Patent ID: 8861093

Claim:
A zoom lens comprising, in order from an object side to an image side: a first lens unit having negative refractive power; a second lens unit having positive refractive power; and a third lens unit having positive refractive power, wherein a distance between every adjacent ones of the first to third lens units varies during zooming, wherein the second lens unit includes, in order from the object side to the image side, a positive lens and a cemented lens in which a positive lens and a negative lens are cemented, and wherein the following conditions are satisfied: 0.100 < f 2/ fT < 0.425 1.75 <Npave <2.50 0.5 < f 3/ fT < 0.9 where f 2 is a focal length of the second lens unit, f 3 is a focal length of the third lens unit, fT is a focal length of the entire zoom lens at a telephoto end, and Npave is an average refractive index of materials of the positive lenses included in the entire zoom lens.