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US 5,499,142 AGranted
Large aperture wide angle type photographic lens system
AssigneeNikon Corporation
InventorKoichi Ohshita
Life of this patent
Estimating the term…
Abstract
A large aperture wide angle type photographic lens system comprises a positive meniscus lens having a convex surface directed toward an object, a bi-concave lens provided at the image side with respect to the positive meniscus lens, a bi-convex lens provided at the image side with respect to the bi-concave lens and a negative meniscus lens having a convex surface directed toward an image and provided at the image side with respect to the bi-convex lens. The characteristics of the lenses have predetermined relationship.
Claims16
A large aperture wide angle type photographic lens system comprising:
- a positive meniscus lens having an object side convex surface directed toward an object and provided coaxially with an optical axis;
- a bi-concave lens provided at an image side of said positive meniscus lens and coaxially with said optical axis and having an image side surface;
- a bi-convex lens provided at an image side of said bi-concave lens and coaxially with said optical axis;
- and
- a negative meniscus lens provided at an image side of said bi-convex lens and coaxially with said optical axis and having an image side convex surface directed toward an image;
- and
- wherein the following conditions are satisfied:
- 0.4<r1/f<0.45
- -0.65<r8/f<-0.4
- 0.43<(d5+d6)/f<0.48
- where:
- r1 is a radius of curvature of said object side convex surface of said positive meniscus lens;
- r8 is a radius of curvature of said image side convex surface of said negative meniscus lens;
- d5 is an axial thickness of said bi-convex lens;
- d6 is an axial distance between said bi-convex lens and said negative meniscus lens;
- and
- f is a compound focal length of the whole lens system.
14 more elements
A large aperture wide angle type photographic lens system comprising:
- a positive meniscus lens having an object side convex surface directed toward an object;
- a bi-concave lens provided at an image side of said positive meniscus lens and provided with an image side surface having an effective diameter;
- a bi-convex lens provided at an image side of said bi-concave lens;
- a negative meniscus lens provided at an image side of said bi-convex lens and having an image side convex surface directed toward an image;
- an aperture stop provided between said bi-concave lens and said bi-convex lens;
- and
- a fixed stop having a smaller diameter than said effective diameter at image side surface of said bi-convex lens and provided between said bi-convex lens and said negative meniscus lens.
4 more elements
A large aperture wide angle type photographic lens system comprising:
- a positive meniscus lens having an object side convex surface directed toward an object;
- a bi-concave lens provided at an image side of said positive meniscus lens and provided with an image side surface;
- a bi-convex lens provided at an image side of said bi-concave lens and having an object side surface and an image side surface;
- and
- a negative meniscus lens provided at an image side of said bi-convex lens and having an image side convex directed toward an image;
- and
- wherein the following conditions are satisfied:
- 0.4<r1/f<0.45
- -0.8<r5/r6<-0.6
- where:
- r1 is a radius of curvature of said object side convex surface of positive meniscus lens;
- r5 is a radius of curvature of said object side surface of bi -convex lens;
- r6 is a radius of curvature of image side surface of said bi-convex lens;
- and
- f is a compound focal length of the whole optical system.
12 more elements
A large aperture wide angle type photographic lens system comprising:
- a positive meniscus lens having an object side convex surface directed toward an object;
- a bi-concave lens provided at an image side of said positive meniscus lens and provided with an image side surface;
- a bi-convex lens provided at an image side of said bi-concave lens and having an object side surface and an image side surface;
- and
- a negative meniscus lens provided at an image side of said bi-convex lens and having an image side convex surface directed toward an image;
- and wherein the following conditions are satisfied:
- 0.18<d5/f<0.3
- -0.8<r5/r6<-0.6
- where:
- d5 is an axial thickness of said bi-convex lens;
- r5 is a radius of curvature of said object side surface of said bi-convex lens;
- r6 is a radius of curvature of said image side surface of said bi-convex lens;
- and
- f is a compound focal length of the whole lens system.
11 more elements
A large aperture wide angle type photographic lens system comprising:
- a positive meniscus lens having an object side convex surface directed toward an object;
- a bi-concave lens provided at an image side of said positive meniscus lens and provided with an image side surface;
- a bi-convex lens provided at an image side of said bi-concave lens and having an object side surface and an image side surface;
- and
- a negative meniscus lens provided at an image side of said bi-convex lens and having an image side convex surface directed toward an image;
- and wherein the following conditions are satisfied:
- 0.4<r1/f<0.45
- 0.55<r4/f<0.65
- -0.65<r8/f<-0.4
- 0.43<(d5+d6)/f<0.48
- where:
- r1 is a radius of curvature of said objective side convex surface of said positive meniscus lens;
- r4 is a radius of curvature of said image side surface of said bi-concave lens;
- r8 is a radius of curvature of said image side convex surface of said negative meniscus lens;
- d5 is an axial thickness of said bi-convex lens;
- d6 is an axial distance between said bi-convex lens and said negative meniscus lens;
- and
- f is a compound focal length of the whole lens system.
15 more elements
A large aperture wide angle type photographic lens system comprising:
- a positive meniscus lens having an object side convex surface directed toward an object;
- a bi-concave lens provided at an image side of said positive meniscus lens and provided with an image side surface;
- a bi-convex lens provided at an image side of said bi-concave lens and having an object side surface and an image side surface;
- and
- a negative meniscus lens provided at an image side of said bi-convex lens and having an image side convex surface directed toward an image;
- and wherein the following conditions are satisfied:
- -0.8<r5/r6<-0.6
- 3.58<n1+n3
- 0.05<n2-n4<0.15
- where:
- r5 is a radius of curvature of said object side surface of bi-convex lens;
- r6 is a radius of curvature of said image side surface of said bi-convex lens;
- n1 is a refractive index of said positive meniscus lens for the d line;
- n2 is a refractive index of said bi-concave lens for the d line;
- n3 is a refractive index of said bi-convex lens for the d line;
- and
- n4 is a refractive index of said negative meniscus lens for the d line.
14 more elements
Dependencies are inferred from the claim text.