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US 6,661,584 B2Granted
Zoom lens and camera having the zoom lens
AssigneeCanon Kabushiki Kaisha
InventorTakeshi Nishimura
Life of this patent
Estimating the term…
Abstract
A zoom lens includes a first to fourth lens unit. Zooming is performed by moving the lens units so that a spacing between the first and the second lens unit at a telephoto end is larger than the spacing between the first and the second lens unit at a wide-angle end, and so that the spacing between the third and the fourth lens unit at the telephoto end is smaller than the spacing between the third and the fourth lens unit at the wide-angle end. If focal lengths of the first and the fourth lens units are f1 and f4, and if the focal length of entire system at the wide-angle end and the focal length of the entire system at the telephoto end are fw and ft, conditions expressed by 0.2<f1/ft<0.5, −0.2<f4/ft<−0.05 and 3.7<ft/fw<6.0 are satisfied.
Claims42
A zoom lens comprising:
- a first lens unit having a positive optical power;
- a second lens unit including a negative biconcave lens and a positive lens in this order from an object side to an image side;
- a third lens unit moved for focusing;
- and
- a fourth lens unit having a negative optical power, said first to fourth lens units being placed in this order from the object side to the image side,
- wherein zooming is performed by moving said lens units so that a spacing between said first lens unit and said second lens unit at a telephoto end is larger than the spacing between said first lens unit and said second lens unit at a wide-angle end, and so that the spacing between said third lens unit and said fourth lens unit at the telephoto end is smaller than the spacing between said third lens unit and said fourth lens unit at the wide-angle end, and
- wherein focal lengths of said first lens unit and said fourth lens units are f1 and f4, respectively, and the focal length of entire system at the wide-angle end and the focal length of the entire system at the telephoto end are fw and ft, respectively, conditions expressed by
- 0.2<f1/ft<0.5
- −0.2<f4/ft<−0.05
- and
- 3.7<ft/fw<6.0
- are satisfied.
9 more elements
A zoom lens comprising:
- a first lens unit having a positive optical power;
- a second lens unit;
- a third lens unit having a negative meniscus lens with a concave surface on an object side and a positive meniscus lens with a convex surface on an image side, said negative and positive meniscus lenses being placed in this order from the object side to the image side, said third lens unit being moved for focusing;
- and
- a fourth lens unit having a negative optical power, said first to fourth lens units being placed in this order from the object side to the image side,
- wherein zooming is performed by moving said lens units so that a spacing between said first lens unit and said second lens unit at the telephoto end is larger than the spacing between said first lens unit and said second lens unit at the wide-angle end, and so that the spacing between said third lens unit and said fourth lens unit at the telephoto end is smaller than the spacing between said third lens unit and said fourth lens unit at the wide-angle end, and
- wherein focal lengths of said first lens unit and said fourth lens units are f1 and f4, respectively, and the focal length of entire system at the wide-angle end and the focal length of the entire system at the telephoto end are fw and ft, respectively, conditions expressed by
- 0.2<f1/ft<0.5
- −0.2<f4/ft<−0.05
- and
- 3.7<ft/fw<6.0
- are satisfied.
9 more elements
A zoom lens comprising:
- a first lens unit having a positive optical power;
- a second lens unit having an aperture stop which is moved integrally with said second lens unit during zooming;
- a third lens unit having a positive optical power, said third lens unit having a negative lens and a positive lens in this order from the object side to the image side;
- and
- a fourth lens unit having a negative optical power, said first to fourth lens units being placed in this order from the object side to the image side,
- wherein zooming is performed by moving said lens units so that the spacing between said first lens unit and said second lens unit at the telephoto end is larger than the spacing between said first lens unit and said second lens unit at the wide-angle end, and so that the spacing between said third lens unit and said fourth lens unit at the telephoto end is smaller than the spacing between said third lens unit and said fourth lens unit at the wide-angle end, and
- wherein the focal lengths of said first lens unit and said fourth lens units are f1 and f4, respectively, the focal length of the entire system at the wide-angle end and the focal length of the entire system at the telephoto end are fw and ft, respectively, an Abbe number of the negative lens in the closest position to the object side in said third lens unit is ν 3n, and the Abbe number of the positive lens closest to the object side in said third lens unit is ν 3p, conditions expressed by
- 0.2<f1/ft<0.5
- −0.2<f4/ft<−0.05
- 3.7<ft/fw<6.0
- and
- 20<ν3p−ν3n<50
- are satisfied.
10 more elements
A zoom lens comprising;
- a first lens unit having a positive optical power;
- a second lens unit having a negative optical power;
- a third lens unit having a positive optical power;
- a fourth lens unit having a negative optical power, said first to fourth lens being placed in this order from the object side to the image side, wherein zooming is performed by moving said lens units so that the spacing between said first lens unit and said second lens unit at the telephoto end is larger than the spacing between said first lens unit and said second lens unit at the wide-angle end, and so that the spacing between said third lens unit and said fourth lens unit at the telephoto end is smaller than the spacing between said third lens unit and said fourth lens unit at the telephoto end is smaller than the spacing between said third lens unit and said fourth lens unit at the wide-angle end, and
- wherein the focal length of said first, second, third, and fourth lens units is f1, f2, f3, and f4, respectively, the focal length of the entire system at the wide-angle end is fw, the distance between said first lens unit and said second lens unit at the wide-angle end is D12w, and the distance between said second lens unit and said third lens unit at the wide-angle end is D23W, at least one of conditions expressed by
- 1.0<f1/fw<2.0
- 2<|f2/fw|<12
- 0.5<f3/fw<0.8
- 0.3<|f4/fw|<0.50
- and
- 0.05<D12w/D23w<0.3
- is satisfied.
9 more elements
A zoom lens comprising:
- a first lens unit having a positive optical power;
- a second lens having a negative optical power;
- a third lens unit having a positive optical power, said third lens unit having a negative meniscus lens with a concave surface on the object side, a positive meniscus lens with a concave surface on the object side, a negative lens, and a positive lens, the negative meniscus lens, the positive meniscus lens, the negative lens and the positive lens being placed in this order from the object side to the image side, at least one of two surfaces of the negative meniscus lens being aspherical;
- and
- a fourth lens unit having a negative optical power, said first to fourth lens units being placed in this order from the object side to the image side,
- wherein zooming is performed by moving said lens units so that the spacing between said first lens unit and said second lens unit at the telephoto end is larger than the spacing between said first lens unit and said second lens unit at the wide-angle end, and so that the spacing between said third lens unit and said fourth lens unit at the telephoto end is smaller than the spacing between said third lens unit and said fourth lens unit at the wide-angle end, and
- the refractive index and the Abbe number of the negative meniscus lens in said third lens unit are Nd31 and ν d31, respectively, the refractive index of the positive lens in said third lens unit is Nd34, and the radius of curvature of the lens surface on the object side and the radius of curvature of the lens surface on the image side of the positive lens in said third lens unit are Ra and Rb, respectively, at least one of conditions expressed by
- 1.6<Nd 31<1.9
- 40<νd 31<60
- 1.45<Nd 34<1.56
- and
- −4<Rb/Ra<−1.3
- is satisfied.
10 more elements
Dependencies are inferred from the claim text.