CN114415339B

CN114415339B - Optical system for image pickup

Info

Publication number: CN114415339B
Application number: CN202210132211.5A
Authority: CN
Inventors: 陈俊谚; 叶冠廷; 郭子杰
Original assignee: Largan Precision Co Ltd
Current assignee: Largan Precision Co Ltd
Priority date: 2019-11-27
Filing date: 2019-11-27
Publication date: 2023-02-28
Anticipated expiration: 2039-11-27
Also published as: CN114415352A; CN112859287B; CN114415344A; CN114415339A; CN112859287A; CN114415352B; CN114415344B

Abstract

The invention discloses an optical system for shooting, which comprises eight lenses, wherein the eight lenses are a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens from an object side to an image side in sequence. The eight lenses respectively have object side surfaces facing the object side direction and image side surfaces facing the image side direction. The first lens element has positive refractive power. The second lens element has a convex object-side surface at a paraxial region. The fifth lens element with positive refractive power. The seventh lens element has a convex object-side surface at a paraxial region. The image-side surface of the eighth lens element is concave at a paraxial region. At least one surface of at least one lens in the image pickup optical system has at least one critical point at the off-axis position. When specific conditions are satisfied, the optical system for image pickup can satisfy both the demands for miniaturization and high image quality.

Description

Optical system for image pickup

The application is a divisional application, and the application date of the original application is as follows: 11 month 27 in 2019; the application numbers are: 201911183015.5; the invention has the name: an optical system for shooting, an image capturing device and an electronic device.

Technical Field

The present invention relates to an optical system for image pickup, and more particularly to an optical system for image pickup which can satisfy both the demands for miniaturization and high image quality.

Background

As the performance of the electronic photosensitive device is improved with the advance of semiconductor technology, the pixel can reach a smaller size, and thus, the optical lens with high imaging quality is an indispensable factor.

With the technology, the application range of the electronic device equipped with the optical lens is wider, and the requirements for the optical lens are more diversified. Since the optical lens of the previous optical lens is not easy to balance the requirements of imaging quality, sensitivity, aperture size, volume or visual angle, the present invention provides an optical lens to meet the requirements.

Disclosure of Invention

The invention provides an optical system for image pickup. The imaging optical system includes eight lenses. When specific conditions are met, the optical system for shooting provided by the invention can meet the requirements of miniaturization and high imaging quality at the same time.

The invention provides an optical system for image pickup, comprising eight lenses. The eight lens elements are, 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. The eight lenses respectively have object side surfaces facing the object side direction and image side surfaces facing the image side direction. The first lens element has positive refractive power. The second lens element has a convex object-side surface at a paraxial region. The fifth lens element with positive refractive power. The seventh lens element has a convex object-side surface at a paraxial region. The eighth lens element has a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region. At least one surface of at least one lens in the image pickup optical system has at least one critical point at the off-axis position. An abbe number of the second lens element is V2, a curvature radius of the object-side surface of the second lens element is R3, a focal length of the image pickup optical system is f, a focal length of the first lens element is f1, a focal length of the fifth lens element is f5, a focal length of the seventh lens element is f7, and a focal length of the eighth lens element is f8, which satisfy the following conditions:

10.0<V2<50.0；

0<R3/f<2.0；

0-and-f 5/f1<9.5; and

-7.5<f8/f7<-0.55。

the invention also provides an optical system for shooting, which comprises eight lenses. The eight lenses are, 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. The eight lenses respectively have object side surfaces facing the object side direction and image side surfaces facing the image side direction. The first lens element has positive refractive power. The second lens element has a convex object-side surface at a paraxial region. The fifth lens element with positive refractive power. The seventh lens element has a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region. The image-side surface of the eighth lens element is concave at a paraxial region. At least one surface of at least one lens in the image pickup optical system has at least one critical point at the off-axis position. An abbe number of the second lens element is V2, a curvature radius of an object-side surface of the second lens element is R3, a focal length of the image pickup optical system is f, a focal length of the first lens element is f1, a focal length of the second lens element is f2, a focal length of the third lens element is f3, a focal length of the fifth lens element is f5, a focal length of the seventh lens element is f7, a focal length of the eighth lens element is f8, and a composite focal length of the first lens element and the second lens element is f12, which satisfies the following conditions:

10.0<V2<50.0；

0<R3/f<2.0；

0<f5/f1<9.5；

-7.5<f8/f7<-0.55；

l f/f2| + | f/f3| <0.70; and

0.35<f/f12<0.75。

when V2 satisfies the above condition, the material of the second lens element can be adjusted to help correct aberrations such as chromatic aberration.

When R3/f satisfies the above condition, the surface shape and refractive power of the second lens element can be adjusted to correct the aberration.

When f5/f1 satisfies the above condition, the refractive power distribution of the imaging optical system can be adjusted to compress the volume and adjust the volume distribution.

When f8/f7 satisfies the above condition, the refractive powers of the seventh lens element and the eighth lens element can be matched with each other to correct aberrations such as spherical aberration.

When the | f/f2| + | f/f3| satisfies the above condition, the refractive powers of the second lens element and the third lens element are matched to correct the aberration.

When f/f12 satisfies the above condition, the first lens and the second lens can be made to cooperate with each other, contributing to the compression of the object-side end volume of the optical system for image pickup.

The above description of the present invention and the following description of the embodiments are provided to illustrate and explain the spirit and principles of the present invention and to provide further explanation of the invention as claimed in the appended claims.

Drawings

Fig. 1 is a schematic view illustrating an image capturing device according to a first embodiment of the invention.

Fig. 2 is a graph of spherical aberration, astigmatism and distortion in the first embodiment from left to right.

FIG. 3 is a schematic view of an image capturing apparatus according to a second embodiment of the invention.

Fig. 4 is a graph of spherical aberration, astigmatism and distortion of the second embodiment, from left to right.

Fig. 5 is a schematic view illustrating an image capturing apparatus according to a third embodiment of the invention.

Fig. 6 is a graph of spherical aberration, astigmatism and distortion of the third embodiment from left to right.

Fig. 7 is a schematic view of an image capturing apparatus according to a fourth embodiment of the invention.

Fig. 8 is a graph of spherical aberration, astigmatism and distortion in the fourth embodiment from left to right.

Fig. 9 is a schematic view illustrating an image capturing apparatus according to a fifth embodiment of the invention.

Fig. 10 is a graph of spherical aberration, astigmatism and distortion in the fifth embodiment from left to right.

Fig. 11 is a schematic view of an image capturing apparatus according to a sixth embodiment of the invention.

Fig. 12 is a graph showing the spherical aberration, astigmatism and distortion of the sixth embodiment in order from left to right.

Fig. 13 is a schematic view of an image capturing apparatus according to a seventh embodiment of the invention.

Fig. 14 is a graph showing the spherical aberration, astigmatism and distortion in order from left to right in the seventh embodiment.

Fig. 15 is a schematic view illustrating an image capturing apparatus according to an eighth embodiment of the invention.

Fig. 16 is a graph showing the spherical aberration, astigmatism and distortion of the eighth embodiment from left to right.

Fig. 17 is a schematic view illustrating an image capturing apparatus according to a ninth embodiment of the invention.

Fig. 18 is a graph showing the spherical aberration, astigmatism and distortion of the ninth embodiment in the order from left to right.

Fig. 19 is a schematic view of an image capturing apparatus according to a tenth embodiment of the invention.

Fig. 20 is a graph showing the spherical aberration, astigmatism and distortion curves of the tenth embodiment from left to right.

Fig. 21 is a perspective view of an image capturing apparatus according to an eleventh embodiment of the invention.

Fig. 22 is a perspective view illustrating a side of an electronic device according to a twelfth embodiment of the invention.

Fig. 23 is a perspective view of the other side of the electronic device of fig. 22.

FIG. 24 is a system block diagram of the electronic device of FIG. 22.

