Lens system having large relative aperture and long focus

Claim 2

A lens system having a large relative aperture and long focus and having an object side and an image side, the system comprising, in series, as viewed from the object side, a positive first lens member having its convex surface facing the object side, a positive second lens member having its convex surface facing the object side, a negative third lens member, and a positive fourth lens member, the third lens member comprising a positive lens and a negative lens, the components of the lens system satisfying the following conditions: (I) 0.4 Σ d ≦ [d1 + d2 + d3 + d4 + d5 + d6] ≦ 0.53 Σ d, and (II) 0.4f ≦ |r6| ≦ 0.7f, n3 > n4, 32 > λ4 > λ3, where d ADSCRIPTS are the center thicknesses of the respective lenses and the air spaces between adjacent lenses, Σ d is the total optical length of the lens system, f is the composite focal length of the lens system, r ADSCRIPTS are the radii of curvature of the surfaces of respective lenses, n ADSCRIPTS are the indices of refraction for the glass used to make the respective lenses, and ν ADSCRIPTS are Abbe numbers for the respective lenses.

Claim 3

A lens system having a large relative aperture and long focus and having an object side and an image side, the system comprising, in series, as viewed from the object side, a positive first lens member having its convex surface facing the object side, a positive second lens member having its convex surface facing the object side, a negative third lens member, and a positive fourth lens member, the third lens member comprising a positive lens and a negative lens, the components of the lens system satisfying the following conditions: (I) 0.4 Σ d ≦ [d1 + d2 + d3 + d4 + d5 + d6] ≦ 0.53 Σ d, and (II) 0.4f ≦ |r6| ≦ 0.7f, n3 > n4, 32 > ν4 > ν3, where d ADSCRIPTS are the center thicknesses of the respective lenses and the air spaces between adjacent lenses, Σ d is the total optical length of the lens system, f is the composite focal length of the lens system, r ADSCRIPTS are the radii of curvature of the surfaces of respective lenses, n ADSCRIPTS are the indices of refraction from the glass used to make the respective lenses, and ν ADSCRIPTS are Abbe numbers for the respective lenses; the lens system having a total composite focal length of 100mm, a relative aperture of 1:2.8, and an angle of view of 18.1° and the following specifications: ______________________________________ r1 = 40.444 d1 = 5.407 n1 = 1.6031 ν1 = 65.41 r2 = 289.580 d2 = 0.444 r3 = 30.222 d3 = 9.630 n2 = 1.6031 ν2 = 65.41 r4 = 67.912 d4 = 2.074 r5 = 173.333 d5 = 3.481 n3 = 1.69895 ν3 = 30.0 r6 = -40.741 d6 = 1.111 n4 = 1.68893 ν4 = 31.1 r7 = 19.884 d7 = 30.000 r8 = 62.222 d8 = 1.630 n5 = 1.7495 ν5 = 35.0 r9 = 195.494 ##STR4## ______________________________________

Claim 4

A lens system having a large relative aperture and long focus and having an object side and an image side, the system comprising, in series, as viewed from the object side, a positive first lens member having its convex surface facing the object side, a positive second lens member having its convex surface facing the object side, a negative third lens member, and a positive fourth lens member, the third lens member comprising a positive lens and a negative lens, the components of the lens system satisfying the following conditions: (I) 0.4 Σ d ≦ [d1 + d2 + d3 + d4 + d5 + d6] ≦ 0.53 Σ d, and (II) 0.4f ≦ |r6| ≦ 0.7f, n3 > n4, 32 > ν4 > ν3, where d ADSCRIPTS are the center thicknesses of the respective lenses and the air spaces between adjacent lenses, Σ d is the total optical length of the lens system, f is the composite focal length of the lens system, r ADSCRIPTS are the radii of curvature of the surfaces of respective lenses, n ADSCRIPTS are the indices of refraction from the glass used to make the respective lenses, and ν ADSCRIPTS are Abbe numbers for the respective lenses; the lens system having a total composite focal length of 100mm, a relative aperture of 1:2.8, and an angle of view of 18.1° and the following specifications: ______________________________________ r1 = 40.444 d1 = 5.407 n1 = 1.6031 ν1 = 65.41 r2 = 289.580 d2 = 0.444 r3 = 30.222 d3 = 9.630 n2 = 1.6031 ν2 = 65.41 r4 = 67.912 d4 = 2.074 r5 = 173.333 d5 = 3.481 n3 = 1.69895 ν3 = 30.0 r6 = -40.741 d6 = 1.111 n4 = 1.68893 ν4 = 31.1 r7 = 19.884 d7 = 30.000 r8 = 62.222 d8 = 1.630 n5 = 1.7495 ν5 = 35.0 r9 = 195.494 ##STR4## ______________________________________

