Zoom lens and image pickup apparatus

1. A zoom lens comprising:

a master lens including in order from an object side to an image side:

a first lens unit having a positive refractive power and configured not to move for zooming;

a second lens unit having a negative refractive power and configured to move for zooming;

at least one lens unit configured to move for zooming; and

a relay lens unit having a positive refractive power and arranged closest to the image side; and

an extender lens unit configured to be insertable into or removable from an optical path of the zoom lens between the at least one lens unit and the relay lens unit to extend a focal length of the zoom lens by one of: being inserted in place of a lens unit arranged adjacent to the relay lens unit and being inserted into a space adjacent to the relay lens unit,

wherein the extender lens unit includes a positive lens Gp, and the positive lens Gp satisfies conditional expressions

θ gF −(−1.6650×10 −7 ·νd 3 +5.2130×10 −5 ·νd 2 −5.6560×10 −3 ·νd+ 0.7370)>0;

0.5450<θ gF ; and

50.0<ν d< 85.0,

where νd and θgF represent an Abbe number and a partial dispersion ratio of the positive lens Gp, respectively, and

wherein an Abbe number νd and a partial dispersion ratio θgF of a material are expressed by expressions

ν d =( Nd− 1)/( NF−NC ); and

θ gF =( Ng−NF )/( NF−NC ),respectively,

where Ng, NF, NC, and Nd represent refractive indices of the material with respect to a g-line (wavelength of 435.8 nm), an F-line (wavelength of 486.1 nm), a C-line (wavelength of 656.3 nm), and a d-line (wavelength of 587.6 nm), respectively.

2. The zoom lens according to claim 1 , wherein the zoom lens satisfies a conditional expression

1.3 <fiew/fw< 3.0,

where fw represents a focal length of the master lens at a wide angle end, and fiew represents a focal length of the zoom lens at the wide angle end in a state in which the extender lens unit is inserted.

3. The zoom lens according to claim 1 , wherein the zoom lens satisfies a conditional expression

0< LGp 1/ Lie< 0.4,

where Lie represents a distance from an apex of a surface of the extender lens unit closest to the object side to an apex of a surface of the extender lens unit closest to the image side, and LGp1 represents a distance from the apex of the surface closest to the object side to an apex of a surface on the object side of a positive lens Gp1, which is arranged closest to the object side of the positive lens Gp.

4. The zoom lens according to claim 1 , wherein the extender lens unit consists of, in order from the object side to the image side, a positive lens and three cemented lenses.

5. The zoom lens according to claim 1 , wherein the extender lens unit consists of, in order from the object side to the image side, at least one positive lens and two cemented lenses.

6. The zoom lens according to claim 1 , wherein the extender lens unit consists of, in order from the object side to the image side, one positive lens, two cemented lenses, and one negative lens.

7. An image pickup apparatus comprising:

a zoom lens; and

an image pickup element configured to receive an image formed by the zoom lens,

wherein the zoom lens comprising:

a master lens including in order from an object side to an image side:

a first lens unit having a positive refractive power and configured not to move for zooming;

a second lens unit having a negative refractive power and configured to move for zooming;

at least one lens unit configured to move for zooming; and

a relay lens unit having a positive refractive power and arranged closest to the image side; and

an extender lens unit configured to be insertable into or removable from an optical path of the zoom lens between the at least one lens unit and the relay lens unit to extend a focal length of the zoom lens by one of: being inserted in place of a lens unit arranged adjacent to the relay lens unit; and being inserted into a space adjacent to the relay lens unit,

wherein the extender lens unit includes a positive lens Gp, and the positive lens Gp satisfies conditional expressions

θ gF −(−1.6650×10 −7 ·νd 3 +5.2130×10 −5 ·νd 2 −5.6560×10 −3 ·νd+ 0.7370)>0;

0.5450<θ gF ; and

50.0<ν d< 85.0,

where νd and θgF represent an Abbe number and a partial dispersion ratio of the positive lens (Gp), respectively, and

wherein an Abbe number νd and a partial dispersion ratio θgF of a material are expressed by expressions

ν d =( Nd− 1)/( NF−NC ); and

θ gF =( Ng−NF )/( NF−NC ),respectively,

where Ng, NF, NC, and Nd represent refractive indices of the material with respect to a g-line (wavelength of 435.8 nm), an F-line (wavelength of 486.1 nm), a C-line (wavelength of 656.3 nm), and a d-line (wavelength of 587.6 nm), respectively.

