US Patent No. 9,804,369

ZOOM LENS AND IMAGING APPARATUS INCLUDING THE SAME


Patent No. 9,804,369
Issue Date October 31, 2017
Title Zoom Lens And Imaging Apparatus Including The Same
Inventorship Yu Inomoto, Saitama (JP)
Assignee Canon Kabushiki Kaisha, Tokyo (JP)

Claim of US Patent No. 9,804,369

1. A zoom lens comprising, in order from an object side to an image side:
a first lens unit having positive refractive power;
a second lens unit having negative refractive power;
a third lens unit having positive refractive power; and
a fourth lens unit having positive refractive power,
wherein, during zooming from a wide-angle end to a telephoto end, the first lens unit does not move and at least the second
lens unit and the fourth lens unit move, and a distance between adjacent lens units varies during zooming,

wherein the first lens unit includes, in order from the object side to the image side thereof, a negative lens, a positive
lens, a positive lens, and a positive lens, and the second lens unit includes three or more lens elements including at least
one positive lens,

wherein one of the positive lenses included in the first lens unit satisfies a following conditional expression:
74.0 wherein the second lens unit includes a positive lens that satisfies a following conditional expression:
10.0 where Abbe number of a material of the one positive lens included in the first lens unit is denoted by ?d1p and Abbe number
of a material of the positive lens provided in the second lens unit is denoted by ?d2p, and

wherein following conditional expressions are satisfied:
?7.30
1.16
3.80
0.95<(TL/?t)/(ft/fw)<1.20, and

?12.00
where a focal length of the first lens unit is denoted by f1, a focal length of the second lens unit is denoted by f2, a focal
length of the third lens unit is denoted by f3, a focal length of the fourth lens unit is denoted by f4, a focal length of
an entire system at the wide-angle end is denoted by fw, and a lateral magnification of the second lens unit during focusing
on an infinite-distance object at the telephoto end is denoted by ?2t, a distance on an optical axis from a lens surface closest
to the object side in the first lens unit to an image plane is denoted by TL, an effective image circle radius at the telephoto
end is denoted by ?, and a focal length of the entire system at the telephoto end is denoted by ft.