FIG. 25 is a diagram illustrating parameters Y11, Y82, yc71, yc72, yc82 and inflection points and critical points of each lens according to the first embodiment of the present invention.

Wherein, the reference numbers:

10. 10a, 10b: image capturing device

11: imaging lens

12: drive device

13: electronic photosensitive element

14: image stabilization module

20: electronic device

21: flash lamp module

22: focusing auxiliary module

23: image signal processor

24: user interface

25: image software processor

26: subject matter

P: point of inflection

C: critical point of

100. 200, 300, 400, 500, 600, 700, 800, 900, 1000: aperture

101. 201, 202, 301, 401, 402, 501, 502, 601, 602, 701, 801, 901, 902, 1001: diaphragm

110. 210, 310, 410, 510, 610, 710, 810, 910, 1010: first lens

111. 211, 311, 411, 511, 611, 711, 811, 911, 1011: object side surface

112. 212, 312, 412, 512, 612, 712, 812, 912, 1012: surface of image side

120. 220, 320, 420, 520, 620, 720, 820, 920, 1020: second lens

121. 221, 321, 421, 521, 621, 721, 821, 921, 1021: object side surface

122. 222, 322, 422, 522, 622, 722, 822, 922, 1022: surface of image side

130. 230, 330, 430, 530, 630, 730, 830, 930, 1030: third lens

131. 231, 331, 431, 531, 631, 731, 831, 931, 1031: object side surface

132. 232, 332, 432, 532, 632, 732, 832, 932, 1032: surface of image side

140. 240, 340, 440, 540, 640, 740, 840, 940, 1040: fourth lens

141. 241, 341, 441, 541, 641, 741, 841, 941, 1041: object side surface

142. 242, 342, 442, 542, 642, 742, 842, 942, 1042: surface of image side

150. 250, 350, 450, 550, 650, 750, 850, 950, 1050: fifth lens element

151. 251, 351, 451, 551, 651, 751, 851, 951, 1051: object side surface

152. 252, 352, 452, 552, 652, 752, 852, 952, 1052: surface of image side

160. 260, 360, 460, 560, 660, 760, 860, 960, 1060: sixth lens element

161. 261, 361, 461, 561, 661, 761, 861, 961, 1061: object side surface

162. 262, 362, 462, 562, 662, 762, 862, 962, 1062: surface of image side

170. 270, 370, 470, 570, 670, 770, 870, 970, 1070: seventh lens element

171. 271, 371, 471, 571, 671, 771, 871, 971, 1071: object side surface

172. 272, 372, 472, 572, 672, 772, 872, 972, 1072: surface of image side

180. 280, 380, 480, 580, 680, 780, 880, 980, 1080: eighth lens element

181. 281, 381, 481, 581, 681, 781, 881, 981, 1081: object side surface

182. 282, 382, 482, 582, 682, 782, 882, 982, 1082: surface of image side

190. 290, 390, 490, 590, 690, 790, 890, 990, 1090: light filtering element

195. 295, 395, 495, 595, 695, 795, 895, 995, 1095: image plane

199. 299, 399, 499, 599, 699, 799, 899, 999, 1099: electronic photosensitive element

Y11: maximum effective radius of the object-side surface of the first lens

Y82: maximum effective radius of image-side surface of the eighth lens element

Yc71: perpendicular distance between critical point of object-side surface of seventh lens and optical axis

Yc72: the vertical distance between the optical axis and the critical point on the image-side surface of the seventh lens element

Yc82: the vertical distance between the optical axis and the critical point on the image-side surface of the eighth lens element

Detailed Description

The detailed features and advantages of the invention are described in detail in the embodiments below, which are sufficient for anyone skilled in the art to understand the technical contents of the invention and implement the invention, and the objects and advantages related to the invention can be easily understood by anyone skilled in the art from the disclosure of the present specification, the scope of protection of the claims and the accompanying drawings. The following examples further illustrate aspects of the present invention in detail, but are not intended to limit the scope of the invention in any way.

The imaging optical system comprises eight lenses, wherein the eight lenses are a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens in sequence from an object side to an image side. The eight lenses respectively have object side surfaces facing the object side direction and image side surfaces facing the image side direction.

The first lens element with positive refractive power; this contributes to the reduction in the volume of the imaging optical system. The first lens element has an object-side surface being convex at a paraxial region; therefore, light rays of each view field can uniformly enter the optical system for shooting, and the peripheral relative illumination of the imaging surface is favorably improved.

The object-side surface of the second lens element may be convex at a paraxial region; therefore, the lens can be matched with the first lens to correct the aberration. The image-side surface of the second lens element can be concave at a paraxial region; this helps correct aberrations such as astigmatism.

The fifth lens element with positive refractive power; this contributes to the reduction in the volume of the imaging optical system.

The seventh lens element with positive refractive power; therefore, the positive refractive power distribution can be dispersed, and the sensitivity of each lens can be reduced when the volume is compressed. The seventh lens element has a convex object-side surface at a paraxial region; therefore, the refractive power of the seventh lens element can be adjusted, and off-axis aberration can be corrected.

The eighth lens element with negative refractive power; therefore, the refractive power distribution at the image side end of the optical system for shooting can be balanced, and the aberration such as spherical aberration and the like can be reduced. The image side surface of the eighth lens element is concave at a paraxial region; therefore, the length of the back focal length can be adjusted, and off-axis aberration such as image bending and the like can be corrected.

In the disclosed optical system for image pickup, at least one of the object-side surface and the image-side surface of at least one lens has at least one critical point at an off-axis position; therefore, the variation degree of the lens surface can be improved, and off-axis aberration correction and peripheral illumination improvement of an imaging surface are facilitated. In the imaging optical system, at least two lenses may have at least one critical point on at least one of the object-side surface and the image-side surface thereof at an off-axis position. In the imaging optical system, each of the at least three lenses may have at least one critical point on at least one of the object-side surface and the image-side surface at an off-axis position. At least one of the object-side surface and the image-side surface of the sixth lens element may have at least one critical point at an off-axis position; this contributes to adjustment of the image-side end volume distribution of the imaging optical system. The object-side surface of the seventh lens element may have at least one critical point at the off-axis position; therefore, the incident angle of the light on the seventh lens can be adjusted, and the generation of stray light is reduced. The image-side surface of the seventh lens element can have at least one critical point at the off-axis position; therefore, the optical lens can be matched with the eighth lens to further correct off-axis aberration. Wherein a vertical distance between a critical point of the object-side surface of the seventh lens element and the optical axis is Yc71, a vertical distance between a critical point of the image-side surface of the seventh lens element and the optical axis is Yc72, and at least one of an off-axis critical point of the object-side surface of the seventh lens element and an off-axis critical point of the image-side surface of the seventh lens element satisfies the following conditions: 0.80-straw Yc72/Yc71<1.5; therefore, the surface shape of the seventh lens can be adjusted to further correct off-axis aberration. Wherein at least one of the off-axis critical point of the object-side surface of the seventh lens element and the off-axis critical point of the image-side surface of the seventh lens element can also satisfy the following condition: 0.90-Ap Yc72/Yc71<1.4. The image-side surface of the eighth lens element can have at least one critical point at the off-axis position; therefore, the off-axis aberration can be corrected, and the incident angle of the light on the imaging surface can be adjusted, so that the illumination of the imaging surface and the response efficiency of the electronic photosensitive element are improved. Wherein, a vertical distance between a critical point of the image-side surface of the eighth lens element and the optical axis is Yc82, a maximum effective radius of the image-side surface of the eighth lens element is Y82, and at least one critical point of the image-side surface of the eighth lens element at the off-axis position can satisfy the following condition: 0.20 yarn of Yc82/Y82<0.60; therefore, the surface shape of the eighth lens can be adjusted to further improve the imaging quality. At least one critical point of the image-side surface of the eighth lens element at the off-axis position may also satisfy the following condition: 0.30 and are < -Yc82/Y82 <0.50. Referring to fig. 25, a schematic diagram of a critical point C and parameters Yc71, yc72, yc82, and Y82 of the third lens element 130, the fourth lens element 140, the sixth lens element 160, the seventh lens element 170, and the eighth lens element 180 according to the first embodiment of the invention is shown.

