Image pickup optical system and image pickup apparatus using the same

摘要

An image pickup optical system includes in order from an object side, a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, and a fourth lens having a negative refractive power. The first lens has a biconvex shape. An image-side surface of the second lens has a shape such that, a concave surface is directed toward an image side. At least an image-side surface of the third lens has a shape such that, a convex surface is directed toward the image side. An aperture is disposed nearest to the object side, and the following conditional expression (1) is satisfied:
0.9where f1 denotes a focal length of the first lens and f denotes a focal length of the overall image pickup optical system.

主权项

1. An image pickup optical system comprising in order from an object side:
a first lens having a positive refractive power; a second lens having a negative refractive power; a third lens having a positive refractive power; and a fourth lens having a negative refractive power,wherein:
the first lens has a biconvex shape, the second lens has a biconcave shape, an object-side surface which is a concave surface directed toward an object side in the vicinity of an optical axis, and an image-side surface which is a concave surface directed toward an image side, at least an image-side surface of the third lens has a shape such that, a convex surface is directed toward the image side, an aperture stop is disposed nearer to the object side than the first lens is, and the following conditional expression (1) is satisfied:
0.9