Imaging lens and imaging apparatus
AssigneeFUJIFILM Corporation
InventorsHiroki Saito, Ryoko Tomioka
Life of this patent
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Abstract
An imaging lens consists of a front group, an aperture stop, and a rear group, in order from an object side. The rear group includes at least one Lp lens that is made of a resin, has a positive refractive power, and is cemented to a lens. Assuming that an Abbe number and a refractive index of the Lp lens are respectively νp and Np, the Lp lens satisfies Conditional Expression represented by 120<νp+94.24×Np<180. The imaging lens satisfies predetermined conditional expressions.
Claims18
An imaging lens consisting of, in order from an object side to an image side, a front group, an aperture stop, and a rear group,
- wherein the rear group includes at least one Lp lens that is made of a resin, has a positive refractive power, and is cemented to a lens,
- an Abbe number of the Lp lens based on a d line is νp,
- a refractive index of the Lp lens at the d line is Np,
- a center thickness of the Lp lens is d,
- a curvature radius of an object side surface of the Lp lens is Rf,
- a curvature radius of an image side surface of the Lp lens is Rr,
- a sum of an air-equivalent distance on an optical axis from a lens surface closest to the image side in the rear group to an image plane and a distance on the optical axis from a lens surface closest to the object side in the front group to the lens surface closest to the image side in the rear group in a state in which an infinite distance object is in focus is TL,
- a distance on the optical axis from the image side surface of the Lp lens to an image point, which is formed by an optical system ranging from a lens surface adjacent to the image side of the aperture stop to the image side surface of the Lp lens, in a case where a point at a position of the aperture stop on the optical axis is set as an object point in a state in which the infinite distance object is in focus is De,
- De is calculated in a case where a medium closer to the image side than the image side surface of the Lp lens is set as air, and a sign of De is negative in a case where the image point is closer to the object side than the image side surface of the Lp lens on the optical axis and is positive in a case where the image point is closer to the image side than the image side surface of the Lp lens,
- an open F number in a state in which the infinite distance object is in focus is FNo,
- a focal length of the imaging lens in a state in which the infinite distance object is in focus is f, and
- a maximum half angle of view in a state in which the infinite distance object is in focus is om,
- Conditional Expressions (1), (2), (3), and (4) are satisfied, which are represented by
- 120<νp+94.24×Np<186 (1),
- 0<d×(1/Rf−1/Rr)<0.05 (2),
- −20<TL×(1/De−1/Rr)<20 (3), and
- 1<FNo×TL/(f×tan ωm)<30 (4), and
- wherein the air-equivalent distance on the optical axis from the lens surface closest to the image side in the rear group to the image plane in a state in which the infinite distance object is in focus is Bf, Conditional Expression (5) is satisfied, which is represented by
- 0.4<Bf/(f×tan ωm)<1.7 (5), or
- wherein
- a focal length of a focus group moving along the optical axis during focusing is ffoc, and
- a focal length of the Lp lens is fp,
- Conditional Expression (12) is satisfied, which is represented by
- 0.04<ffoc/fp<0.36 (12).
Dependencies are inferred from the claim text.