Patent ID: 7295381

Claim:
A zoom lens comprising, in order from an object side to an image side: a first lens unit having a negative refractive power; and a second lens unit having a positive refractive power, wherein an interval between the first lens unit and the second lens unit changes during zooming, wherein the first lens unit includes, in order from the object side to the image side, a negative lens and a positive lens, wherein a refractive index of a material of the negative lens (n 1 ), a refractive index of a material of the positive lens (n 2 ), a focal length of the first lens unit (f 1 ), a power of an air lens between the negative lens and the positive lens (φair), the negative lens having a radius of curvature (r 1 a ) of its surface facing the object side, the negative lens having a radius of curvature (r 1 b ) of its surface facing the image side, the positive lens having a radius of curvature (r 2 a ) of its surface facing the object side, the positive lens having a radius of curvature (r 2 b ) of its surface facing the image side satisfy the following conditions: 0.10 <n 2 −n 1<0.35 −0.80<φair· f 1<−0.10 −50<( r 1 b+r 2 a )/( r 1 b−r 2 a )<−8 0.25<( r 1 a+r 2 b )/( r 1 a−r 2 b )<0.80.