Optical system and camera device having same
An optical system has, sequentially from an object side to an image side, a first lens group including at least one lens and having a negative refractive power, a second lens group including at least one lens and having a positive refractive power, and a third lens group including at least one lens and having a negative refractive power. During focusing, distances from the first lens group and the third lens group to an imaging plane on an optical axis are fixed, and the second lens group is movable along the optical axis.
1 . An optical system, comprising:
a first lens group comprising, sequentially from an object side to an image side, at least one lens and having a negative refractive power, a second lens group comprising at least one lens and having a positive refractive power, and a third lens group comprising at least one lens and having a negative refractive power,
wherein during focusing, distances between the first lens group and an imaging plane and between the third lens group and the imaging plane on an optical axis are fixed, and the second lens group moves along the optical axis,
wherein when a lateral magnification of the second lens group focusing at infinity is b2, a lateral magnification of the third lens group focusing at infinity is b3, a focal length of the optical system focusing at infinity is f, a focal length of the second lens group is f2, a focal length of the third lens group is f3, a total value of distances from a lens face closest to the object side to a lens face closest to the image side in each lens group is OAL123, and a maximum image height is Y,
at least one of the following formulas (1) to (4) is satisfied:
-
1.2
≤
f
3
/
f
≤
-
0.1
(
1
)
-
0.4
≤
b
2
≤
-
0.06
(
2
)
0.3
≤
O
A
L
123
/
Y
≤
2.3
and
1.
≤
b
3
≤
1.3
(
3
)
0.6
≤
f
2
/
f
≤
0.9
,
and
(
4
)
wherein the second lens group is movable in a direction orthogonal to the optical axis, and it is satisfied that:
1.
≤
(
1
-
b
2
)
×
b
3
≤
1.9
.
2 . The optical system according to claim 1 , wherein,
it is satisfied that:
1.
1
5
≤
(
1
-
b
2
)
×
b
3
≤
1.8
.
3 . The optical system according to claim 1 , wherein,
when a focal length of the first lens group is f1, it is satisfied that:
-
1
6
.
0
0
≤
f
1
/
f
≤
-
1.8
.
4 . The optical system according to claim 3 , wherein,
it is satisfied that:
-
1
0
.
0
0
≤
f
1
/
f
≤
-
2
.
0
0
.
5 . The optical system according to claim 1 , further comprising:
an aperture device located between the first lens group and the second lens group and having an adjustable aperture diameter.
6 . The optical system according to claim 1 , wherein,
when a distance from a lens face closest to the object side to the imaging plane in the optical system is OAL, it is satisfied that:
1.
2
0
≤
OAL
/
f
≤
2
.
3
0
.
7 . The optical system according to claim 6 , wherein,
it is satisfied that:
1.
3
5
≤
OAL
/
f
≤
2
.
1
0
.
8 . The optical system according to claim 1 , wherein,
it is satisfied that:
1.
0
0
≤
(
1
-
b
2
2
)
×
b
3
2
≤
1.7
.
9 . The optical system according to claim 8 , wherein,
it is satisfied that:
1.
1
0
≤
(
1
-
b
2
2
)
×
b
3
2
≤
1.6
.
10 . The optical system according to claim 8 , wherein,
it is satisfied that:
1.54
≤
nd
1
≤
1.69
.
11 . The optical system according to claim 1 , wherein,
when a refractive index of the at least one lens in the first lens group on a d-line is nd1 and an Abbe number based on the d-line of the at least one lens in the first lens group is vd1, it is satisfied that:
1.
5
0
≤
nd
1
≤
1.7
and
15.
≤
vd
1
≤
60.
.
12 . The optical system according to claim 1 , wherein,
when a refractive index of the at least one lens in the third lens group on a d-line is nd3 and an Abbe number based on the d-line of the at least one lens in the third lens group is vd3, it is satisfied that:
1.5
≤
n
d
3
≤
1.7
and
15.
≤
vd
3
≤
6
0
.
0
0
.
13 . The optical system according to claim 1 , wherein,
at least the first lens group among the first lens group, the second lens group, and the third lens group is movable towards the image side when not photographing.
14 . A camera device, comprising:
an optical system according to claim 1 ; and
a photographing element arranged at an imaging plane of the optical system.
15 . The optical system according to claim 1 , wherein,
it is satisfied that:
-
1
.
1
0
≤
f
3
/
f
≤
-
0
.
5
0
.
16 . The optical system according to claim 1 , wherein,
it is satisfied that:
-
0.38
≤
b
2
≤
-
0
.
1
0
.
17 . The optical system according to claim 1 , wherein,
it is satisfied that:
0.5
≤
OAL
123
/
Y
≤
2
.
0
0
.
18 . The optical system according to claim 1 , wherein,
it is satisfied that:
1.
0
5
<
¯
b
3
≤
1.26
.
19 . The optical system according to claim 1 , wherein,
it is satisfied that:
0
.
7
0
≤
f
2
/
f
≤
0
.
8
5
.