Imaging lens and imaging apparatus
View Patent ↗An imaging lens includes negative first lens having a concave image-side surface, positive second lens having a convex object-side surface in a paraxial region, an aperture stop, and positive third lens having a convex image-side surface in the paraxial region, which are arranged in this order from an object side. The Abbe numbers of materials constituting the first lens and the third lens for d-line are greater than or equal to 40. The Abbe number of a material constituting the second lens for d-line is less than or equal to 40. When the focal length of an entire system is f, and the center thickness of the second lens is D 3 , and the focal length of the first lens is f 1 , the following formulas (1′) and (2) are satisfied: 1.7< D 3/ f <2.9; and (1′) −5.0< f 1/ f <−1.8. (2)
1. An imaging lens consisting of:
a negative first lens having a concave image-side surface;
a positive second lens having a convex object-side surface in a paraxial region;
an aperture stop; and
a positive third lens having a convex image-side surface in the paraxial region, which are arranged in this order from an object side,
wherein the Abbe numbers of materials constituting the first lens and the third lens for d-line are greater than or equal to 40, and the Abbe number of a material constituting the second lens for d-line is less than or equal to 26, and
wherein when the focal length of an entire system is f, and the center thickness of the second lens is D 3 , and the focal length of the first lens is f 1 , the following formulas (1′) and (2) are satisfied:
1.7 <D 3 /f< 2.9 (1′); and
−5.0 <f 1 /f<− 1.8 (2).
2. The imaging lens according to claim 1 , wherein when the focal length of an entire system is f, and the focal length of the third lens is f 3 , the following formula (5) is satisfied:
1.00 <f 3 /f< 2.50 (5).
3. The imaging lens according to claim 1 , wherein when the focal length of an entire system is f, and the curvature radius of the object-side surface of the second lens in a paraxial region is R 3 , the following formula (6) is satisfied:
2.0 <R 3 /f< 10.0 (6).
4. The imaging lens according to claim 1 , wherein when the focal length of an entire system is f, and a distance in air between the first lens and the second lens on an optical axis is D 2 , the following formula (7) is satisfied:
0.9 <D 2 /f< 2.5 (7).
5. The imaging lens according to claim 1 , wherein when the focal length of an entire system is f, and the center thickness of the first lens is D 1 , the following formula (8) is satisfied:
0.4 <D 1 /f< 1.5 (8).
6. The imaging lens according to claim 1 , wherein when the focal length of an entire system is f, and the combined focal length of the first lens and the second lens is f 12 , the following formula (9) is satisfied:
4.0 <|f 12 /f|< 50.0 (9).
7. The imaging lens according to claim 1 , wherein when the focal length of an entire system is f, and the focal length of the second lens is f 2 , the following formula (10) is satisfied:
4.0 <f 2 /f< 20.0 (10).
8. The imaging lens according to claim 1 , wherein when the curvature radius of the object-side surface of the second lens in the paraxial region is R 3 , and the curvature radius of the object-side surface of the second lens at an effective diameter edge is RX 3 , the following formula (11) is satisfied:
0.1 <|RX 3 |/R 3<1.0 (11).
9. The imaging lens according to claim 1 , wherein when the focal length of an entire system is f, and the combined focal length of the second lens and the third lens is f 23 , the following formula (12) is satisfied:
1.00 <f 23 /f< 1.85 (12).
10. The imaging lens according to claim 1 , wherein the lens system consists of only three lenses of the first lens, the second lens and the third lens.
11. The imaging lens according to claim 1 , wherein when the focal length of an entire system is f, and the center thickness of the second lens is D 3 , the following formula (1-1) is satisfied:
1.7< D 3/ f< 2.5 (1-1).
12. The imaging lens according to claim 1 , wherein when the focal length of an entire system is f, and the focal length of the first lens is f 1 , the following formula (2-1) is satisfied:
−3.8< f 1/ f <−2.5 (2-1).
13. An imaging apparatus comprising:
the imaging lens according to claim 1 .
14. An imaging lens consisting of:
a negative first lens having a concave image-side surface;
a positive second lens having a convex object-side surface in a paraxial region;
an aperture stop; and
a positive third lens having a convex image-side surface in the paraxial region, which are arranged in this order from an object side,
wherein the Abbe numbers of materials constituting the first lens and the third lens for d-line are greater than or equal to 40, and the Abbe number of a material constituting the second lens for d-line is less than or equal to 26, and
wherein when the focal length of the first lens is f 1 , and the focal length of the second lens is f 2 , and the focal length of the third lens is f 3 , and the combined focal length of the second lens and the third lens is f 23 , the following formulas (3A) and (4) are satisfied:
3.0 <f 2 /f 3<50.0 (3A); and
1.3 <|f 1 /f 23|<4.0 (4).
15. The imaging lens according to claim 14 , wherein when the focal length of an entire system is f, and the focal length of the first lens is f 1 , the following formula (2) is satisfied:
−5.0 <f 1 /f<− 1.8 (2).
16. The imaging lens according to claim 14 , wherein when the focal length of the second lens is f 2 , and the focal length of the third lens is f 3 , the following formula (3A-1) is satisfied:
3.5< f 2/ f 3<6.0 (3A-1).
17. The imaging lens according to claim 14 , wherein when the focal length of the first lens is f 1 , and the combined focal length of the second lens and the third lens is f 23 , the following formula (4-1) is satisfied:
1.6<| f 1/ f 23|<2.2 (4-1).
18. An imaging apparatus comprising:
the imaging lens according to claim 14 .
19. An imaging lens consisting of:
a negative first lens having a concave image-side surface;
a positive second lens having a convex object-side surface in a paraxial region;
an aperture stop; and
a positive third lens having a convex image-side surface in the paraxial region, which are arranged in this order from an object side,
wherein the Abbe numbers of materials constituting the first lens and the third lens for d-line are greater than or equal to 40, and the Abbe number of a material constituting the second lens for d-line is less than or equal to 26, and the refractive index of the material constituting the second lens for d-line is greater than or equal to 1.62 and less than or equal to 1.8, and
wherein when the focal length of the second lens is f 2 , and the focal length of the third lens is f 3 , the following formula (3A) is satisfied:
3.0 <f 2 /f 3<50.0 (3A).
20. An imaging apparatus comprising:
the imaging lens according to claim 19 .