Zoom lens and image pickup apparatus equipped with zoom lens
A zoom lens includes, in order from an object side to an image side, a first lens unit of a positive refractive power, a second lens unit of a negative refractive power, a third lens unit of a positive refractive power, a fourth lens unit of a positive refractive power, and a fifth lens unit, the second and fourth lens units being moved during zooming, a distance between the first and second lens units increasing at a telephoto end in comparison with a wide-angle end, wherein the fifth lens unit includes a first lens subunit of a negative refractive power, and a second lens subunit of a positive refractive power, the first lens subunit is moved to have a component perpendicular to an optical axis to change an image-forming position, and a condition 0.5<|(1−β 5 n )×β 5 p |<2.0 is satisfied.
1. A zoom lens comprising, in order from an object side to an image side, a first lens unit of a positive refractive power, a second lens unit of a negative refractive power, a third lens unit of a positive refractive power, a fourth lens unit of a positive refractive power, and a fifth lens unit of a positive or negative refractive power, the second and fourth lens units being moved during zooming, a distance between the first and second lens units increasing at a telephoto end in comparison with a wide-angle end,
wherein the fifth lens unit includes a first lens subunit of a negative refractive power, and a second lens subunit of a positive refractive power located on the image side of the first lens subunit, the first lens subunit is moved to have a component perpendicular to an optical axis to change an image-forming position, and
wherein following condition is satisfied:
0.5<|(1−β5 n )×β5 p|< 2.0,
where β 5 n denotes a lateral magnification of the first lens subunit, and β 5 p denotes a lateral magnification of the second lens subunit.
2. The zoom lens according to claim 1 , wherein the fifth lens unit includes, in order from the object side to the image side, the first lens subunit and the second lens subunit, and
wherein following condition is satisfied:
0.5 <|f 5 n/f 5 p|< 2.0,
where f 5 n and f 5 p denote focal lengths of the first lens subunit and the second lens subunit, respectively.
3. The zoom lens according to claim 1 , wherein following condition is satisfied:
0.01 <|f 5 n/f 5|<0.30,
where f 5 n and f 5 denote focal lengths of the first lens subunit and the fifth lens unit, respectively.
4. The zoom lens according to claim 1 , wherein the fifth lens unit does not move for zooming.
5. The zoom lens according to claim 1 , wherein the first lens subunit includes a cemented lens, obtained by cementing positive and negative lenses, or a single negative lens.
6. The zoom lens according to claim 1 , wherein following condition is satisfied:
0.5 <f 3 /f 4<2.0,
where f 3 and f 4 denote focal lengths of the third and fourth lens units, respectively.
7. The zoom lens according to claim 1 , wherein the first and third lens units do not move for zooming.
8. The zoom lens according to claim 1 , wherein following condition is satisfied:
5.0 <ft/|f 2|<25.0,
where f 2 denotes a focal length of the second lens unit, and ft denotes a focal length of the entire zoom lens at the telephoto end.
9. The zoom lens according to claim 1 , wherein following condition is satisfied:
1.0 <|f 5/√( fw×ft )|<50.0,
where f 5 denotes a focal length of the fifth lens unit, and fw and ft denote focal lengths of the entire zoom lens at the wide-angle end and the telephoto end, respectively.
10. An image pickup apparatus comprising the zoom lens according to claim 1 and an image sensor configured to receive an image formed by the zoom lens.