Zoom lens and image pickup apparatus including the same
A zoom lens includes first to fourth lens units in order from the object side to the image side. The first, third, and fourth lens units have a positive refractive power. The second lens unit has a negative refractive power. Distances between the lens units are changed during zooming. The first lens unit is composed of a cemented lens including a first lens having a negative refractive power and a second lens having a positive refractive power arranged in order from the object side to the image side. The Nd1a and νd1a are a refractive index and an Abbe number, respectively, of a material of the first lens for the d-line and are adequately set.
1. A zoom lens comprising:
a first lens unit having a positive refractive power;
a second lens unit having a negative refractive power;
a third lens unit having a positive refractive power; and
a fourth lens unit having a positive refractive power,
wherein the first, second, third and fourth lens units are arranged in order from the object side to the image side, respectively,
wherein distances between the lens units are changed during zooming,
wherein the first lens unit is composed of a cemented lens including a first lens having a negative refractive power and a second lens having a positive refractive power arranged in order from the object side to the image side, and
wherein, when Nd1a and νd1a are a refractive index and an Abbe number, respectively, of a material of the first lens for a d-line,
the following conditions are satisfied:
ν d 1 a< 23.8
Nd 1 a> 0.0186×ν d 1 a+ 1.594,
wherein, when m 1 is a difference between positions of the first lens unit at a wide-angle end and a telephoto end along an optical axis, f 1 is a focal length of the first lens unit, fG 1 a is a focal length of the first lens, and fw is a focal length of the entire system of the zoom lens at the wide-angle end, the following conditions are satisfied:
m 1/ fw> 3.0
| fG 1 a|/f 1>2.0.
2. The zoom lens according to claim 1 ,
wherein, when f 2 is a focal length of the second lens unit and fw is a focal length of the entire lens system of the zoom lens at the wide-angle end, the following condition is satisfied:
−2.0 <f 2/ fw<− 0.7.
3. The zoom lens according to claim 1 ,
wherein the second lens unit includes at least one positive lens and at least one negative lens.
4. The zoom lens according to claim 3 ,
wherein, when νd2a is an Abbe number for the d-line of a material of a positive lens which is closest to the object side in the second lens unit, the following condition is satisfied:
ν d 2 a< 19.5.
5. The zoom lens according to claim 1 , wherein the zoom lens forms an image on a solid-state image pickup element.
6. An image pickup apparatus, comprising:
the zoom lens according to claim 1 ; and
a solid-state image pickup element which receives an image formed by the zoom lens.
7. The zoom lens according to claim 1 , wherein,
when f 1 is a focal length of the first lens unit and fw is a focal length of the entire lens system of the zoom lens at the wide-angle end, the following condition is satisfied:
5.0< f 1/ fw< 10.0.
8. The zoom lens according to claim 1 , wherein,
when f 1 is a focal length of the first lens unit and f 2 is a focal length of the second lens unit, the following condition is satisfied:
0.10<| f 2/ f 1|<0.25.
9. A zoom lens comprising:
a first lens unit having a positive refractive power;
a second lens unit having a negative refractive power;
a third lens unit having a positive refractive power; and
a fourth lens unit having a positive refractive power,
wherein the first, second, third and fourth lens units are arranged in order from the object side to the image side, respectively,
wherein distances between the lens units are changed during zooming,
wherein the first lens unit is composed of a cemented lens including a first lens having a negative refractive power and a second lens having a positive refractive power arranged in order from the object side to the image side, and
wherein, when Nd1a and νd1a are a refractive index and an Abbe number, respectively, of a material of the first lens for a d-line,
the following conditions are satisfied:
ν d 1 a< 23.8
Nd 1 a> 0.0186×ν d 1 a+ 1.594,
wherein, when f 1 is a focal length of the first lens unit and fw is a focal length of the entire lens system of the zoom lens at the wide-angle end, the following condition is satisfied:
5.0< f 1/ fw< 10.0.
10. The zoom lens according to claim 9 ,
wherein, when f 2 is a focal length of the second lens unit and fw is a focal length of the entire lens system of the zoom lens at the wide-angle end, the following condition is satisfied:
−2.0 <f 2/ fw<− 0.7.
11. The zoom lens according to claim 9 ,
wherein the second lens unit includes at least one positive lens and at least one negative lens.
12. The zoom lens according to claim 9 , wherein the zoom lens forms an image on a solid-state image pickup element.
13. An image pickup apparatus, comprising:
the zoom lens according to claim 9 ; and
a solid-state image pickup element which receives an image formed by the zoom lens.
14. A zoom lens comprising:
a first lens unit having a positive refractive power;
a second lens unit having a negative refractive power;
a third lens unit having a positive refractive power; and
a fourth lens unit having a positive refractive power,
wherein the first, second, third and fourth lens units are arranged in order from the object side to the image side, respectively,
wherein distances between the lens units are changed during zooming,
wherein the first lens unit is composed of a cemented lens including a first lens having a negative refractive power and a second lens having a positive refractive power arranged in order from the object side to the image side, and
wherein, when Nd1a and νd1a are a refractive index and an Abbe number, respectively, of a material of the first lens for a d-line,
the following conditions are satisfied:
ν d 1 a< 23.8
Nd 1 a> 0.0186×ν d 1 a+ 1.594,
wherein, when f 1 is a focal length of the first lens unit and f 2 is a focal length of the second lens unit, the following condition is satisfied:
0.10<| f 2/ f 1|<0.25.
15. The zoom lens according to claim 14 ,
wherein, when f 2 is a focal length of the second lens unit and fw is a focal length of the entire lens system of the zoom lens at the wide-angle end, the following condition is satisfied:
−2.0 <f 2/ fw<− 0.7.
16. The zoom lens according to claim 14 ,
wherein the second lens unit includes at least one positive lens and at least one negative lens.
17. The zoom lens according to claim 14 , wherein the zoom lens forms an image on a solid-state image pickup element.
18. An image pickup apparatus, comprising:
the zoom lens according to claim 14 ; and
a solid-state image pickup element which receives an image formed by the zoom lens.
19. A zoom lens, comprising:
a first lens unit having a positive refractive power;
a second lens unit having a negative refractive power;
a third lens unit having a positive refractive power; and
a fourth lens unit having a positive refractive power,
wherein the first, second, third and fourth lens units are arranged in order from the object side to the image side, respectively,
wherein distances between the lens units are changed during zooming,
wherein the first lens unit is composed of a cemented lens including a first lens having a negative refractive power and a second lens having a positive refractive power arranged in order from the object side to the image side, and
wherein, when Nd1a and νd1a are a refractive index and an Abbe number, respectively, of a material of the first lens for a d-line, and
wherein, when νd2a is an Abbe number for the d-line of a material of a positive lens which is closest to the object side in the second lens unit, the following conditions are satisfied:
ν d 1 a< 23.8
Nd 1 a> 0.0186×ν d 1 a+ 1.594
ν d 2 a< 19.5.
20. The zoom lens according to claim 19 ,
wherein the second lens unit includes at least one positive lens and at least one negative lens.
21. The zoom lens according to claim 19 , wherein the zoom lens forms an image on a solid-state image pickup element.
22. An image pickup apparatus, comprising:
the zoom lens according to claim 19 ; and
a solid-state image pickup element which receives an image formed by the zoom lens.