Zoom lens and imaging apparatus including the same
A zoom lens includes a first lens unit with positive refractive power, a second lens unit with negative refractive power, an intermediate group including an aperture stop and at least one lens unit, and a rear group including at least two lens units placed in this order from an object side to an image side, and an interval between adjacent lens units changes during zooming. The lens unit of the rear group placed closest to the object side has the strongest negative refractive power among lens units placed closer to the image side than the aperture stop. In zooming from a wide-angle end to a telephoto end, every lens unit of the first lens unit, the intermediate group, and the rear group moves toward the object side, and the second lens unit moves along a convex trajectory toward the image side. The zoom lens satisfies predetermined inequalities.
1 . A zoom lens comprising a plurality of lens units, the plurality of lens units consisting of a first lens unit with positive refractive power, a second lens unit with negative refractive power, an intermediate group including an aperture stop and at least one lens unit, and a rear group including at least two lens units placed in this order from an object side to an image side, wherein an interval between adjacent lens units changes during zooming,
wherein a lens unit of the rear group that is placed closest to the object side has the strongest negative refractive power among lens units placed closer to the image side than the aperture stop,
wherein, in zooming from a wide-angle end to a telephoto end, every lens unit included in the first lens unit, the intermediate group, and the rear group moves toward the object side, and the second lens unit moves along a convex trajectory toward the image side, and
wherein the following inequalities are satisfied:
3.30< f 1/| f 2|<5.90,
1.40<| f 2|/ bfw< 2.50, and
1.00< fn/f 2<1.60,
where f1 is a focal length of the first lens unit, f2 is a focal length of the second lens unit, bfw is a back focus of an entire system at a wide-angle end, and fn is a combined focal length of the rear group at the wide-angle end.
2 . The zoom lens according to claim 1 , wherein the following inequality is satisfied:
1.31< f 1/ ft< 2.81,
where ft is a focal length of the entire system at the telephoto end.
3 . The zoom lens according to claim 1 , wherein the following inequality is satisfied:
0.66<| f 2|/ fw< 1.41,
where fw is a focal length of the entire system at the wide-angle end.
4 . The zoom lens according to claim 1 , wherein the following inequality is satisfied:
1.14< Lt/ft< 2.49,
where Lt is a length from a lens surface closest to the object side to a lens surface closest to the image side on an optical axis at the telephoto end, and ft is a focal length of the entire system at the telephoto end.
5 . The zoom lens according to claim 1 , wherein the following inequality is satisfied:
0.43< fp/|fn|< 1.04,
where fp is a combined focal length of the intermediate group at the wide-angle end.
6 . The zoom lens according to claim 1 , wherein the following inequality is satisfied:
0.19<| fn/f 1<0.46.
7 . The zoom lens according to claim 1 , wherein the lens unit of the rear group that is placed closest to the object side moves during focusing.
8 . The zoom lens according to claim 7 , wherein the following inequality is satisfied:
1.00< ff/f 2<2.74,
where ff is a focal length of the lens unit of the rear group that is placed closest to the object side.
9 . The zoom lens according to claim 7 , wherein the following inequality is satisfied:
0.67< ff/fn< 2.04,
where ff is a focal length of the lens unit of the rear group that is placed closest to the object side.
10 . The zoom lens according to claim 1 , wherein the following inequality is satisfied:
0.28< fp/ft< 0.56,
where fp is a combined focal length of the intermediate group at the wide-angle end, and ft is a focal length of the entire system at the telephoto end.
11 . The zoom lens according to claim 1 , wherein the following inequality is satisfied:
0.88<| fn/fw< 2.03,
where fw is a focal length of the entire system at the wide-angle end.
12 . The zoom lens according to claim 1 , wherein the following inequality is satisfied:
0.38<| fn|/ft< 0.85,
where ft is a focal length of the entire system at the telephoto end.
13 . The zoom lens according to claim 1 , wherein the following inequality is satisfied:
2.83< Lt/fp< 5.92,
where Lt is a length from a lens surface closest to the object side to a lens surface closest to the image side on an optical axis at the telephoto end, and fp is a combined focal length of the intermediate group at the wide-angle end.
14 . The zoom lens according to claim 1 , wherein the following inequality is satisfied:
1.74< Lt/|fn|< 4.37,
where Lt is a length from a lens surface closest to the object side to a lens surface closest to the image side on an optical axis at the telephoto end.
15 . The zoom lens according to claim 1 , wherein the first lens unit consists of one lens.
16 . The zoom lens according to claim 1 , wherein the second lens unit consists of four lenses.
17 . The zoom lens according to claim 1 , wherein the intermediate group consists of a third lens unit with positive refractive power, a fourth lens unit with negative refractive power, and a fifth lens unit with positive refractive power placed in this order from the object side to the image side.
18 . The zoom lens according to claim 1 , wherein the intermediate group consists of a third lens unit with positive refractive power and a fourth lens unit with positive refractive power placed in this order from the object side to the image side.
19 . The zoom lens according to claim 1 , wherein the rear group consists of a lens unit with negative refractive power and a lens unit with negative refractive power placed in this order from the object side to the image side.
20 . The zoom lens according to claim 1 , wherein the rear group consists of a lens unit with negative refractive power and a lens unit with positive refractive power placed in this order from the object side to the image side.
21 . The zoom lens according to claim 1 , wherein the rear group consists of a lens unit with negative refractive power, a lens unit with negative refractive power, and a lens unit with positive refractive power placed in this order from the object side to the image side.
22 . An apparatus comprising:
a zoom lens; and
a sensor configured to receive an image formed by the zoom lens,
wherein the zoom lens comprising a plurality of lens units, the plurality of lens units consisting of, a first lens unit with positive refractive power, a second lens unit with negative refractive power, an intermediate group including an aperture stop and at least one lens unit, and a rear group including at least two lens units placed in this order from an object side to an image side, wherein an interval between adjacent lens units changes during zooming,
wherein a lens unit of the rear group that is placed closest to the object side has the strongest negative refractive power among lens units placed closer to the image side than the aperture stop,
wherein, in zooming from a wide-angle end to a telephoto end, every lens unit included in the first lens unit, the intermediate group, and the rear group moves toward the object side, and the second lens unit moves along a convex trajectory toward the image side, and
wherein the following inequalities are satisfied:
3.30< f|/|f 2|<5.90,
1.40<| f 2|/ bfw< 2.50, and
1.00< fn/f 2<1.60,
where f1 is a focal length of the first lens unit, f2 is a focal length of the second lens unit, bfw is a back focus of an entire system at a wide-angle end, and fn is a combined focal length of the rear group at the wide-angle end.