In the disclosed optical system for image pickup, each of the at least three lenses may have at least one inflection point on at least one of an object-side surface and an image-side surface thereof; therefore, the lens surface variation degree can be improved, and the aberration and the compression volume can be corrected. In the imaging optical system, each of the at least four lenses may have at least one inflection point on at least one of the object-side surface and the image-side surface. In the imaging optical system, each of the at least five lenses may have at least one inflection point on at least one of an object-side surface and an image-side surface thereof. Wherein, all lenses in the optical system for image pickup have at least one inflection point on the object side surface and the image side surface; therefore, the lens surface variation degree can be further improved so as to correct the aberration and the compression volume. Referring to FIG. 25, a schematic diagram of an inflection point P of each lens according to the first embodiment of the invention is shown.

The distance between the seventh lens element and the eighth lens element on the optical axis may be the largest distance between two adjacent lens elements on the optical axis in the imaging optical system. Therefore, the distribution of the lens can be adjusted, and the area of an imaging surface can be increased and off-axis aberration can be corrected. In the present invention, the distance between two adjacent lenses on the optical axis refers to the distance between two adjacent mirror surfaces of two adjacent lenses on the optical axis.

The abbe number of the second lens is V2, which satisfies the following condition: 10.0-V2-woven fabric(s) are 50.0. Therefore, the material of the second lens can be adjusted, and aberration such as chromatic aberration and the like can be corrected. Wherein the following conditions may also be satisfied: 11.0-V2-woven fabric (40.0). Wherein the following conditions may also be satisfied: 12.0-V2-woven fabric (30.0). Wherein the following conditions are also satisfied: 13.0-V2-woven fabric 25.0.

The focal length of the first lens is f1, and the focal length of the fifth lens is f5, which satisfies the following conditions: 0-woven fabric f5/f1; or f5/f1<9.5. Therefore, the refractive power distribution of the optical system for shooting can be adjusted to compress the volume and adjust the volume distribution. Wherein the following conditions may also be satisfied: 0.10 were woven fabric of f5/f1. Wherein the following conditions may also be satisfied: 0.30< -f5/f 1. Wherein the following conditions may also be satisfied: 0.50 were woven so as to have f5/f1. Wherein the following conditions may also be satisfied: f5/f1<5.0. Wherein the following conditions may also be satisfied: f5/f1<3.0. Wherein the following conditions may also be satisfied: f5/f1<2.0. Wherein the following conditions may also be satisfied: 0 s/f 1<9.5. Wherein the following conditions may also be satisfied: 0< -f5/f 1<3.0. Wherein the following conditions may also be satisfied: 0.10 sP 5/f1<5.0. Wherein the following conditions may also be satisfied: 0.30 were woven so as to have f5/f1<2.0.

The thickness of the fifth lens element on the optical axis is CT5, and the thickness of the seventh lens element on the optical axis is CT7, which satisfy the following conditions: 0.10-straw CT7/CT5<1.3. Therefore, the distribution of the image side end lenses of the image pickup optical system can be adjusted, and the image side end volume can be compressed. Wherein the following conditions are also satisfied: 0.20 and are (CT7/CT 5) less than 1.0. Wherein the following conditions may also be satisfied: 0.40-straw CT7/CT5<0.70.

The thickness of the second lens element along the optical axis is CT2, and the thickness of the third lens element along the optical axis is CT3, which satisfy the following conditions: 0.10-straw CT3/CT2<1.5. Therefore, the second lens and the third lens can be matched with each other, and the compression of the object side end volume of the optical system for image pickup is facilitated. Wherein the following conditions are also satisfied: 0.60-straw CT3/CT2<1.5. Wherein the following conditions are also satisfied: 0.80-straw CT3/CT2<1.5.

The focal length of the seventh lens is f7, and the focal length of the eighth lens is f8, which satisfies the following conditions: -7.5 sj 8/f7< -0.55. Therefore, the refractive powers of the seventh lens element and the eighth lens element can be matched with each other to correct aberrations such as spherical aberration. Wherein the following conditions may also be satisfied: -4.0 and sj 8/f7< -0.60. Wherein the following conditions may also be satisfied: -1.5 sj f8/f7< -0.65.

The second lens element has a curvature radius of the object-side surface of R3 and a focal length of the image-capturing optical system of f, and satisfies the following conditions: 0< -R3/f <2.0. Therefore, the surface shape and the refractive power of the second lens element can be adjusted to correct the aberration. Wherein the following conditions may also be satisfied: 0.15 sP R3/f <1.4. Wherein the following conditions may also be satisfied: 0.30 sP R3/f <0.90.

The thickness of the third lens element along the optical axis is CT3, and the thickness of the fifth lens element along the optical axis is CT5, which satisfy the following conditions: 1.0 yarn of CT5/CT3; or CT5/CT3<10. Therefore, the third lens and the fifth lens can be matched with each other, and the volume distribution of the object side end and the image side end of the optical system for image pickup is balanced. Wherein the following conditions may also be satisfied: 1.5 sP CT5/CT3. Wherein the following conditions are also satisfied: 1.8 sP CT5/CT3. Wherein the following conditions may also be satisfied: 2.0 sP CT5/CT3. Wherein the following conditions may also be satisfied: 2.2 were woven into CT5/CT3. Wherein the following conditions may also be satisfied: CT5/CT3<5.0. Wherein the following conditions may also be satisfied: CT5/CT3<4.5. Wherein the following conditions may also be satisfied: 1.0 sP CT5/CT3<5.0. Wherein the following conditions may also be satisfied: 2.0 sP CT5/CT3<5.0.

The abbe number of the second lens is V2, the abbe number of the third lens is V3, and the abbe number of the fourth lens is V4, which satisfies the following conditions: 30.0 TsV2 + V3+ V4 Ts120.0. Therefore, the materials of the second lens, the third lens and the fourth lens can be matched with each other to further correct chromatic aberration. Wherein the following conditions may also be satisfied: 35.0 yarn formed from Tp V2+ V3+ V4 yarn formed from Tp and Tp 110.0. Wherein the following conditions may also be satisfied: 40.0 yarn of Tp V2+ V3+ V4 yarn of Tp 100.0.

The abbe number of the first lens is V1, the abbe number of the second lens is V2, the abbe number of the third lens is V3, the abbe number of the fourth lens is V4, the abbe number of the fifth lens is V5, the abbe number of the sixth lens is V6, the abbe number of the seventh lens is V7, the abbe number of the eighth lens is V8, the abbe number of the ith lens is Vi, the refractive index of the first lens is N1, the refractive index of the second lens is N2, the refractive index of the third lens is N3, the refractive index of the fourth lens is N4, the refractive index of the fifth lens is N5, the refractive index of the sixth lens is N6, the refractive index of the seventh lens is N7, the refractive index of the eighth lens is N8, the refractive index of the ith lens is Ni, the minimum value of Vi/Ni is (Vi/Ni) min, which can satisfy the following conditions: 6.0< (Vi/Ni) min <12.0, wherein i =1, 2, 3, 4, 5, 6, 7 or 8. Therefore, the material distribution of the optical system for shooting can be adjusted, and the aberration and the compression volume can be corrected.

A radius of curvature of the object-side surface of the fifth lens element is R9, and a radius of curvature of the image-side surface of the fifth lens element is R10, which satisfy the following condition: -1.5< (R9 + R10)/(R9-R10) <1.5. Therefore, the surface shape of the fifth lens can be adjusted to control the light traveling direction, and balance among the visual angle, the volume and the size of the imaging surface is facilitated. Wherein the following conditions may also be satisfied: -1.1< (R9 + R10)/(R9-R10) <1.1.