Claim 5

A lens system having a large relative aperture and long focus and having an object side and an image side, the system comprising, in series, as viewed from the object side, a positive first lens member having its convex surface facing the object side, a positive second lens member having its convex surface facing the object side, a negative third lens member, and a positive fourth lens member, the third lens member comprising a positive lens and a negative lens, the components of the lens system satisfying the following conditions: (I) 0.4 Σ d ≦ [d1 + d2 + d3 + d4 + d5 + d6] ≦ 0.53 Σ d, and (II) 0.4f ≦ |r6| ≦ 0.7f, n3 > n4, 32 > ν4 > ν3, where d ADSCRIPTS are the center thicknesses of the respective lenses and the air spaces between adjacent lenses, Σ d is the total optical length of the lens system, f is the composite focal length of the lens system, r ADSCRIPTS are the radii of curvature of the surfaces of respective lenses, n ADSCRIPTS are the indices of refraction for the glass used to make the respective lenses, and ν ADSCRIPTS are Abbe numbers for the respective lenses; the lens system having a total composite focal length of 100mm, a relative aperture of 1:2.8, and an angle of view of 18.1° and the following specifications: ______________________________________ r1 = 41.630 d1 = 5.407 n1 = 1.62041 ν1 = 60.3 r2 = 300.296 d2 = 0.444 r3 = 28.778 d3 = 9.630 n2 = 1.62041 ν2 = 60.3 r4 = 61.593 d4 = 2.074 r5 = 157.876 d5 = 3.481 n3 = 1.78470 ν3 = 26.1 r6 = -58.637 d6 = 1.111 n4 = 1.74000 ν4 = 28.2 r7 = 19.616 d7 = 25.704 r8 = 62.222 d8 = 1.630 n5 = 1.72825 ν5 = 28.3 r9 = 186.713 ##STR5## ______________________________________

Claim 6

A lens system having a large relative aperture and long focus and having an object side and an image side, the system comprising, in series, as viewed from the object side, a positive first lens member having its convex surface facing the object side, a positive second lens member having its convex surface facing the object side, a negative third lens member, and a positive fourth lens member, the third lens member comprising a positive lens and a negative lens, the components of the lens system satisfying the following conditions: (I) 0.4 Σ d ≦ [d1 + d2 + d3 + d4 + d5 + d6] ≦ 0.53 Σ d, and (II) 0.4f ≦ |r6| ≦ 0.7f, n3 > n4, 32 > ν4 > ν3, where d ADSCRIPTS are the center thicknesses of the respective lenses and the air spaces between adjacent lenses, Σ d is the total optical length of the lens system, f is the composite focal length of the lens system, r ADSCRIPTS are the radii of curvature of the surfaces of respective lenses, n ADSCRIPTS are the indices of refraction for the glass used to make the respective lenses, and ν ADSCRIPTS are Abbe numbers for the respective lenses; the lens system having a total composite focal length of 100mm, a relative aperture of 1:2.8, and an angle of view of 18.1° and the following specifications: ______________________________________ r1 = 41.630 d1 = 5.407 n1 = 1.62041 ν1 = 60.3 r2 = 300.296 d2 = 0.444 r3 = 28.778 d3 = 9.630 n2 = 1.62041 ν2 = 60.3 r4 = 61.593 d4 = 2.074 r5 = 157.876 d5 = 3.481 n3 = 1.78470 ν3 = 26.1 r6 = -58.637 d6 = 1.111 n4 = 1.74000 ν4 = 28.2 r7 = 19.616 d7 = 25.704 r8 = 62.222 d8 = 1.630 n5 = 1.72825 ν5 = 28.3 r9 = 186.713 ##STR5## ______________________________________

