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US 10,310,240 B2Granted
Zoom lens and image pickup apparatus including the same
AssigneeCanon Kabushiki Kaisha
InventorShin Kuwashiro
Life of this patent
Estimating the term…
Abstract
A zoom lens includes, in order from an object side to an image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, a fourth lens unit having a negative refractive power, and a rear unit including at least one lens unit. In the zoom lens, the locus of movement, the focal length, the amount of displacement during zooming, and the shapes of lens surfaces are appropriately set for each lens unit.
Claims14
A zoom lens comprising, in order from an object side to an image side:
- a first lens unit having a positive refractive power;
- a second lens unit having a negative refractive power;
- a third lens unit having a positive refractive power;
- a fourth lens unit having a negative refractive power;
- and
- a rear lens group including at least one lens unit, wherein
- the first lens unit does not move for zooming,
- during zooming from a wide angle end to a telephoto end, each of the third lens unit and the fourth lens unit moves toward the object side, and an interval between each adjacent two of the lens units varies, and
- the zoom lens satisfies the following conditional expressions:
- 0.1<f3/|m3|<0.9,
- −1.4<f4/|m4|<−0.1, and
- 1.5<(R2a+R1a)/(R2a−R1a)<30.0,
- where f3 is a focal length of the third lens unit, f4 is a focal length of the fourth lens unit, m3 is an amount of displacement of the third lens unit in the zooming from the wide angle end to the telephoto end, m4 is an amount of displacement of the fourth lens unit in the zooming from the wide angle end to the telephoto end, R1a is a radius of curvature of a lens surface nearest to the object side in the first lens unit, and R2a is a radius of curvature of a lens surface nearest to the image side in the first lens unit.
10 more elements
A zoom lens comprising, in order from an object side to an image side:
- a first lens unit having a positive refractive power;
- a second lens unit having a negative refractive power;
- a third lens unit having a positive refractive power;
- a fourth lens unit having a negative refractive power;
- and
- a rear group including at least one lens unit, wherein
- the first lens unit does not move for zooming,
- each of the third lens unit and the fourth lens unit moves toward the object side during zooming from a wide angle end to a telephoto end, thereby varying an interval between each adjacent two of the lens units during the zooming,
- the third lens unit includes a plurality of positive lenses, and
- the zoom lens satisfies the following conditional expressions:
- 0.1<f3/|m3|<0.9,
- −1.4<f4/|m4|<−0.1, and
- 1.5<(R2a+R1a)/(R2a-R1a)<30.0,
- where f3 is a focal length of the third lens unit, f4 is a focal length of the fourth lens unit, m3 is an amount of displacement of the third lens unit in the zooming from the wide angle end to the telephoto end, m4 is an amount of displacement of the fourth lens unit in the zooming from the wide angle end to the telephoto end, R1a is a radius of curvature of a lens surface nearest to the object side in the first lens unit, and R2a is a radius of curvature of a lens surface nearest to the image side in the first lens unit, and
- wherein at least two of the positive lenses of the third lens unit are formed from a material satisfying the following conditional expression:
- 0.010<θgF−(0.644−0.00168×νd)<0.070,
- where νd is an Abbe number of the material, and θgF is a partial dispersion ratio of the material.
14 more elements
A zoom lens comprising, in order from an object side to an image side:
- a first lens unit having a positive refractive power;
- a second lens unit having a negative refractive power;
- a third lens unit having a positive refractive power;
- a fourth lens unit having a negative refractive power;
- and
- a rear group including at least one lens unit, wherein
- the first lens unit does not move for zooming,
- each of the third lens unit and the fourth lens unit moves toward the object side during zooming from a wide angle end to a telephoto end, thereby varying an interval between each adjacent two of the lens units during the zooming, and
- the zoom lens satisfies the following conditional expressions:
- 0.1<f3/|m3|<0.9,
- −1.4<f4/|m4|<−0.1,
- 1.5<(R2a+R1a)/(R2a−R1a)<30.0, and
- 0.5<m2/ft<1.3,
- where f3 is a focal length of the third lens unit, f4 is a focal length of the fourth lens unit, m3 is an amount of displacement of the third lens unit in the zooming from the wide angle end to the telephoto end, m4 is an amount of displacement of the fourth lens unit in the zooming from the wide angle end to the telephoto end, R1a is a radius of curvature of a lens surface nearest to the object side in the first lens unit, R2a is a radius of curvature of a lens surface nearest to the image side in the first lens unit, m2 is a distance between positions of the second lens unit on an optical axis during the zooming from the wide angle end to the telephoto end, one of the positions being closest to the object and the other position being closest to the image, and ft is a focal length of the zoom lens at the telephoto end.
11 more elements
Dependencies are inferred from the claim text.