| 摘要 |
PROBLEM TO BE SOLVED: To provide a zoom lens that has a zooming ratio of about 20 times and an F number of 2.0 or less at a short focal length-end, is inexpensively composed of a relatively small number of lenses, sufficiently corrects aberration even in a wavelength region of near infrared light, and has high resolution power.SOLUTION: A zoom lens is composed of four groups having positive, negative, negative and positive refractive power, and only a second lens group G2 and a third lens group G3 are moved when zooming. A fourth lens group G4 includes, in order from an object side, a positive lens L41 having a convex surface on the object side, a negative lens L42 having a concave surface on an image side, a positive lens L43, a negative lens L44, and a positive lens L45. The zoom lens satisfies a conditional expression: 0.1<(R411-R422)/(R411+R422)<0.6, where a curvature radius of the object side surface of the positive lens L41 is represented by R411 and a curvature radius of the image side surface of the negative lens L42 is represented by R422. |
