Patent ID: 8721094

Claim:
A lens system comprising, in order from an object side: a first lens group; and a second lens group having positive refractive power; the first lens group including a sub-lens group having positive refractive power, and a sub-lens group having negative refractive power, the sub-lens group having negative refractive power including a meniscus lens having a convex surface facing the object side, the following conditional expressions being satisfied: 1.910<ndh −0.400 <f/f 1<0.500 24.0<νdh where ndh denotes a refractive index at d-line (wavelength=587.6 nm) of a lens having the highest refractive index at d-line in the lens system, f 1 denotes a focal length of the first lens group, f denotes a focal length of the lens system, and νdh denotes an Abbe number at d-line of the lens having the highest refractive index at d-line in the lens system, an antireflection coating being formed on at least one optical surface in the first lens group and the second lens group, and the antireflection coating including at least one layer formed by a wet-process.