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US 10,379,325 B2Granted
Optical system and optical apparatus including the same
AssigneeCanon Kabushiki Kaisha
InventorsShunji Iwamoto, Shinichiro Saito, Satoshi Maetaki, Takahiro Hatada, Suguru Inoue
Life of this patent
Estimating the term…
Abstract
An optical system includes a negative lens satisfying the following conditional expressions: 30≤νd≤40, 1.225≤[nd−(14.387/νd)]≤1.276, and 0.4300≤[θgF−(2.9795/νd)]≤0.5010, where νd is an Abbe number of the negative lens, θgF is a partial dispersion ratio of the negative lens at a g-line and an F-line, and nd is a refractive index of the negative lens at a d-line.
Claims14
An optical system comprising:
- a negative lens,
- wherein the following conditional expressions are satisfied:
- 30≤νd≤40;
- 1.225≤[nd−(14.387/νd)]≤1.276;
- and
- 0.4300≤[θgF−(2.9795/νd)]≤0.5010,
- where νd is an Abbe number of the negative lens, θgF is a partial dispersion ratio of the negative lens at a g-line and an F-line, and nd is a refractive index of the negative lens at a d-line.
4 more elements
An optical system comprising:
- an aperture stop;
- a first negative lens disposed on a light incident side of the aperture stop and having a concave surface that faces an image side;
- and
- a second negative lens disposed on a light emission side of the aperture stop and having a concave surface that faces an object side,
- wherein the following conditional expressions are satisfied:
- 30≤νd1≤40;
- 30≤νd2≤40;
- 1.225≤[nd1−(14.387/νd1)]≤1.276;
- 1.225≤[nd2−(14.387/νd2)]≤1.276;
- 0.4300≤[θgF1−(2.9795/νd1)]≤0.5010;
- and
- 0.4300≤[θgF2−(2.9795/νd2)]≤0.5010,
- where νd1 is an Abbe number of the first negative lens, νd2 is an Abbe number of the second negative lens, θgF1 is a partial dispersion ratio of the first negative lens at a g-line and an F-line, θgF2 is a partial dispersion ratio of the second negative lens at the g-line and the F-line, nd1 is a refractive index of the first negative lens at a d-line, and nd2 is a refractive index of the second negative lens at the d-line.
10 more elements
Dependencies are inferred from the claim text.