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US 11,768,361 B2Granted
Zoom lens and image capturing apparatus
AssigneeCanon Kabushiki Kaisha
InventorShohei Kikuchi
Life of this patent
Estimating the term…
Abstract
A zoom lens ZL includes: a first lens unit L1 having a positive refractive power, a second lens unit L2 having a negative refractive power, and a third lens unit L3 having a positive refractive power, an N−1th lens unit, and an Nth lens unit, the lens units being arranged in order from an object side to an image side. The N−1th lens unit and the Nth lens unit are located on the image side with respect to an aperture stop SP.
Claims15
A zoom lens comprising:
- a first lens unit having a positive refractive power;
- a second lens unit having a negative refractive power;
- and a third lens unit having a positive refractive power, the lens units being arranged in order from an object side to an image side, and further comprising:
- an N-1th lens unit located second from the image side;
- and an Nth lens unit located closest to the image side, a distance between adjacent ones of the lens units changing during zooming,
- wherein the N-1th lens unit and the Nth lens unit are located on the image side with respect to an aperture stop,
- wherein the third lens unit includes at least three negative lenses,
- wherein at least one of the N-1th lens unit and the Nth lens unit has a negative refractive power,
- wherein, in a case where the N-1th lens unit and the Nth lens unit have a negative refractive power, the N-1th lens unit is referred to as an image-side lens unit, and in a case where only one of the N-1th lens unit and the Nth lens unit has a negative refractive power, the lens unit having a negative refractive power is referred to as an image-side lens unit,
- wherein a combined refractive power of lenses from a lens unit having the aperture stop to the lens unit located adjacent to the object side of the image-side negative lens unit at a wide-angle end when focusing on an object at infinity is a positive refractive power,
- wherein a combined refractive power of lenses from the image-side negative lens unit to the image side at the wide-angle end when focusing on an object at infinity is a negative refractive power, and
- wherein the following inequalities are satisfied:
- 0.40<fw/skw<2.90 (1)
- −8.50<f1/f2<−5.90 (2)
- 1.07<|(Rg2r1+Rg2r2)/(Rg2r1−Rg2r2)| (3)
- −1.27<fn/fp<−0.70 (4)
- where fw is a focal length of the zoom lens at the wide-angle end when focusing on an object at infinity, skw is a back focus at the wide-angle end when focusing on an object at infinity, f1 is a focal length of the first lens unit, f2 is a focal length of the second lens unit, Rg2r1, is a curvature radius of a surface at a most object side of the second lens unit, Rg2r2 is a curvature radius of a surface at a most image side of the second lens unit, fp is a combined focal length of the lenses from and including the lens unit having the aperture stop to and including the lens unit located adjacent to the object side of the image-side negative lens unit at the wide-angle end when focusing on an object at infinity, and fn is a combined focal length of the lenses from and including the image-side negative lens unit to the image plane at the wide-angle end when focusing on an object at infinity.
14 more elements
An image capturing apparatus comprising:
- a zoom lens;
- and
- an image sensor that receives an image formed by the zoom lens,
- wherein the zoom lens includes
- a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power, the lens units being arranged in order from an object side to an image side, and also includes an N-1th lens unit located second from the image side, and an Nth lens unit located closest to the image side,
- wherein a distance between adjacent ones of the lens units changes during zooming,
- wherein the N-1th lens unit and the Nth lens unit are located on the image side with respect to an aperture stop,
- wherein the third lens unit includes at least three negative lenses,
- wherein at least one of the N-1th lens unit and the Nth lens unit has a negative refractive power,
- wherein, in a case where the N-1th lens unit and the Nth lens unit have a negative refractive power, the N-1th lens unit is referred to as an image-side lens unit, and in a case where only one of the N-1th lens unit and the Nth lens unit has a negative refractive power, the lens unit having a negative refractive power is referred to as an image-side lens unit,
- wherein a combined refractive power of lenses from a lens unit having the aperture stop to the lens unit located adjacent to the object side of the image-side negative lens unit at a wide-angle end when focusing on an object at infinity is a positive refractive power,
- wherein the combined refractive power of the lenses from the image-side negative lens unit to the image plane at the wide-angle end when focusing on an object at infinity is a negative refractive power, and wherein the following inequalities are satisfied:
- 0.40<fw/skw<2.90 (1)
- −8.50<f1/f2<−5.90 (2)
- 1.07<|(Rg2r1+Rg2r2)/(Rg2r1−Rg2r2)| (3)
- −1.27<fn/fp<−0.70 (4)
- where fw is a focal length of the zoom lens at the wide-angle end when focusing on an object at infinity, skw is a back focus at the wide-angle end when focusing on an object at infinity, f1 is a focal length of the first lens unit, f2 is a focal length of the second lens unit, Rg2r1 is a curvature radius of a surface at a most object side of the second lens unit, Rg2r2 is a curvature radius of a surface at a most image side of the second lens unit, fp is a combined focal length of the lenses from and including the lens unit having the aperture stop to and including the lens unit located adjacent to the object side of the image-side negative lens unit at the wide-angle end when focusing on an object at infinity, and fn is a combined focal length of the lenses from and including the image-side negative lens unit to the image plane at the wide-angle end when focusing on an object at infinity.
14 more elements
Dependencies are inferred from the claim text.