| 摘要 |
Provided is a wide angle image pickup optical system composed of four lenses, the wide angle image pickup optical system that is capable of sufficiently decreasing various types of aberrations including chromatic aberration of magnification. The wide angle image pickup optical system includes the following arranged from the object side to the image plane side: a first lens that is a negative meniscus lens having a convex surface on the object side; a second lens that is negative; a third lens that is positive; an aperture stop; and a fourth lens that is positive , wherein the following expressions are satisfied, where &ngr;2, &ngr;3, and &ngr;4 represent abbe numbers of materials that form the second to fourth lenses with respect to a d-line, respectively, f2 and f3 represent focal distances of the second and third lenses, respectively, and f represents a focal distance of the whole optical system: &ngr;2>35 (1) &ngr;3<45 (2) &ngr;4>35 (3) &ngr;2-&ngr;3≥10 (4) &ngr;4-&ngr;3≥10 (5) -2.3 ≤ f2/f ≤ -1.5 (6) 3.0 ≤ f3/f ≤ 4.0 (7) |
