Search

US-20260126626-A1 - SYSTEM, IMAGING DEVICE INCLUDING SYSTEM, AND LENS DEVICE INCLUDING SYSTEM

US20260126626A1US 20260126626 A1US20260126626 A1US 20260126626A1US-20260126626-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, a rear unit having positive refractive power, and at least ten lenses. The rear unit includes an aspherical lens having an inflection point, and, when the focal length of the system as a whole is denoted by f, the focal length of the front unit is denoted by f1, the maximum image height of the system is denoted by ImgH, and the overall length of the system is denoted by L, the system satisfies a predetermined inequality.

Inventors

  • Mayu OHHORI

Assignees

  • CANON KABUSHIKI KAISHA

Dates

Publication Date
20260507
Application Date
20251016
Priority Date
20241107

Claims (19)

  1. 1 . A system comprising, in order from an object side to an image side: a front unit having negative refractive power; an aperture stop; a rear unit having positive refractive power; and at least ten lenses, wherein the rear unit includes an aspherical lens A having an inflection point, and wherein the following inequalities are satisfied: - 2 . 9 ⁢ 8 < f ⁢ 1 / f < 0 .00 0. 40 < ImgH / L where f denotes a focal length of the system as a whole, f1 denotes a focal length of the front unit, ImgH denotes a maximum image height of the system, and L denotes an overall length of the system.
  2. 2 . The system according to claim 1 , wherein the following inequality is satisfied: 0.52 < fG ⁢ 1 / f ⁢ 1 where fG1 denotes a focal length of a lens G 1 disposed closest to an object among lenses included in the front unit.
  3. 3 . The system according to claim 1 , wherein the front unit includes a positive lens.
  4. 4 . The 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 toward an image.
  5. 5 . The system according to claim 1 , wherein the following inequality is satisfied: - 3. < f ⁢ ω ⁢ 1 / ❘ "\[LeftBracketingBar]" fl ❘ "\[RightBracketingBar]" < 0. 0 ⁢ 0 where fω1 denotes an off-axis focal length of the front unit in a meridional direction.
  6. 6 . The 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.
  7. 7 . The system according to claim 1 , wherein the following inequality is satisfied: 48. < ω < 70. where ω [°] denotes a half angle of view corresponding to a maximum image height of the system.
  8. 8 . The system according to claim 1 , wherein the following inequality is satisfied: 14. < v ⁢ d < 4 ⁢ 0 . 0 where 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.
  9. 9 . The system according to claim 8 , wherein the following inequality is satisfied: 1.5 < n ⁢ d < 1.7 where nd denotes a refractive index of a material of the negative lens GN 1 with respect to a d-line.
  10. 10 . The system according to claim 1 , wherein the following inequality is satisfied: 0. 40 < ImgH / L < 3. .
  11. 11 . The system according to claim 1 , wherein the following inequality is satisfied: 0.52 < fG ⁢ 1 / f ⁢ 1 < 2. where fG1 denotes a focal length of a lens G 1 disposed closest to an object among lenses included in the front unit.
  12. 12 . The system according to claim 1 , wherein the 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.
  13. 13 . The 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 the axis and concave on an image side and a peripheral portion that is convex on an image side.
  14. 14 . The system according to claim 1 , wherein an object-side lens surface of a lens GR 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, the lens GR 1 being disposed on an object side of and adjacent to a lens included in the rear unit and disposed closest to an image, and wherein an image-side lens surface of the lens GR 1 includes a portion that is near the axis and concave on an image side and a peripheral portion that is convex on an image side.
  15. 15 . The system according to claim 1 , wherein an object-side lens surface of a negative lens GN 1 disposed closest to an object among negative lenses included in the rear unit 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 the axis and concave on an image side and a peripheral portion that is convex on an image side.
  16. 16 . The system according to claim 1 , wherein the front unit consists of three lenses, and the rear unit consists of seven lenses.
  17. 17 . The system according to claim 1 , wherein the front unit consists of four lenses, and the rear unit consists of seven lenses.
  18. 18 . An imaging device comprising: a system; and an imaging element that receives an image formed by the system, wherein the system comprising, in order from an object side to an image side: a front unit having negative refractive power; an aperture stop; a rear unit having positive refractive power; and at least ten lenses, wherein the rear unit includes an aspherical lens having an inflection point, and wherein the following inequalities are satisfied: - 2 . 9 ⁢ 8 < f ⁢ 1 / f < 0 .00 0. 40 < ImgH / L where f denotes a focal length of the system as a whole, f1 denotes a focal length of the front unit, ImgH denotes a maximum image height of the system, and L denotes an overall length of the system.
  19. 19 . A lens device comprising: a system; and an operation unit configured to be operated by a user, wherein the system comprising, in order from an object side to an image side: a front unit having negative refractive power; an aperture stop; a rear unit having positive refractive power; and at least ten lenses, wherein the rear unit includes an aspherical lens having an inflection point, and wherein the following inequalities are satisfied: - 2 . 9 ⁢ 8 < f ⁢ 1 / f < 0 .00 0. 40 < ImgH / L . where f denotes a focal length of the system as a whole, f1 denotes a focal length of the front unit, ImgH denotes a maximum image height of the system, and L denotes an overall length of the system.

Description

BACKGROUND Field of the Technology The aspect of the embodiments relates to a system suitable for a digital still camera, a digital video camera, a monitoring camera, an onboard camera, a smartphone camera, and the like, an imaging device including a system, and a lens device including a system. Description of the Related Art In a wide-angle optical system, distortion aberration generated in the optical system can be corrected by disposing a lens unit on the object side with respect to an aperture. 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 including, in order from an object side to an image side, a front unit having negative refractive power, an aperture stop, a rear unit having positive refractive power, and at least ten lenses, wherein the rear unit includes an aspherical lens having an inflection point, and the following inequalities are satisfied: -2.9⁢8<f⁢1/f<0.000.40<ImgH/Lwhere f denotes a focal length of the system as a whole, f1 denotes a focal length of the front unit, ImgH denotes a maximum image height of the system, and L denotes an overall length of the system. Features of the 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 a hit point of an off-axis ray on an optical surface. FIG. 10 is a schematic view of an imaging device in which the optical system of one of Examples 1 to 4 is used. FIG. 11 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 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 an imaging device, such as a digital still camera, a digital video camera, a monitoring camera, or 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 specification refers to a group of lenses that are isolated from each other by an aperture stop SP. In addition, each lens unit may consist of one lens or may consist of 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 solid-state image sensing device, such as a CCD sensor or a CMOS sensor, is arranged on the image plane IP. When the optical system L0 of each of the examples is used as an imaging optical system of a silver-halide film camera, the image plane IP serves as a photosensitive surface corresponding to a film surface. Note that the optical system in each of the examples may be used as a projection