Zoom lens and image pickup apparatus including the same
AssigneeCanon Kabushiki Kaisha
InventorKenji Shinohara
Life of this patent
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Abstract
A zoom lens according to the present invention includes, in order from an object side to an image side: a first lens unit having a negative refractive power; a second lens unit having a positive refractive power; and a third lens unit having a positive refractive power, in which a distance between adjacent lens units varies during zooming, the configuration of the second lens unit, the curvature radius Rb2obj of a lens surface of a cemented lens GRb2 on the object side included in the second lens unit, the curvature radius Rb2img of a lens surface of the cemented lens GRb2 on the image side, the focal length f2bimg of the cemented lens GRb2, and the focal length f2 of the second lens unit are appropriately set.
Claims11
A zoom lens comprising, in order from an object side to an image side:
- a first lens unit having a negative refractive power;
- a second lens unit having a positive refractive power;
- and a third lens unit having a positive refractive power, a distance between the adjacent lens units varying during zooming,
- wherein the second lens unit includes a plurality of lenses, a cemented lens GRb2 is disposed nearest to the image side in the second lens unit, and the cemented lens GRb2 includes a negative lens and a positive lens cemented to the image side of the negative lens, and
- provided that a lens surface of the cemented lens GRb2 on the object side has a curvature radius Rb2obj, a lens surface of the cemented lens GRb2 on the image side has a curvature radius of Rb2img, the cemented lens GRb2 has a focal length f2bimg, and a focal length of the second lens unit is f2, following conditional expressions are satisfied,
- 1.65<(Rb2obj+Rb2img)/(Rb2obj−Rb2img)<50.00,
- and
- 1.0<f2bimg/f2<10.0.
An image pickup apparatus, comprising:
- a zoom lens;
- and
- an image pickup element configured to receive an image formed by the zoom lens,
- the zoom lens comprising, in order from an object side to an image side:
- a first lens unit having a negative refractive power;
- a second lens unit having a positive refractive power;
- and a third lens unit having a positive refractive power,
- wherein a distance between adjacent lens units varies during zooming,
- the second lens unit includes a plurality of lenses, a cemented lens GRb2 is disposed nearest to the image side in the second lens unit, and the cemented lens GRb2 includes a negative lens and a positive lens cemented to the image side of the negative lens, and
- provided that a lens surface of the cemented lens GRb2 on the object side has a curvature radius Rb2obj, a lens surface of the cemented lens GRb2 on the image side has a curvature radius of Rb2img, the cemented lens GRb2 has a focal length f2bimg, and a focal length of the second lens unit is f2, following conditional expressions are satisfied,
- 1.65<(Rb2obj+Rb2img)/(Rb2obj−Rb2img)<50.00,
- and
- 1.0<f2bimg/f2<10.0.
Dependencies are inferred from the claim text.