Photographing optical lens assembly, image capturing unit and electronic device
A photographing optical lens assembly includes, in order from an object to an image side, a first lens group, a second lens group and a third lens group. The first lens group includes a first lens element and a second lens element. The second lens group includes a third lens element, a fourth lens element and a fifth lens element. The third lens group includes a sixth lens element, a seventh lens element and an eighth lens element. The first lens element has positive refractive power. The seventh lens element has an object-side surface and an image-side surface being both aspheric. The eighth lens element has an image-side surface being concave in a paraxial region thereof, wherein both an object-side surface and the image-side surface thereof are aspheric, and the image-side surface of the eighth lens element has at least one inflection point.
1. A photographing optical lens assembly comprising eight lens elements, the eight lens elements being, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element, a sixth lens element, a seventh lens element and an eighth lens element, and each of the eight lens elements having an object-side surface facing toward the object side and an image-side surface facing toward the image side;
wherein a total number of lens elements in the photographing optical lens assembly is eight, the first lens element has positive refractive power, at least one of the object-side surface and the image-side surface of the sixth lens element is aspheric, the image-side surface of the eighth lens element is concave in a paraxial region thereof, the image-side surface of the eighth lens element is aspheric and has at least one inflection point, and there is an air gap in a paraxial region between each of all adjacent lens elements of the photographing optical lens assembly;
wherein a focal length of the photographing optical lens assembly is f, an entrance pupil diameter of the photographing optical lens assembly is EPD, a maximum value among refractive indexes of all lens elements of the photographing optical lens assembly is Nmax, and the following conditions are satisfied:
f
/
EPD
<
2.6
;
and
1.55
<
Nmax
<
1.7
.
2. The photographing optical lens assembly of claim 1 , wherein the object-side surface of the second lens element is convex in a paraxial region thereof, the image-side surface of the second lens element is concave in a paraxial region thereof, the object-side surface and the image-side surface of the seventh lens element are both aspheric, and the object-side surface of the eighth lens element is aspheric.
3. The photographing optical lens assembly of claim 1 , wherein the object-side surface of the eighth lens element is convex in a paraxial region thereof.
4. The photographing optical lens assembly of claim 1 , wherein the seventh lens element has positive refractive power, and the image-side surface of the seventh lens element is convex in a paraxial region thereof.
5. The photographing optical lens assembly of claim 1 , wherein the eighth lens element has negative refractive power; an axial distance between the object-side surface of the first lens element and an image surface is TL, and the following condition is satisfied:
T
L
<
1
2
.
0
millimeters
.
6. The photographing optical lens assembly of claim 1 , wherein the sixth lens element has negative refractive power, the seventh lens element is made of plastic material, and the eighth lens element is made of plastic material.
7. The photographing optical lens assembly of claim 1 , wherein half of a maximal field of view of the photographing optical lens assembly is HFOV, and the following condition is satisfied:
30.
<
degrees
<
H
F
O
V
<
50.
degrees
.
8. The photographing optical lens assembly of claim 1 , wherein a curvature radius of the image-side surface of the eighth lens element is R16, and the following condition is satisfied:
1
.
0
<
f
/
R
16
<
4
.
5
.
9. The photographing optical lens assembly of claim 1 , wherein a focal length of the seventh lens element is f7, and the following condition is satisfied:
0
.
7
4
≤
f
/
f
7
≤
1
.
7
8
.
10. The photographing optical lens assembly of claim 1 , wherein a central thickness of the third lens element is CT3, a central thickness of the fourth lens element is CT4, and the following condition is satisfied:
0
.
2
3
≤
C
T
3
/
C
T
4
≤
1
.
3
5
.
11. The photographing optical lens assembly of claim 1 , wherein an axial distance between the second lens element and the third lens element is T23, an axial distance between the fifth lens element and the sixth lens element is T56, and the following condition is satisfied:
1
.
4
6
≤
T
23
/
T
56
≤
4.93
.
12. The photographing optical lens assembly of claim 1 , wherein a sum of axial distances between each of all adjacent lens elements of the photographing optical lens assembly is ΣAT, an axial distance between the image-side surface of the eighth lens element and an image surface is BL, a sum of central thicknesses of all lens elements of the photographing optical lens assembly is ΣCT, and the following condition is satisfied:
(
∑
AT
+
BL
)
/
∑
C
T
<
0.8
.
13. The photographing optical lens assembly of claim 1 , wherein a curvature radius of the object-side surface of the eighth lens element is R15, a curvature radius of the image-side surface of the eighth lens element is R16, and the following conditions are satisfied:
f
/
E
P
D
≤
1.95
;
and
-
0.5
<
(
R
15
-
R
16
)
/
(
R
15
+
R
1
6
)
<
2
.
5
.
14. The photographing optical lens assembly of claim 1 , wherein an Abbe number of the first lens element is V1, an Abbe number of the second lens element is V2, an Abbe number of the sixth lens element is V6, and the following condition is satisfied:
(
V
2
+
V
6
)
/
V
1
<
1
.
0
.
15. The photographing optical lens assembly of claim 1 , wherein at least one of the object-side surface and the image-side surface of the seventh lens element has at least one non-axial critical point; a vertical distance between the at least one non-axial critical point and an optical axis is Yc7, and the following condition is satisfied:
0
.
1
0
<
Yc
7
/
f
<
0
.
6
0
.