Imaging lens and imaging apparatus equipped with the imaging lens
View Patent ↗An imaging lens is constituted by six lenses, including: a first lens having a positive refractive power and a convex surface toward the object side; a second lens having a negative refractive power and a convex surface toward the object side; a third lens having a positive refractive power; a fourth lens having a positive refractive power; a fifth lens having a positive refractive power and a convex surface toward the object side; and a sixth lens having a negative refractive power, provided in this order from the object side. The imaging lens satisfies a predetermined conditional formula.
1. An imaging lens consisting of six lenses, including:
a first lens having a positive refractive power and a convex surface toward the object side;
a second lens having a negative refractive power and a convex surface toward the object side;
a third lens having a positive refractive power;
a fourth lens having a positive refractive power;
a fifth lens having a positive refractive power and a convex surface toward the object side; and
a sixth lens having a negative refractive power, provided in this order from the object side;
the imaging lens satisfying the following conditional formulae:
f 23/ f<− 2.5 (1);
2< f 34/ f< 4.5 (2)
wherein f 23 is the combined focal length of the second lens and the third lens, f 34 is the combined focal length of the third lens and the fourth lens, and f is the focal length of the entire system.
2. An imaging lens as defined in claim 1 , wherein:
the third lens has a convex surface toward the image side.
3. An imaging lens as defined in any claim 1 that further satisfies the conditional formula below:
−7.8< f 56/ f<− 1.2 (3)
wherein f 56 is the combined focal length of the fifth lens and the sixth lens, and f is the focal length of the entire system.
4. An imaging lens as defined in claim 1 that further satisfies the conditional formula below:
−1.75< f 2/ f<− 1.3 (4)
wherein f 2 is the focal length of the second lens, and f is the focal length of the entire system.
5. An imaging lens as defined in claim 1 that further satisfies the conditional formula below:
15< f 4/ f< 120 (6)
wherein f 4 is the focal length of the fourth lens, and f is the focal length of the entire system.
6. An imaging lens as defined in claim 1 that further satisfies the conditional formula below:
−5< f 3/ f 2<−1 (7)
wherein f 3 is the focal length of the third lens, and f 2 is the focal length of the second lens.
7. An imaging lens as defined in claim 1 that further satisfies the conditional formula below:
1< CT 3/ CT 4<6 (9)
wherein CT 3 is the thickness of the third lens along the optical axis, and CT 4 is the thickness of the fourth lens along the optical axis.
8. An imaging lens as defined in claim 1 that further satisfies the conditional formula below:
1.7< CT 5/ CT 6<5 (10)
wherein CT 5 is the thickness of the fifth lens along the optical axis, and CT 6 is the thickness of the sixth lens along the optical axis.
9. An imaging lens as defined in claim 1 that further satisfies the conditional formula below:
2.3<( L 3 r−L 3 f )/( L 3 r+L 3 f )<8.5 (11)
wherein L 3 r is the paraxial radius of curvature of the surface of the third lens toward the image side, and L 3 f is the paraxial radius of curvature of the surface of the third lens toward the object side.
10. An imaging lens as defined in claim 1 that further satisfies the conditional formula below:
−20<( L 6 r−L 6 f )/( L 6 r+L 6 f )<−3.5 (12)
wherein L 6 r is the paraxial radius of curvature of the surface of the sixth lens toward the image side, and L 6 f is the paraxial radius of curvature of the surface of the sixth lens toward the object side.
11. An imaging lens as defined in claim 1 , further comprising:
an aperture stop positioned at the object side of the surface of the second lens toward the object side.
12. An imaging lens as defined in claim 1 that further satisfies the conditional formula below:
0.5< f ·tan ω/ L 6 r< 20 (13)
wherein f is the focal length of the entire system, ω is half the maximum angle of view when focused on an object at infinity, and L 6 r is the paraxial radius of curvature of the surface of the sixth lens toward the image side.
13. An imaging lens as defined in claim 1 that further satisfies the conditional formula below:
f 23/ f<− 2.8 (1-1)
wherein f 23 is the combined focal length of the second lens and the third lens, and f is the focal length of the entire system.
14. An imaging lens as defined in claim 1 that further satisfies the conditional formula below:
2.2< f 34/ f< 4.2 (2-1)
wherein f 34 is the combined focal length of the third lens and the fourth lens, and f is the focal length of the entire system.
15. An imaging lens as defined in claim 1 that further satisfies the conditional formula below:
−6.8< f 56/ f<− 2.2 (3-1)
wherein f 56 is the combined focal length of the fifth lens and the sixth lens, and f is the focal length of the entire system.
16. An imaging apparatus equipped with an imaging lens as defined in claim 1 .
17. An imaging lens consisting of six lenses, including:
a first lens having a positive refractive power and a convex surface toward the object side;
a second lens having a negative refractive power and a convex surface toward the object side;
a third lens having a positive refractive power;
a fourth lens having a positive refractive power;
a fifth lens having a positive refractive power and a convex surface toward the object side; and
a sixth lens having a negative refractive power, provided in this order from the object side;
the imaging lens satisfying the following conditional formulae:
f 23/ f<− 2.5 (1);
2< f 3/ f< 9 (5)
wherein f 23 is the combined focal length of the second lens and the third lens, f 3 is the focal length of the third lens, and f is the focal length of the entire system.
18. An imaging lens consisting of six lenses, including:
a first lens having a positive refractive power and a convex surface toward the object side;
a second lens having a negative refractive power and a convex surface toward the object side;
a third lens having a positive refractive power;
a fourth lens having a positive refractive power;
a fifth lens having a positive refractive power and a convex surface toward the object side; and
a sixth lens having a negative refractive power, provided in this order from the object side;
the imaging lens satisfying the following conditional formulae:
f 23/ f<− 2.5 (1);
1.15< f 1/ f 5<3 (8)
wherein f 23 is the combined focal length of the second lens and the third lens, f is the focal length of the entire system, f 1 is the focal length of the first lens, and f 5 is the focal length of the fifth lens.