Zoom lens and image pickup apparatus
AssigneeCanon Kabushiki Kaisha
InventorsYonghee Lee, Tomoya Yamada, Yu Inomoto
Life of this patent
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Abstract
A zoom lens includes in order from an object side to an image side: a first lens unit having a positive refractive power not moving for zooming; at least three lens units moving during zooming; and a final lens unit having a positive refractive power, wherein an interval between adjacent lens units changes during zooming, a refractive index and an Abbe number of positive lenses arranged closest to the object side among positive lenses included in the first lens unit, a focal length of the first lens unit, a focal length of the zoom lens at a wide angle end, a focal length of the zoom lens at a telephoto end, and a back focus of the zoom lens at the wide angle end are appropriately set.
Claims11
A zoom lens comprising in order from an object side to an image side:
- a first lens unit having a positive refractive power which does not move for zooming;
- at least three lens units which move during zooming;
- and a final lens unit having a positive refractive power, wherein an interval between adjacent lens units changes during zooming,
- wherein the first lens unit includes in order from the object side to the image side:
- a first lens subunit having a negative refractive power, a second lens subunit having a positive refractive power, and a third lens subunit having a positive refractive power,
- wherein an interval between adjacent lens subunits changes during focusing,
- wherein the first lens subunit does not move for focusing, at least the second lens subunit moves for focusing, and the third lens subunit does not move for focusing,
- wherein at least two lens units among the at least three lens units which move during zooming have negative refractive powers,
- wherein the zoom lens comprises an aperture stop arranged in or adjacent to the final lens unit,
- wherein following inequalities are satisfied,
- 1.86≤np≤2.15
- 15.0≤vp≤22.0
- 2.35≤ft/f1≤6.00
- 0.28≤fw/BF≤0.43
- −3.00≤fp1/f11≤−1.90
- where np and vp represent a refractive index and an Abbe number of a positive lens arranged closest to the object side among positive lenses included in the first lens unit, respectively, f1 represents a focal length of the first lens unit, fw represents a focal length of the zoom lens at a wide angle end, ft represents a focal length of the zoom lens at a telephoto end, BF denotes a back focus of the zoom lens at the wide angle end, fp1 represents a focal length of the positive lens arranged closest to the object side in the first lens unit, and f11 represents a focal length of the first lens subunit.
An image pickup apparatus comprising a zoom lens and an image pickup element for picking up an image formed by the zoom lens,
- wherein the zoom lens comprises in order from an object side to an image side:
- a first lens unit having a positive refractive power which does not move for zooming;
- at least three lens units which move during zooming;
- and a final lens unit having a positive refractive power, wherein an interval between adjacent lens units changes during zooming,
- wherein the first lens unit includes in order from the object side to the image side:
- a first lens subunit having a negative refractive power;
- a second lens subunit having a positive refractive power, and a third lens subunit having a positive refractive power,
- wherein an interval between adjacent lens subunits changes during focusing,
- wherein the first lens subunit does not move for focusing, at least the second lens subunit moves for focusing, and the third lens subunit does not move for focusing,
- wherein at least two lens units among the at least three lens units which move during zooming have negative refractive powers,
- wherein the zoom lens comprises an aperture stop arranged in or adjacent to the final lens unit,
- wherein following inequalities are satisfied,
- 1.86≤np≤2.15
- 15.0≤vp≤22.0
- 2.35≤ft/f1≤6.00
- 0.28≤fw/BF≤0.43
- −3.00≤fp1/f11≤−1.90
- where np and vp represent a refractive index and an Abbe number of a positive lens arranged closest to the object side among positive lenses included in the first lens unit, respectively, f1 represents a focal length of the first lens unit, fw represents a focal length of the zoom lens at a wide angle end, ft represents a focal length of the zoom lens at a telephoto end, BF denotes a back focus of the zoom lens at the wide angle end, fp1 represents a focal length of the positive lens arranged closest to the object side in the first lens unit, and f11 represents a focal length of the first lens subunit.
Dependencies are inferred from the claim text.