Claims
- 1. A super-wide angle lens, sequentially from an object side, comprising:
- a first negative lens L1;
- a second negative lens L2; and
- a third positive lens L3,
- wherein said first negative lens L1 with its concave surface toward an image side has an image-side surface with a curvature larger than that on an object-side surface,
- said second negative lens L2 is disposed at a predetermined spacing from said first negative lens L1 and takes a negative meniscus shape with its convex surface toward the object side,
- said third positive lens L3 has its convex surface toward the object side,
- said second negative lens L2 and said third positive lens L3 are combined to constitute a cemented lens, and
- an on-axis thickness of said second negative lens L2 is larger than an on-axis thickness of said third positive lens L3.
- 2. The super-wide angle lens according to claim 1, wherein said super-wide angle lens satisfies the following conditions:
- 0.8<.vertline.f1.vertline./f<2.0
- 0.7<.vertline.f1.vertline./f23<1.3
- where f1 is the focal length of said first negative lens L1, f23 is the synthesized focal length of said second negative lens L2 and said third positive lens L3, and f is the focal length of said whole lens system.
- 3. A super-wide angle lens, sequentially from an object side, comprising at least:
- a first negative lens L1;
- a second negative lens L2; and
- a third positive lens L3,
- wherein said first negative lens L1 with its concave surface toward an image side has an image-side surface with a curvature larger than that on an object-side surface,
- said second negative lens L2 is disposed at a predetermined spacing from said first negative lens L1 and takes a negative meniscus shape with its convex surface toward the object side,
- said third positive lens L3 has its convex surface toward the object side, and
- said super-wide angle lens satisfies the following conditions:
- 0.4<d3/f<1.0
- 0.7<r3/f<1.4
- 0.3<r4/f<0.9
- where r3 is the radius of curvature of the object-side surface of said second negative lens L2, r4 is the radius of curvature of the image-side surface of said second negative lens, d3 is the on-axis thickness of said second negative lens L2, and f is the focal length of said whole lens system.
- 4. The super-wide angle lens according to claim 3, wherein said super-wide angle lens satisfies the following conditions:
- 0.08<n2-n3
- 4<.nu.2.multidot..nu.3.multidot.(n2-n3)/(.nu.3-.nu.2)<12
- where n2 is the refractive index of said second negative lens L2 with respect to the d-line, .nu.2 is the Abbe's number of said second negative lens L2, n3 is the refractive index of said third positive lens L3 with respect to the d-line, and .nu.3 is the Abbe's number of said third positive lens L3.
- 5. The super-wide angle lens according to claim 3, wherein said super-wide angle lens satisfies the following conditions:
- 0.8<.vertline.f1.vertline./f<2.0
- 0.7<.vertline.f1.vertline./f23<1.3
- where f1 is the focal length of said first negative lens L1, f23 is the synthesized focal length of said second negative lens L2 and said third positive lens L3, and f is the focal length of said whole lens system.
- 6. The super-wide angle lens according to claim 3, wherein said super-wide angle lens satisfies the following conditions:
- 45<.nu.1
- -0.06<r2/r1<0.06
- where .nu.1 is the Abbe's number of said first negative lens L1, r1 is the radius of curvature of the object-side surface of said first negative lens L1, and r2 is the radius of curvature of the image-side surface of said first negative lens.
- 7. The super-wide angle lens according to claim 3, wherein said second negative lens L2 and said third positive lens L3 are combined to constitute a cemented lens.
- 8. The super-wide angle lens according to claim 7, wherein said super-wide angle lens satisfies the following conditions:
- 0.08<n2-n3
- 4<.nu.2.multidot..nu.3.multidot.(n2-n3)/(.nu.3-.nu.2)<12
- where n2 is the refractive index of said second negative lens L2 with respect to the d-line, .nu.2 is the Abbe's number of said second negative lens L2, n3 is the refractive index of said third positive lens L3 with respect to the d-line, and .nu.3 is the Abbe's number of said third positive lens L3.
