Imaging lens and imaging apparatus
An imaging lens includes a first lens that is a negative meniscus lens having a concave surface facing the image side of the imaging lens, a second lens that is a positive lens having a convex surface facing the object side of the imaging lens, a third lens that is a negative lens having a concave surface facing the image side, a fourth lens that is a double-convex lens, a fifth lens that is a negative meniscus lens having a concave surface facing the object side, and a sixth lens that is a negative lens, which are arranged in this order from the object side.
1. An imaging lens comprising:
a first lens that is a negative meniscus lens having a concave surface facing the image side of the imaging lens;
a second lens that is a positive lens having a convex surface facing the object side of the imaging lens;
a third lens that is a negative lens having a concave surface facing the image side;
a fourth lens that is a double-convex lens;
a fifth lens that is a negative meniscus lens having a concave surface facing the object side; and
a sixth lens that is a negative lens, which are arranged in this order from the object side.
2. An imaging lens, as defined in claim 1 , wherein the following Formula (1) is satisfied:
1.65<( N 2+ N 3+ N 4)/3 (1),
where
N 2 is the refractive index of the second lens with respect to e-line,
N 3 is the refractive index of the third lens with respect to e-line, and
N 4 is the refractive index of the fourth lens with respect to e-line.
3. An imaging lens, as defined in claim 1 , wherein the following Formula (2) is satisfied:
1.50<( N 1+ N 6)/2<1.66 (2),
where
N 1 is the refractive index of the first lens with respect to e-line, and
N 6 is the refractive index of the sixth lens with respect to e-line.
4. An imaging lens, as defined in claim 1 , wherein the following Formula (3) is satisfied:
0.5 <f 1/ f 56<1.5 (3),
where
f 1 is the focal length of the first lens with respect to e-line, and
f 56 is the combined focal length of the fifth lens and the sixth lens with respect to e-line.
5. An imaging lens, as defined in claim 1 , wherein the following Formula (4) is satisfied:
0.45 <Dp/f< 1.10 (4),
where
Dp is a distance, on an optical axis, between an object-side surface of the second lens and an image-side surface of the fourth lens, and
f is the focal length of the entire system of the imaging lens with respect to e-line.
6. An imaging lens, as defined in claim 1 , wherein the following Formula (5) is satisfied:
0.7 <f 2/ f 34<1.2 (5),
where
f 2 is the focal length of the second lens with respect to e-line, and
f 34 is the combined focal length of the third lens and the fourth lens with respect to e-line.
7. An imaging lens, as defined in claim 1 , wherein the following Formula (6) is satisfied:
0.20 <Dn/f< 0.70 (6),
where
Dn is a distance, on an optical axis, between an image-side surface of the fourth lens and an image-side surface of the sixth lens, and
f is the focal length of the entire system of the imaging lens with respect to e-line.
8. An imaging lens, as defined in claim 1 , wherein the following Formula (7) is satisfied:
0<ν4−ν3<25 (7),
where
ν 3 is the Abbe number of the third lens with respect to d-line, and
ν 4 is the Abbe number of the fourth lens with respect to d-line.
9. An imaging lens, as defined in claim 1 , wherein the third lens and the fourth lens are cemented together to form a cemented lens having positive refractive power as a whole.
10. An imaging lens, as defined in claim 1 , wherein the following Formulas (8) and (9) are satisfied:
1.65 <N 5 (8);
and
1.0 <R 5 im/R 5 ob< 3.0 (9),
where
N 5 is the refractive index of the fifth lens with respect to e-line,
R 5 ob is a radius of curvature of an object-side surface of the fifth lens, and
R 5 im is a radius of curvature of an image-side surface of the fifth lens.
11. An imaging lens, as defined in claim 1 , wherein the following Formula (10) is satisfied:
0.0≦ f/|R 2 im| <0.67 (10),
where
f is the focal length of the entire system of the imaging lens with respect to e-line, and
R 2 im is a radius of curvature of an image-side surface of the second lens.
12. An imaging lens, as defined in claim 1 , wherein the following Formula (11) is satisfied:
0.0 f/|R 3 ob |<0.67 (11),
where
f is the focal length of the entire system of the imaging lens with respect to e-line, and
R 3 ob is a radius of curvature of an object-side surface of the third lens.
13. An imaging lens, as defined in claim 1 , wherein the sixth lens is a meniscus lens having a convex surface facing the image side.
14. An imaging apparatus comprising:
an imaging lens, as defined in claim 1 .