Patent ID: 6972909

Claim:
A zoom lens comprising, in order from an object side to an image side: a first lens unit having positive optical power; a second lens unit having negative optical power; a third lens unit having positive optical power; and a fourth lens unit having positive optical power, wherein the second lens unit and the fourth lens unit move during zooming, wherein the second lens unit consists of, in order from the object side to the image side, a lens 21 having a negative refractive power in which absolute value of refractive power in an image-side surface is larger than that in an object-side surface, a lens 22 having a negative refractive power and whose object-side surface is concave, and a lens 23 having a positive refractive power in which absolute value of refractive power in an object-side surface is larger than that in an image-side surface, and wherein with air intervening between the lens 22 and the lens 23 , the following condition is satisfied: υ 23 <20.0, N 23 >1.9, −0.1 <f 2 /f 2 t<− 0.05, where f2 represents a focal length of the second lens unit, ft represents a focal length of the entire system at a telephoto end zoom position, and υ 23 and N 23 represent an Abbe number and a refractive index of a material forming the lens 23 , respectively.