Optical imaging system
An optical imaging system includes a fixed-focus lens group and a variable-focus lens group disposed in this order from an object side, wherein the fixed-focus lens group includes a first lens, a second lens, and a third lens disposed in this order from an object side, wherein the first lens has positive refractive power, and wherein the second lens has negative refractive power.
1 . An optical imaging system, comprising:
a fixed-focus lens group and a variable-focus lens group disposed in this order from an object side,
wherein the fixed-focus lens group includes a first lens having positive refractive power, a second lens having negative refractive power, a third lens having positive refractive power, a fourth lens having negative refractive power, and a fifth lens having positive refractive power disposed in this order from an object side,
wherein the fixed-focus lens group has a total number of five lenses with refractive power, and
wherein the second lens has a concave image-side surface.
2 . The optical imaging system of claim 1 , wherein the first lens has a convex object-side surface.
3 . The optical imaging system of claim 1 , wherein the third lens has a convex object-side surface.
4 . The optical imaging system of claim 1 , further comprising:
an optical path changing element disposed on an object side of the fixed-focus lens group or between lenses of the fixed-focus lens group.
5 . The optical imaging system of claim 1 , wherein the fourth lens has a concave image-side surface.
6 . The optical imaging system of claim 1 , wherein at least one of conditional expressions as below is satisfied:
2.0<TTL/ f 1<4.0, and
−5.0<TTL/ f 2<−0.2,
where TTL is a distance from an object-side surface of the first lens to an imaging plane of the optical imaging system, f1 is a focal length of the first lens, and f2 is a focal length of the second lens.
7 . The optical imaging system of claim 1 , wherein a conditional expression as below is satisfied:
25< V 1− V 2,
where V1 is an Abbe number of the first lens, and V2 is an Abbe number of the second lens.
8 . A camera module comprising:
a housing; and
the optical imaging system of claim 1 disposed in the housing.
9 . An optical imaging system, comprising:
a fixed-focus lens group; and
a variable-focus lens group disposed on an image side of the fixed-focus lens group,
wherein the fixed-focus lens group includes a first lens having positive refractive power, a second lens having negative refractive power, a third lens having positive refractive power, a fourth lens having negative refractive power, and a fifth lens having positive refractive power disposed in this order from an object side,
wherein the fixed-focus lens group has a total number of five lenses with refractive power, and
wherein a conditional expression as below is satisfied:
0.8<TTL/ f< 1.0,
where TTL is a distance from an object-side surface of the first lens to an imaging plane of the optical imaging system, and f is a focal length of the optical imaging system.
10 . The optical imaging system of claim 9 , wherein a conditional expression as below is satisfied:
28.0 mm< fA< 36.0 mm,
where fA is a focal length of the fixed-focus lens group.
11 . The optical imaging system of claim 9 , wherein a conditional expression as below is satisfied:
−600 mm< fB< 20.0 mm,
where fB is a focal length of the variable-focus lens group.
12 . The optical imaging system of claim 9 , further comprising:
an optical path changing element disposed on an object side of the fixed-focus lens group or between lenses of the fixed-focus lens group.
13 . A camera module comprising:
a housing; and
the optical imaging system of claim 9 disposed in the housing.
14 . An optical imaging system, comprising:
a fixed-focus lens group and a variable-focus lens group disposed in this order from an object side,
wherein the fixed-focus lens group includes a first lens having positive refractive power, a second lens having negative refractive power, a third lens having positive refractive power, a fourth lens having negative refractive power, and a fifth lens having positive refractive power disposed in this order from an object side,
wherein the fixed-focus lens group has a total number of five lenses with refractive power,
wherein the second lens has a concave image-side surface, and
wherein at least one of conditional expressions as below is satisfied:
28.0 mm< fA< 36.0 mm, and
−600 mm< fB< 20.0 mm,
where fA is a focal length of the fixed-focus lens group and fB is a focal length of the variable-focus lens group.
15 . A camera module comprising:
a housing;
the optical imaging system of claim 14 disposed in the housing; and
an energy generator configured to supply energy to operate the variable-focus lens group.