Optical system, optical apparatus, and image pickup apparatus
AssigneeCanon Kabushiki Kaisha
InventorTatsuro Watanabe
Life of this patent
Estimating the term…
Abstract
An optical system includes a first unit fixed during focusing, a second unit configured to move during focusing, and a third unit fixed during focusing on an image side of the second unit. The first unit includes a first optical element having a first reflective surface that has a concave shape toward an object side, and a second optical element having a second reflective surface that has a convex shape toward an image side. Light incident on the optical system from an object is reflected by the first reflective surface, thereafter is reflected by the second reflective surface, and thereafter passes through the second unit. A predetermined inequality is satisfied.
Claims18
An optical system comprising:
- a first unit fixed during focusing;
- a second unit configured to move during focusing;
- and
- a third unit fixed during focusing on an image side of the second unit,
- wherein the first unit includes:
- a first optical element having a first reflective surface that has a concave shape toward an object side;
- and
- a second optical element having a second reflective surface that has a convex shape toward the image side,
- wherein the second unit includes a negative lens having a concave shape toward the image side,
- wherein light incident on the optical system from an object is reflected by the first reflective surface, thereafter is reflected by the second reflective surface, and thereafter passes through the second unit, and
- wherein the following inequalities are satisfied:
- nM1 ≤1.690
- 0.440≤L/f≤0.800
- where nM1 is a refractive index of the first optical element for d-line, L is a distance on an optical axis from a surface closest to the object of the optical system to the image plane, and f is a focal length of the optical system.
An optical apparatus comprising:
- an optical system;
- and
- a holding member configured to hold the optical system,
- wherein the optical system includes
- a first unit fixed during focusing;
- a second unit configured to move during focusing;
- and
- a third unit fixed during focusing on an image side of the second unit,
- wherein the first unit includes:
- a first optical element having a first reflective surface that has a concave shape toward an object side;
- and
- a second optical element having a second reflective surface that has a convex shape toward the image side,
- wherein the second unit includes a negative lens having a concave shape toward the image side,
- wherein light incident on the optical system from an object is reflected by the first reflective surface, thereafter is reflected by the second reflective surface, and thereafter passes through the second unit, and
- wherein the following inequalities are satisfied:
- nM1≤1.690
- 0.440≤L/f≤0.800
- where nM1 is a refractive index of the first optical element for d-line, L is a distance on an optical axis from a surface closest to the object of the optical system to the image plane, and f is a focal length of the optical system.
An image pickup apparatus comprising:
- an optical system;
- and
- an image sensor configured to image an object via the optical system,
- a first unit fixed during focusing;
- a second unit configured to move during focusing;
- and
- a third unit fixed during focusing on an image side of the second unit,
- wherein the first unit includes:
- a first optical element having a first reflective surface that has a concave shape toward an object side;
- and
- a second optical element having a second reflective surface that has a convex shape toward the image side,
- wherein the second unit includes a negative lens having a concave shape toward the image side,
- wherein light incident on the optical system from an object is reflected by the first reflective surface, thereafter is reflected by the second reflective surface, and thereafter passes through the second unit, and
- wherein the following inequalities are satisfied:
- nM1 ≤1.690
- 0.440≤L/f≤0.800
- where nM1 is a refractive index of the first optical element for d-line, L is a distance on an optical axis from a surface closest to the object of the optical system to the image plane, and f is a focal length of the optical system.
Dependencies are inferred from the claim text.