Zoom lens, extender lens, and imaging apparatus
A zoom lens has, in order from an object side, a focusing unit including a focusing lens group moving for focusing, a variable magnification unit including at least two variable magnification lens groups moving while changing a mutual interval for variable magnification, an aperture stop, and an image forming unit including an image forming lens group. The image forming unit consists of, in order from the object side, an M 1 lens group, an M 2 N lens group, and an M 3 lens group. The M 2 N lens group is replaceable with an M 2 E lens group that enlarges an image forming magnification. The M 2 E lens group satisfies predetermined conditional expressions (1) to (4).
1. A zoom lens having, in order from an object side, a focusing unit including a focusing lens group moving for focusing, a variable magnification unit including at least two variable magnification lens groups moving while changing a mutual interval for variable magnification, an aperture stop, and an image forming unit including an image forming lens group,
wherein the image forming unit consists of an M 1 lens group, an M 2 N lens group, and an M 3 lens group in order from the object side,
the M 2 N lens group is replaceable with an M 2 E lens group that enlarges an image forming magnification,
in a case where an Abbe number of a positive lens of the M 2 E lens group is νd1, an average value of temperature change coefficients from 0° C. to 40° C. of a refractive index with respect to d line in the air is dn/dt, and dn/dt of the positive lens of the M 2 E lens group is dn/dt1, the M 2 E lens group comprises at least one positive lens satisfying conditional expressions (1) and (2), and
55<ν d 1 (1)
5.5< dn/dt 1<10 (2)
in a case where an average value of dn/dt of the positive lenses of the M 2 E lens group is dn/dt_ave_P, and an average value of dn/dt of negative lenses of the M 2 E lens group is dn/dt_ave_N, conditional expressions (3) and (4) are satisfied.
3.5< dn/dt _ave_ P< 6 (3)
1.5< dn/dt _ave_ N< 6 (4)
2. The zoom lens according to claim 1 ,
wherein, in a case where a partial dispersion ratio of the positive lens of the M 2 E lens group between g line and F line is θgF, the at least one positive lens satisfying the conditional expressions (1) and (2) satisfies a conditional expression (5).
0.62<θ gF+ 0.001625×ν d 1<0.67 (5)
3. The zoom lens according to claim 1 ,
wherein, in a case where a partial dispersion ratio of the positive lens of the M 2 E lens group between g line and F line is θgF, and an average value of (θgF+0.001625×νd1) of the positive lenses of the M 2 E lens group is (θgF+0.001625×νd1)_ave_P, a conditional expression (6) is satisfied.
0.62<(θ gF+ 0.001625×ν d 1)_ave_ P< 0.67 (6)
4. The zoom lens according to claim 1 ,
wherein, in a case where an average value of refractive indexes of the negative lenses of the M 2 E lens group is nd_ave_N, and an average value of refractive indexes of the positive lenses of the M 2 E lens group is nd_ave_P, a conditional expression (7) is satisfied.
0.01< nd _ave_ N−nd _ave_ P< 0.2 (7)
5. The zoom lens according to claim 1 ,
wherein the M 2 E lens group comprises at least three cemented lenses each comprising at least one positive lens and at least one negative lens.
6. The zoom lens according to claim 5 ,
wherein, in a case where an Abbe number for d line of the positive lens composing the cemented lens of the M 2 E lens group is νd_P1, an Abbe number for d line of the positive lens composing the cemented lens of the M 2 E lens group is νd_P2, an Abbe number for d line of the negative lens composing the cemented lens of the M 2 E lens group is νd_N1, and an Abbe number for d line of the negative lens composing the cemented lens of the M 2 E lens group is νd_N2,
at least two of the cemented lenses in the M 2 E lens group satisfy a conditional expression (8), and
10<ν d _ P 1−ν d _ N 1<30 (8)
at least one of the cemented lenses in the M 2 E lens group satisfies a conditional expression (9).
10<ν d _ N 2−ν d _ P 2<35 (9)
7. The zoom lens according to claim 5 ,
wherein the M 2 E lens group consists of, in order from the object side, the three cemented lenses, and a negative meniscus lens concave toward the object side.
8. The zoom lens according to claim 1 ,
wherein the focusing lens group has a positive refractive power,
the variable magnification unit consists of, in order from the object side, a V 1 lens group having a negative refractive power, a V 2 lens group having a positive refractive power, and a V 3 lens group having a positive refractive power,
the image forming unit has a positive refractive power, and
at the time of variable magnification from a wide angle end to a telephoto end, the V 1 lens group and a combined group consisting of the V 2 lens group and the V 3 lens group simultaneously pass through points where a lateral magnification is −1.
9. The zoom lens according to claim 1 ,
wherein the M 1 lens group has a negative refractive power, and the M 2 E lens group and the M 3 lens group have a positive refractive power.
10. The zoom lens according to claim 1 ,
wherein the positive lens satisfying the conditional expressions (1) and (2) satisfies at least one of a conditional expression (1-1) or (2-1).
55<ν d 1<70 (1-1)
5.75< dn/dt 1<8.5 (2-1)
11. The zoom lens according to claim 1 ,
wherein the positive lens satisfying the conditional expressions (1) and (2) satisfies at least one of a conditional expression (1-2) or (2-2).
55<ν d 1<60 (1-2)
6< dn/dt 1<7.5 (2-2)
12. The zoom lens according to claim 1 ,
wherein at least one of a conditional expressions (3-1) or (4-1) is satisfied.
3.75< dn/dt _ave_ P< 5.5 (3-1)
2< dn/dt _ave_ N< 5 (4-1)
13. The zoom lens according to claim 1 ,
wherein a conditional expression (3-2) is satisfied.
4< dn/dt _ave_ P< 5 (3-2)
14. The zoom lens according to claim 2 ,
wherein the at least one positive lens satisfying the conditional expressions (1) and (2) satisfies a conditional expression (5-1).
0.63<θ gF+ 0.001625×ν d 1<0.66 (5-1)
15. The zoom lens according to claim 3 ,
wherein a conditional expression (6-1) is satisfied.
0.63<(θ gF+ 0.001625×ν d 1)_ave_ P< 0.66 (6-1)
16. The zoom lens according to claim 4 ,
wherein a conditional expression (7-1) is satisfied.
0.01< nd _ave_ N−nd _ave_ P< 0.15 (7-1)
17. The zoom lens according to claim 6 ,
wherein the at least two of the cemented lenses in the M 2 E lens group satisfy a conditional expression (8-1).
17<ν d _ P 1−ν d _ N 1<30 (8-1)
18. The zoom lens according to claim 6 ,
wherein the at least one of the cemented lenses in the M 2 E lens group satisfies a conditional expression (9-1).
17<ν d _ N 2−ν d _ P 2<35 (9-1)
19. An extender lens consisting of the M 2 E lens group in the zoom lens according to claim 1 .
20. An imaging apparatus comprising:
the zoom lens according to claim 1 .