Ultra-wide angle photographic lens

Claim 2

In an ultra-wide angle photographic lens consisting of six lens components, the improvement wherein the first lens component beginning at the object side is a single negative meniscus with its convex surfaces directed to the object side, the second lens component consisting of two lens elements cemented to each other to form a negative meniscus as a whole with the convex surfaces thereof directed to the object side, the third lens component consisting of two lens elements cemented to each other to form a negative lens as a whole, the fourth lens component consisting of two lens elements, a positive and a negative cemented to each other to form a positive lens as a whole, the fifth lens component consisting of a single positive meniscus with its concave surfaces directed to the object side, while the siXth lens component consists of two lens elements cemented to each other to form a positive lens as a whole, said photographic lens satisfying the following conditions: f < f123 < 2.5f (1) n2> n3 ; 15f<r4 < 35f (2) Nu 4 > Nu 5 ; f< r7 < 3.5f (3) f <r15 < 3.5f (4) Nu 9 < 30 ; Nu 10 > 50 (5) where: f resultant focal length of the entire system f123 resultant focal length of the first, the second and the third lens components inclusive ri (i 1 - 16) the radius of curvature of each of the surfaces of the lens elements, i beginning at the object side di (i 1 - 15) the thickness of each of the lens elements and the air gap between the adjacent lens elements, i beginning at the object side ni (i 1 - 10) the refractive index of each of the lens elements, i beginning at the object side Nu i (i 1 - 10) Abbe number of each of the lens elements, i beginning at the object side.

Claim 3

Ultra-wide angle photographic lens according to claim 1, which satisfies the following numerical data: r1 11.8788 d1 0.3404 n1 1.5891 Nu 1 61.0 r2 2.5106 d2 2.3830 r3 8.4135 d3 0.5167 n2 1.7847 Nu 2 25.6 r4 18.4891 d4 0.2432 n3 1.5891 Nu 3 61.0 r5 2.1550 d5 1.7556 r6 -37.9278 d6 0.1945 n4 1.67 Nu 4 57.8 r7 2.1550 d7 0.5957 n5 1.6668 Nu 5 33.0 r8 12.2238 d8 1.0057 r9 18.9741 d9 0.2432 n6 1.7865 Nu 6 50.1 r10 1.3584 d10 0.8377 n7 1.6032 Nu 7 42.3 r11 -5.6012 d11 1.5210 r12 -7.7271 d12 0.5678 n8 1.5173 Nu 8 69.3 r13 -3.1809 d13 0.0243 r14 3.3374 d14 0.1824 n9 1.9229 Nu 9 20.9 r15 2.0547 d15 0.6237 n10 1.5173 Nu 10 69.3 r16 -3.6401 f 1.0 ; f123 -1.545f Back Focus fB 4.5855 .

Claim 4

In an ultra-wide angle photographic lens consisting of six lens components, the improvement wherein the first lens component beginning at the object side is a single negative meniscus with its convex surfaces directed to the object side, the second lens component consisting of two lens elements, a positive and a negative cemented to each other to form a negative meniscus as a whole with the convex surfaces thereof directed to the object side, the third lens component consisting of two lens elements closely spaced from each other by a small air gap to provide a negative power as a whole, the fourth lens component consisting of two lens elements cemented to each other to form a positive lens as a whole, the fifth lens component consisting of A single positive meniscus with its concave surfaces directed to the object side, while the sixth lens component consists of two lens elements cemented to each other to form a positive lens as a whole, said photographic lens satisfying the following conditions: f < f123 < 2.5f (1) n2> n3 ; 15f <r4 < 35f (2) Nu 4> Nu 5 ; f< r7 ; r8 < 3.5f (3) 3) f < r16 < 3.5f (4) 4) Nu 9 < 30 ; Nu 10 > 50 (5) where: f resultant focal length of the entire system f123 resultant focal length of the first, the second and the third lens components, inclusive ri (i 1 --- 17) the radius of curvature of each of the surfaces of the lens elements, i beginning at the object side di (i 1 - 16) the thickness of each of the lens elements and the air gap between the adjacent lens elements, i beginning at the object side ni (i 1 - 10) the refractive index of each of the lens elements, i beginning at the object side Nu i (i 1 - 10) Abbe number of each of the lens elements, i beginning at the object side

Claim 5

In an ultra-wide angle photographic lens consisting of six lens components, the improvement wherein the first lens component beginning at the object side is a single negative meniscus with its convex surfaces directed to the object side, the second lens component consisting of two lens elements, a positive and a negative cemented to each other to form a negative meniscus as a whole with the convex surfaces thereof directed to the object side, the third lens component consisting of two lens elements closely spaced from each other by a small air gap to provide a negative power as a whole, the fourth lens component consisting of two lens elements cemented to each other to form a positive lens as a whole, the fifth lens component consisting of A single positive meniscus with its concave surfaces directed to the object side, while the sixth lens component consists of two lens elements cemented to each other to form a positive lens as a whole, said photographic lens satisfying the following conditions: f < f123 < 2.5f (1) n2> n3 ; 15f <r4 < 35f (2) Nu 4> Nu 5 ; f< r7 ; r8 < 3.5f (3) 3) f < r16 < 3.5f (4) 4) Nu 9 < 30 ; Nu 10 > 50 (5) where: f resultant focal length of the entire system f123 resultant focal length of the first, the second and the third lens components, inclusive ri (i 1 --- 17) the radius of curvature of each of the surfaces of the lens elements, i beginning at the object side di (i 1 - 16) the thickness of each of the lens elements and the air gap between the adjacent lens elements, i beginning at the object side ni (i 1 - 10) the refractive index of each of the lens elements, i beginning at the object side Nu i (i 1 - 10) Abbe number of each of the lens elements, i beginning at the object side

Claim 6

Ultra-wide angle photographic lens according to claim 3, which satisfies the following numerical data: r1 12.5508 d1 0.3406 n1 1.5891 Nu 1 61.0 r2 2.3973 d2 2.0581 r3 6.7504 d3 0.4841 n2 1.7847 Nu 2 25.6 r4 23.0172 d4 0.2433 n3 1.5891 Nu 3 61.0 r5 2.0662 d5 1.0668 r6 -30.4548 d6 0.1910 n4 1.67 Nu 4 57.3 r7 2.7598 d7 0.0255 r8 3.0080 d8 0.5681 n5 1.6668 Nu 5 33.0 r9 -40.5882 d9 0.8687 r10 -10.6177 d10 0.2433 n6 1.7865 Nu 6 50.1 r11 1.0641 d11 0.8722 n7 1.6034 Nu 7 38.0 r12 -8.5301 d12 1.2638 r13 -82.8154 d13 0.5340 n8 1.5184 Nu 8 60.1 r14 -3.1680 d14 0.0243 r15 3.2395 d15 0.1825 n9 1.9229 Nu 9 20.9 r16 1.8270 d16 0.7992 n10 1.5184 Nu 10 60.1 r17 -2.8557 f 1.0 ; f 123 - 2.04f Back Focus fB 4.5616 .