Optical system and image pickup apparatus including the same
AssigneeCanon Kabushiki Kaisha
InventorsYuichi Gyoda, Kohei Kimura
Life of this patent
Estimating the term…
Abstract
An optical system includes an aperture stop, and a focus lens unit arranged on an image side of the aperture stop, the focus lens unit having a negative refractive power and moving during focusing. The focus lens unit moves toward the image side during focusing from infinity to close distance. The focus lens unit includes a positive lens PL and a negative lens NL. An Abbe number νdNL of the material of the negative lens NL, a refractive index NdNL of the material of the negative lens NL at d-line, and an Abbe number νdPL of the material of the positive lens PL are set appropriately.
Claims16
An optical system comprising:
- an aperture stop;
- and
- a focus lens unit arranged on an image side of the aperture stop, the focus lens unit having a negative refractive power and moving during focusing, wherein
- the focus lens unit moves toward the image side during focusing from infinity to close distance and includes a positive lens PL and a negative lens NL, and
- the following conditional expressions are satisfied:
- 23.0<νdNL<40.0;
- 2.44<NdNL−0.0003×νdNL2+0.034×νdNL<2.64;
- and
- νdPL<23.0,
- where νdNL denotes an Abbe number of a material of the negative lens NL, NdNL denotes a refractive index of the material of the negative lens NL at d-line, and νdPL denotes an Abbe number of a material of the positive lens PL.
An image pickup apparatus comprising:
- an optical system;
- and
- an image pickup element which receives a light image formed by the optical system,
- wherein the optical system includes an aperture stop, and a focus lens unit arranged on an image side of the aperture stop, the focus lens unit having a negative refractive power and moving during focusing,
- the focus lens unit moves toward the image side during focusing from infinity to close distance, and includes a positive lens PL and a negative lens NL, and
- the following conditional expressions are satisfied:
- 23.0<νdNL<40.0;
- 2.44<NdNL−0.0003×νdNL2+0.034×νdNL<2.64;
- and
- νdPL<23.0,
- where νdNL denotes an Abbe number of a material of the negative lens NL, NdNL denotes a refractive index of the material of the negative lens NL at d-line, and νdPL denotes an Abbe number of a material of the positive lens PL.
Dependencies are inferred from the claim text.