8. An extender lens unit configured to be insertable into or removable from an optical path of an image pickup apparatus to extend a focal length of the image pickup apparatus,

wherein the extender lens unit includes a positive lens Gp, and the positive lens Gp satisfies conditional expressions

θ gF −(−1.6650×10−7 ·νd 3+5.2130×10−5 ·νd 2−5.6560×10−3 ·νd+ 0.7370)>0;

0.5450<θ gF ; and

50.0<ν d< 85.0,

where νd and θgF represent an Abbe number and a partial dispersion ratio of the positive lens Gp, respectively, and

wherein an Abbe number νd and a partial dispersion ratio θgF of a material are expressed by expressions

ν d =( Nd− 1)/( NF−NC ); and

θ gF =( Ng−NF )/( NF−NC ), respectively,

where Ng, NF, NC, and Nd represent refractive indices of the material with respect to a g-line (wavelength of 435.8 nm), an F-line (wavelength of 486.1 nm), a C-line (wavelength of 656.3 nm), and a d-line (wavelength of 587.6 nm), respectively.

9. The extender lens unit according to claim 8 , wherein the extender lens unit satisfies a conditional expression

1.3 <fiew/fw< 3.0,

where fw represents a focal length of a master lens, and fiew represents a focal length of the image pickup apparatus in a state in which the extender lens unit is inserted into the optical path.

10. The extender lens unit according to claim 8 , wherein the extender lens unit satisfies a conditional expression

0< LGp 1/ Lie< 0.4,

where Lie represents a distance from an apex of a surface of the extender lens unit closest to an object side to an apex of a surface of the extender lens unit closest to an image side, and LGp1 represents a distance from the apex of the surface closest to the object side to an apex of a surface on the object side of a positive lens Gp1, which is arranged closest to the object side of the positive lens Gp.

11. The extender lens unit according to claim 8 , wherein the extender lens unit consists of, in order from an object side to an image side, a positive lens and three cemented lenses.

12. The extender lens unit according to claim 1 , wherein the extender lens unit consists of, in order from the object side to the image side, at least one positive lens and two cemented lenses.

13. The extender lens unit according to claim 1 , wherein the extender lens unit consists of, in order from the object side to the image side, one positive lens, two cemented lenses, and one negative lens.

14. An image pickup apparatus comprising:

an extender lens unit; and

an image pickup element configured to receive an image formed via the extender lens unit,

wherein the extender lens unit includes a positive lens Gp, and the positive lens Gp satisfies conditional expressions

θ gF −(−1.6650×10−7 ·νd 3+5.2130×10−5 ·νd 2−5.6560×10−3 ·νd+ 0.7370)>0;

0.5450<θ gF ; and

50.0<ν d< 85.0,

where νd and θgF represent an Abbe number and a partial dispersion ratio of the positive lens Gp, respectively, and

wherein an Abbe number νd and a partial dispersion ratio θgF of a material are expressed by expressions

ν d =( Nd− 1)/( NF−NC ); and

θ gF =( Ng−NF )/( NF−NC ), respectively,

where Ng, NF, NC, and Nd represent refractive indices of the material with respect to a g-line (wavelength of 435.8 nm), an F-line (wavelength of 486.1 nm), a C-line (wavelength of 656.3 nm), and a d-line (wavelength of 587.6 nm), respectively.