An axial distance TD between the object-side surface of the first lens element and the image-side surface of the eighth lens element, and an axial thickness CT5 of the fifth lens element satisfy the following condition: 3.0 sP TD/CT5<7.0. This makes it possible to adjust the lens distribution and contribute to the overall length of the imaging optical system.

The focal length of the image pickup optical system is f, the focal length of the second lens is f2, and the focal length of the third lens is f3, which satisfies the following conditions: l f/f2| + | f/f3| <0.70. Therefore, the refractive powers of the second lens element and the third lens element can be matched with each other to correct the aberration.

The focal length of the image pickup optical system is f, and the combined focal length of the first lens and the second lens is f12, which satisfies the following conditions: 0.35-plus f/f12<0.75. Therefore, the first lens and the second lens can be matched with each other, and the compression of the object side end volume of the optical system for image pickup is facilitated.

Half of the maximum viewing angle in an optical system for image pickup is HFOV, which can satisfy the following conditions: 30.0[ degree ] < HFOV <50.0[ degree ]. Therefore, the optical system for shooting has the characteristic of wide visual angle, and can avoid the distortion caused by overlarge visual angle. Wherein the following conditions may also be satisfied: 35.0[ degrees ] < HFOV <45.0[ degrees ].

The abbe number of the second lens is V2, the refractive index of the second lens is N2, and the following conditions can be satisfied: 6.0 are constructed V2/N2<15.0. Therefore, the material of the second lens can be adjusted to correct aberration such as chromatic aberration.

The abbe number of the sixth lens is V6, which satisfies the following condition: 15.0-V6-woven fabric(s) are 50.0. Therefore, the material of the sixth lens can be adjusted to correct chromatic aberration.

The thickness of the first lens element on the optical axis is CT1, and the thickness of the fifth lens element on the optical axis is CT5, which satisfy the following conditions: 1.1-straw CT5/CT1<2.0. Thereby, the lens distribution can be adjusted, which helps to compress the volume. Wherein the following conditions may also be satisfied: 1.2-straw CT5/CT1<1.8.

An axial distance TD between the object-side surface of the first lens element and the image-side surface of the eighth lens element, and a focal length f2 of the second lens element satisfy the following conditions: -1.0 sTD/f 2<0.80. Therefore, the lens is beneficial to adjusting the lens and the refractive power distribution so as to compress the volume and correct the aberration. Wherein the following conditions may also be satisfied: -0.60 and Tds/f 2<0.60.

The focal length of the image pickup optical system is f, the focal length of the second lens is f2, the focal length of the third lens is f3, and the focal length of the fourth lens is f4, and the following conditions are satisfied: -0.90 sj/f 2+ f/f3+ f/f4<0.20. Therefore, the refractive powers of the second lens element, the third lens element and the fourth lens element can be matched with each other to correct the aberration.

The focal length of the fifth lens element is f5, and the thickness of the fifth lens element on the optical axis is CT5, which satisfies the following condition: 1.0 sP 5/CT5<30. Therefore, the refractive power of the fifth lens element can be adjusted to compress the volume. Wherein the following conditions are also satisfied: 2.0 sP 5/CT5<20. Wherein the following conditions may also be satisfied: 3.0 sP 5/CT5<10.

The aperture value (F-number) of the imaging optical system is Fno, which satisfies the following condition: 1.0-Fno-2.2. Therefore, the balance between the aperture size and the depth of field can be obtained. Wherein the following conditions are also satisfied: 1.2-Fno-1.8.

The maximum effective radius of the object-side surface of the first lens element is Y11, and the maximum effective radius of the image-side surface of the eighth lens element is Y82, which satisfy the following conditions: 1.8 are constructed Y82/Y11<3.0. Therefore, the outer diameters of the object side end and the image side end of the shooting optical system can be adjusted, and the balance among the visual angle, the volume and the size of an imaging surface can be favorably achieved. Referring to fig. 25, a schematic diagram of parameters Y11 and Y82 according to the first embodiment of the invention is shown.

The radius of curvature of the object-side surface of the first lens element is R1, and the radius of curvature of the image-side surface of the first lens element is R2, which satisfy the following conditions: -0.60 sR1/R2 <0.80. Therefore, the surface shape of the first lens can be adjusted, and the light traveling direction can be adjusted to form wide-angle configuration. Wherein the following conditions may also be satisfied: -0.30 sR1/R2 <0.70.

A focal length of the imaging optical system is f, a radius of curvature of the object-side surface of the sixth lens element is R11, and a radius of curvature of the image-side surface of the sixth lens element is R12, which satisfy the following conditions: 2.5 are woven as f/| R11| + f/| R12| <7.5. Therefore, the surface shape and the refractive power of the sixth lens element can be adjusted, which is helpful for correcting aberration by matching with the fifth lens element.

The abbe number of the second lens is V2, and the abbe number of the fourth lens is V4, which satisfies the following conditions: 20.0 TsV2 + V4 are woven into 65.0. Therefore, the materials of the second lens and the fourth lens can be matched with each other to further correct chromatic aberration. Wherein the following conditions may also be satisfied: 25.0 TsV2 + V4 are woven into 50.0.

The thickness of the first lens element on the optical axis is CT1, the thickness of the second lens element on the optical axis is CT2, the thickness of the third lens element on the optical axis is CT3, the thickness of the fourth lens element on the optical axis is CT4, and the thickness of the fifth lens element on the optical axis is CT5, which satisfy the following conditions: 0.10< (CT 2+ CT3+ CT 4)/(CT 1+ CT 5) <1.0. Thereby, the lens distribution can be adjusted to compress the volume of the optical system for image pickup. Wherein the following conditions may also be satisfied: 0.20< (CT 2+ CT3+ CT 4)/(CT 1+ CT 5) <0.75.

In the imaging optical system, the sum of the thicknesses of the lenses on the optical axis is Σ CT, and the thickness of the fifth lens on the optical axis is CT5, which satisfies the following conditions: 2.5< Σ CT/CT5<6.0. Thus, the lens distribution can be adjusted to compress the volume of the optical system for image pickup, and the wide-angle arrangement can be facilitated. Wherein the following conditions are also satisfied: 3.0< Σ CT/CT5<5.0.

The distance TL from the object-side surface of the first lens element to the image plane on the optical axis satisfies the following condition: 3.0[ mm ] < TL <15.0[ mm ]. Therefore, the optical system for image pickup can have a proper length to fit various applications.

The distance TL from the object-side surface of the first lens element to the image plane on the optical axis and the focal length f of the image capturing optical system satisfy the following conditions: 1.0 and < -TL/f <1.6. Therefore, the balance between the visual angle and the total length can be obtained.

The distance TL from the object-side surface of the first lens element to the image plane on the optical axis is, the maximum imaging height of the image-capturing optical system is ImgH (half of the total length of the diagonal line of the effective sensing area of the electronic photosensitive element), which satisfies the following conditions: 1.0 sT/ImgH <2.0. Therefore, the balance between the total length and the size of the imaging surface can be obtained.

The focal length of the image pickup optical system is f, the focal length of the first lens element is f1, the focal length of the second lens element is f2, the focal length of the third lens element is f3, the focal length of the fourth lens element is f4, the focal length of the fifth lens element is f5, the focal length of the sixth lens element is f6, the focal length of the seventh lens element is f7, and the focal length of the eighth lens element is f8, and at least one of the following conditions is satisfied: 0.20-woven fabric f/f1<1.0; -1.2 and < -f/f 2<1.2; -0.40 woven-of-piles f/f3<0.40; -1.0 and < -f/f 4<1.0;0.20 and < -f/f 5<1.0; -1.2-woven fabric f/f6<1.0;0<f/f7<2.0; and-2.0 < -f/f 8<0. Therefore, the refractive power of the lens can be adjusted, which is beneficial to correcting aberration, compressing volume and adjusting visual angle. Wherein at least one of the following conditions may also be satisfied: 0.30 yarn-over-f 1<0.90; -0.40 and/or-2 <0.40; -0.30 woven-of-piles f/f3<0.30; -0.80 woven-of-piles f/f4<0.40;0.35 yarn of woven fabric (f/f 5) is less than 0.90; -1.0 and < -f/f 6<0.50;0.20 yarn-over f/f7<1.8; and-1.7-woven fabric f/f8< -0.30.

