Zoom lens and imaging apparatus having the same
A zoom lens includes a focus lens group having a negative refractive power. The focus lens group is configured to move during focusing. In the zoom lens, a distance between lens groups arranged adjacent to each other changes for zooming and/or focusing. In the zoom lens, a positive lens group having a positive refractive power is provided. The positive lens group is arranged adjacent to the focus lens group on an image side thereof. The positive lens group moves during zooming. The focus lens group includes, in order from an object side to an image side, a positive lens and a negative lens. In the zoom lens, a curvature radius of an image-side surface of the positive lens included in the focus lens group and a curvature radius of an object-side surface of the negative lens included in the focus lens group are each set appropriately.
1. A zoom lens comprising:
a first lens group;
a second lens group, on an image side of the first lens group;
a focus lens group having a negative refractive power, and configured to move during focusing, wherein the focus lens group is on an image side of the second lens group, and
a positive lens group having a positive refractive power and arranged adjacent to the focus lens group on an image side of the focus lens group, wherein the positive lens group includes one or more lenses,
wherein the focus lens group includes, in order from an object side of the focus lens group to the image side of the focus lens group, a positive lens and a negative lens,
wherein a distance between lens groups of the zoom lens arranged adjacent to each other changes for zooming and/or focusing, and
wherein the following conditions are satisfied:
0.50<( RF−RR )/( RF+RR )<200.00, and
| RR|<|RF|
where RR represents a curvature radius of an object-side surface of the negative lens included in the focus lens group, and RF represents a curvature radius of an image-side surface of the positive lens included in the focus lens group.
2. The zoom lens according to claim 1 , wherein the positive lens group is configured to move during zooming.
3. The zoom lens according to claim 1 , wherein the focus lens group consists of the positive lens and the negative lens.
4. The zoom lens according to claim 1 , wherein the following condition is satisfied:
0.00<( Drt−Dft )/( Drw−Dfw )<85.00
where,
Drw represents a distance along an optical axis, at a wide-angle end, between the positive lens group and the focus lens group,
Dfw represents a distance along the optical axis, at the wide-angle end, between the focus lens group and a lens group arranged adjacent on the object side of the focus lens group,
Drt represents a distance along the optical axis, at a telephoto end, between the positive lens group and the focus lens group, and
Dft represents a distance along the optical axis, at the telephoto end, between the focus lens group and a lens group arranged adjacent on the object side of the focus lens group.
5. The zoom lens according to claim 1 , wherein the following condition is satisfied:
−50.0<( Ra−Rb )/( Ra+Rb )<120.0
where,
Ra represents a curvature radius of a most-image-side lens surface in a lens group arranged adjacent to the focus lens group on the object side of the focus lens group, and
Rb represents a curvature radius of a most-object-side lens surface in the focus lens group.
6. The zoom lens according to claim 1 , wherein the following condition is satisfied:
−0.30<( Rc−Rd )/( Rc+Rd )<2.50
where,
Rc represents a curvature radius of a most-image-side lens surface in the focus lens group, and
Rd represents a curvature radius of a most-object-side lens surface in the positive lens group.
7. The zoom lens according to claim 1 , wherein the following condition is satisfied:
−21.0 <fnp/fnn<− 2.5
where,
fnp represents a focal length of the positive lens included in the focus lens group, and
fnn represents a focal length of the negative lens included in the focus lens group.
8. The zoom lens according to claim 1 , wherein the following condition is satisfied:
0.10 <Dft/Drt< 1.80
where,
Drt represents a distance along an optical axis, at a telephoto end, between the positive lens group and the focus lens group, and
Dft represents a distance along the optical axis, at the telephoto end, between the focus lens group and a lens group arranged adjacent on the object side of the focus lens group.
9. The zoom lens according to claim 1 , wherein the following condition is satisfied:
0.10 <Dfw/Drw< 2.60
where,
Drw represents a distance along an optical axis, at a wide-angle end, between the positive lens group and the focus lens group, and
Dfw represents a distance along the optical axis, at the wide-angle end, between the focus lens group and a lens group arranged adjacent on the object side of the focus lens group.
10. The zoom lens according to claim 1 , wherein the following condition is satisfied:
0.30<fair/ fn< 2.30
where,
fair represents a focal length of an air lens formed between the image-side surface of the positive lens included in the focus lens group and the object-side surface of the negative lens included in the focus lens group, and
fn represents a focal length of the focus lens group.
11. The zoom lens according to claim 1 , wherein the following condition is satisfied:
−4.20 <fp/fn<− 0.50
where,
fp represents a focal length of the positive lens group, and
fn represents the focal length of the focus lens group.
