Zoom lens and image pickup apparatus

Patent metadata

Field	Value
Publication number	US-11294156-B2
Application number	US-202016794521-A
Country	US
Kind code	B2
Filing date	Feb 19, 2020
Priority date	Feb 22, 2019
Publication date	Apr 5, 2022
Grant date	Apr 5, 2022

Abstract

A zoom lens includes in order from an object side, a positive first unit, one or two second units including a negative lens unit closest to the image side, and monotonously moved to the image side for zooming to a telephoto end, one or two third units including a negative lens unit closest to the object side, and moved for zooming, and a positive fourth unit disposed closest to the image side, in which the first unit includes, in order from the object side, a negative subunit, a positive subunit moved for focusing, and a positive subunit, and a focal length of the first unit, a composite focal length at the telephoto end of the second unit, a maximum moving amount for zooming of the lens unit included in the second unit, and a maximum Abbe number of the negative lens included in the second unit are properly set.

First claim

What is claimed is:

1. A zoom lens comprising in order from an object side to an image side:
a first lens unit having a positive refractive power and configured not to be moved for zooming;
one or two second lens units including a lens unit closest to the image side and having a negative refractive power, the one or two second lens units configured to be monotonously moved to the image side for zooming from a wide angle end to a telephoto end;
one or two third lens units including a lens unit closest to the object side and having a negative refractive power, the one or two third lens units configured to be moved for zooming; and
a fourth lens unit closest to the image side and having a positive refractive power,
wherein the first lens unit comprises, in order from the object side to the image side, a 1a lens subunit having a negative refractive power and configured not to be moved for focusing, a 1b lens subunit having a positive refractive power and configured to be moved for focusing, and a 1c lens subunit having a positive refractive power and configured not to be moved for focusing,
wherein conditional expressions
1.0<| f 1/ f 2 t |<2.5,
2.0< m 2/ f 2 t |<5.0,
65<ν2 n , and

1.8< n 1 anav

are satisfied where f1 represents a focal length of the first lens unit, f2t represents a composite focal length at the telephoto end of the one or two second lens units, m2 represents a maximum moving amount of at least one moving amount, of at least one lens unit included in the one or two second lens units, for zooming from the wide angle end to the telephoto end, ν2n represents a maximum Abbe number of at least one Abbe number of at least one negative lens included in the one or two second lens units, a sign of the moving amount is positive in a case where the lens unit moves to the image side, n1anav represents an average value of at least one refractive index, with respect to a d-line, of at least one negative lens included in the 1a lens subunit, and an Abbe number ν is defined by an expression
ν=( nd− 1)/( nF−nC )

where nF represents a refractive index with respect to an F-line, nd represents a refractive index with respect to the d-line, and nC represents a refractive index with respect to a C-line.

2. An imaging apparatus comprising:
a zoom lens of claim 1 ; and
an imaging element that receives an image formed by the zoom lens.

3. A zoom lens comprising in order from an object side to an image side:
a first lens unit having a positive refractive power and configured not to be moved for zooming;
one or two second lens units including a lens unit closest to the image side and having a negative refractive power, the one or two second lens units configured to be monotonously moved to the image side for zooming from a wide angle end to a telephoto end;
one or two third lens units including a lens unit closest to the object side and having a negative refractive power, the one or two third lens units configured to be moved for zooming; and
a fourth lens unit closest to the image side and having a positive refractive power,
wherein the first lens unit comprises, in order from the object side to the image side, a 1a lens subunit having a negative refractive power and configured not to be moved for focusing, a 1b lens subunit having a positive refractive power and configured to be moved for focusing, and a 1c lens subunit having a positive refractive power and configured not to be moved for focusing,
wherein conditional expressions
1.0| f 1/ f 2 t |<2.5,
2.0| m 2/ f 2 t |<5.0,
65<ν2 n , and

