Zoom lens and image pick-up apparatus having the same

摘要

A zoom lens includes, in order from the object side to the 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 negative refractive power, and a rear lens group including a plurality of lens units and having a positive refractive power as a whole. The distances between adjacent lens units are changed during zooming. The third lens unit is moved during focusing. The focal length, fw, of the entire zoom lens system at the wide-angle end; the focal length, ft, of the entire zoom lens system at the telephoto end; the combined focal length, f12w, of the first and second lens units at the wide-angle end; and the combined focal length, f12t, of the first and second lens units at the telephoto end are appropriately set to satisfy predetermined conditions.

主权项

1. 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 negative refractive power; and a rear lens group including a plurality of lens units and having a positive refractive power as a whole, wherein the rear lens group consists of, in order from an object side to an image side:
a fourth lens unit having a positive refractive power, anda fifth lens unit having a positive refractive power;ora fourth lens unit having a positive refractive power,a fifth lens unit having a negative refractive power, anda sixth lens unit having a positive refractive power; wherein distances between adjacent lens units of the rear lens group are changed during zooming, wherein the first lens unit moves during zooming, and the third lens unit moves during focusing, wherein conditions 3.7<|f12w/fw|<8.5 and 1.0<|f12t/ft|<5.5 are satisfied, where fw is a focal length of the zoom lens at a wide-angle end, ft is a focal length of the zoom lens at a telephoto end, f12w is a combined focal length of the first and second lens units at the wide-angle end, and f12t is a combined focal length of the first and second lens units at the telephoto end, and wherein f12w is calculated from 1/f12w=1/f1+1/f2−dw/(f1·f2), and f12t is calculated from 1/f12t=1/f1+1/f2−dt/(f1·f2), where f1 is a focal length of the first lens unit, f2 is a focal length of the second lens unit, dw is a distance between a principal point of the first lens unit and a principal point of the second lens unit at the wide-angle end, and dt is a distance between a principal point of the first lens unit and a principal point of the second lens unit at the telephoto end.