12. The zoom lens according to claim 1 , further comprising an aperture stop arranged on the object side relative to the focus lens group.
13. The zoom lens according to claim 1 , further comprising, in order from an object side of the zoom lens to an image side of the zoom lens:
the first lens group having a positive refractive power;
the second lens group having a negative refractive power;
a third lens group having a positive refractive power; and
a fourth lens group having a positive refractive power,
wherein the focus lens group is a fifth lens group disposed or located after the fourth lens group on an image side of the fourth lens group and the positive lens group is a sixth lens group disposed or located after the focus lens group.
14. The zoom lens according to claim 1 , further comprising, in order from an object side of the zoom lens to an image side of the zoom lens:
the first lens group having a positive refractive power;
the second lens group having a negative refractive power; and
a third lens group having a positive refractive power,
wherein the focus lens group is a fourth lens group disposed or located after the third lens group on an image side of the third lens group and the positive lens group is a fifth lens group disposed or located after the focus lens group.
15. The zoom lens according to claim 1 , further comprising, in order from an object side of the zoom lens to an image side of the zoom lens:
the first lens group having a negative refractive power; and
the second lens group having a positive refractive power,
wherein the focus lens group is a third lens group disposed or located after the second lens group on an image side of the second lens group and the positive lens group is a fourth lens group disposed or located after the focus lens group.
16. The zoom lens according to claim 1 , further comprising, in order from an object side of the zoom lens to an image side of the zoom lens:
the first lens group having a negative refractive power;
the second lens group having a positive refractive power; and
a third lens group having a positive refractive power,
wherein the focus lens group is a fourth lens group disposed or located after the third lens group on an image side of the third lens group and the positive lens group is a fifth lens group disposed or located after the focus lens group.
17. The zoom lens according to claim 1 , further comprising, in order from an object side of the zoom lens to an image side of the zoom lens:
the first lens group having a positive refractive power;
the second lens group having a negative refractive power;
a third lens group having a positive refractive power; and
a fourth lens group having a negative refractive power,
wherein the focus lens group is a fifth lens group disposed or located after the fourth lens group on an image side of the fourth lens group and the positive lens group is a sixth lens group disposed or located after the focus lens group.
18. The zoom lens according to claim 1 , further comprising, in order from an object side of the zoom lens to an image side of the zoom lens:
the first lens group having a positive refractive power;
the second lens group having a negative refractive power;
a third lens group having a positive refractive power;
a fourth lens group having a positive refractive power; and
a fifth lens group having a negative refractive power,
wherein the focus lens group is a sixth lens group disposed or located after the fifth lens group on an image side of the fifth lens group and the positive lens group is a seventh lens group disposed or located after the focus lens group.
19. The zoom lens according to claim 1 , further comprising, in order from an object side of the zoom lens to an image side of the zoom lens:
the first lens group having a negative refractive power;
the second lens group having a positive refractive power; and
a third lens group having a negative refractive power,
wherein the focus lens group is a fourth lens group disposed or located after the third lens group on an image side of the third lens group and the positive lens group is a fifth lens group disposed or located after the focus lens group.
20. The zoom lens according to claim 1 , further comprising, in order from an object side of the zoom lens to an image side of the zoom lens:
the first lens group having a negative refractive power;
the second lens group having a positive refractive power;
a third lens group having a positive refractive power; and
a fourth lens group having a negative refractive power,
wherein the focus lens group is a fifth lens group disposed or located after the fourth lens group on an image side of the fourth lens group and the positive lens group is a sixth lens group disposed or located after the focus lens group.
21. The zoom lens according to claim 1 , wherein the zoom lens is configured to form an image on a solid-state image sensor.
22. An imaging apparatus comprising:
a zoom lens; and
an image sensor configured to receive an image formed by the zoom lens,
wherein the zoom lens comprises:
a first lens group;
a second lens group, on an image side of the first lens group;
a focus lens group, on an image side of the second lens group; and
a positive lens group;
wherein the focus lens group has a negative refractive power, and is configured to move during focusing, and
wherein the positive lens group has a positive refractive power and is arranged adjacent to the focus lens group on an image side of the focus lens group, wherein the positive lens group includes one or more lenses,
wherein the focus lens group includes, in order from an object side of the focus lens group to the image side of the focus lens group, a positive lens and a negative lens,
wherein a distance between lens groups of the zoom lens arranged adjacent to each other changes for zooming and/or focusing, and
wherein the following conditions are satisfied:
0.50<( RF−RR )/( RF+RR )<200.00, and
| RR|<|RF|
where RR represents a curvature radius of an object-side surface of the negative lens included in the focus lens group, and RF represents a curvature radius of an image-side surface of the positive lens included in the focus lens group.