Zoom lens and image pickup apparatus equipped with the same
A zoom lens includes 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 fourth lens unit having positive refractive power. During zooming from a wide-angle end to a telephoto end, each lens unit moves so that a distance between the first lens unit and the second lens unit increases, and a distance between the second lens unit and the third lens unit decreases. Each of the first lens unit, the second lens unit, and the third lens unit consists of a single positive lens and a single negative lens, and the fourth lens unit consists of a single positive lens. Focal lengths of the entire zoom lens at the wide-angle end and the telephoto end and focal lengths of the first lens unit and the second lens unit are appropriately set.
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 fourth lens unit having positive refractive power,
wherein, during zooming from a wide-angle end to a telephoto end, each lens unit moves in such a manner that a distance between the first lens unit and the second lens unit increases, and a distance between the second lens unit and the third lens unit decreases,
wherein each of the first lens unit, the second lens unit, and the third lens unit consists of a single positive lens and a single negative lens, and the fourth lens unit consists of a single positive lens, and
wherein the following conditions are satisfied:
6.0 <f 1 /fw< 20.0
0.05 <|f 2 |/ft< 0.40
where fw and ft are focal lengths of the entire zoom lens at the wide-angle end and the telephoto end, respectively, and f 1 and f 2 are focal lengths of the first lens unit and the second lens unit, respectively.
2. The zoom lens according to claim 1 , wherein the following condition is satisfied:
20 <νd 3 p−νd 3 n< 70
where νd 3 p and νd 3 n are Abbe numbers of materials of the positive lens and the negative lens of the third lens unit, respectively.
3. The zoom lens according to claim 1 , wherein the following condition is satisfied:
0.3 <f 3 p/f 3 n< 0.9
where f 3 p and f 3 n are focal lengths of the positive lens and the negative lens of the third lens unit, respectively.
4. The zoom lens according to claim 1 , wherein the following condition is satisfied:
0.2 <f 4 /ft< 0.7
where f 4 is a focal length of the fourth lens unit.
5. The zoom lens according to claim 1 , wherein the following condition is satisfied:
0.1<(β3 t/β 3 w )/(β2 t/β 2 w )<2.5
where β 2 w and β 2 t are lateral magnifications of the second lens unit at the wide-angle end and the telephoto end, respectively, and β 3 w and β 3 t are lateral magnifications of the third lens unit at the wide-angle end and the telephoto end, respectively.
6. The zoom lens according to claim 1 , wherein the following condition is satisfied:
0.05<( m 1 ×m 2)/( f 1 ×f 2)<0.60
where m 1 and m 2 are amounts of movement of the first lens unit and the second lens unit during zooming from the wide-angle end to the telephoto end, respectively.
7. The zoom lens according to claim 1 , wherein the following condition is satisfied:
1.6 <f 3 /fw< 4.0
where f 3 is a focal length of the third lens unit.
8. The zoom lens according to claim 1 , wherein the following condition is satisfied:
0.1 <D 2 /|m 2|<3.0
where m 2 is an amount of movement of the second lens unit during zooming from the wide-angle end to the telephoto end, and D 2 is a thickness of the second lens unit on an optical axis.
9. The zoom lens according to claim 1 , wherein the following condition is satisfied:
0.05<( D 2 +D 3)/(| m 2 |+|m 3|)<0.90
where D 2 and D 3 are thicknesses of the second lens unit and the third lens unit on an optical axis, respectively, and m 2 and m 3 are amounts of movement of the second lens unit and the third lens unit during zooming from the wide-angle end to the telephoto end, respectively.
10. The zoom lens according to claim 1 , wherein the following condition is satisfied:
1.8<β2 t/β 2 w< 7.0
where β 2 w and β 2 t are lateral magnifications of the second lens unit at the wide-angle end and the telephoto end, respectively.
11. The zoom lens according to claim 1 , wherein the following condition is satisfied:
0.35 <f 3 /f 4<0.80
where f 3 and f 4 are focal lengths of the third lens unit and the fourth lens unit, respectively.
12. The zoom lens according to claim 1 , wherein the following condition is satisfied:
1.7 <N 1 n< 2.6
where N 1 n is a refractive index of a material of the negative lens of the first lens unit.
13. The zoom lens according to claim 1 , wherein the following condition is satisfied:
0.005 <D 3 /Lt< 0.090
where D 3 is a thickness of the third lens unit on an optical axis, and Lt is a total lens length at the telephoto end.
14. The zoom lens according to claim 1 , wherein the following condition is satisfied:
1.0<(1−β3 t )/β4 t< 2.5
where β 3 t and β 4 t are lateral magnifications of the third lens unit and the fourth lens unit, respectively.
15. The zoom lens according to claim 1 , wherein the zoom lens is configured to form an image on a solid-state image sensor.
16. An image pickup apparatus comprising:
a zoom lens; and
a solid-state 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 fourth lens unit having positive refractive power,
wherein, during zooming from a wide-angle end to a telephoto end, each lens unit moves in such a manner that a distance between the first lens unit and the second lens unit increases, and a distance between the second lens unit and the third lens unit decreases,
wherein each of the first lens unit, the second lens unit, and the third lens unit consists of a single positive lens and a single negative lens, and the fourth lens unit consists of a single positive lens, and
wherein the following conditions are satisfied:
6.0 <f 1 /fw< 20.0
0.05 <|f 2 |/ft< 0.40
where fw and ft are focal lengths of the entire zoom lens at the wide-angle end and the telephoto end, respectively, and f 1 and f 2 are focal lengths of the first lens unit and the second lens unit, respectively.