Zoom lens and image pickup apparatus having the same
AssigneeCanon Kabushiki Kaisha
InventorYasuaki Hagiwara
Life of this patent
Estimating the term…
Abstract
A zoom lens includes, from the object side to the image side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group having positive refractive power. At least the second and fourth lens groups are moved along the optical axis during zooming. The second lens group includes, from the object side to the image side, three negative lenses and one positive lens and satisfies 0.54<|f2|/√(fw·ft)<0.66 where f2 is the focal length of the second lens group, and fw and ft are the focal lengths of the entire optical system at the wide-angle end and at the telephoto end, respectively.
Claims6
A zoom lens comprising, in order from the object side to the image side:
- a first lens group having positive refractive power;
- a second lens group having negative refractive power;
- a third lens group having positive refractive power;
- and
- a fourth lens group having positive refractive power, at least the second and fourth lens groups are moved along the optical axis during zooming, and
- wherein the second lens group includes, in order from the object side to the image side, three negative lenses and one positive lens and satisfies
- 0.54<|f2|/√(fw·ft)<0.66
- where f2 is the focal length of the second lens group, and fw and ft are the focal lengths of the entire optical system at the wide-angle end and at the telephoto end, respectively.
Dependencies are inferred from the claim text.