| 摘要 |
PROBLEM TO BE SOLVED: To solve such a problem that in a conventional optical system, when it is attempted that an F-number is made smaller and the size of an optical system is made smaller, the influence of various aberrations, especially the influence of a coma aberration is increased.SOLUTION: An imaging optical system includes, in order from an object side, a first lens having positive refractive power, a second lens having negative refractive power, a third lens having positive refractive power, a fourth lens having positive refractive power, and a fifth lens having negative refractive power. The fourth lens is a meniscus lens having a convex surface toward an image side and a diaphragm is arranged on the most object side. The imaging optical system satisfies the following conditional expression (1): 0.5<TL/(2×IH)<1.5 (1). |
