Patent ID: 7283314

Claim:
A zoom lens comprising, in order from an object side to an image side: a first lens unit with a negative refractive power; a second lens unit with a positive refractive power; and a third lens unit with a positive refractive power, wherein each of the first and second lens units moves for zooming such that a first gap between the first lens unit and the second lens unit when the zoom lens is at a wide-angle end is smaller than the first gap when the zoom lens is at a telephoto end and such that a second gap between the second lens unit and the third lens unit when the zoom lens is at the wide-angle end is larger than the second gap when the zoom lens is at the telephoto end, and wherein the second lens unit includes at least one positive cemented lens, wherein, where a first lens cemented lens has the largest refractive power among the at least one positive cemented lens, the first cemented lens includes a first positive lens element and a first negative lens element, and the following conditions are satisfied: 0.9 <f 2 c/f 2<1.5 1.8<( N 2 p+N 2 n )/2 15<ν2 n−ν 2 p< 30 where f 2 c is the focal length of the first cemented lens, f 2 is the focal length of the second lens unit, N 2 p is the refractive index of a material of the first positive lens element included in the first cemented lens, N 2 n is the refractive index of a material of the first negative lens element included in the first cemented lens, ν 2 p is the Abbe number of the material of the first positive lens element included in the first cemented lens, and ν 2 n is the Abbe number of the material of the first negative lens element included in the first cemented lens.