ZOOM LENS

摘要

PROBLEM TO BE SOLVED: To provide a zoom lens which is relatively bright and is well subjected to aberration correction from a visible region to a near IR region. SOLUTION: The zoom lens of four-group configuration (G1 to G4) of positive, negative, positive, and positive, successively from an object side, is well corrected in axial chromatic aberration from the visible region to the near IR region by especially satisfying conditional expressions (1) to (3). Further, the lens is made compact by satisfying conditional expression (4). In the respective expressions, nd2 represents the refractive indices of the second lens L12 to a d ray; vd1 and vd2 represent Abbe numbers to the d ray of the first and second lenses L11 and L12; f1 represents synthetic focal length of primary iens group G1; fw represents the focal length of the entire system at a wide angle end. However, the conditional expression (1): vd1<45, the conditional expression (2): nd2<1.52, the conditional expression (3): vd2>63, the conditional expression (4): 6