| 摘要 |
There is provided an optical system configured of 4-sheet lenses to have a wide angle of view. The optical system includes: a first lens having a positive refractive power, with both surfaces being convex; a second lens having a negative refractive power, with both surfaces thereof being concave; a third lens having a positive refractive power and a meniscus shape; and a fourth lens having a negative refractive power, with both surfaces thereof being concave, all of which are disposed in order from an object to a front upper surface. In the optical system, the refractive powers of the first lens to the fourth lens satisfy the following Conditional Expression 1. f   1 f   4 < - 1.1 Conditional   Expression   1 In Conditional Expression, f1: a focal distance of the first lens and f4: a focal distance of the fourth lens. |
