Lens system and camera having the same
AssigneeCanon Kabushiki Kaisha
InventorMakoto Sekita
Life of this patent
Estimating the term…
Abstract
In a lens system, a first lens having negative optical power and a meniscus shape with a convex surface facing an object side, a second lens having positive optical power and a double-convex shape, a third lens having negative optical power and a double-concave shape, a fourth lens having positive optical power, and a fifth lens having positive optical power and a double-convex shape are arranged sequentially from a front side to a rear side. Letting D1,2 be an interval between said first and second lenses, D2,3 an interval between said second and third lenses, bf be a back focus of the entire system, and f be a focal length of the entire system, at least one of three conditions given by 0.6<D1,2/f<1.0, 0.55<D2,3/f<0.85, and 0.9<bf/f<1.1 is satisfied.
Claims11
A lens system comprising, sequentially from a front side to a rear side:
- a first lens having negative optical power and a meniscus shape with a convex surface facing an object side;
- a second lens having positive optical power and a double-convex shape;
- a third lens having negative optical power and a double-concave shape;
- a fourth lens having positive optical power;
- and
- a fifth lens having positive optical power and a double-convex shape,
- wherein letting D1,2 be an interval between said first and second lenses, D2,3 an interval between said second and third lenses, bf be a back focus of the entire system, and f be a focal length of the entire system, at least one of three conditions given by
- 0.6<D1,2/f<1.0 0.55<D2,3/f<0.85 0.9<bf/f<1.1
- is satisfied.
A lens system comprising, sequentially from a front side to a rear side:
- a first lens having negative optical power and a meniscus shape with a convex surface facing an object side;
- a second lens having positive optical power and a double-convex shape;
- an aperture stop
- a third lens having negative optical power and a double-concave shape;
- a fourth lens having positive optical power;
- and
- a fifth lens having positive optical power and a double-convex shape,
- wherein letting r9 be a radius of curvature of an image-side lens surface of said fourth lens and r10 and r11 be radii of curvature of object- and image-side lens surfaces of said fifth lens, conditions given by
- −0.75<r9/r10<−0.5 −1.7<(r10−r11)/(r10+r11)<−0.9
- are satisfied.
Dependencies are inferred from the claim text.