| 摘要 |
PROBLEM TO BE SOLVED: To provide a rationally priced and thermally stable zoom lens, capable of reducing the movement of an image plane to the rear element of the zoom lens caused by thermal reaction of a plastic lens. SOLUTION: This zoom lens includes a positive power 1st lens group, having a 1st lens element and a 2nd lens element, and a negative power 2nd lens group having a 3rd lens element. The 1st lens element can be made from plastic, has meniscus shape that is concave or convex toward the object side, and has an aspherical surface on either or both sides. The 1st lens group includes a variable iris, having a mechanical aperture stop positioned in between the 1st lens element and the 2nd lens element.
|
