Zoom lens, and image pickup apparatus having the same
AssigneeCanon Kabushiki Kaisha
InventorsTakeharu NAKADA, Shunji IWAMOTO
Life of this patent
Estimating the term…
Abstract
A zoom lens comprising a plurality of lens units. The plurality of lens units consists of, 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. A distance between adjacent lens units changes during zooming from a wide-angle end to a telephoto end. The first lens unit includes three or more lenses. The first lens unit is fixed relative to an image plane during zooming. A predetermined inequality is satisfied.
Claims26
A zoom lens comprising a plurality of lens units, the plurality of lens units consisting of, 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 a distance between adjacent lens units changes during zooming from a wide-angle end to a telephoto end,
- wherein the first lens unit includes three or more lenses,
- wherein the first lens unit and the fourth lens unit are fixed relative to an image plane during zooming,
- wherein the first lens unit includes a first negative lens and a second negative lens, which is disposed on the image side of the first negative lens,
- wherein the third lens unit consists of one or two single negative lenses,
- wherein the third lens unit is a focus lens unit that moves during focusing, and
- wherein the following inequalities are satisfied:
- 0.85
- <
- (
- -
- f
-
- 1
- )
- /
- f
-
- 2
- <
- 2
- .00
- [
- [
- 0.
- 0
-
- 0
- <
- ]
- ]
- 0.21
- ≤
- (
- -
- f
-
- 1
- )
- /
- f
-
- 4
- <
- 0.55
- 0.
- <
- LD
-
- 1
- /
- TTL
- <
- 0.27
- 0.
- 37
- <
- BF
-
- w
- /
- (
- -
- f
-
- 1
- )
- <
- 1.5
- 1.
- 61
- ≤
- fn
-
- 2
- /
- f
-
- 1
- <
- 10.
- where f1 is a focal length of the first lens unit, f2 is a focal length of the second lens unit, f4 is a focal length of the fourth lens unit, LD1 is a distance on an optical axis from a lens surface on the object side of a lens closest to an object in the first lens unit to a lens surface on the image side of a lens closest to the image plane in the first lens unit, TTL is a distance on the optical axis from the lens surface on the object side of the lens closest to the object in the zoom lens at the wide-angle end to the image plane, BFw an air conversion amount of a distance on the optical axis from a lens surface on the image side of the lens closest to the image plane in the zoom lens at the wide-angle end to the image plane, and fn2 is a focal length of the second negative lens.
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An image pickup apparatus comprising:
- a zoom lens;
- and
- an image sensor configured to receive image light formed by the zoom lens,
- the zoom lens comprising a plurality of lens units, the plurality of lens units consisting of, 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 a distance between adjacent lens units changes during zooming from a wide-angle end to a telephoto end,
- wherein the first lens unit includes three or more lenses,
- wherein the first lens unit and the fourth lens unit are fixed relative to an image plane during zooming,
- wherein the following inequalities are satisfied:
- 0.85
- <
- (
- -
- f
-
- 1
- )
- /
- f
-
- 2
- <
- 2
- .00
- [
- [
- 0.
- 0
-
- 0
- <
- ]
- ]
- 0.21
- ≤
- (
- -
- f
-
- 1
- )
- /
- f
-
- 4
- <
- 0.55
- 0.
- <
- LD
-
- 1
- /
- TTL
- <
- 0.27
- 0.
- <
- BFw
- /
- (
- -
- f
-
- 1
- )
- <
- 1.5
- 1.61
- ≤
- fn
-
- 2
- /
- f
-
- 1
- <
- 10.
- where f1 is a focal length of the first lens unit, f2 is a focal length of the second lens unit, f4 is a focal length of the fourth lens unit, LD1 is a distance on an optical axis from a lens surface on the object side of a lens closest to an object in the first lens unit to a lens surface on the image side of a lens closest to the image plane in the first lens unit, TTL is a distance on the optical axis from the lens surface on the object side of the lens closest to the object in the zoom lens at the wide-angle end to the image plane, BFw an air conversion amount of a distance on the optical axis from a lens surface on the image side of the lens closest to the image plane in the zoom lens at the wide-angle end to the image plane, and fn2 is a focal length of the second negative lens.
Dependencies are inferred from the claim text.