Claim 7

A lens system having a large relative aperature and long focus and having an object side and an image side, the system comprising, in series, as viewed from the object side, a positive first lens member having its convex surface facing the object side, a positive second lens member having its convex surface facing the object side, a negative third lens member, and a positive fourth lens member, the third lens member comprising a positive lens and a negative lens, the components of the lens system satisfying the following conditions: (I) 0.4 Σ d ≦ [d1 + d2 + d3 + d4 + d5 + d6] ≦ 0.53 Σ d, and (II) 0.4 f ≦ |r6| ≦ 0.7f, n3 > n4, 32 > ν4 > ν3, where d ADSCRIPTS are the center thicknesses of the respective lenses and the air spaces between adjacent lenses, Σ d is the total optical length of the lens system, f is the composite focal length of the lens system, r ADSCRIPTS are the radii of curvature of the surfaces of respective lenses, n ADSCRIPTS are the indices of refraction for the glass used to make the respective lenses, and ν ADSCRIPTS are Abbe numbers for the respective lenses; the lens system having a total composite focal length of 100mm, a relative aperture of 1:2.8, and an angle of view of 18.1° and the following specifications: ______________________________________ r1 = 41.407 d1 = 5.407 n1 = 1.60881 ν1 = 58.9 r2 = 288.507 d2 = 0.444 r3 = 28.000 d3 = 9.630 n2 = 1.60881 ν2 = 58.9 r4 = 59.138 d4 = 2.074 r5 = 191.111 d5 = 3.481 n3 1.91761 ν3 = 21.4 r6 = -68.889 d6 = 1.111 n4 = 1.80518 ν4 = 25.5 r7 = 20.221 d7 = 18.000 r8 = 76.296 d8 = 1.630 n5 = 1.72825 ν5 = 28.3 r9 = 1750.370 ##STR6## ______________________________________

Claim 8

A lens system having a large relative aperature and long focus and having an object side and an image side, the system comprising, in series, as viewed from the object side, a positive first lens member having its convex surface facing the object side, a positive second lens member having its convex surface facing the object side, a negative third lens member, and a positive fourth lens member, the third lens member comprising a positive lens and a negative lens, the components of the lens system satisfying the following conditions: (I) 0.4 Σ d ≦ [d1 + d2 + d3 + d4 + d5 + d6] ≦ 0.53 Σ d, and (II) 0.4 f ≦ |r6| ≦ 0.7f, n3 > n4, 32 > ν4 > ν3, where d ADSCRIPTS are the center thicknesses of the respective lenses and the air spaces between adjacent lenses, Σ d is the total optical length of the lens system, f is the composite focal length of the lens system, r ADSCRIPTS are the radii of curvature of the surfaces of respective lenses, n ADSCRIPTS are the indices of refraction for the glass used to make the respective lenses, and ν ADSCRIPTS are Abbe numbers for the respective lenses; the lens system having a total composite focal length of 100mm, a relative aperture of 1:2.8, and an angle of view of 18.1° and the following specifications: ______________________________________ r1 = 41.407 d1 = 5.407 n1 = 1.60881 ν1 = 58.9 r2 = 288.507 d2 = 0.444 r3 = 28.000 d3 = 9.630 n2 = 1.60881 ν2 = 58.9 r4 = 59.138 d4 = 2.074 r5 = 191.111 d5 = 3.481 n3 1.91761 ν3 = 21.4 r6 = -68.889 d6 = 1.111 n4 = 1.80518 ν4 = 25.5 r7 = 20.221 d7 = 18.000 r8 = 76.296 d8 = 1.630 n5 = 1.72825 ν5 = 28.3 r9 = 1750.370 ##STR6## ______________________________________