Patent ID: 7630145

Claim:
A zoom lens comprising, in order from an object side to an image side: a first lens unit that does not move for zooming and has positive refractive power; a second lens unit that is configured to move during zooming and has negative refractive power; a third lens unit that is configured to move during zooming and has negative refractive power; and a fourth lens unit that does not move for zooming and has positive refractive power, wherein the first lens unit has, in order from the object side to the image side, a first lens subunit that does not move during focusing and has negative refractive power, a second lens subunit that is configured to move along an optical axis during focusing and has positive refractive power, and a third lens subunit that does not move during focusing and has positive refractive power, wherein the second lens subunit satisfies the conditions 0.95 <hz/ht inf<1.50, 0.83 <hw/hz< 1.16, and ht mod/ ht inf>1.0 and has at least one aspherical lens surface AS12, where, in lens surfaces of the second lens subunit, htinf is the maximum height of incidence of axial rays when the zoom lens is set at a telephoto end of the zooming range and focused on an object at infinity, htmod is the maximum height of incidence of the axial rays when the zoom lens is set at the telephoto end of the zooming range and focused on an object at a very short distance, hw is the maximum height of incidence of off-axis rays when the zoom lens is set at a wide-angle end and focused on an object at infinity, and hz is the maximum height of incidence of the off-axis rays when the zoom lens is set at a zoom ratio of Z 1/4 and focused on an object at infinity, where Z is the maximum zoom ratio, wherein, if the aspherical lens surface AS12 has positive refractive power, the aspherical lens surface AS12 is shaped such that the positive refractive power decreases from the center toward the periphery thereof, and wherein, if the aspherical lens surface AS12 has negative refractive power, the aspherical lens surface AS12 is shaped such that the negative refractive power increases from the center toward the periphery thereof.