- 9. The super-wide angle lens according to claim 8, wherein said super-wide angle lens satisfies the following conditions:
- 0.8<.vertline.f1.vertline./f<2.0
- 0.7<.vertline.f1.vertline./f23<1.3
- where f1 is the focal length of said first negative lens L1, f23 is the synthesized focal length of said second negative lens L2 and said third positive lens L3, and f is the focal length of said whole lens system.
- 10. The super-wide angle lens according to claim 9, wherein said super-wide angle lens satisfies the following conditions:
- 45<.nu.1
- -0.06<r2/r1<0.06
- where .nu.1 is the Abbe's number of said first negative lens L1, r1 is the radius of curvature of the object-side surface of said first negative lens L1, and r2 is the radius of curvature of the image-side surface of said first negative lens.
- 11. A super-wide angle lens, sequentially from an object side, consisting of:
- a first negative lens L1;
- a second negative lens L2; and
- a third positive lens L3,
- wherein said first negative lens L1 with its concave surface toward an image side has an image-side surface with a curvature larger than that on an object-side surface,
- said second negative lens L2 is disposed at a predetermined spacing from said first negative lens L1 and takes a negative meniscus shape with its convex surface toward the object side, and
- said third positive lens L3 has its convex surface toward the object side.
- 12. The super-wide angle lens according to claim 11, wherein said super-wide angle lens satisfies the following conditions:
- 0.8<.vertline.f1.vertline./f<2.0
- 0.7<.vertline.f1.vertline./f23<1.3
- where f1 is the focal length of said first negative lens L1, f23 is the synthesized focal length of said second negative lens L2 and said third positive lens L3, and f is the focal length of said whole lens system.
- 13. The super-wide angle lens according to claim 11, wherein said second negative lens L2 and said third positive lens L3 are combined to constitute a cemented lens.
- 14. The super-wide angle lens according to claim 13, wherein said super-wide angle lens satisfies the following conditions:
- 0.8<.vertline.f1.vertline./f<2.0
- 0.7<.vertline.f1.vertline./f23<1.3
- where f1 is the focal length of said first negative lens L1, f23 is the synthesized focal length of said second negative lens L2 and said third positive lens L3, and f is the focal length of said whole lens system.
- 15. A super-wide angle lens, sequentially from an object side, comprising:
- a first lens L1 having a negative refracting power;
- a second lens L2 having a negative refracting power; and
- a third lens L3 having a positive refracting power,
- wherein said first lens L1 has its concave surface toward an image-side and has a larger curvature on an image-side surface than on an object-side surface,
- said second lens L2 is disposed at a predetermined spacing from said first lens L1, and takes a meniscus shape with its convex surface toward the object side,
- said third lens L3 has its convex surface toward the object side, and
- said second lens L2 and said third lens L3 are combined to constitute a cemented positive lens element L23 having a positive refracting power as a whole,
- said super-wide angle lens satisfying the following condition:
- 0. 5<.nu.2r3/(.nu.1r2)<0.8
- where r2 is the radius of curvature of the image-side surface of said first lens L1, r3 is the radius of curvature of the object-side surface of said second lens L2, .nu.1 is the Abbe's number of said first lens L1, and .nu.2 is the Abbe's number of said second lens L2.
- 16. The super-wide angle lens according to claim 15, wherein said super-wide angle lens satisfies the following condition:
- 4.6<.nu.3r3/(.nu.2r4)<5.05
- where r3 is the radius of curvature of the object-side surface of said second lens L2, r4 is the radius of curvature of the image-side surface of said second lens L2, .nu.2 is the Abbe's number of said second lens L2, and .nu.3 is the Abbe's number of said third lens L3.
Parent Case Info
This is a Continuation-In-Part of U.S. patent application Ser. No. 08/658,460 filed Jun. 5, 1996.
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
4525038 |
Muller |
Jun 1985 |
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Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
658460 |
Jun 1996 |
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