Patent ID: 8351132

Claim:
An image pickup optical system having five lenses, comprising in order from an object side: a first lens having a biconvex shape, and a positive refractive power; a second lens having a negative refractive power; a third lens having a meniscus shape with a concave surface thereof directed toward the object side, and a negative refractive power; a fourth lens having a meniscus shape with a concave surface thereof directed toward the object side, and a positive refractive power; and a fifth lens having a negative refractive power, wherein the third lens and the fourth lens are cemented, and the negative refractive power at a central portion of the third lens increases gradually toward a peripheral portion thereof, and the positive refractive power at a central portion of the fourth lens decreases gradually toward a peripheral portion thereof, and a cemented surface of the third lens and the fourth lens is an aspheric surface, and the cemented surface becomes a concave surface all the time with respect to the object side, at the central portion and the peripheral portion.