US 7,548,385 B2 · Wide-angle lens system

Abstract

A wide-angle lens system includes a negative first meniscus lens element, a positive second lens element, a positive third biconvex lens element, and a negative fourth meniscus lens element, in this order from the object; wherein said wide-angle lens system satisfies the following condition: 0.25<H/(p3+p4)<0.60 wherein H designates the distance between the second principal point of the positive third biconvex lens element and the first principal point of the negative fourth meniscus lens element, when the focal length of the entire wide-angle lens system is normalized to 1.0; p3 designates the refractive power of the positive third biconvex lens element when the focal length of the entire wide-angle lens system is normalized to 1.0; f3 designates the focal length of the positive third biconvex lens element when the focal length of the entire wide-angle lens system is normalized to 1.0, i.e., p3=1/f3; p4 designates the refractive power of the negative fourth meniscus lens element when the focal length of the entire wide-angle lens system is normalized to 1.0; and f4 designates the focal length of the negative fourth meniscus lens element wherein the focal length of the entire wide-angle lens system is normalized to 1.0, i.e., p4=1/f4.

Claims14

Dependent claims

A wide-angle lens system comprises a negative first meniscus lens element having the convex surface facing toward an object, a positive second lens element, a positive third biconvex lens element, and a negative fourth meniscus lens element having the convex surface facing toward an image, in this order from the object;

wherein said wide-angle lens system satisfies the following condition:
0.25<H/(p3+p4)<0.60
wherein
H designates the distance between the second principal point of said positive third biconvex lens element and the first principal point of said negative fourth meniscus lens element, when the focal length of the entire wide-angle lens system is normalized to 1.0;
p3 designates the refractive power of said positive third biconvex lens element when the focal length of the entire wide-angle lens system is normalized to 1.0;
f3 designates the focal length of said positive third biconvex lens element when the focal length of the entire wide-angle lens system is normalized to 1.0, i.e., p3=1/f3;
p4 designates the refractive power of said negative fourth meniscus lens element when the focal length of the entire wide-angle lens system is normalized to 1.0;
and
f4 designates the focal length of said negative fourth meniscus lens element wherein the focal length of the entire wide-angle lens system is normalized to 1.0, i.e., p4=1/f4.

6 more elements

wherein said wide-angle lens system satisfies the following condition:
0.032<A−B<0.06
wherein
A=(nt3−1)×(1-nt4)/(R7×R8/f2);
B=(nd3−1)×(1-nd4)/(R7×R8/f2);
nt3 designates the refractive index of the t-line of said positive third biconvex lens element;
nt4 designates the refractive index of the t-line of said negative fourth meniscus lens element;
nd3 designates the refractive index of the d-line of said positive third biconvex lens element;
nd4 designates the refractive index of the d-line of said negative fourth meniscus lens element;
R7 designates the radius of curvature of the image-side surface of said positive third biconvex lens element;
R8 designates the radius of curvature of the object-side surface of said negative fourth meniscus lens element;
and
f designates the focal length of the entire wide-angle lens system.

10 more elements

wherein said wide-angle lens system satisfies the following condition:
v4<23
25<(v3−v4)
wherein
v3 designates the Abbe number of said positive third biconvex lens element;
and
v4 designates the Abbe number of said negative fourth meniscus lens element.

4 more elements

Dependencies are inferred from the claim text.

Wide-angle lens system

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Wide-angle lens system

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Abstract

Claims14