Optical system and imaging apparatus including the same
AssigneeCanon Kabushiki Kaisha
InventorsShinichiro Saito, Makoto Nakahara, Suguru Inoue, Akira Mizuma, Masakazu Yamagishi
Life of this patent
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Abstract
An optical system includes a first lens unit having positive refractive power, a second lens unit, and a third lens unit having negative refractive power arranged in order from an object side to an image side. The second lens unit moves in focusing, thereby changing a distance between adjacent lens units. The first lens unit includes a positive lens, and the third lens unit includes a negative lens. A focal length of the positive lens, a focal length of the negative lens, a focal length of the third lens unit, and a back focus of the optical system are appropriately set.
Claims17
An optical system comprising:
- a first lens unit having positive refractive power, a second lens unit, and a third lens unit having negative refractive power arranged in order from an object side to an image side,
- wherein the second lens unit moves in focusing, thereby changing a distance between adjacent lens units,
- wherein the first lens unit includes a positive lens,
- wherein the third lens unit includes a negative lens, and
- wherein the following conditional expressions are satisfied:
- LD/f<1.000
- 0.010<Sk/fGp<0.170
- 0.050<fGn/f3<0.155
- where LD is a distance on an optical axis between a lens surface in the optical system closest to the object side and an image plane, f is a focal length of the optical system, Sk is a back focus of the optical system, fGp is a focal length of a positive lens Gp being a closest positive lens with respect to the object side in the first lens unit, fGn is a focal length of a negative lens Gn being a closest negative lens with respect to the image side in the third lens unit, and f3 is a focal length of the third lens unit.
An imaging apparatus comprising:
- an optical system and an imaging element configured to receive light of an image formed by the optical system,
- wherein the optical system includes a first lens unit having positive refractive power, a second lens unit, and a third lens unit having negative refractive power arranged in order from an object side to an image side,
- wherein the second lens unit moves in focusing, thereby changing a distance between adjacent lens units,
- wherein the first lens unit includes a positive lens,
- wherein the third lens unit includes a negative lens, and
- wherein the following conditional expressions are satisfied:
- LD/f<1.000
- 0.010<Sk/fGp<0.170
- 0.050<fGn/f3<0.155
- where LD is a distance on an optical axis between a lens surface in the optical system closest to the object side and an image plane, f is a focal length of the optical system, Sk is a back focus of the optical system, fGp is a focal length of a positive lens Gp being a closest lens with respect the object side in the first lens unit, fGn is a focal length of a negative lens Gn being a closest lens with respect to the image side in the third lens unit.
Dependencies are inferred from the claim text.