−4.5×10 −3 <(θ1 apav−θ 1 anav )/(ν1 apav−ν 1 anav )<−2.0×10 −3

are satisfied where f1 represents a focal length of the first lens unit, f2t represents a composite focal length at the telephoto end of the one or two second lens units, m2 represents a maximum moving amount of at least one moving amount, of at least one lens unit included in the one or two second lens units, for zooming from the wide angle end to the telephoto end, ν2n represents a maximum Abbe number of at least one Abbe number of at least one negative lens included in the one or two second lens units, a sign of the moving amount is positive in a case where the lens unit moves to the image side, ν1apav represents an average value of at least one Abbe number of at least one positive lens included in the 1a lens subunit, ν1anav represents an average value of at least one Abbe number of at least one negative lens included in the 1a lens subunit, θ1apav represents an average value of at least one relative partial dispersion of at least one positive lens included in the 1a lens subunit, θ1anav represents an average value of at least one relative partial dispersions of at least one negative lens included in the 1a lens subunit, and an Abbe number ν is defined by an expression
ν=( nd− 1)/( nF−nC )

where nF represents a refractive index with respect to an F-line, nd represents a refractive index with respect to a d-line, and nC represents a refractive index with respect to a C-line, and a relative partial dispersion θ is defined by an expression
θ=( ng−nF )/( nF−nC )

where ng represents a refractive index with respect to a g-line.

4. An imaging apparatus comprising:
a zoom lens of claim 3 ; and
an imaging element that receives an image formed by the zoom lens.

5. A zoom lens comprising in order from an object side to an image side:
a first lens unit having a positive refractive power and configured not to be moved for zooming;
one or two second lens units including a lens unit closest to the image side and having a negative refractive power, the one or two second lens units configured to be monotonously moved to the image side for zooming from a wide angle end to a telephoto end;
one or two third lens units including a lens unit closest to the object side and having a negative refractive power, the one or two third lens units configured to be moved for zooming; and
a fourth lens unit closest to the image side and having a positive refractive power,
wherein the first lens unit comprises, in order from the object side to the image side, a 1a lens subunit having a negative refractive power and configured not to be moved for focusing, a 1b lens subunit having a positive refractive power and configured to be moved for focusing, and a 1c lens subunit having a positive refractive power and configured not to be moved for focusing,
wherein conditional expressions
1.0<| f 1/ f 2 t |<2.5,
2.0| m 2/ f 2 t |<5.0,
65<ν2 n , and

1.5< f 1 b/f 1<6.0

are satisfied where f1 represents a focal length of the first lens unit, f2t represents a composite focal length at the telephoto end of the one or two second lens units, m2 represents a maximum moving amount of at least one moving amount, of at least one lens unit included in the one or two second lens units, for zooming from the wide angle end to the telephoto end, ν2n represents a maximum Abbe number of at least one Abbe number of at least one negative lens included in the one or two second lens units, a sign of the moving amount is positive in a case where the lens unit moves to the image side, f1b represents a focal length of the 1b lens subunit, and an Abbe number ν is defined by an expression
ν=( nd− 1)/( nF−nC )

where nF represents a refractive index with respect to an F-line, nd represents a refractive index with respect to a d-line, and nC represents a refractive index with respect to a C-line.

6. An imaging apparatus comprising:
a zoom lens of claim 5 ; and
an imaging element that receives an image formed by the zoom lens.

7. A zoom lens comprising in order from an object side to an image side:
a first lens unit having a positive refractive power and configur

Assignees

• Canon Kk

Inventors

• Inomoto Yu

Classifications

• H04N23/55

  Optical parts specially adapted for electronic image sensors; Mounting thereof · CPC title

• G02B27/005

  for correction of secondary colour or higher-order chromatic aberrations · CPC title

• G02B15/144109 Primary

  arranged +--+ · CPC title

• G02B15/17 Primary

  arranged +-- · CPC title

• G02B27/0062

  by controlling the dispersion of a lens material, e.g. adapting the relative partial dispersion · CPC title