Claims
- 1. A small-sized zoom lens comprising, from front to rear, a first lens unit of positive refractive power and a second lens unit of negative refractive power, zooming being performed by varying a separation between said first and second lens units, wherein said first lens unit comprises, in order from the object side to the image side, a bi-concave negative lens and at least two positive lenses, said second lens unit has a first lens and a second lens of negative refractive power having a concave surface facing an object side, and said second lens unit has at least one aspheric surface, and wherein letting focal lengths of said first and second lens units be denoted by f1 and f2, respectively, a shortest focal length of said zoom lens by fw, a refractive index and an Abbe number of a material of said first lens by N2F and .nu.2F, respectively, a refractive index of a material of said second lens by N2R, and focal lengths of said first and second lenses by f2F and f2R, respectively, the following conditions are satisfied:
- 0.4<f1/fw<0.9
- 0.444<.vertline.f2/fw.vertline.<0.671
- 1.055<N2F-(.nu.2F/200)<1.505
- -0.142<f2R/f2F<0.078
- N2R<1.65.
- 2.
- 2. A small-sized zoom lens according to claim 1 satisfying the following condition:
- 2.025<N2R+.nu.2R/125<2.151
- where .nu.2R is an Abbe number of a material of said second lens.
- 3. A small-sized zoom lens comprising, from front to rear, a first lens unit of positive refractive power and a second lens unit of negative refractive power, zooming being performed by varying a separation between said first and second lens units, wherein said first lens unit comprises four lenses, including, in order from the object side to the image side, a bi-concave negative lens and at least two positive lenses, said second lens unit has a first lens and a negative second lens having a concave surface facing an object side, and said second lens unit has at least one aspheric surface, wherein letting focal lengths of said first and second lens units be denoted by f1 and f2, respectively, a shortest focal length of said zoom lens by fw, and a refractive index and an Abbe number of said second lens by N2R and .nu.2R, respectively, the following conditions are satisfied:
- 0.4<f1/fw<0.9
- 0.444<.vertline.f2/fw.vertline.<0.671
- 2.025<N2R+.nu.2R/125<2.151
- -0.142<f2R/f2F<0.078,
- wherein f2F and f2R are focal lengths of said first and second lenses, respectively, and
- wherein a rearmost lens of said first lens unit is a bi-convex lens.
- 4. A small-sized zoom lens according to claim 1 or 3, satisfying the following condition:
- .nu.2F<55
- where .nu.2F is an Abbe number of a material of said first lens.
- 5. A small-sized zoom lens according to claim 1 or 3, wherein said first lens unit comprises, from front to rear, a positive first lens, a negative second lens, a positive third lens and a positive fourth lens, and wherein letting a refractive index and an Abbe number of a material of said first lens in said first lens unit be denoted by N11 and .nu.11, respectively, the following condition is satisfied:
- 1.651<N11 +.nu.11/100<2.201.
- 6. A small-sized zoom lens according to claim 1 or 3, wherein said first lens unit comprises, from front to rear, a positive first lens, a negative second lens, a positive third lens and a positive fourth lens, and wherein letting a refractive index of a material of said first lens in said first lens unit be denoted by N11, the following condition is satisfied:
- N11<1.65.
- 7.
- 7. A small-sized zoom lens according to claim 3, satisfying the following condition:
- 1.055<N2F-(.nu.2F/200)<1.505
- where N2F and .nu.2F are a refractive index and an Abbe number of a material of said first lens in said second lens unit, respectively.
- 8. A small-sized zoom lens according to claim 3, wherein said second lens unit consists of said first lens and said second lens.
