Claims
- 1. A zoom lens comprising, in order from an object side to an image side:a first lens unit of positive optical power; a second lens unit of negative optical power arranged to move during a variation of magnification, said second lens unit consisting of, in order from the object side to the image side, a negative lens, a negative lens, a positive lens and a negative lens; a third lens unit of positive optical power, said third lens unit having a plurality of positive lenses and a negative lens; and a fourth lens unit of positive optical power arranged to move during the variation of magnification, said fourth lens unit being moved to effect focusing, wherein the following condition is satisfied: 0.25<(Fm−Fw)/(Ft−Fw)<0.45 where Fm is a focal length of the entire zoom lens in a position where said fourth lens unit has moved a maximum distance during the variation of magnification with focusing on an infinitely distant object, Fw is a focal length of the entire zoom lens at a wide-angle end, and Ft is a focal length of the entire zoom lens at a telephoto end.
- 2. A zoom lens according to claim 1, further satisfying the following conditions:−8.5<f1/f2<−7.0 0.1<D34t/Ft<0.2 where f1 and f2 are focal lengths of said first lens unit and said second lens unit, respectively, and D34t is the separation between said third lens unit and said fourth lens unit at the telephoto end with focusing on an infinitely distant object.
- 3. A zoom lens according to claim 1, wherein at least one of said third lens unit and said fourth lens unit has an aspherical lens.
- 4. A zoom lens according to claim 1, further comprising a stop, said stop being disposed closest to the object on the object side of said third lens unit.
- 5. A zoom lens according to claim 1, further satisfying at least one of the following conditions:−0.45<f2/(Fw×Ft)0.5<−0.25 12.0<f1/Fw<16.0 4.0<f4/Fw<6.0 1.75<N2A where f1, f2 and f4 are focal lengths of said first lens unit, said second lens unit and said fourth lens unit, respectively, and N2A is the average refractive index of materials of the negative lenses included in said second lens unit.
- 6. A zoom lens according to claim 1, wherein, during a variation of magnification from the wide-angle end to the telephoto end, said second lens unit moves toward the image side, said fourth lens unit so moves as to compensate for a shift of an image plane caused by the variation of magnification, and said first lens unit and said third lens unit remain stationary.
- 7. An optical apparatus comprising a zoom lens according to claim 1.
Priority Claims (1)
Number |
Date |
Country |
Kind |
10-272568 |
Sep 1998 |
JP |
|
Parent Case Info
This application is a division of application Ser. No. 09/389,454 filed Sep. 3, 1999, now U.S. Pat. No. 6,118,593.
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