| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a zoom lens that is small in size in the entire system and has a high zoom ratio and high optical performance in the entire zoom range.SOLUTION: The zoom lens comprises, successively from an object side to an image side, a first lens group to fourth lens group having positive, negative, positive, and positive refractive powers, respectively, in which each lens group moves so as to vary a distance between adjoining lens groups upon zooming. The first lens group comprises, successively from the object side to the image side, negative, positive and positive lenses. The second lens group comprises, from the object side to the image side, a biconcave negative lens where an absolute value of a radius of curvature on a lens surface is smaller on the image side than on the object side, and a meniscus positive lens that is convex on the object side; and an average n2a of refractive indices to d-line of materials of lenses constituting the second lens group is appropriately set.</p> |
