens, and a positive lens arranged in order from the object side. A composite focal length fF of the first lens group G1 and the second lens group G2 at the wide angle end, a distance L2s along the optical axis from a most image side surface of the second lens group G2 to an aperture stop at the wide angle end, and a distance Ls3 along the optical axis from the aperture stop to a most object side surface of the third lens group G3 at the wide angle end satisfy predefined conditional expressions. |
