IMAGE FORMING OPTICAL SYSTEM, IMAGE PICKUP APPARATUS USING THE SAME, AND INFORMATION PROCESSING APPARATUS

摘要

An optical system includes, in order from the object side, an aperture, a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, a fourth lens having a positive refractive power and having a meniscus shape with a convex surface facing the image side, and a fifth lens having a negative refractive power. The optical system satisfies a certain condition.

主权项

1. An image forming optical system comprising, in order from the object side, an aperture, a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens, a fourth lens having a meniscus shape with a convex surface facing the image side, and a fifth lens having a negative refractive power, and the image forming optical system satisfying the following conditional expression:
φs9/φs10<0.65, where φs9 is the effective diameter of the fourth lens on its image side, and φs10 is the effective diameter of the fifth lens on its object side.