The focal length of the image pickup optical system is f, and the combined focal length of the second lens and the third lens is f23, which satisfies the following conditions: -0.40 and f/f23<0.20. Therefore, the second lens and the third lens can be matched with each other to correct the aberration.

The radius of curvature of the object-side surface of the second lens element is R3, and the radius of curvature of the image-side surface of the second lens element is R4, which satisfies the following condition: 0.50 sR3/R4 <2.0. Therefore, the surface shape of the second lens can be adjusted to correct astigmatic aberration and the like. Wherein the following conditions may also be satisfied: 0.70 sR3/R4 <1.5.

All technical features of the optical system for image pickup of the present invention can be combined and configured to achieve corresponding effects.

In the optical system for camera shooting disclosed by the invention, the material of the lens can be glass or plastic. If the lens is made of glass, the degree of freedom of the arrangement of the refractive power of the optical system for image pickup can be increased, and the influence of the external environmental temperature change on the image formation can be reduced. If the lens is made of plastic, the production cost can be effectively reduced. In addition, a spherical surface or an Aspherical Surface (ASP) can be arranged on the mirror surface, wherein the spherical lens can reduce the manufacturing difficulty, and if the aspherical surface is arranged on the mirror surface, more control variables can be obtained so as to reduce the aberration and the number of lenses and effectively reduce the total length of the optical system for shooting. Furthermore, the aspheric surface can be manufactured by plastic injection molding or molding glass lens.

In the imaging optical system disclosed in the present invention, when the lens surface is an aspherical surface, it means that all or a part of the optically effective area of the lens surface is an aspherical surface.

In the optical system for camera shooting disclosed by the invention, additives can be selectively added into any (more than one) lens material to change the transmittance of the lens to light rays with a specific waveband, so that stray light and color cast are reduced. For example: the additive can have the function of filtering light rays in a wave band of 600 nanometers to 800 nanometers in the system, so that redundant red light or infrared light can be reduced; or the light with wave band of 350 nm to 450 nm can be filtered out to reduce the redundant blue light or ultraviolet light, therefore, the additive can prevent the light with specific wave band from causing interference to the imaging. In addition, the additives can be mixed homogeneously in the plastic and made into lenses by injection molding techniques.

In the optical system for photographing disclosed by the invention, if the lens surface is a convex surface and the position of the convex surface is not defined, the convex surface can be positioned at the position close to the optical axis of the lens surface; if the lens surface is concave and the position of the concave surface is not defined, it means that the concave surface can be located at the position of the lens surface near the optical axis. If the refractive power or focal length of the lens element does not define the position of the lens region, it means that the refractive power or focal length of the lens element can be the refractive power or focal length of the lens element at the paraxial region.

In the imaging optical system disclosed in the present invention, the Inflection Point (Inflection Point) of the lens surface is a boundary Point at which the curvature of the lens surface changes in positive and negative directions. The Critical Point (Critical Point) of the lens surface refers to a tangent Point on a tangent line of a plane perpendicular to the optical axis and tangent to the lens surface, and the Critical Point is not located on the optical axis.

In the imaging optical system disclosed in the present invention, the imaging surface of the imaging optical system may be a flat surface or a curved surface having any curvature, particularly a curved surface having a concave surface facing the object side, depending on the electro-photosensitive element.

In the imaging optical system disclosed in the present invention, one or more imaging correction elements (flat field elements, etc.) can be selectively arranged between the lens closest to the imaging plane and the imaging plane to achieve the effect of correcting the image (image curvature, etc.). The optical properties of the image modifying element, such as curvature, thickness, refractive index, position, profile (convex or concave, spherical or aspherical, diffractive, fresnel, etc.) can be adjusted to suit the requirements of the image capturing device. In general, the preferred imaging correction element is configured such that a thin plano-concave element having a concave surface facing the object side is disposed near the imaging surface.

The optical system for image pickup disclosed in the present invention may be provided with at least one Stop, which may be located before the first lens, between the lenses or after the last lens, and the Stop may be of a type such as a flare Stop (Glare Stop) or a Field Stop (Field Stop), which may be used to reduce stray light and help to improve image quality.

In the imaging optical system disclosed in the present invention, the diaphragm may be disposed as a front diaphragm or a middle diaphragm. The front diaphragm means that the diaphragm is arranged between the object to be shot and the first lens, and the middle diaphragm means that the diaphragm is arranged between the first lens and the imaging surface. If the diaphragm is a front diaphragm, a longer distance can be generated between the Exit Pupil (Exit Pupil) and the imaging surface, so that the Exit Pupil has a Telecentric (telecentricity) effect, and the image receiving efficiency of a CCD (charge coupled device) or a CMOS (complementary metal oxide semiconductor) of the electronic photosensitive element can be increased; the intermediate diaphragm contributes to an increase in the field angle of the imaging optical system.

The present invention can be properly configured with a variable aperture device, which can be a mechanical component or a light control device, which can control the size and shape of the aperture by electrical or electronic signals. The mechanical component can comprise a blade group, a shielding plate and other movable parts; the light regulating element may include a light filtering element, an electrochromic material, a liquid crystal layer, and other shielding materials. The variable aperture element can enhance the image adjusting capability by controlling the light input amount or the exposure time of the image. In addition, the variable aperture element can also be an aperture of the present invention, and the image quality, such as the depth of field or the exposure speed, can be adjusted by changing the aperture value.

The following provides a detailed description of the embodiments with reference to the accompanying drawings.

< first embodiment >

Referring to fig. 1 to fig. 2, in which fig. 1 is a schematic view of an image capturing device according to a first embodiment of the invention, and fig. 2 is a graph of spherical aberration, astigmatism and distortion in the first embodiment from left to right. As shown in fig. 1, the image capturing device includes an image capturing optical system (not labeled) and an electronic photosensitive element 199. The imaging optical system includes, in order from an object side to an image side, an aperture stop 100, a first lens element 110, a second lens element 120, a third lens element 130, a stop 101, a fourth lens element 140, a fifth lens element 150, a sixth lens element 160, a seventh lens element 170, an eighth lens element 180, a Filter element (Filter) 190, and an image plane 195. The photosensitive element 199 is disposed on the image forming surface 195. The imaging optical system includes eight lenses (110, 120, 130, 140, 150, 160, 170, 180), and there is no other lens to be interpolated between the lenses.

The first lens element 110 with positive refractive power has a convex object-side surface 111 at a paraxial region and a concave image-side surface 112 at a paraxial region, and both surfaces are aspheric, and the image-side surface 112 has two inflection points.

The second lens element 120 with positive refractive power has a convex object-side surface 121 at a paraxial region and a concave image-side surface 122 at a paraxial region, and is aspheric, the object-side surface 121 has two inflection points and the image-side surface 122 has one inflection point.

The third lens element 130 with negative refractive power has a convex object-side surface 131 at a paraxial region and a concave image-side surface 132 at a paraxial region, and is aspheric, the object-side surface 131 has an inflection point, the image-side surface 132 has an inflection point, the object-side surface 131 has a critical point at an off-axis region, and the image-side surface 132 has a critical point at an off-axis region.

The fourth lens element 140 with positive refractive power has a convex object-side surface 141 at a paraxial region and a concave image-side surface 142 at a paraxial region, and is aspheric, the object-side surface 141 has an inflection point, the image-side surface 142 has an inflection point, the object-side surface 141 has a critical point at an off-axis region, and the image-side surface 142 has a critical point at an off-axis region.

The fifth lens element 150 with positive refractive power has a concave object-side surface 151 at a paraxial region and a convex image-side surface 152 at a paraxial region, and is made of plastic material, wherein both surfaces are aspheric, and the object-side surface 151 has an inflection point and the image-side surface 152 has an inflection point.

