Patent ID: 8390937

Claim:
A zoom lens comprising, in order from an object side: a first lens group having positive refractive power; a second lens group having negative refractive power; and a third lens group having positive refractive power, each distance between said lens groups adjacent to each other changing upon zooming from a wide-angle end state to a telephoto end state, said first lens group having a cemented lens including a negative lens, and said third lens group having a cemented lens, and the following conditional expressions being satisfied: 1.90 <Ndn< 2.50 4.50 <f 1 /fw< 7.00 where Ndn denotes a refractive index with respect to the d-line (λ=587.56 nm) of the negative lens of the first lens group, f 1 denotes a focal length of said first lens group, and fw denotes a focal length of said zoom lens in the wide-angel end state.