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US 5,111,338 AGranted
Zoom Lens
AssigneeCanon Kabushiki Kaisha
InventorHiroki Nakayama
Life of this patent
Estimating the term…
Abstract
A zoom lens comprising, from front to rear, a first lens unit of negative power, a seconde lens unit of positive power, a third lens unit of positive power and a fourth lens unit of negative power, wherein zooming from the wide-angle end to the telephoto end is performed by moving at least the second and fourth lens units toward the object side in such a way that the air separations between the first and second lens units and between the third and fourth lens units are shorter in the telephoto end than in the wide-angle end.
Claims17
A zoom lens comprising:
- from front to rear,
- a first lens unit having a negative refractive power;
- a second lens unit having a positive refractive power;
- a third lens unit having a positive refractive power;
- and
- a fourth lens unit having a negative refractive power;
- wherein zooming from the wide-angle end to the telephoto end is performed by having at least said second and fourth lens unit toward the object side in such a way that a separation between said first lens unit and said second lens unit and a separation between said third lens unit and said fourth lens unit are shorter in the telephoto end than in the wide-angle end wherein, further, said second and fourth lens units also are moved in such a way that the magnifications of said second lens unit and said fourth lens unit increase, and the amount of variation of the magnification for said second lens unit is larger than that for said fourth lens unit.
4 more elements
A zoom lens comprising:
- from front to rear,
- a first lens unit having a negative refractive power;
- a second lens unit having a positive refractive power;
- a third lens unit having a positive refractive power;
- and
- a fourth lens unit having a negative refractive power,
- wherein zooming from the wide-angle end to the telephoto end is performed by moving at least said second and fourth lens units toward the object side, and wherein the amount of variation of the magnification of said second lens unit is larger than that of said fourth lens unit.
4 more elements
A zoom lens comprising:
- from front to rear,
- a first lens unit having a negative refractive power;
- a second lens unit having a positive refractive power;
- a third lens unit having a positive refractive power;
- and
- a fourth lens unit having a negative refractive power,
- wherein zooming from the wide-angle end to the telephoto end is performed by moving at least said second and fourth lens units toward the object side in such a way that a separation between said first lens unit and said second lens unit and a separation between said third lens unit and said fourth lens unit are shorter in the telephoto end than in the wide-angle end, while satisfying the following conditions:
- 0. 3</51 M.sub.2 /.DELTA.f.vertline.<0.9
- 0.3<.vertline.M.sub.4 /.DELTA.f.vertline.<0.9
- where M.sub.2 and M.sub.4 are the amounts of movement of said second and fourth lens units respectively with zooming from the wide-angle end to the telephoto end, and .DELTA.f is the amount of variation of the focal length of the entire lens system.
7 more elements
Dependencies are inferred from the claim text.