Zoom lens and image pickup apparatus having the same

摘要

A zoom lens includes a first lens unit having negative refractive power, a second lens unit having positive refractive power, a third lens unit having negative refractive power, and a fourth lens unit having positive refractive power, in order from an object side to an image side, each lens unit moving during zooming, and the third lens unit moving toward the object side during focusing from an infinitely-distant object to a nearby object. A focal length f3 of the third lens unit, a composite focal length f12t of the first lens unit and the second lens unit at a telephoto end, a focal length fw of the entire system at a wide-angle end, and a focal length ft of the entire system at the telephoto end are appropriately set.

主权项

1. A zoom lens comprising, in order from an object side to an image side:
a first lens unit having negative refractive power; a second lens unit having positive refractive power; a third lens unit having negative refractive power; and a fourth lens unit having positive refractive power, wherein each lens unit moves during zooming, wherein the third lens unit moves toward the object side during focusing from an infinitely-distant object to a nearby object, and wherein, when a focal length of the third lens unit is f3, a composite focal length of the first lens unit and the second lens unit at a telephoto end is f12t, a focal length of the entire zoom lens at a wide-angle end is fw, and a focal length of the entire zoom lens at the telephoto end is ft, the mathematical conditions below are satisfied:
−1.50