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US-20260126627-A1 - OPTICAL SYSTEM, IMAGING DEVICE, AND LENS DEVICE

US20260126627A1US 20260126627 A1US20260126627 A1US 20260126627A1US-20260126627-A1

Abstract

A system includes, in order from an object side to an image side, a front unit having negative refractive power, an aperture stop, and a rear unit having positive refractive power. The system includes at least eight lenses, the rear unit includes an aspherical lens A having an inflection point, and, when the maximum image height of the system is denoted by ImgH, the optical overall length of the system is denoted by L, the focal length of the front unit is denoted by fl, and the focal length of a first lens G 1 included in the front unit and disposed closest to an object is denoted by fG 1 , the system satisfies a predetermined inequality.

Inventors

  • Mayu OHHORI

Assignees

  • CANON KABUSHIKI KAISHA

Dates

Publication Date
20260507
Application Date
20251106
Priority Date
20241107

Claims (18)

  1. 1 . An optical system comprising, in order from an object side to an image side: a front unit having negative refractive power; an aperture stop; and a rear unit having positive refractive power, wherein the optical system includes at least eight lenses, wherein the rear unit includes an aspherical lens A having an inflection point, and wherein the following inequalities are satisfied: 0.4 < ImgH / L ⁢ 0.52 < fG ⁢ 1 / f ⁢ 1 ⁢ - 2.98 < f ⁢ 1 / f < 0 . 0 ⁢ 0 ⁢ 12. < vd < 4 ⁢ 0 . 0 where ImgH denotes a maximum image height of the optical system, L denotes an optical overall length of the optical system, fl denotes a focal length of the front unit, fG 1 denotes a focal length of a first lens G 1 included in the front unit and disposed closest to an object, f denotes a focal length of the optical system as a whole, and vd denotes an Abbe number of a material of a negative lens GN 1 disposed closest to an object among negative lenses included in the rear unit.
  2. 2 . The optical system according to claim 1 , wherein, in the rear unit, a positive lens, another positive lens, and a negative lens are disposed in order from a position closest to an object to an image.
  3. 3 . The optical system according to claim 1 , wherein the following inequality is satisfied: 0. < f ⁢ ω ⁢ 1 / f ⁢ 1 < 3. where fω1 denotes an off-axis focal length of the front unit in a sagittal direction.
  4. 4 . The optical system according to claim 1 , wherein the following inequality is satisfied: - 6 . 0 ⁢ 0 < fGR / f ⁢ 2 < - 2. where fGR denotes a focal length of a lens GR included in the rear unit and disposed closest to an image, and f2 denotes a focal length of the rear unit.
  5. 5 . The optical optical system according to claim 1 , wherein the optical system includes a lens B that is made from a resin material, and wherein at least one of an object-side lens surface and an image-side lens surface of the lens B is an aspherical surface.
  6. 6 . The optical system according to claim 1 , wherein the following inequality is satisfied: 0. < Sag / Ea < 0.25 where Sag denotes a distance between a surface vertex of an object-side lens surface of the first lens G 1 and an effective diameter position in an axis direction, and Ea denotes an effective diameter of the first lens G 1 .
  7. 7 . The optical system according to claim 1 , wherein the following inequality is satisfied: 4.8 < ω < 70. where ω [° ] denotes a half angle of view corresponding to a maximum image height of the optical system.
  8. 8 . The optical system according to claim 1 , wherein the following inequality is satisfied: 1.5 < nd < 1.7 where nd denotes a refractive index of a material of the negative lens GN 1 with respect to a d-line.
  9. 9 . The optical system according to claim 1 , wherein the following inequality is satisfied: 0.4 < ImgH / L ≤ 3. .
  10. 10 . The optical system according to claim 1 , wherein the following inequality is satisfied: 0.52 < fG ⁢ 1 / f ⁢ 1 ≤ 2. .
  11. 11 . The optical system according to claim 1 , wherein an object-side lens surface of the negative lens GN 1 includes a portion that is near an axis and convex on an object side and a peripheral portion that is concave on an object side, and wherein an image-side lens surface of the negative lens GN 1 includes a portion that is near an axis and concave on an image side and a peripheral portion that is convex on an image side.
  12. 12 . The optical system according to claim 1 , wherein an object-side lens surface of a lens GR included in the rear unit and disposed closest to an image includes a portion that is near an axis and convex on an object side and a peripheral portion that is concave on an object side, and wherein an image-side lens surface of the lens GR includes a portion that is near an axis and concave on an image side and a peripheral portion that is convex on an image side.
  13. 13 . The optical system according to claim 1 , wherein the front unit includes two lenses, and the rear unit includes six lenses.
  14. 14 . The optical system according to claim 1 , wherein the front unit includes three lenses, and the rear unit includes six lenses.
  15. 15 . The optical system according to claim 1 , wherein the front unit includes three lenses, and the rear unit includes seven lenses.
  16. 16 . The optical system according to claim 1 , wherein the front unit includes four lenses, and the rear unit includes seven lenses.
  17. 17 . A device comprising: an optical system; and an element that receives an image formed by the optical system, wherein the optical system includes, in order from an object side to an image side, a front unit having negative refractive power, an aperture stop, and a rear unit having positive refractive power, wherein the optical system includes at least eight lenses, wherein the rear unit includes an aspherical lens A having an inflection point, and wherein the following inequalities are satisfied: 0.4 < ImgH / L ⁢ 0.52 < fG ⁢ 1 / f ⁢ 1 ⁢ - 2.98 < f ⁢ 1 / f < 0 . 0 ⁢ 0 ⁢ 12. < vd < 4 ⁢ 0 . 0 where ImgH denotes a maximum image height of the system, L denotes an optical overall length of the system, fl denotes a focal length of the front unit, fG 1 denotes a focal length of a first lens G 1 included in the front unit and disposed closest to an object, f denotes a focal length of the system as a whole, and vd denotes an Abbe number of a material of a negative lens GN 1 disposed closest to an object among negative lenses included in the rear unit.
  18. 18 . A lens device comprising: an optical system; and an operation unit configured to be operated by a user, wherein the optical system includes, in order from an object side to an image side, a front unit having negative refractive power, an aperture stop, and a rear unit having positive refractive power, wherein the optical system includes at least eight lenses, wherein the rear unit includes an aspherical lens A having an inflection point, and wherein the following inequalities are satisfied: 0.4 < ImgH / L ⁢ 0.52 < fG ⁢ 1 / f ⁢ 1 ⁢ - 2.98 < f ⁢ 1 / f < 0 . 0 ⁢ 0 ⁢ 12. < vd < 4 ⁢ 0 . 0 where ImgH denotes a maximum image height of the optical system, L denotes an optical overall length of the system, fl denotes a focal length of the front unit, fG 1 denotes a focal length of a first lens G 1 included in the front unit and disposed closest to an object, f denotes a focal length of the optical system as a whole, and vd denotes an Abbe number of a material of a negative lens GN 1 disposed closest to an object among negative lenses included in the rear unit.

