Converter lens, interchangeable lens, and image-capturing apparatus
AssigneeCanon Kabushiki Kaisha
InventorsShinichiro Saito, Hiroki Ebe
Life of this patent
Estimating the term…
Abstract
A converter lens (RCL) has a negative refractive power, which is disposed on an image side of a master lens (ML) to make a focal length of an entire system longer than that of the master lens alone. The converter lens comprises a most image-side lens element (LT) disposed closest to an image side in the converter lens, wherein the most image-side lens element has a lens surface having a convex shape toward an image side, a lens disposed closest to an image side in the converter lens has a positive refractive power, and mN<mP and 0.0≤LR2/AR2<1.0 are satisfied.
Claims20
A converter lens having a negative refractive power, which is disposed on an image side of a master lens to make a focal length of an entire system longer than a focal length of the master lens alone, the converter lens comprising:
- a most image-side lens element disposed closest to an image side in the converter lens, and
- at least one negative lens,
- wherein the most image-side lens element has a lens surface having a convex shape toward an image side,
- wherein a lens disposed closest to an image side in the converter lens has a positive refractive power, and
- wherein the following conditional expressions are satisfied:
- mN<mP
- 1.80<nAN<2.20
- where mP is the number of positive lens components of the converter lens, mN is the number of negative lens components of the converter lens, and nAN is an average refractive index at a d line of materials of all negative lenses included in the converter lens.
An interchangeable lens comprising:
- a master lens;
- and
- a converter lens having a negative refractive power, which is disposed on an image side of the master lens to make a focal length of an entire system longer than a focal length of the master lens alone,
- wherein the converter lens includes a most image-side lens element disposed closest to an image side in the converter lens and at least one negative lens,
- wherein the most image-side lens element has a lens surface having a convex shape toward an image side,
- wherein a lens disposed closest to an image side in the converter lens has a positive refractive power, and
- wherein the following conditional expressions are satisfied:
- mN<mP
- 1.80<nAN<2.20
- where mP is the number of positive lens components of the converter lens, mN is the number of negative lens components of the converter lens, and nAN is an average refractive index at a d line of materials of all negative lenses included in the converter lens.
Dependencies are inferred from the claim text.