US 4,212,517 AGranted

Photographic lens system

AssigneeOlympus Optical Co., Ltd.

InventorToru Fujii

Life of this patent

Estimating the term…

Abstract

A photographic lens system of modified Gauss type comprising a first, second, third fourth and fifth lens components in which the first and second lens components are positive meniscus lenses arranged convex toward the object side, the third lens component is a negative meniscus lens arranged convex toward the object side, the fourth lens component is a negative cemented meniscus doublet comprising a biconcave lens and biconvex lens, the fifth lens component is a biconvex lens, the photographic lens system being compact and light in weight and having a long back focal length and aberrations corrected favorably.

Claims3

Dependent claims

A photographic lens system comprising a first, second, third, fourth and fifth lens components, said first lens component being a positive meniscus lens arranged convex toward the object side, said second lens component being a positive meniscus lens arranged convex toward the object side, said third lens component being a negative meniscus lens arranged convex toward the object side, said fourth lens component being a negative cemented meniscus doublet comprising a biconcave lens with its surface of smaller radius of curvature arranged toward the object side and a biconvex lens with its surface of smaller radius of curvature arranged toward the image side, said fifth lens component being a biconvex lens with its surface of smaller radius of curvature arranged toward the image side, said photographic lens system satisfying the following conditions:

(1) 1.69<n.sub.1, n.sub.2 <1.75 1.68<n.sub.3 <1.70
(2) 48<.nu..sub.1, .nu..sub.2 <50
(3) 30<.nu..sub.3 <32
(4) n.sub.5, n.sub.6 =1.713
(5) 1.2f<f.sub.1 <1.3f
(6) 0.62f<f.sub.12 <0.63f
(7) 3f<f.sub.123 <3.2f
(8) -0.47f<f.sub.4 <-0.44f
(9) 0.5f<f.sub.5 <0.6f
(10) 1.06f<f.sub.6 <1.07f
(11) 4f<r.sub.2 <4.5f
(12) 0.67f<r.sub.4 <0.7f
(13) 1.0f<r.sub.5 <1.2f
(14) 0.29f<r.sub.6 <0.3f
(15) -0.35f<r.sub.7 <-0.29f
(16) 3.9f<r.sub.10 <4.7f
(17) 0.017f<d.sub.4 <0.02f
(18) 0.23f<d.sub.6 <0.25f
(19) 0.13f<d.sub.3 +d.sub.4 +d.sub.5 <0.15f
(20) d.sub.7 +d.sub.8 =0.1319f
(21) 0.08<n.sub.5 -n.sub.4 <0.11
wherein reference symbol f represents the focal length of the lens system as a whole, reference symbol f.sub.1 represents the focal length of the first lens component, reference symbols f.sub.4 and f.sub.5 respectively represent focal lengths of respective lenses constituting the fourth lens component, reference symbol f.sub.6 represents the focal length of the fifth lens component, reference symbol f.sub.12 represents the total focal length of the first and second lens components, reference symbol f.sub.123 represents the total focal length of the first, second and third lens components, reference symbol r.sub.2 represents the radius of curvature of the surface on the image side of the first lens component, reference symbol r.sub.4 represents the radius of curvature of the surface on the image side of the second lens component, reference symbols r.sub.5 and r.sub.6 respectively represent radii of curvature of respective surfaces of the third lens component, reference symbols r.sub.7 and r.sub.8 respectively represent radii of curvature of the surface on the object side and cemented surface of the fourth lens component, reference symbol r.sub.10 represents the radius of curvature of the surface on the object side of the fifth lens component, reference symbol d.sub.4 represents the airspace between the second and third lens components, reference symbol d.sub.6 represents the airspace between the third and fourth lens components, reference symbol (d.sub.3 +d.sub.4 +d.sub.5) represents the distance from the surface on the object side of the second lens component to the surface on the image side of the third lens component, reference symbol (d.sub.7 +d.sub.8) represents the thickness of the fourth lens component, and reference symbols n.sub.1, n.sub.2, n.sub.3, n.sub.4, n.sub.5 and n.sub.6 respectively represent refractive indices of respective lenses in the order from the object side toward the image side, and .nu. .sub.1, .nu..sub.2 and .nu..sub.3 respectively represent Abbe's numbers of the first, second and third lens components.

19 more elements

Dependencies are inferred from the claim text.

patentgrep

Loading patent…

Abstract

(1) 1.69<n.sub.1, n.sub.2 <1.75 1.68<n.sub.3 <1.70
(2) 48<.nu..sub.1, .nu..sub.2 <50
(3) 30<.nu..sub.3 <32
(4) n.sub.5, n.sub.6 =1.713
(5) 1.2f<f.sub.1 <1.3f
(6) 0.62f<f.sub.12 <0.63f
(7) 3f<f.sub.123 <3.2f
(8) -0.47f<f.sub.4 <-0.44f
(9) 0.5f<f.sub.5 <0.6f
(10) 1.06f<f.sub.6 <1.07f
(11) 4f<r.sub.2 <4.5f
(12) 0.67f<r.sub.4 <0.7f
(13) 1.0f<r.sub.5 <1.2f
(14) 0.29f<r.sub.6 <0.3f
(15) -0.35f<r.sub.7 <-0.29f
(16) 3.9f<r.sub.10 <4.7f
(17) 0.017f<d.sub.4 <0.02f
(18) 0.23f<d.sub.6 <0.25f
(19) 0.13f<d.sub.3 +d.sub.4 +d.sub.5 <0.15f
(20) d.sub.7 +d.sub.8 =0.1319f
(21) 0.08<n.sub.5 -n.sub.4 <0.11
wherein reference symbol f represents the focal length of the lens system as a whole, reference symbol f.sub.1 represents the focal length of the first lens component, reference symbols f.sub.4 and f.sub.5 respectively represent focal lengths of respective lenses constituting the fourth lens component, reference symbol f.sub.6 represents the focal length of the fifth lens component, reference symbol f.sub.12 represents the total focal length of the first and second lens components, reference symbol f.sub.123 represents the total focal length of the first, second and third lens components, reference symbol r.sub.2 represents the radius of curvature of the surface on the image side of the first lens component, reference symbol r.sub.4 represents the radius of curvature of the surface on the image side of the second lens component, reference symbols r.sub.5 and r.sub.6 respectively represent radii of curvature of respective surfaces of the third lens component, reference symbols r.sub.7 and r.sub.8 respectively represent radii of curvature of the surface on the object side and cemented surface of the fourth lens component, reference symbol r.sub.10 represents the radius of curvature of the surface on the object side of the fifth lens component, reference symbol d.sub.4 represents the airspace between the second and third lens components, reference symbol d.sub.6 represents the airspace between the third and fourth lens components, reference symbol (d.sub.3 +d.sub.4 +d.sub.5) represents the distance from the surface on the object side of the second lens component to the surface on the image side of the third lens component, reference symbol (d.sub.7 +d.sub.8) represents the thickness of the fourth lens component, and reference symbols n.sub.1, n.sub.2, n.sub.3, n.sub.4, n.sub.5 and n.sub.6 respectively represent refractive indices of respective lenses in the order from the object side toward the image side, and .nu. .sub.1, .nu..sub.2 and .nu..sub.3 respectively represent Abbe's numbers of the first, second and third lens components.

19 more elements