Description

BACKGROUND Field of the Technology The disclosure in the present specification relates to a system that is suitable for a digital still camera, a digital video camera, a monitoring camera, an onboard camera, a smartphone camera, and the like, a device including the system, and a lens device including the system. Description of the Related Art Wide-angle optical systems are required to have high optical performance while having a small size. Japanese Patent Laid-Open No. 2023-184065 discloses a wide-angle optical system in which a front lens unit having negative refractive power, an aperture stop, and a rear lens unit having positive refractive power are disposed in order from the object side. SUMMARY A system as one aspect of the present disclosure is a system including, in order from an object side to an image side, a front unit having negative refractive power, an aperture stop, and a rear unit having positive refractive power, in which the system includes at least eight lenses, the rear unit includes an aspherical lens A having an inflection point, and the following inequalities are satisfied: 0.4<ImgH/L0.52<fG⁢1/f⁢1-2.9⁢8<f⁢1/f<0.0⁢012.<vd<4⁢0.0where ImgH denotes a maximum image height of the system, L denotes an optical overall length of the system, fl denotes a focal length of the front unit, fG1 denotes a focal length of a first lens G1 included in the front unit and disposed closest to an object, f denotes a focal length of the system as a whole, and vd denotes an Abbe number of a material of a negative lens GN1 disposed closest to an object among negative lenses included in the rear unit. Features of the present disclosure will become apparent from the following description of embodiments with reference to the attached drawings. The following description of embodiments is described by way of example. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of an optical system of Example 1 during infinity focus. FIG. 2 is a longitudinal aberration diagram corresponding to Example 1. FIG. 3 is a sectional view of an optical system of Example 2 during infinity focus. FIG. 4 is a longitudinal aberration diagram corresponding to Example 2. FIG. 5 is a sectional view of an optical system of Example 3 during infinity focus. FIG. 6 is a longitudinal aberration diagram corresponding to Example 3. FIG. 7 is a sectional view of an optical system of Example 4 during infinity focus. FIG. 8 is a longitudinal aberration diagram corresponding to Example 4. FIG. 9 is a schematic view relating to the sag amount of a first lens G1. FIG. 10 is a schematic view relating to a hit point of an off-axis ray on an optical surface. FIG. 11 is a schematic view of an imaging device in which the optical system of one of Examples 1 to 4 is used. FIG. 12 is a schematic view of a lens device in which the optical system of one of Examples 1 to 4 is used. DESCRIPTION OF THE EMBODIMENTS Hereinafter, an embodiment disclosed in the present specification will be described in detail with reference to the drawings. In the drawings, identical members are given identical reference numbers, and duplicated description thereof will be omitted. FIGS. 1, 3, 5, and 7 are sectional views of optical systems L0 of Examples 1 to 4, respectively, during infinity focus. The optical system L0 of each of the examples is to be used in imaging devices, such as a digital still camera, a digital video camera, a monitoring camera, and an onboard camera. In each of the sectional views, the left side is the object side, and the right side is the image side. The optical system L0 of each of the examples includes a plurality of lens units. Note that a lens unit in the present specification refers to a group of lenses that are isolated from each other by an aperture stop SP. In addition, each lens unit may include one lens or may include a plurality of lenses. In addition, each lens unit may include an aspherical lens, a Fresnel lens, a meta-lens, a diffractive optical element, and the like. In the optical system L0 of each of the examples, Li denotes, among the lens units included in the optical system L0, an i-th (i is a natural number) lens unit counted from the object side. In addition, Gk denotes, among the lenses included in the optical system, a k-th (k is a natural number) lens counted from the object side. In the optical system L0 of each of the examples, L1 (LF) denotes a front unit as a lens unit disposed on the object side with respect to the aperture stop. In addition, L2 (LR) denotes a rear unit as a lens unit disposed on the image side with respect to the aperture stop. In each of the sectional views, SP is the aperture stop. In addition, FL is an optical element corresponding to an optical filter, a low-pass filter, an infrared cut filter, or the like. IP is an image plane, and, when the optical system L0 of each of the examples is used as an imaging optical system of a digital still camera or a digital video camera, an imaging surface of a so