Patent ID: 8279526

Claim:
A photographing optical system comprising: a plurality of lenses in an optical path, each lens having optical surfaces; an optical element formed of resin in the optical path; and a plurality of depressions or protrusions of a size not larger than wavelengths of visible light, and without having a periodic structure or being in a random arrangement, formed on at least two optical surfaces of the plurality of lenses which are located on a light incidence side of the optical element, the plurality of depressions or protrusions configured to scatter ultraviolet light and prevent reflection of visible light, wherein the following conditional expression is satisfied: 0<A2/D12<2.0, in which A2 is an effective diameter of one of two optical surfaces closest to the optical element, and D12 is a distance between the two optical surfaces, wherein the plurality of depressions or protrusions satisfies the following conditional expressions: Sa> 1%, Sb< 1%, and Rb< 5%, wherein Sa is a scattering rate at a wavelength of 360 nm, Sb is a scattering rate at a wavelength of 550 nm, and Rb is a reflectance at a wavelength of 550 nm.