| 摘要 |
<p>[Problem] To obtain a zoom lens that is more compact, lighter in weight, less susceptible to fluctuation in the angle of view during focusing, and capable of higher performance. [Solution] A zoom lens (1) comprises, in the stated order from the object side, a positive first lens group (G1) fixed during magnification change, a negative second lens group (G2) that moves to the image side during a magnification change from a wide-angle end to a telephoto end, a negative third lens group (G3) for correcting image plane fluctuations during magnification change, and a positive fourth lens group (G4) fixed during magnification change. The first lens group (G1) comprises a negative first lens group forward group (G1f), a positive first lens group mid-group (G1m), and a positive first lens group rearward group (G1r), in the stated order from the object side. The first lens group forward group (G1f) comprises two negative lenses and a positive lens in the stated order from the object side. Focusing is carried out by moving only the first lens group mid-group (G1m) in the direction of an optical axis. The conditional formula (1) 2.5 < f1/fw < 5.4 is satisfied in regard to the focal length f1 of the first lens group (G1) and the focal length fw of the entire system at the wide-angle end.</p> |