The sixth lens element 160 with negative refractive power has a concave object-side surface 161 at a paraxial region and a convex image-side surface 162 at a paraxial region, and both surfaces are aspheric, the object-side surface 161 has two inflection points, the image-side surface 162 has two inflection points, and the image-side surface 162 has a critical point at an off-axis region.

The seventh lens element 170 with positive refractive power has a convex object-side surface 171 at a paraxial region and a concave image-side surface 172 at a paraxial region, and is aspheric, the object-side surface 171 has two inflection points, the image-side surface 172 has an inflection point, the object-side surface 171 has a critical point at an off-axis region, and the image-side surface 172 has a critical point at an off-axis region.

The eighth lens element 180 with negative refractive power has a convex object-side surface 181 at a paraxial region and a concave image-side surface 182 at a paraxial region, and is aspheric, the object-side surface 181 has two inflection points, the image-side surface 182 has three inflection points, the object-side surface 181 has a critical point at an off-axis region, and the image-side surface 182 has a critical point at an off-axis region.

The filter 190 is made of glass, and is disposed between the eighth lens element 180 and the image forming surface 195, and does not affect the focal length of the imaging optical system.

The curve equation of the aspherical surface of each lens described above is as follows:

x: displacement of the point on the aspheric surface parallel to the optical axis from the intersection point of the aspheric surface and the optical axis to a point on the aspheric surface with a distance Y from the optical axis;

y: the vertical distance between a point on the aspheric curve and the optical axis;

r: a radius of curvature;

k: the cone coefficient; and

ai: the ith order aspheric coefficients.

In the imaging optical system according to the first embodiment, the focal length of the imaging optical system is f, the aperture value of the imaging optical system is Fno, and half of the maximum field angle of the imaging optical system is HFOV, and the numerical values thereof are as follows: f =5.69 millimeters (mm), fno =1.51, hfov =39.4 degrees (deg.).

The abbe number of the first lens 110 is V1, the abbe number of the second lens 120 is V2, the abbe number of the third lens 130 is V3, the abbe number of the fourth lens 140 is V4, the abbe number of the fifth lens 150 is V5, the abbe number of the sixth lens 160 is V6, the abbe number of the seventh lens 170 is V7, the abbe number of the eighth lens 180 is V8, the abbe number of the ith lens is Vi, the refractive index of the first lens 110 is N1, the refractive index of the second lens 120 is N2, the refractive index of the third lens 130 is N3, the refractive index of the fourth lens 140 is N4, the refractive index of the fifth lens 150 is N5, the refractive index of the sixth lens 160 is N6, the refractive index of the seventh lens 170 is N7, the refractive index of the eighth lens 180 is N8, the refractive index of the ith lens is Ni, the minimum value of Vi/Ni is (Vi/Ni) min, which satisfies the following conditions: (Vi/Ni) min =10.90. In this embodiment, (Vi/Ni) min is equal to V3/N3, V4/N4, and V6/N6.

The abbe number of the second lens 120 is V2, which satisfies the following condition: v2=20.4.

The abbe number of the second lens 120 is V2, the abbe number of the third lens 130 is V3, and the abbe number of the fourth lens 140 is V4, which satisfy the following conditions: v2+ V3+ V4=57.2.

The abbe number of the second lens 120 is V2, and the abbe number of the fourth lens 140 is V4, which satisfy the following conditions: v2+ V4=38.8.

The abbe number of the second lens 120 is V2, the refractive index of the second lens 120 is N2, and the following conditions are satisfied: V2/N2=12.29.

The abbe number of the sixth lens 160 is V6, which satisfies the following condition: v6=18.4.

The total of the lens thicknesses of the respective lenses in the imaging optical system on the optical axis is Σ CT, and the thickness of the fifth lens 150 on the optical axis is CT5, which satisfy the following conditions: Σ CT/CT5=3.56. In the present embodiment, Σ CT is the sum of the thicknesses of the first lens element 110, the second lens element 120, the third lens element 130, the fourth lens element 140, the fifth lens element 150, the sixth lens element 160, the seventh lens element 170, and the eighth lens element 180 on the optical axis.

The thickness of the first lens element 110 on the optical axis is CT1, the thickness of the second lens element 120 on the optical axis is CT2, the thickness of the third lens element 130 on the optical axis is CT3, the thickness of the fourth lens element 140 on the optical axis is CT4, and the thickness of the fifth lens element 150 on the optical axis is CT5, which satisfy the following conditions: (CT 2+ CT3+ CT 4)/(CT 1+ CT 5) =0.41.

The thickness of the second lens element 120 on the optical axis is CT2, and the thickness of the third lens element 130 on the optical axis is CT3, which satisfy the following conditions: CT3/CT2=1.00.

The thickness of the first lens element 110 on the optical axis is CT1, and the thickness of the fifth lens element 150 on the optical axis is CT5, which satisfies the following conditions: CT5/CT1=1.50.

The thickness of the third lens element 130 on the optical axis is CT3, and the thickness of the fifth lens element 150 on the optical axis is CT5, which satisfies the following conditions: CT5/CT3=4.25.

The thickness of the fifth lens element 150 on the optical axis is CT5, and the thickness of the seventh lens element 170 on the optical axis is CT7, which satisfy the following conditions: CT7/CT5=0.49.

An axial distance TD between the object-side surface 111 and the image-side surface 182 of the eighth lens element, and an axial thickness CT5 of the fifth lens element 150 satisfy the following conditions: TD/CT5=5.64.

An axial distance TD between the object-side surface 111 and the image-side surface 182 of the eighth lens element and the focal length f2 of the second lens element 120 satisfy the following condition: TD/f2=0.23.

The distance TL from the object-side surface 111 to the image plane 195 on the optical axis satisfies the following condition: TL =7.85[ mm ].

An optical axis distance TL from the object-side surface 111 of the first lens element to the image plane 195, and a focal length f of the image-capturing optical system satisfy the following conditions: TL/f =1.38.

The distance TL from the object-side surface 111 of the first lens element to the image plane 195 on the optical axis is, the maximum imaging height ImgH of the optical system for image capture satisfies the following conditions: TL/ImgH =1.64.

A radius of curvature of the object-side surface 111 of the first lens element is R1, and a radius of curvature of the image-side surface 112 of the first lens element is R2, which satisfy the following conditions: R1/R2=0.55.

The second lens element has an object-side surface 121 with a radius of curvature R3 and an imaging optical system with a focal length f, which satisfy the following conditions: r3/f =0.47.

The radius of curvature of the object-side surface 121 of the second lens element is R3, and the radius of curvature of the image-side surface 122 of the second lens element is R4, which satisfies the following condition: R3/R4=0.90.

A radius of curvature of the object-side surface 151 of the fifth lens element is R9, and a radius of curvature of the image-side surface 152 of the fifth lens element is R10, which satisfy the following conditions: (R9 + R10)/(R9-R10) =1.03.

The focal length of the image-pickup optical system is f, and the focal length of the first lens 110 is f1, which satisfies the following conditions: f/f1=0.42.

The focal length of the image pickup optical system is f, and the focal length of the second lens 120 is f2, which satisfies the following conditions: f/f2=0.20.

The focal length of the image pickup optical system is f, the focal length of the second lens 120 is f2, and the focal length of the third lens 130 is f3, which satisfy the following conditions: i f/f2| + | f/f3| =0.40.

The focal length of the image pickup optical system is f, the focal length of the second lens 120 is f2, the focal length of the third lens 130 is f3, and the focal length of the fourth lens 140 is f4, which satisfy the following conditions: f/f2+ f/f3+ f/f4=0.02.

The focal length of the image pickup optical system is f, and the focal length of the third lens 130 is f3, which satisfies the following conditions: f/f3= -0.20.

