Imaging optical system
AssigneeSigma Corporation
InventorsKen Asakura, Noriyuki Ogasawara
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Abstract
It is aimed at providing an imaging optical system which is small-sized and lightweight, has a small-sized and lightweight focusing unit, and is therefore appropriate for a small-sized and lightweight telephoto lens. An imaging optical system of the present invention includes, in order from an object side toward an image side, a first lens group G1 having a positive power as a whole, a second lens group G2 including a lens that moves on an optical axis during focusing, and a third lens group G3 having a power, and satisfies predetermined conditional expressions.
Claims13
An imaging optical system comprising, in order from an object side toward an image side:
- a first lens group G1 having a positive power as a whole, a second lens group G2 including a lens that moves on an optical axis during focusing, and a third lens group G3 having a power, wherein
- following conditional expressions below are satisfied:
- -
- 34.
- <
- Φ_G2G3
- /
- Φ
- <
- -
- 6.6
- (
- 1
- )
- 1.
- <
- D_EXP
- /
- H_Img
- <
- 4.6
- (
- 2
- )
- 0.4
- <
- LT
- /
- f
- <
- 1.
- (
- 3
- )
- where
- Φ denotes power of the imaging optical system when focusing on infinity,
- Φ_G2G3 denotes composite power of the second lens group G2 and the third lens group G3 when focusing on infinity,
- D_EXP denotes a distance on the optical axis from an exit pupil to an image surface in the imaging optical system when focusing on infinity,
- H_Img denotes a maximum image height,
- LT denotes a distance on the optical axis from a surface closest to the object side to the image surface in the imaging optical system when focusing on infinity, and
- f denotes a focal length of the imaging optical system when focusing on infinity.
Dependencies are inferred from the claim text.