| 摘要 |
<p>[Problems to be Solved] In imaging lenses, to realize a compact and bright lens system having a wide angle of view and a long back focus. [Means for Solving the Problems] An imaging lens which includes a first lens (L1) having a meniscus shape with a convex surface of the object side and a negative refractive power, a second lens (L2) having a biconvex shape and a positive refractive power, a third lens (L3) having a concave surface on the image side and a negative refractive power, and a fourth lens (L4) having a convex surface on the object side and a positive refractive power arranged in order from the object side, and being configured to satisfy a conditional expressions (1) L12/f<0.82 and (2) :2.3<L12×R2F 2 /f 2 <10.0 simultaneously, where L12: is the distance between the first lens (L1) and the second lens (L2) on the optical axis, f is the focal length of the entire lens system, and R2F is the radius of curvature of the object side lens surface of the second lens (L2).</p> |