The focal length of the image pickup optical system is f, and the focal length of the fourth lens 140 is f4, which satisfy the following conditions: f/f4=0.02.

The focal length of the image pickup optical system is f, and the focal length of the fifth lens 150 is f5, which satisfies the following conditions: f/f5=0.73.

The focal length of the image pickup optical system is f, and the focal length of the sixth lens 160 is f6, which satisfy the following conditions: f/f6= -0.27.

The focal length of the image pickup optical system is f, and the focal length of the seventh lens 170 is f7, which satisfies the following conditions: f/f7=0.48.

The focal length of the image pickup optical system is f, and the focal length of the eighth lens 180 is f8, which satisfy the following conditions: f/f8= -0.66.

The focal length of the image pickup optical system is f, and the combined focal length of the first lens 110 and the second lens 120 is f12, which satisfies the following conditions: f/f12=0.62.

The focal length of the image pickup optical system is f, and the combined focal length of the second lens element 120 and the third lens element 130 is f23, which satisfies the following conditions: f/f23=0.02.

A focal length of the imaging optical system is f, a radius of curvature of the object-side surface 161 of the sixth lens element is R11, and a radius of curvature of the image-side surface 162 of the sixth lens element is R12, which satisfy the following conditions: f/| R11| + f/| R12| =5.69.

The focal length of the fifth lens element 150 is f5, and the thickness of the fifth lens element 150 on the optical axis is CT5, which satisfies the following condition: f5/CT5=6.84.

The focal length of the first lens 110 is f1, and the focal length of the fifth lens 150 is f5, which satisfies the following conditions: f5/f1=0.58.

The focal length of the seventh lens 170 is f7, and the focal length of the eighth lens 180 is f8, which satisfies the following conditions: f8/f7= -0.73.

The maximum effective radius of the object-side surface 111 of the first lens element is Y11, and the maximum effective radius of the image-side surface 182 of the eighth lens element is Y82, which satisfy the following condition: Y82/Y11=2.12.

A vertical distance between a critical point of the seventh lens object-side surface 171 and the optical axis is Yc71, and a vertical distance between a critical point of the seventh lens image-side surface 172 and the optical axis is Yc72, which satisfy the following conditions: yc72/Yc71=1.24.

The vertical distance between the optical axis and the critical point of the image-side surface 182 of the eighth lens element is Yc82, and the maximum effective radius of the image-side surface 182 of the eighth lens element is Y82, which satisfies the following condition: yc82/Y82=0.42.

Please refer to the following table one and table two.

In the following description, the detailed structural data of the first embodiment of fig. 1 are shown, wherein the units of the radius of curvature, the thickness and the focal length are millimeters (mm), and the surfaces 0 to 21 sequentially represent the surfaces from the object side to the image side. Table two shows the aspheric data in the first embodiment, where k is the cone coefficient in the aspheric curve equation, and A4 to a20 represent the 4 th to 20 th order aspheric coefficients of each surface. In addition, the following tables of the embodiments correspond to the schematic diagrams and aberration graphs of the embodiments, and the definitions of the data in the tables are the same as those of the first and second tables of the first embodiment, which will not be described herein.

< second embodiment >

Referring to fig. 3 to 4, wherein fig. 3 is a schematic view of an image capturing apparatus according to a second embodiment of the invention, and fig. 4 is a graph of spherical aberration, astigmatism and distortion of the second embodiment in order from left to right. As shown in fig. 3, the image capturing device includes an optical system (not shown) for capturing images and an electronic photosensitive element 299. The imaging optical system includes, in order from an object side to an image side, an aperture stop 200, a first lens element 210, a second lens element 220, a stop 201, a third lens element 230, a stop 202, a fourth lens element 240, a fifth lens element 250, a sixth lens element 260, a seventh lens element 270, an eighth lens element 280, a filter element 290, and an image plane 295. The electro-optic element 299 is disposed on the image plane 295. The imaging optical system includes eight lenses (210, 220, 230, 240, 250, 260, 270, 280), and there is no other lens to be interpolated between the lenses.

The first lens element 210 with positive refractive power has a convex object-side surface 211 at a paraxial region and a convex image-side surface 212 at a paraxial region, wherein both surfaces are aspheric, the image-side surface 212 has three inflection points, and the image-side surface 212 has a critical point at an off-axis region.

The second lens element 220 with negative refractive power has a convex object-side surface 221 at a paraxial region and a concave image-side surface 222 at a paraxial region, and is aspheric, the object-side surface 221 has an inflection point, the image-side surface 222 has an inflection point, and the object-side surface 221 has a critical point at an off-axis region.

The third lens element 230 with positive refractive power has a convex object-side surface 231 at a paraxial region and a concave image-side surface 232 at a paraxial region, and is aspheric, wherein the object-side surface 231 has two inflection points and the image-side surface 232 has two inflection points.

The fourth lens element 240 with positive refractive power has a convex object-side surface 241 in a paraxial region and a concave image-side surface 242 in a paraxial region, both surfaces are aspheric, the object-side surface 241 has an inflection point, the image-side surface 242 has an inflection point, the object-side surface 241 has a critical point in an off-axis region, and the image-side surface 242 has a critical point in an off-axis region.

The fifth lens element 250 with positive refractive power has a concave object-side surface 251 and a convex image-side surface 252 at a paraxial region, and both surfaces are aspheric, and the object-side surface 251 and the image-side surface 252 have inflection points respectively.

The sixth lens element 260 with negative refractive power has a concave object-side surface 261 and a convex image-side surface 262 in a paraxial region, both surfaces are aspheric, the object-side surface 261 has two inflection points, the image-side surface 262 has two inflection points, and the image-side surface 262 has a critical point in an off-axis region.

The seventh lens element 270 with positive refractive power has a convex object-side surface 271 with a convex surface at a paraxial region thereof and a concave image-side surface 272 with a concave surface at a paraxial region thereof, both surfaces are aspheric, the object-side surface 271 has two inflection points, the image-side surface 272 has four inflection points, the object-side surface 271 has a critical point at an off-axis region thereof, and the image-side surface 272 has a critical point at an off-axis region thereof.

The eighth lens element 280 with negative refractive power has a convex object-side surface 281 at a paraxial region and a concave image-side surface 282 at a paraxial region, and is aspheric, the object-side surface 281 has three inflection points, the image-side surface 282 has an inflection point, the object-side surface 281 has two off-axis critical points, and the image-side surface 282 has an off-axis critical point.

The filter 290 is made of glass, and is disposed between the eighth lens element 280 and the image plane 295, and does not affect the focal length of the imaging optical system.

Please refer to the following table three and table four.

In the second embodiment, the curve equation of the aspherical surface represents the form as in the first embodiment. In addition, the definitions described in the following table are the same as those in the above embodiments, and are not repeated herein.

< third embodiment >

Referring to fig. 5 to 6, wherein fig. 5 is a schematic view of an image capturing apparatus according to a third embodiment of the invention, and fig. 6 is a graph showing spherical aberration, astigmatism and distortion in the third embodiment from left to right. As shown in fig. 5, the image capturing device includes an optical system (not labeled) for capturing images and an electronic photosensitive element 399. The imaging optical system includes, in order from an object side to an image side, an aperture stop 300, a first lens element 310, a second lens element 320, a third lens element 330, a fourth lens element 340, a fifth lens element 350, a sixth lens element 360, a stop 301, a seventh lens element 370, an eighth lens element 380, a filter element 390, and an image plane 395. The electro-optic element 399 is disposed on the image forming surface 395. The imaging optical system includes eight lenses (310, 320, 330, 340, 350, 360, 370, and 380), and there is no other lens to be inserted between the lenses.

The first lens element 310 with positive refractive power has a convex object-side surface 311 at a paraxial region and a concave image-side surface 312 at a paraxial region, and is made of plastic material.

The second lens element 320 with positive refractive power has a convex object-side surface 321 at a paraxial region and a concave image-side surface 322 at a paraxial region, and both surfaces are aspheric, and the image-side surface 322 has an inflection point.

