| 摘要 |
PURPOSE:To obtain a zoom lens which has superior image forming performance by moving all four lenses which is divergent, convergent, divergent, and convergent, successively from an object side to and from an image plane during power variation, and satisfying specific conditions. CONSTITUTION:The 1st lens group G1 includes a positive lens element L1 which has a large-curvature surface on the object side, a negative meniscus lens element L2 having a convex surface on the object side, and a negative lens element L3 formed by cementing a negative and a positive lens together successively from the object side. Further, the 2nd, the 3rd, and 4th lens groups G2, G3, and G4 are provided. Then, inequalities I and II hold, where r1 and r2 are the radii of curvature of the object- and image-side surfaces of the positive lens component L1 closest to the object side in the 1st lens group G1 and n3 and n4 are the refractive indexes of the negative and positive lenses forming the negative cemented lens element L3. |
