| US 7,538,957 B2 | ||
| Photographing optical system and image pickup apparatus including the same | ||
| Hiroshi Endo, Utsunomiya (Japan) | ||
| Assigned to Canon Kabushiki Kaisha, Tokyo (Japan) | ||
| Filed on Oct. 09, 2007, as Appl. No. 11/869,666. | ||
| Claims priority of application No. 2006-277725 (JP), filed on Oct. 11, 2006. | ||
| Prior Publication US 2008/0088950 A1, Apr. 17, 2008 | ||
| Int. Cl. G02B 3/00 (2006.01) | ||
| U.S. Cl. 359—754 [359/737] | 29 Claims |
| 1. A photographing optical system comprising:
a positive lens provided closer to the object side of the system than the intersection (P) of the light axis and a paraxial
chief ray; and
a negative lens provided closer to the image side of the system than the intersection (P),
wherein the positive lens and the negative lens are both formed of materials satisfying the following two conditions when
the maximum height of a paraxial marginal ray, passing through a lens surface, from the light axis at a location closer to
the object side than the intersection (P) is greater than a maximum height of the paraxial marginal ray, passing through a
lens surface, from the light axis at a location closer to the image side than the intersection (P):
−0.0015×νd +0.6425 <θgF, and
60 <νd where νd is the Abbe number and θgF is the partial dispersion ratio.
|