Patent ID: 7605859

Claim:
An image pickup optical system that forms a subject image on an electronic image pickup device and optically reduces color flares due to chromatic aberrations, the image pickup optical system comprising: at least one optical element configured to receive a light beam; and a wavelength correction element configured to control spectral characteristics of the received light beam; wherein the wavelength correction element is configured such that: a wavelength contributing to color flares, μ 1 , is allowed to exist within a wavelength range of d-line or shorter, and a wavelength λc whose transmittance is a half value of d-line transmittance satisfies the following condition (14): λ1 ≦λc≦d -line(587.56 nm); (14) where μ 1 satisfies the following condition (13): ( Lλ−Ld )/ F min =0.05 mm; (13) where F min is the minimum F-number of said optical system, Lλ is the absolute value of spherical aberrations for a marginal ray at an arbitrary wavelength k, and Ld is the absolute value of spherical aberration for a d-line (587.56 nm) marginal ray when the F-number is F min .