Optical system and optical apparatus including the same
AssigneeCanon Kabushiki Kaisha
InventorTakayoshi Yokoyama
Life of this patent
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Abstract
An optical system in which a maximum value of a height from an optical axis of a paraxial marginal ray closer to an expanded side than a point of intersection between an optical axis and a paraxial chief ray, includes a lens unit Lr including at least one refractive optical element Gn of a negative refractive power. In the optical system, νd (Gn) as an Abbe number of a material of the refractive optical element Gn, θgF (Gn) as a partial dispersion ratio regarding g and F-lines, FGn as a focal lengths of the refractive optical element Gn, and Fr as focal lengths of the lens unit Lr are set appropriately.
Claims12
An optical system in which a maximum value of a height from an optical axis of a paraxial marginal ray closer to an expanded side than a point P, P denoting a point of intersection between an optical axis and a paraxial chief ray, and in a lens surface of the expanded side is larger than a maximum value of a height from an optical axis closer to a reduced side than the point P in which the paraxial marginal ray passes through the lens surface,
- the optical system comprising:
- closer to the reduced side than the point P, a lens unit Lr including at least one refractive optical element Gn of a negative refractive power in which light entrance and exit surfaces are both refractive surfaces made of solid-state material,
- wherein when an Abbe number of a material of the refractive optical element Gn is νd (Gn), a partial dispersion ratio regarding g and F-lines is θgF (Gn), and a focal length of the refractive optical element Gn is FGn, a focal length of the lens unit Lr is Fr, the following conditions are satisfied:
- −2.100×10−3·νd(Gn)+0.693<θgF(Gn)
- 0.55<θgF(Gn)<0.90
- 0.02<|FGn/Fr|<10.00.
An optical system comprising:
- sequentially from an object side to an image side, a first lens unit of a positive refractive power and a second lens unit of a negative refractive power;
- an aperture stop;
- and
- closer to a reduced side than the aperture stop, a lens unit Lr including at least one refractive optical element Gn of a negative refractive power in which light entrance and exit surfaces are both refractive surfaces made of solid-state material,
- wherein when an Abbe number of a material of the refractive optical element Gn, and a partial dispersion ratio regarding g and F-lines are respectively νd (Gn) and θgF (Gn), and focal lengths of the refractive optical element Gn and the lens unit Lr are respectively FGn and Fr, the following conditions are satisfied:
- −2.100×10−3·νd(Gn)+0.693<θgF(Gn)
- 0.55<θgF(Gn)<0.90
- 0.02<|FGn/Fr|<10.00.
Dependencies are inferred from the claim text.