Zoom lens and image pickup apparatus including the same
A zoom lens includes, in order from an object side to an image side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having positive refractive power, and a rear lens group including one or more lens units. The distance between adjacent lens units changes during zooming. The first lens unit is closer to the object side at a telephoto end than at the wide-angle end. The second lens unit includes a first negative lens, a second negative lens, and a third negative lens in this order from the object side. The focal lengths of the zoom lens at the wide-angle end and at the telephoto end, the focal length of the first lens unit, and the focal length of the second lens unit are appropriately set based on predetermined mathematical conditions.
1. A zoom lens comprising in order from an object side to an image side:
a first lens unit having positive refractive power;
a second lens unit having negative refractive power;
a third lens unit having positive refractive power; and
a rear lens group including one or more lens units,
wherein a distance between adjacent lens units changes during zooming;
the first lens unit is closer to the object side at a telephoto end than at the wide-angle end;
the second lens unit includes three negative lenses which are continuously arranged from the object side to the image side; and
following conditions are satisfied:
22.0< f 1/ fW< 35.0
20.0<| fT/f 2|<50.0
where fW is a focal length of the zoom lens at the wide-angle end, fT is a focal length of the zoom lens at the telephoto end, f1 is a focal length of the first lens unit, and f2 is a focal length of the second lens unit.
2. The zoom lens according to claim 1 , wherein a following condition is satisfied:
9.0<| f 1/ f 2|<15.0.
3. The zoom lens according to claim 1 , wherein a following condition is satisfied:
10.0<| M 1/ fW|< 30.0
where M1 is an amount of movement on an optical axis of the first lens unit during zooming from the wide-angle end to the telephoto end.
4. The zoom lens according to claim 1 , wherein a following condition is satisfied,
10.0< fT/M 2<40.0
where M2 is an amount of movement on an optical axis of the second lens unit during zooming from the wide-angle end to the telephoto end.
5. The zoom lens according to claim 1 , wherein a following condition is satisfied:
0.50< f 21/ f 2<2.00
where f21 is a focal length of the first negative lens of the second lens unit.
6. The zoom lens according to claim 1 , wherein a following condition is satisfied;
0.80<( R 1+ R 2)/( R 1− R 2)<1.20
where R1 is a radius of curvature of an object-side lens surface of the first negative lens of the second lens unit, and R2 is a radius of curvature of an image-side lens surface of the first negative lens of the second lens unit.
7. The zoom lens according to claim 1 , further comprising:
an aperture stop between the second lens unit and the third lens unit,
wherein a following condition is satisfied:
−6.0< MS/fW<− 2.0
where MS is an amount of movement on an optical axis of the aperture stop during zooming from the wide-angle end to the telephoto end.
8. The zoom lens according to claim 1 , wherein a following condition is satisfied:
10.0< fT/f 3<25.0
where f3 is a focal length of the third lens unit.
9. The zoom lens according to claim 1 , wherein focusing from an object at infinity to a nearby object is performed by moving a lens unit of the rear lens group in a direction towards the object side.
10. The zoom lens according to claim 1 , wherein the rear lens group consists of a fourth lens unit having positive refractive power and disposed closest to the image side.
11. The zoom lens according to claim 10 , wherein focusing from an object at infinity to a nearby object is performed by moving the fourth lens unit in a direction towards the object side.
12. The zoom lens according to claim 1 , wherein the rear lens group consists of a fourth lens unit having negative refractive power and a fifth lens unit having positive refractive power.
13. The zoom lens according to claim 12 , wherein focusing from an object at infinity to a nearby object is performed by moving the fifth lens unit in a direction towards the object side.
14. The zoom lens according to claim 1 , wherein the rear lens group consists of a fourth lens unit having positive refractive power and a fifth lens unit having positive refractive power.
15. The zoom lens according to claim 14 , wherein focusing from an object at infinity to a nearby object is performed by moving the fifth lens unit in a direction towards the object side.
16. An image pickup apparatus comprising:
a zoom lens; and
an image sensor configured to receive an image formed by the zoom lens,
wherein the zoom lens comprises, in order from an object side to an image side:
a first lens unit having positive refractive power;
a second lens unit having negative refractive power;
a third lens unit having positive refractive power; and
a rear lens group including one or more lens units,
wherein a distance between adjacent lens units changes during zooming;
the first lens unit is closer to the object side at a telephoto end than at the wide-angle end;
the second lens unit includes a first negative lens, a second negative lens, and a third negative lens in this order from the object side to the image side; and
following conditions are satisfied:
22.0< f 1/ fW< 35.0
20.0<| fT/f 2|<50.0
where fW is a focal length of the zoom lens at the wide-angle end, fT is a focal length of the zoom lens at the telephoto end, f1 is a focal length of the first lens unit, and f2 is a focal length of the second lens unit.