| 摘要 |
<p>[Problem] To provide a zoom lens for projection, having a five-lens group structure, which exhibits excellent aberration correction even if the angle of view is widened. [Solution] Essentially, a first lens group (G1) having negative refractive power, and second-fifth lens groups (G2-G5) all having positive refractive power are arranged in order from the magnification side, and the reduction side is a telecentric structure. Additionally: during a change in magnification, the first lens group (G1) and the fifth lens group (G5) are fixed, and the second-fourth lens groups (G2-G4) are movable; the fourth lens group (G4) is formed so as to include at least three positive lenses (L11, L13, L14); and the lens (L10) in the fourth lens group (G4) which is furthest toward the magnification side has a convex surface on the magnification side thereof. Furthermore, the following conditional expression is satisfied, wherein fw is the focal length of the entire system at the wide-angle end and f4 is the focal length of the fourth lens group (G4): 7.5<f4/fw<14.5...(1).</p> |
