Imaging lens, and imaging apparatus including the imaging lens
View Patent ↗An imaging lens substantially consists of a negative first lens group and a positive second lens group in this order from the object side. The first lens group substantially consists of only a first lens, which is one biconcave lens. The second lens group substantially consists of, in the following order from the object side: a cemented lens, which is formed by bonding a second lens, i.e., a biconvex lens, and a third lens, i.e., a negative meniscus lens, in this order from the object side, and which has a positive refractive power as a whole; an aperture stop; and a cemented lens that is formed by bonding a fourth lens, i.e., a biconvex lens and a fifth lens, i.e., a negative meniscus lens in this order from the object side and that has a positive refractive power as a whole.
1. An imaging lens, consisting of, in the recited order from an object side:
a negative first lens group consisting of only a first lens, which is a single biconcave lens; and
a positive second lens group consisting of a cemented lens that is formed by bonding a second lens, which is a biconvex lens, and a third lens, which is a negative meniscus lens, in this order from the object side and that has a positive refractive power as a whole; an aperture stop; and a cemented lens that is formed by bonding a fourth lens which is a biconvex lens and a fifth lens which is a negative meniscus lens in this order from the object side and that has a positive refractive power as a whole,
wherein the imaging lens satisfies conditional expression (5) given below:
1.5<(dsi)/ f< 3.2 (5),
where:
dsi: the distance (the back focus portion corresponds to the air conversion distance) between an aperture stop and an image formation surface on the optical axis; and
f: the focal length of the entire lens system.
2. The imaging lens of claim 1 , wherein the imaging lens satisfies a conditional expression (3) given below:
0.5< fg 2/ f< 2.5 (3),
where:
fg 2 : the focal length of the second lens group; and
f: the focal length of the entire lens system.
3. The imaging lens of claim 1 , wherein the imaging lens satisfies a conditional expression (4) given below:
−2< f 1/ fg 2<0 (4),
where:
f 1 : the focal length of the first lens; and
fg 2 : the focal length of the second lens group.
4. An imaging apparatus, comprising the imaging lens of claim 1 .
5. An imaging lens, consisting of in the recited order from an object side:
a negative first lens group consisting of only a first lens, which is a single biconcave lens; and
a positive second lens group consisting of a cemented lens that is formed by bonding a second lens, which is a positive lens, and a third lens, which is a negative lens, in this order from the object side and that has a positive refractive power as a whole; an aperture stop; and a cemented lens that is formed by bonding a fourth lens which is a positive lens and a fifth lens which is a negative lens in this order from the object side and that has a positive refractive power as a whole,
wherein the imaging lens satisfies a conditional expression (1a) given below:
50<ν d 2+ν d 3<110 (1a),
where:
νd 2 : the Abbe number at the d line of the second lens; and
νd 3 : the Abbe number at the d line of the third lens.
6. The imaging lens of claim 5 , wherein the imaging lens satisfies a conditional expression (1a′) given below:
60<ν d 2+ν d 3<100 (1a′).
7. The imaging lens of claim 6 , wherein the second lens which is a biconvex lens, the third lens which is a negative lens with a concave surface toward the object side, the fourth lens which is a biconvex lens, and the fifth lens which is a negative lens with a concave surface toward the object side.
8. The imaging lens of claim 6 , the third lens has a meniscus shape.
9. The imaging lens of claim 6 , the fifth lens has a meniscus shape.
10. The imaging lens of claim 6 , wherein the imaging lens comprises a cemented lens, which is formed by cementing the fourth lens and the fifth lens together and which has a positive refractive power as a whole.
11. The imaging lens of claim 5 , wherein the imaging lens satisfies a conditional expression (1a″) given below:
65<ν d 2+ν d 3<85 (1a″).
12. The imaging lens of claim 5 , wherein the second lens which is a biconvex lens, the third lens which is a negative lens with a concave surface toward the object side, the fourth lens which is a biconvex lens, and the fifth lens which is a negative lens with a concave surface toward the object side.
13. The imaging lens of claim 5 , the third lens has a meniscus shape.
14. The imaging lens of claim 5 , the fifth lens has a meniscus shape.
15. The imaging lens of claim 5 , wherein the imaging lens comprises a cemented lens, which is formed by cementing the fourth lens and the fifth lens together and which has a positive refractive power as a whole.
16. The imaging lens of claim 5 , wherein the imaging lens satisfies a conditional expression (3) given below:
0.5< fg 2/ f< 2.5 (3),
where:
fg 2 : the focal length of the second lens group; and
f: the focal length of the entire lens system.
17. An imaging apparatus, comprising the imaging lens of claim 5 .
18. An imaging lens, consisting of, in the recited order from an object side:
a negative first lens group consisting of only a first lens, which is a single biconcave lens; and
a positive second lens group consisting of a cemented lens that is formed by bonding a second lens, which is a biconvex lens, and a third lens, which is a negative meniscus lens, in this order from the object side and that has a positive refractive power as a whole; an aperture stop; and a cemented lens that is formed by bonding a fourth lens which is a biconvex lens and a fifth lens which is a negative meniscus lens in this order from the object side and that has a positive refractive power as a whole,
wherein the imaging lens satisfies a conditional expression (6) given below:
0.42<(dsi)/ L< 1 (6),
where:
L: the total optical length.