Imaging lens system
An imaging lens system includes: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens, sequentially disposed from an object side. The third lens has a refractive index temperature coefficient of 2.2 to 3.5 [10 −6 /° C.], and 0<f34*0.8<f, where f is a focal length of the imaging lens system and f34 is a composite focal length of the third lens and the fourth lens.
1 . An imaging lens system, comprising:
a first lens having a convex object-side surface, a second lens having a convex image-side surface, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens, sequentially disposed from an object side,
wherein the imaging lens system has a total number of seven lenses with refractive power,
wherein the third lens has a refractive index temperature coefficient of 2.2 to 3.5 [10-6/° C.],
wherein 0<f34*0.8<f and 20<V1/Nd1<30, where f is a focal length of the imaging lens system, f34 is a composite focal length of the third lens and the fourth lens, V1 is an Abbe number of the first lens, and Nd 1 is a refractive index of the first lens,
wherein a thickness of the third lens is greater than a thickness of fourth lens, and
wherein an absolute value of a radius of curvature of the object-side surface of the first lens is greater than an absolute value of a radius of curvature of an object-side surface of the third lens.
2 . The imaging lens system of claim 1 , wherein the first lens, the second lens, and the third lens are formed of a material different from a material of the fourth lens, the fifth lens, the sixth lens, and the seventh lens.
3 . The imaging lens system of claim 1 , wherein
35 <V 2 /Nd 2<45,
where V2 is an Abbe number of the second lens, and Nd2 is a refractive index of the second lens.
4 . The imaging lens system of claim 1 , wherein
20 <V 3 /Nd 3<30,
where V3 is an Abbe number of the third lens, and Nd3 is a refractive index of the third lens.
5 . The imaging lens system of claim 1 , wherein
10 <V 5 /Nd 5<20,
where V5 is an Abbe number of the fifth lens, and Nd5 is a refractive index of the fifth lens.
6 . The imaging lens system of claim 1 , wherein
30 <V 6 /Nd 6<40,
where V6 is an Abbe number of the sixth lens, and Nd6 is a refractive index of the sixth lens.
7 . The imaging lens system of claim 1 , wherein
27 <V min 13 /Nd min 13<37,
where V min 13 is a minimum value among Abbe numbers of the first lens, the second lens, and the third lens, and Nd min 13 is a minimum value among refractive indices of the first lens, the second lens, and the third lens.
8 . The imaging lens system of claim 1 , wherein
30 <V max 47 /Nd max 47<35,
where V max 47 is a maximum value among Abbe numbers of the fourth lens, the fifth lens, the sixth lens, and the seventh lens, and Nd max 47 is a maximum value among refractive indices of the fourth lens, the fifth lens, the sixth lens, and the seventh lens.
9 . The imaging lens system of claim 1 , wherein
0.4 <f/f 3<0.9,
where f3 is a focal length of the third lens.