Patent ID: 8248707

Claim:
A zoom lens comprising, in order from an object side to an image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, a fourth lens unit having a positive refractive power, the first and third lens units being fixed and the second and fourth lens units being moved in zooming, wherein the second lens unit includes, in order from the object side to the image side, a sub-first lens having a negative refractive power, a sub-second lens having a negative refractive power, a sub-third lens having a negative refractive power, and a sub-fourth lens having a positive refractive power, and wherein the following conditional expressions are satisfied: 0.01 <|f 2/√( fw*ft )|<0.35 0.070 <D 2 /TL< 0.105 where fw is a focal length of an overall system at a wide angle end, ft is a focal length of the overall system at a telephoto end, f2 is a focal length of the second lens unit, TL is a distance on an optical axis from a lens surface closest to an object plane to an image plane when a distance from a lens surface closest to the image plane to the image plane is aerially converted, and D2 is a distance on the optical axis from a lens surface closest to the object plane in the second lens unit to the lens surface closest to the image plane in the second lens unit.