Zoom lens
In a zoom lens of a fixed total length, at the time of changing the magnification from the wide-angle end toward the telephoto end, the first lens group is anchored while the second lens group is moved, and the third and fourth lens groups are moved so as to be located at the object side of the telephoto end relative to the wide-angle end, such that: the interval between the second and third lens groups is decreased at the telephoto end relative to the wide-angle end; the interval between the third and fourth lens groups is increased at the telephoto end relative to the wide-angle end; and the interval between the fourth and fifth lens groups is increased at the telephoto end relative to the wide-angle end, and at the time of focusing a near object point from a remote object point, the second lens group is moved.
1. A zoom lens having a macro mode that includes a first mode allowing zooming and focusing including infinity and a second mode allowing obtaining an imaging magnification absolute value greater than 0.25 times, the zoom lens comprising:
a lens group A having a positive refractive power;
a lens group B having a negative refractive power and arranged at the image side relative to the lens group A so as to be neighbored by the lens group A with an interval of air interposed between them;
a focus lens group having a negative refractive power and arranged at the object side relative to the lens group A so as to be movable in the direction of the optical axis in an focusing operation; and
an object side lens group having a negative refractive power and arranged at the object side relative to the focus lens group so as to change the distance between itself and the focus lens group at the time of the focusing operation; wherein,
in the first mode, at the time of zooming from the wide-angle end to the telephoto end,
the lens group A is adapted to move so as to be located at the object side to reduce the distance between itself and the focus lens group at the telephoto end rather than at the wide-angle end; and
the lens group B is adapted to move so as to be located at the object side to increase the distance between itself and the lens group A at the telephoto end rather than at the wide-angle end;
the zoom lens operating for focusing including infinity focusing by moving the focus lens group having a negative refractive power in the direction of the optical axis; and
in the second mode,
the lens group A is located within the moving range of the lens group A in the first mode for zooming from the wide-angle end to the telephoto end; and
the lens group B is located at the image side relative to a first position and at the object side relative to a second position;
the first position being a position at which the lens group B is located in the first mode when the lens group A in the first mode is located at the position same as the position of the lens group A in the second mode;
the second position being a position of the lens group B at the wide-angle end in the first mode,
the zoom lens operating for focusing by moving the focus lens group having a negative refractive power in the direction of the optical axis.
2. The zoom lens having a macro mode according to claim 1 , wherein
the zoom lens satisfies the conditional formula (2-1) shown below:
0.2 <f obj/ f focus<5.0 (2-1),
where
f obj is the focal length of the object side lens group; and
f focus is the focal length of the focus lens group.
3. The zoom lens having a macro mode according to claim 1 , wherein
the zoom lens satisfies the conditional formula (2-2) shown below:
1.2 <DAwt/DBwt< 3.0 (2-2),
where
DAwt is the difference between the position of the lens group A at the telephoto end and the position of the lens group A at the wide-angle end; and
DBwt is the difference between the position of the lens group B at the telephoto end and the position of the lens group B at the wide-angle end.
4. The zoom lens having a macro mode according to claim 1 , wherein
the zoom lens satisfies the conditional formula (2-3) shown below:
0 ≦MBm 2 /DABm 2<1.8 (2-3),
where
MBm2 is the difference between the position of the lens group B in the second mode and the position of the lens group B at the wide-angle end; and
DABm2 is the distance between the lens group A and the lens group B in the second mode.
5. The zoom lens having a macro mode according to claim 1 , wherein
the zoom lens satisfies the conditional formula (2-4) shown below:
0.4 <MBm 2 /MBm 1<0.96 (2-4),
where
MBm2 is the difference between the position of the lens group B in the second mode and the position of the lens group B at the wide-angle end; and
MBm1 is the difference between the position of the lens group B in the first mode when the lens group A is located at the position same as the position of the lens group A in the second mode and the position of the lens group B at the wide-angle end.
6. The zoom lens having a macro mode according to claim 1 , wherein
the zoom lens satisfies the conditional formula (2-5) shown below:
0.5 <MAm 2 /DAwt< 0.98 (2-5),
where
MAm2 is the difference between the position of the lens group A in the second mode and the position of the lens group A at the wide-angle end; and
DAwt is the difference between the position of the lens group A at the telephoto end and the position of the lens group A at the wide-angle end.
7. The zoom lens having a macro mode according to claim 1 , wherein
the object side lens group is anchored at the time of the zooming and focusing.
8. The zoom lens having a macro mode according to claim 1 , wherein
the object side lens group is the lens group that is arranged at the most object side in the zoom lens.
9. The zoom lens having a macro mode according to claim 1 , further comprising:
an aperture diaphragm arranged between the air interval immediately in front of the lens group A at the object side and the image side air interval of the lens group A and located at the object side at the telephoto end rather than at the wide-angle end.
10. The zoom lens having a macro mode according to claim 1 , wherein,
at the time of zooming from the wide-angle end to the telephoto end, the focus lens group moves toward the image side and subsequently toward the object side so as to change the distance between the object side lens group and the focus lens group.
11. The zoom lens having a macro mode according to claim 1 , wherein
the focus lens group consists of a lens component whose inside is filled with a medium.
12. The zoom lens having a macro mode according to claim 1 , further comprising:
a lens group C arranged at the image side relative to the lens group B and having a positive refractive power, the distance between itself and the lens group B changing at the time of the zooming.
13. The zoom lens having a macro mode according to claim 12 , wherein
the lens group C is a lens group arranged at the most image side in the zoom lens and is rigidly anchored at the time of the zooming and focusing.
14. The zoom lens having a macro mode according to claim 1 , wherein
the zoom lens comprises the object side lens group, the focus lens group, the lens group A, the lens group B and a lens group C having a positive refractive power, sequentially arranged in the above-mentioned order from the object side; and
the object side lens group and the lens group C are rigidly anchored at the time of the zooming and focusing.
15. The zoom lens having a macro mode according to claim 14 , wherein
the focus lens group is moved toward the image side and subsequently toward the object side at the time of the zooming.
16. The zoom lens having a macro mode according to claim 14 , wherein
the focus lens group is rigidly anchored at the time of the zooming.
17. The zoom lens having a macro mode according to claim 1 , further comprising:
a lens group D having a positive refractive power and arranged at the object side relative to the object side lens group in such a way that the distance between the lens group D and the object side lens group changes at the time of the zooming.