Image picking-up system, image capturing apparatus and electronic device
An image picking-up system includes seven lens elements, which are, in order from an object side to an image side, a first lens group including a first lens element and a second lens element, a second lens group including a third lens element and a fourth lens element, and a third lens group including a fifth lens element, a sixth lens element and a seventh lens element. The third lens element has positive refractive power. The fourth lens element has an image-side surface being concave in a paraxial region thereof. At least one surface of object-side surfaces and image-side surfaces of the seven lens elements includes at least one inflection point.
1. An image picking-up system comprising seven lens elements, the seven 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 and a seventh lens element;
wherein each of the seven lens elements has an object-side surface facing towards the object side and an image-side surface facing towards the image side;
wherein the first lens element has negative refractive power; the image-side surface of the second lens element is concave in a paraxial region thereof; the third lens element has positive refractive power; the object-side surface of the seventh lens element is convex in a paraxial region thereof, and the image-side surface of the seventh lens element is concave in a paraxial region thereof and comprises at least one convex shape in an off-axis region thereof;
wherein a focal length of the image picking-up system is f, a focal length of the third lens element is f3, a maximum among refractive indices of all lens elements of the image picking-up system is Nmax, an f-number of the image picking-up system is Fno, and the following conditions are satisfied:
0.70< f/f 3<2.50;
1.639≤ N max<1.72; and
1.20< Fno< 2.60.
2. The image picking-up system of claim 1 , wherein the seventh lens element has negative refractive power.
3. The image picking-up system of claim 1 , wherein the object-side surface of the second lens element is convex in a paraxial region thereof.
4. The image picking-up system of claim 1 , wherein a number of the lens elements of the image picking-up system having an Abbe number smaller than 30 is Nv30, and the following condition is satisfied:
3≤ Nv 30.
5. The image picking-up system of claim 1 , wherein a maximum among axial distances between each of adjacent lens elements of the image picking-up system is ATmax, a minimum among central thicknesses of all lens elements of the image picking-up system is CTmin, and the following condition is satisfied:
0.40< AT max/CTmin≤3.16.
6. The image picking-up system of claim 1 , wherein the maximum among the refractive indices of all lens elements of the image picking-up system is Nmax, and the following condition is satisfied:
1.671≤ N max<1.72.
7. The image picking-up system of claim 1 , wherein an axial distance between the image-side surface of the seventh lens element and an image surface is BL, an axial distance between the object-side surface of the first lens element and the image surface is TL, an axial distance between the first lens element and the second lens element is T12, a minimum among central thicknesses of all lens elements of the image picking-up system is CTmin, and the following conditions are satisfied:
0.10< BL/TL< 0.35; and
T 12/CTmin<2.50.
8. The image picking-up system of claim 1 , wherein the f-number of the image picking-up system is Fno, and the following condition is satisfied:
1.20< Fno≤ 2.20.
9. The image picking-up system of claim 1 , wherein each of the seven lens elements is a non-cemented lens element; a vertical distance between a maximum effective radius position of the object-side surface of the first lens element and an optical axis is Y11, a vertical distance between a maximum effective radius position of the image-side surface of the seventh lens element and the optical axis is Y72, and the following condition is satisfied:
0.25< Y 11/ Y 72<1.30.
10. The image picking-up system of claim 1 , further comprising:
an aperture stop disposed between the second lens element and the third lens element.
11. The image picking-up system of claim 1 , wherein an axial distance between the object-side surface of the first lens element and an image surface is TL, the focal length of the image picking-up system is f, a curvature radius of the object-side surface of the seventh lens element is R13, a curvature radius of the image-side surface of the seventh lens element is R14, and the following conditions are satisfied:
0.80< TL/f< 2.50; and
0<( R 13+ R 14)/( R 13− R 14)<10.0.
12. An image capturing apparatus, comprising:
the image picking-up system of claim 1 ; and
an image sensor disposed on an image surface of the image picking-up system.
13. An electronic device, comprising:
the image capturing apparatus of claim 12 .
14. An image picking-up system comprising seven lens elements, the seven 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 and a seventh lens element;
wherein each of the seven lens elements has an object-side surface facing towards the object side and an image-side surface facing towards the image side;
wherein the third lens element has positive refractive power; the image-side surface of the fifth lens element is concave in a paraxial region thereof; the image-side surface of the seventh lens element is concave in a paraxial region thereof and comprises at least one convex shape in an off-axis region thereof;
wherein a focal length of the image picking-up system is f, a focal length of the third lens element is f3, a maximum among refractive indices of all lens elements of the image picking-up system is Nmax, an f-number of the image picking-up system is Fno, and the following conditions are satisfied:
0.70< f/f 3<2.50;
1.660≤ N max<1.72; and
1.20< Fno< 2.60.
15. The image picking-up system of claim 14 , wherein the first lens element has negative refractive power, and at least one of the object-side and the image-side surfaces of the first lens element comprises at least one Inflection point.
16. The image picking-up system of claim 14 , wherein the sixth lens element has positive refractive power; an axial distance between the first lens element and the second lens element is T12, a minimum among central thicknesses of all lens elements of the image picking-up system is CTmin, and the following condition is satisfied:
T 12/CTmin≤1.05.
17. The image picking-up system of claim 14 , wherein the f-number of the image picking-up system is Fno, and the following condition is satisfied:
1.20< Fno≤ 1.90.
18. The image picking-up system of claim 14 , wherein the maximum among the refractive indices of all lens elements of the image picking-up system is Nmax, and the following condition is satisfied:
1.671≤ N max<1.72.
19. The image picking-up system of claim 14 , wherein a half of a maximum field of view of the image picking-up system is HFOV, and the following condition is satisfied:
0.20<tan( H FOV)<1.50.
20. The image picking-up system of claim 14 , wherein the focal length of the image picking-up system is f, a focal length of the second lens element is f2, a focal length of the fourth lens element is f4, and the following conditions are satisfied:
−0.20< f/f 2<0.50; and
−2.80< f/f 4<−0.40.
21. The image picking-up system of claim 14 , wherein a sum of axial distances between each of adjacent lens elements of the image picking-up system is ΣAT, a sum of central thicknesses of all lens elements of the image picking-up system is ΣCT, a maximum among the central thicknesses of all lens elements of the image picking-up system is CTmax, a vertical distance between a critical point in the off-axis region on the image-side surface of the seventh lens element and an optical axis is Yc72, and the following conditions are satisfied:
Σ AT /ΣCT<0.75; and
0.20<CTmax/ Yc 72<4.0.
22. The image picking-up system of claim 14 , further comprising:
an aperture stop disposed on an object side of the fourth lens element, wherein an axial distance between the object-side surface of the first lens element and an image surface is TL, a maximum image height of the image picking-up system is ImgH, an axial distance between the aperture stop and the image-side surface of the seventh lens element is SD, an axial distance between the object-side surface of the first lens element and the image-side surface of the seventh lens element is TD, and the following conditions are satisfied:
1.0< TL /Img H≤ 2.0; and
0.50< SD/TD< 1.20.