| 摘要 |
PURPOSE: To provide a zoom lens featuring a small size, light weight, high specifications and high performance while having a large aperture diameter and high zoom ratio. CONSTITUTION: This zoom lens has, successively from an object side, a first lens group G1 having a positive refracting power, a second lens group G2 having a negative refracting power, a third lens group G3 having a negative refracting power and a fourth lens group G4 having a positive refracting power. The zoom lens is provided with the second lens group G2 and the third lens group G3 movably along the optical axis at the time of variable magnification from a wide angle end to a telephoto end. The first lens group G1 and the fourth lens group G4 are fixed along the optical axis. At least one face of the second lens group G2 has an aspherical face formed as an aspherical face. This aspherical face is so formed that the positive refracting power increases gradually or the negative refracting power decreases gradually from the optical axis to the periphery as compared with a spherical face having a paraxial radius of curvature. The zoom lens satisfies the conditions 10<-4> .h/2<|dx5|<|dx7|<|dx10|<10<-1> .h/2, 16<Zm.
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