Patent ID: 8879164

Claim:
A zoom lens comprising, in order from an object side: a first lens unit having a positive refractive power, which does not move for varying magnification; a second lens unit having a negative refractive power, which moves during varying magnification; a third lens unit having a positive refractive power, which moves during varying magnification; and a fourth lens unit having a positive refractive power, which does not move for varying magnification, wherein the first lens unit comprises, in order from the object side, a first lens subunit having a negative refractive power, which does not move for focusing, a second lens subunit having a positive refractive power, which moves during focusing, and a third lens subunit having a positive refractive power, which does not move for focusing; the third lens unit forms such a locus as to move toward an image side during varying magnification toward a telephoto end from a wide angle end and then move toward the object side; and the following expressions are satisfied: −2.2 <f 1 /f 2<−0.8, −0.7<1/β3 w< 0.5, −0.55 <f 2 /f 3<−0.25, and −6.0 <f 12 /f 11<−2.5, where f 1 represents a focal length of the first lens unit, f 2 represents a focal length of the second lens unit, f 3 represents a focal length of the third lens unit, β 3 w represents a magnification of the third lens unit at the wide angle end, f 11 represents a focal length of the first lens subunit and f 12 represents a focal length of the second lens subunit.