Imaging lens and imaging apparatus
View Patent ↗An imaging lens substantially consists of negative first lens, positive second lens, negative third lens, positive fourth lens, positive fifth lens, and negative sixth lens in this order from an object side. At least one of second lens through sixth lens satisfies the following conditional expression (1), and the imaging lens, as a whole, satisfies the following conditional expression (2): (1/τ i )×( f/fi )<0 (1); and Σ(1/τ i )×( f/fi )<0 ( i =1 through 6) (2).
1. An imaging lens substantially consisting of:
a first lens having negative refractive power;
a second lens having positive refractive power;
a third lens having negative refractive power;
a fourth lens having positive refractive power;
a fifth lens having positive refractive power; and
a sixth lens having negative refractive power in this order from an object side,
wherein at least one of the second lens through the sixth lens satisfies the following conditional expression (1), and the imaging lens, as a whole, satisfies the following conditional expression (2):
(1/τ i )×( f/fi )<0 (1); and
Σ(1/τ i )×( f/fi )<0 ( i= 1 through 6) (2), where
τi: a thermal Abbe number of an i-th lens,
f: a focal length of an entire system, and
fi: a focal length of the i-th lens.
2. The imaging lens, as defined in claim 1 , wherein the first lens has a meniscus shape with its convex surface facing the object side.
3. The imaging lens, as defined in claim 1 , wherein the sixth lens has a concave surface facing the object side.
4. The imaging lens, as defined in claim 1 , wherein the fourth lens has a convex surface facing an image side.
5. The imaging lens, as defined in claim 1 , wherein the fifth lens has a convex surface facing the object side.
6. The imaging lens, as defined in claim 1 , wherein the second lens has a convex surface facing the object side.
7. The imaging lens, as defined in claim 1 , wherein the third lens has a concave surface facing the object side.
8. The imaging lens, as defined in claim 1 , wherein all of the first lens through the sixth lens are glass lenses.
9. The imaging lens, as defined in claim 1 , wherein at least one of the second lens through the sixth lens satisfies the following conditional expression (1-1):
(1/τ i )×( f/fi )<−5 e −6 (1-1).
10. The imaging lens, as defined in claim 9 , wherein at least one of the second lens through the fifth lens satisfies the conditional expression (1-1).
11. The imaging lens, as defined in claim 1 , wherein at least one of the second lens through the sixth lens satisfies the following conditional expression (1-2):
(1/τ i )×( f/fi )<−10 e −6 (1-2).
12. The imaging lens, as defined in claim 11 , wherein at least one of the second lens through the fifth lens satisfies the conditional expression (1-2).
13. The imaging lens, as defined in claim 1 , wherein the following conditional expression (2-1) is satisfied:
Σ(1/τ i )×( f/fi )<−5 e −6 ( i= 1 through 6) (2-1).
14. The imaging lens, as defined in claim 1 , wherein the following conditional expression (2-2) is satisfied:
Σ(1/τ i )×( f/fi )<−10 e −6 ( i= 1 through 6) (2-2).
15. An imaging apparatus comprising the imaging lens, as defined in claim 1 .