Patent ID: 8625204

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; and a fourth lens unit having a positive refractive power, each of the first lens unit, the second lens unit, the third lens unit, and the fourth lens unit moving along an optical axis of the zoom lens from a wide-angle end to a telephoto end to perform zooming, wherein the first lens unit includes not more than two lenses, the second lens unit includes not more than three lenses including at least a positive lens and a negative lens, the third lens unit includes a single lens having a positive refractive power and a single lens having a negative power in order from the object side to the image side, and the fourth lens unit consists of a single lens, and wherein the following conditions are satisfied: 1.0<(β3 t/β 3 w )/(β2 t/β 2 w ) T 12 /ft< 0.30 0.8 <|f 2 |/fw< 5.0 where β3t and β3w are imaging magnifications on the telephoto end and the wide-angle end of the third lens unit, β2t and β2w are imaging magnifications on the telephoto end and the wide-angle end of the second lens unit, T12 is a sum of thicknesses on the optical axis of the first lens unit and the second lens unit, f2 is a focal length of the second lens unit, ft and fw are focal lengths at the telephoto end and the wide-angle end of the entire zoom lens.