| US 7,545,577 B2 | ||
| Zoom lens and image pickup apparatus including the same | ||
| Hiroyuki Hamano, Koga (Japan); and Kenji Obu, Utsunomiya (Japan) | ||
| Assigned to Canon Kabushiki Kaisha, Tokyo (Japan) | ||
| Filed on Feb. 27, 2008, as Appl. No. 12/38,657. | ||
| Claims priority of application No. 2007-049012 (JP), filed on Feb. 28, 2007. | ||
| Prior Publication US 2008/0273249 A1, Nov. 06, 2008 | ||
| Int. Cl. G02B 15/14 (2006.01) | ||
| U.S. Cl. 359—676 [359/568; 359/740] | 9 Claims |
| 1. A zoom lens comprising:
a first lens unit having positive refractive power and being disposed closest to an object side;
an aperture disposed closer to an image side than the first lens unit; and
a rear lens group including one or more lens units at the image side of the aperture,
wherein the first lens unit and at least one lens unit among the rear lens group are moved at the time of zooming,
wherein the first lens unit includes a first diffraction optical part having positive power, the rear lens group includes
a second diffraction optical part having positive power, and
wherein when assuming that the focal length of the first diffraction optical part is fd1, the focal length of the second diffraction optical part is fd2, the distance between the first diffraction optical part and the aperture is L1 at the telephoto end, the distance between the second diffraction optical part and the aperture is L2 at the wide-angle end, and the focal length of the entire system at the wide-angle end and telephoto end are fw and ft respectively,
the following conditional expressions are satisfied
4.0<fd1/fd2<15.0
0.3<L1/ft<0.9
1.5<L2/fw<7.0.
|