Zoom lens and imaging apparatus
AssigneeSony Corporation
InventorHiroki Yamano
Life of this patent
Estimating the term…
Abstract
A zoom lens includes, in order from an object side to an image side: a first lens group that has a positive refractive power; a second lens group that has a negative refractive power; and a third lens group that has a positive refractive power, wherein the second lens group is constituted by three lenses of a first negative lens, a second negative lens, and a positive lens which are arranged in order from the object side to the image side, wherein an aspheric surface is formed on at least an object side of the positive lens in a shape of which a curvature gradually decreases as an outer periphery of the lens gets closer from an optical axis, and wherein the following Conditional Expressions (1) and (2) are satisfied: 0.8<10×(R22r−R23f)/(R22r+R23f)<1.8 (1) 3.0<100×{D(2,23)/TH2}<7.0 (2).
Claims9
A zoom lens comprising, in order from an object side to an image side:
- a first lens group that has a positive refractive power;
- a second lens group that has a negative refractive power;
- and
- a third lens group that has a positive refractive power,
- wherein the second lens group is constituted by three lenses of a first negative lens, a second negative lens, and a positive lens which are arranged in order from the object side to the image side,
- wherein an aspheric surface is formed on at least an object side of the positive lens in a shape of which a curvature gradually decreases as an outer periphery of the lens gets closer from an optical axis, and
- wherein the following Conditional Expressions (1) and (2) are satisfied
- 0.8<10×(R22r−R23f)/(R22r+R23f)<1.8 (1)
- 3.0<100×{D(2,23)/TH2}<7.0 (2)
- where R22r is a paraxial radius of curvature of an image side surface of the second negative lens in the second lens group, R23f is a paraxial radius of curvature of the object side surface of the positive lens in the second lens group, D(2, 23) is an air space, which is present between the second negative lens and the positive lens of the second lens group, on the optical axis, and TH2 is a thickness on the optical axis from a surface closest to the object side in the second lens group to a surface closest to the image side.
An imaging apparatus comprising:
- a zoom lens;
- and
- an imaging device converting an optical image formed by the zoom lens into an electric signal,
- wherein the zoom lens includes, in order from an object side to an image side, a first lens group that has a positive refractive power, a second lens group that has a negative refractive power, and a third lens group that has a positive refractive power,
- wherein the second lens group is constituted by three lenses of a first negative lens, a second negative lens, and a positive lens which are arranged in order from the object side to the image side,
- wherein an aspheric surface is formed on at least an object side of the positive lens in a shape of which a curvature gradually decreases as an outer periphery of the lens gets closer from an optical axis, and
- wherein the following Conditional Expressions (1) and (2) are satisfied
- 0.8<10×(R22r−R23f)/(R22r+R23f)<1.8 (1)
- 3.0<100×{D(2,23)/TH2}<7.0 (2)
- where R22r is a paraxial radius of curvature of an image side surface of the second negative lens in the second lens group, R23f is a paraxial radius of curvature of the object side surface of the positive lens in the second lens group, D(2, 23) is an air space, which is present between the second negative lens and the positive lens of the second lens group, on the optical axis, and TH2 is a thickness on the optical axis from a surface closest to the object side in the second lens group to a surface closest to the image side.
Dependencies are inferred from the claim text.