Photographic lens
AssigneeFuji Photo Film Co., Ltd.
InventorKazumi Koike
Life of this patent
Estimating the term…
Abstract
A photographic lens has a first and second positive lens. The first lens is a meniscus lens having a convex object side surface. The second lens is a double-convex lens. The photographic lens satisfies the following conditions: 5.6≦f<8; F1>F2; 0.39<F/F1≦0.5; 0.15<R1/F<0.19; 1.4<(F/R3)·f≦3.0; and R3>|R4| wherein F is an overall focal length, F1 is a focal length of the first lens, F2 is a focal length of the second lens, f is a ratio of the overall focal length F to an effective aperture size defined by the first stop, R1 is a radius of curvature of the object side surface of the first lens, R3 and R4 are radii of curvature of the object side spherical surface and of an average spherical surface of the image side aspherical surface of the second lens.
Claims4
A photographic lens comprising a first lens element, a second lens element disposed on image side of said first lens element, and a first stop disposed between said first and second lens elements, said first lens element being a meniscus lens having a convex object side surface, said second lens element being a double-convex lens, said photographic lens satisfying the following conditions:
- 5.6≦f<8;
- F1>F2;
- 0.39<F/F1≦0.5;
- 0.15<R1/F<0.19;
- 1.4<(F/R3)·f≦3.0;
- and
- R3>|R4|
- wherein F is an overall focal length of the photographic lens, F1 is a focal length of said first lens element, F2 is a focal length of said second lens element, f is a ratio of the overall focal length F to an effective aperture size that is defined by the first stop, R1 is a radius of curvature of the object side surface of said first lens element, and R3 and R4 are radii of curvature of the object side spherical surface and of an average spherical surface of the image side aspherical surface of the second lens element respectively.
Dependencies are inferred from the claim text.