Zoom lens and electronic apparatus including the same
A zoom lens includes: in an order from an object side to an image side, a first lens group having a positive refractive power; a 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, when zooming is performed from a wide angle position to a telephoto position, the first through fourth lens groups move, and the first lens group includes a first negative lens and a second positive lens from the object side. The zoom lens may be part of an electronic apparatus, such as a photographing apparatus.
1. A zoom lens comprising, in an order from an object side to an image side:
a first lens group having a positive refractive power;
a 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, when zooming is performed from a wide angle position to a telephoto position, the first through fourth lens groups move, and
wherein the first lens group comprises a first negative lens and a second positive lens from the object side, the second lens group comprises a third negative lens, a fourth negative lens, and a fifth positive lens, and the third negative lens comprises a concave surface at an object side thereof,
wherein
( D/Z )/ fw< 0.32
( Dt/Z )/ fw< 1.3
0< R 1/ R 2<2.5
nG 5>2.0
where Dt is an optical overall length of the zoom lens in the telephoto position, Z is a zoom ratio, D is a sum of thicknesses of entire lenses of the first through fourth lens groups, R1 is a radius of curvature of the image side of the second positive lens of the first lens group, R2 is a radius of curvature of the object side of the third negative lens of the second lens group, fw is a focal length in the wide angle position, and nG5 is a refractive index of the fifth positive lens of the second lens group.
2. The zoom lens of claim 1 , wherein:
nG 1>1.9
where nG1 is a refractive index of the first negative lens of the first lens group.
3. The zoom lens of claim 1 , wherein:
L/ft< 0.7
f 1/ fw< 6.0
f 1/ ft< 0.7
where L is a sum of movement distances of the first through fourth lens groups when zooming is performed from the wide angle position to the telephoto position, ft is a focal length in the telephoto position, f1 is a focal length of the first lens group, and fw is a focal length in the wide angle position.
4. The zoom lens of claim 1 , wherein:
| f 2/ fw|< 1.3
f 2/ ft< 0.16,
where f2 is a focal length of the second lens group.
5. The zoom lens of claim 1 , wherein the third lens group comprises doublet lenses.
6. The zoom lens of claim 1 , wherein:
D 1( w−t )/ Z< 1.7
D 2( w−t )/ Z< 0.15
where D1(w−t) is a movement distance of the first lens group when zooming is performed from the wide angle position to the telephoto position, and D2(w−t) is a movement distance of the second lens group when zooming is performed from the wide angle position to the telephoto position.
7. The zoom lens of claim 1 , wherein each of the first through fourth lens groups comprises at least one aspherical surface.
8. The zoom lens of claim 1 , wherein:
2.8< Fno _ w< 3.5
where Fno_w is Fno in the wide angle position.
9. The zoom lens of claim 1 , wherein, when the zoom lens performs zooming, a distance between the first lens group and the second lens group increases, a distance between the second lens group and the third lens group is reduced, and a distance between the third lens group and the fourth lens group increases.
10. The zoom lens of claim 1 , wherein the fourth lens group performs focusing according to a variation in a distance from an object.
11. The zoom lens of claim 1 , wherein the fourth lens group comprises plastic lenses.
12. The zoom lens of claim 1 , wherein the zoom lens has an 8× or more and 12× or less zoom ratio.
13. The zoom lens of claim 1 , wherein the first negative lens and the second positive lens are cemented as doublet lenses.
14. The zoom lens of claim 1 , wherein the third negative lens and the fourth negative lens are bi-concave lenses.
15. An electronic apparatus comprising:
a zoom lens; and
an imaging device that receives an image formed by the zoom lens,
wherein the zoom lens comprises, in an order from an object side to an image side:
a first lens group having a positive refractive power;
a 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, when zooming is performed from a wide angle position to a telephoto position, the first through fourth lens groups move,
wherein the first lens group includes a first negative lens and a second positive lens from the object side, the second lens group includes a third negative lens, a fourth negative lens, and a fifth positive lens, and the third negative lens includes a concave surface at an object side thereof,
wherein:
( D/Z )/ fw< 0.32
( Dt/Z )/ fw< 1.3
0< R 1/ R 2<2.5
nG 5>2.0
where Dt is an optical overall length of the zoom lens in the telephoto position, Z is a zoom ratio, D is a sum of thicknesses of entire lenses of the first through fourth lens groups, R1 is a radius of curvature of the image side of the second positive lens of the first lens group, R2 is a radius of curvature of the object side of the third negative lens of the second lens group, fw is a focal length in the wide angle position, and nG5 is a refractive index of the fifth positive lens of the second lens group.