- 9. A small-sized zoom lens comprising, from front to rear, a first lens unit of positive refractive power and a second lens unit of negative refractive power, zooming being performed by varying a separation between said first and second lens units, wherein said first lens unit comprises, in order from the object side to the image side, a bi-concave negative lens and at least two positive lenses, said second lens unit has a first lens and a negative second lens having a concave surface facing an object side, and said second lens unit has at least one aspheric surface, and wherein letting focal lengths of said first and second lens units be denoted by f1 and f2, respectively, a shortest focal length of said zoom lens by fw, and a refractive index of said second lens by N2R, the following conditions are satisfied:
- 0.4<f1/fw<0.9
- 0.444<.vertline.f2/fw.vertline.<0.671
- N2R<1.65
- -0.142<f2R/f2F<0.078
- wherein f2F and f2R represent a focal length of said first lens and said second lens, respectively.
- 10. A small-sized zoom lens according to claim 9, wherein said second lens unit consists of said first lens and said second lens.
- 11. A small-sized zoom lens comprising, from front to rear, a first lens unit of positive refractive power and a second lens unit of negative refractive power, zooming being performed by varying a separation between said first and second lens units, wherein said first lens unit comprises, in order from the object side to the image side, a bi-concave negative lens and at least two positive lenses, said second lens unit has a first lens and a second lens of negative refractive power having a concave surface facing an object side, and said second lens unit has at least one aspheric surface, wherein letting focal lengths of said first and second lens units be denoted by f1 and f2, respectively, a shortest focal length of said zoom lens by fw, a refractive index and an Abbe number of a material of said first lens by N2F and .nu.2F, respectively, and focal lengths of said first and second lenses by f2F and f2R, respectively, the following conditions are satisfied:
- 0.4<f1/fw<0.9
- 0.444<.vertline.f2/fw.vertline.<0.671
- 1.055<N2F-(.nu.2F/200)<1.505
- -0.142<f2R/f2F<0.078, and
- wherein a rearmost lens of said first lens unit is a bi-convex lens.
- 12. A small-sized zoom lens comprising, from front to rear, a first lens unit of positive refractive power and a second lens unit of negative refractive power, zooming being performed by varying a separation between said first and second lens units, wherein said first lens unit comprises, in order from the object size to the image side, a negative lens and at least two positive lenses, said second lens unit has a first lens and a negative second lens having a concave surface facing an object side, and said second lens unit has at least one aspheric surface, wherein letting focal lengths of said first and second lens units be denoted by f1 and f2, respectively, a shortest focal length of said zoom lens by fw, and a refractive index and an Abbe number of said second lens by N2R and .nu.2R, respectively, the following conditions are satisfied:
- 0.4<f1/fw<0.9
- 0.444<.vertline.f2/fw.vertline.<0.671
- 2.025<N2R+.nu.2R/125<2.151
- -0.142<f2R/f2F<0.078,
- wherein f2F and f2F are focal lengths of said first and second lenses, respectively,
- wherein a rearmost lens of said first lens unit is a bi-convex lens, and
- wherein said negative lens of said first lens unit is a bi-concave lens.
Priority Claims (1)
Number |
Date |
Country |
Kind |
5-318969 |
Nov 1993 |
JPX |
|
Parent Case Info
This application is a continuation of application Ser. No. 08/344,637 filed Nov. 18, 1994, now abandoned.
US Referenced Citations (7)
Foreign Referenced Citations (15)
Number |
Date |
Country |
56-128911 |
Oct 1981 |
JPX |
57-201213 |
Dec 1982 |
JPX |
60-170816 |
Sep 1985 |
JPX |
60-191216 |
Sep 1985 |
JPX |
62-56917 |
Mar 1987 |
JPX |
62-90611 |
Apr 1987 |
JPX |
62-113120 |
May 1987 |
JPX |
62-256915 |
Nov 1987 |
JPX |
62-284319 |
Dec 1987 |
JPX |
63-161422 |
Jul 1988 |
JPX |
6452111 |
Feb 1989 |
JPX |
1193807 |
Aug 1989 |
JPX |
2284109 |
Nov 1990 |
JPX |
3116110 |
May 1991 |
JPX |
3127008 |
May 1991 |
JPX |
Continuations (1)
|
Number |
Date |
Country |
Parent |
344637 |
Nov 1994 |
|