IMAGING LENS UNIT

摘要

PROBLEM TO BE SOLVED: To provide an imaging lens unit having a zoom lens system of about three times of a zoom ratio which has a high optical performance with a light weight and a compact structure. SOLUTION: A negative, positive and positive zoom lens system has a first group (Gr1) movable at a variable power time, a second group (Gr2) movable at the variable power time and a third group (Gr3) fixed at the variable power time, sequentially provided from a long conjugate length side. The lens system conducts the variable power by changing intervals of the groups. An imaging element (SR) transforms an optical image formed by the zoom lens system into an electrical signal. The first group (Gr2) has a diffraction grating surface (S1#), the second group (Gr2) has a diffraction grating surface (S3#), and the second group (Gr2) satisfies a conditional formula: 1.80