Retrofocus, wide-angle lens

1. A retrofocus, wide-angle lens formed of two lens groups, in order from the object side, as follows:

a first lens group having negative refractive power;

a stop; and

a second lens group having positive refractive power; wherein

said first lens group includes a meniscus lens element having positive refractive power with its convex surface on the object side, two meniscus lens elements, each of negative refractive power with its convex surface on the object side, and a lens that has a center thickness that is greater than the center thickness of any of said three meniscus lens elements; and

said second lens group includes a cemented lens component that includes a lens element having negative refractive power that is cemented to a biconvex lens element, an air space, and a meniscus lens component having negative refractive power with its concave surface on the object side.

2. The retrofocus, wide-angle lens of claim 1 , wherein said meniscus lens component of said second lens group consists of a lens element.

3. The retrofocus, wide-angle lens of claim 2 , wherein said meniscus lens component of said second lens group is separated from said biconvex lens element only by said air space.

4. The retrofocus, wide-angle lens of claim 3 , wherein the following condition is satisfied:

1 <|R/R′|< 1.08

where

R is the radius of curvature of the object-side lens surface of said meniscus lens component of said second lens group; and

R′ is the radius of curvature of the image-side lens surface of said biconvex lens element.

5. The retrofocus, wide-angle lens of claim 4 , wherein the following conditions are satisfied:

νB−νA> 25

νB> 65

1.38 <|φ/R′|< 1.65

where

νA is the Abbe number at the d-line of the lens material of the lens element having negative refractive power of the cemented lens component of the second lens group;

νB is the Abbe number at the d-line of the lens material of said biconvex lens element of the second lens group; and

φ is the effective diameter of the image-side lens surface of said biconvex lens element of the second lens group.

6. The retrofocus, wide-angle lens of claim 5 , wherein said second lens group comprises, in order from the object side:

the meniscus lens component having positive refractive power with its convex surface on the image side;

the lens element of said cemented lens component having negative refractive power;

the biconvex lens element of said cemented lens component;

the meniscus lens component having negative refractive power with its concave surface on the object side; and

a second meniscus lens component having positive refractive power with its convex surface on the image side.

7. The retrofocus, wide-angle lens of claim 2 , wherein the following condition is satisfied:

1 <|R/R′|< 1.08

where

R is the radius of curvature of the object-side lens surface of said meniscus lens component of said second lens group; and

R′ is the radius of curvature of the image-side lens surface of said biconvex lens element.

8. The retrofocus, wide-angle lens of claim 7 , wherein the following conditions are satisfied:

νB−νA> 25

νB>65

1.38 <|φ/R′| <1.65

where

νA is the Abbe number at the d-line of the lens material of the lens element having negative refractive power of the cemented lens component of the second lens group;

νB is the Abbe number at the d-line of the lens material of said biconvex lens element of the second lens group; and

φ is the effective diameter of the image-side lens surface of said biconvex lens element of the second lens group.

9. The retrofocus, wide-angle lens of claim 8 , wherein said second lens group comprises, in order from the object side:

the meniscus lens component having positive refractive power with its convex surface on the image side;

the lens element of said cemented lens component having negative refractive power;

the biconvex lens element of said cemented lens component;

the meniscus lens component having negative refractive power with its concave surface on the object side; and

a second meniscus lens component having positive refractive power with its convex surface on the image side.

10. The retrofocus, wide-angle lens of claim 7 , wherein said second lens group comprises, in order from the object side:

the meniscus lens component having positive refractive power with its convex surface on the image side;

the lens element of said cemented lens component having negative refractive power;

the biconvex lens element of said cemented lens component;

the meniscus lens component having negative refractive power with its concave surface on the object side; and

a second meniscus lens component having positive refractive power with its convex surface on the image side.

11. The retrofocus, wide-angle lens of claim 1 , wherein said meniscus lens component of said second lens group is separated from said biconvex lens element only by said air space.

12. The retrofocus, wide-angle lens of claim 11 , wherein the following condition is satisfied:

1 <|R/R′|< 1.08

where

R is the radius of curvature of the object-side lens surface of said meniscus lens component of said second lens group; and

R′ is the radius of curvature of the image-side lens surface of said biconvex lens element.

13. The retrofocus, wide-angle lens of claim 12 , wherein the following conditions are satisfied:

νB−νA> 25

νB>65

1.38 <|φ/R′| <1.65

where

νA is the Abbe number at the d-line of the lens material of the lens element having negative refractive power of the cemented lens component of the second lens group;

νB is the Abbe number at the d-line of the lens material of said biconvex lens element of the second lens group; and

φ is the effective diameter of the image-side lens surface of said biconvex lens element of the second lens group.

14. The retrofocus, wide-angle lens of claim 13 , wherein said second lens group comprises, in order from the object side;

the meniscus lens component having positive refractive power with its convex surface on the image side;

the lens element of said cemented lens component having negative refractive power;

the biconvex lens element of said cemented lens component;

the meniscus lens component having negative refractive power with its concave surface on the object side; and

a second meniscus lens component having positive refractive power with its convex surface on the image side.

15. The retrofocus, wide-angle lens of claim 1 , wherein the following condition is satisfied:

1 <|R/R′|< 1.08

where

R is the radius of curvature of the object-side lens surface of said meniscus lens component of said second lens group; and

R′ is the radius of curvature of the image-side lens surface of said biconvex lens element.

16. The retrofocus, wide-angle lens of claim 15 , wherein the following conditions are satisfied:

νB−νA> 25

νB>65

1.38 <|φ/R′|< 1.65

where

νA is the Abbe number at the d-line of the lens material of the lens element having negative refractive power of the cemented lens component of the second lens group;

νB is the Abbe number at the d-line of the lens material of said biconvex lens element of the second lens group; and

φ is the effective diameter of the image-side lens surface of said biconvex lens element of the second lens group.

17. The retrofocus, wide-angle lens of claim 16 , wherein said second lens group comprises, in order from the object side:

the meniscus lens component having positive refractive power with its convex surface on the image side;

the lens element of said cemented lens component having negative refractive power;

the biconvex lens element of said cemented lens component;

the meniscus lens component having negative refractive power with its concave surface on the object side; and

a second meniscus lens component having positive refractive power with its convex surface on the image side.

18. The retrofocus, wide-angle lens of claim 1 , wherein the following conditions are satisfied:

νB−νA> 25

νB>65

1.38 <|φ/R′|< 1.65

where

νA is the Abbe number at the d-line of the lens material of the lens element having negative refractive power of the cemented lens component of the second lens group;

νB is the Abbe number at the d-line of the lens material of said biconvex lens element of the second lens group;

φ is the effective diameter of the image-side lens surface of said biconvex lens element of the second lens group; and

R′ is the radius of curvature of the image-side lens surface of said biconvex lens element.

19. The retrofocus, wide-angle lens of claim 18 , wherein said second lens group comprises, in order from the object side:

the meniscus lens component having positive refractive power with its convex surface on the image side;

the lens element of said cemented lens component having negative refractive power;

the biconvex lens element of said cemented lens component;

the meniscus lens component having negative refractive power with its concave surface on the object side; and

a second meniscus lens component having positive refractive power with its convex surface on the image side.

20. The retrofocus, wide-angle lens of claim 1 , wherein said second lens group comprises, in order from the object side:

the meniscus lens component having positive refractive power with its convex surface on the image side;

the lens element of said cemented lens component having negative refractive power;

the biconvex lens element of said cemented lens component;

the meniscus lens component having negative refractive power with its concave surface on the object side; and

a second meniscus lens component having positive refractive power with its convex surfac e on the image side.