The third lens element 330 with negative refractive power has a convex object-side surface 331 at a paraxial region and a concave image-side surface 332 at a paraxial region, both surfaces are aspheric, the object-side surface 331 has an inflection point, the image-side surface 332 has two inflection points, the object-side surface 331 has a critical point at an off-axis region, and the image-side surface 332 has two critical points at an off-axis region.

The fourth lens element 340 with negative refractive power has a concave object-side surface 341 in a paraxial region thereof and a convex image-side surface 342 in a paraxial region thereof, wherein both surfaces are aspheric, the image-side surface 342 has three inflection points, and the image-side surface 342 has two off-axis critical points.

The fifth lens element 350 with positive refractive power has a convex object-side surface 351 at a paraxial region and a convex image-side surface 352 at a paraxial region, and is aspheric, wherein the object-side surface 351 has two inflection points, the image-side surface 352 has an inflection point, and the object-side surface 351 has a critical point at an off-axis region.

The sixth lens element 360 with positive refractive power has a concave object-side surface 361 at a paraxial region thereof and a convex image-side surface 362 at a paraxial region thereof, and both surfaces are aspheric, the object-side surface 361 has two inflection points, the image-side surface 362 has two inflection points, and the image-side surface 362 has a critical point at an off-axis region thereof.

The seventh lens element 370 with positive refractive power has a convex object-side surface 371 at a paraxial region and a concave image-side surface 372 at a paraxial region, both surfaces are aspheric, the object-side surface 371 has three inflection points, the image-side surface 372 has an inflection point, the object-side surface 371 has a critical point at an off-axis region, and the image-side surface 372 has a critical point at an off-axis region.

The eighth lens element 380 with negative refractive power has a convex object-side surface 381 and a concave image-side surface 382 at a paraxial region, and is made of plastic material, wherein both surfaces of the eighth lens element are aspheric, the object-side surface 381 has four inflection points, the image-side surface 382 has two inflection points, the object-side surface 381 has a critical point at an off-axis region, and the image-side surface 382 has a critical point at an off-axis region.

The filter 390 is made of glass, and is disposed between the eighth lens element 380 and the image forming surface 395 without affecting the focal length of the imaging optical system.

Please refer to table five and table six below.

In the third embodiment, the curve equation of the aspherical surface represents the form as in the first embodiment. In addition, the definitions described in the following table are the same as those in the above embodiments, and are not repeated herein.

< fourth embodiment >

Referring to fig. 7 to fig. 8, in which fig. 7 is a schematic view of an image capturing device according to a fourth embodiment of the invention, and fig. 8 is a graph of spherical aberration, astigmatism and distortion in turn from left to right in the fourth embodiment. As shown in fig. 7, the image capturing device includes an optical system (not labeled) for capturing images and an electronic photosensitive element 499. The imaging optical system includes, in order from an object side to an image side, an aperture stop 400, a first lens 410, a second lens 420, an aperture stop 401, a third lens 430, a fourth lens 440, an aperture stop 402, a fifth lens 450, a sixth lens 460, a seventh lens 470, an eighth lens 480, a filter element 490, and an image plane 495. The electrophotographic photosensitive member 499 is disposed on the image plane 495. The imaging optical system includes eight lenses (410, 420, 430, 440, 450, 460, 470, 480), and there is no other lens to be interpolated between the lenses.

The first lens element 410 with positive refractive power has an object-side surface 411 being convex in a paraxial region thereof and an image-side surface 412 being convex in a paraxial region thereof, both surfaces being aspheric, and the image-side surface 412 has two inflection points and the image-side surface 412 has a critical point in an off-axis region thereof.

The second lens element 420 with negative refractive power has a convex object-side surface 421 at a paraxial region and a concave image-side surface 422 at a paraxial region, and is aspheric, wherein the object-side surface 421 has two inflection points and the image-side surface 422 has one inflection point.

The third lens element 430 with positive refractive power has a convex object-side surface 431 at a paraxial region and a concave image-side surface 432 at a paraxial region, and is aspheric, the object-side surface 431 has an inflection point, the image-side surface 432 has two inflection points, the object-side surface 431 has a critical point at an off-axis region, and the image-side surface 432 has a critical point at an off-axis region.

The fourth lens element 440 with negative refractive power has a convex object-side surface 441 at a paraxial region and a concave image-side surface 442 at a paraxial region, wherein both surfaces are aspheric, the object-side surface 441 has three inflection points, the image-side surface 442 has three inflection points, the object-side surface 441 has three critical points at an off-axis region, and the image-side surface 442 has a critical point at an off-axis region.

The fifth lens element 450 with positive refractive power has a convex object-side surface 451 at a paraxial region and a convex image-side surface 452 at a paraxial region, and both surfaces are aspheric, and the image-side surface 452 has an inflection point.

The sixth lens element 460 with negative refractive power has a convex object-side surface 461 at a paraxial region and a concave image-side surface 462 at a paraxial region, and is aspheric, the object-side surface 461 has an inflection point, the image-side surface 462 has two inflection points, the object-side surface 461 has a critical point on an off-axis region, and the image-side surface 462 has a critical point on an off-axis region.

The seventh lens element 470 with positive refractive power has a convex object-side surface 471 at a paraxial region thereof, a concave image-side surface 472 at a paraxial region thereof, both surfaces thereof being aspheric, the object-side surface 471 having three inflection points, the image-side surface 472 having three inflection points, the object-side surface 471 having a critical point at an off-axis region thereof, and the image-side surface 472 having a critical point at an off-axis region thereof.

The eighth lens element 480 with negative refractive power has a concave object-side surface 481 at a paraxial region and a concave image-side surface 482 at a paraxial region, both surfaces are aspheric, the object-side surface 481 has an inflection point, the image-side surface 482 has an inflection point, the object-side surface 481 has a critical point at an off-axis region, and the image-side surface 482 has a critical point at an off-axis region.

The filter element 490 is made of glass, and is disposed between the eighth lens 480 and the image plane 495, and does not affect the focal length of the imaging optical system.

Please refer to table seven and table eight below.

In a fourth embodiment, the aspherical surface curve equation is given in the form of the first embodiment. In addition, the definitions described in the following table are the same as those in the above embodiments, and are not repeated herein.

< fifth embodiment >

Referring to fig. 9 to 10, wherein fig. 9 is a schematic view of an image capturing apparatus according to a fifth embodiment of the invention, and fig. 10 is a graph of spherical aberration, astigmatism and distortion of the fifth embodiment in order from left to right. As shown in fig. 9, the image capturing device includes an optical system (not shown) for capturing images and an electronic photosensitive element 599. The imaging optical system includes, in order from an object side to an image side, an aperture stop 500, a first lens 510, a second lens 520, a stop 501, a third lens 530, a stop 502, a fourth lens 540, a fifth lens 550, a sixth lens 560, a seventh lens 570, an eighth lens 580, a filter 590, and an image plane 595. The electron sensor 599 is disposed on the image plane 595. The imaging optical system includes eight lenses (510, 520, 530, 540, 550, 560, 570, 580) and there is no other lens to be interpolated between the lenses.

The first lens element 510 with positive refractive power has a convex object-side surface 511 at a paraxial region and a convex image-side surface 512 at a paraxial region, wherein both surfaces are aspheric, the image-side surface 512 has an inflection point, and the image-side surface 512 has a critical point at an off-axis region.

The second lens element 520 with negative refractive power has a convex object-side surface 521 at a paraxial region and a concave image-side surface 522 at a paraxial region, and is aspheric, the object-side surface 521 has an inflection point, the image-side surface 522 has an inflection point, and the object-side surface 521 has a critical point at an off-axis region.

The third lens element 530 with positive refractive power has a convex object-side surface 531 at a paraxial region and a concave image-side surface 532 at a paraxial region, and is aspheric, wherein the object-side surface 531 has two inflection points, the image-side surface 532 has two inflection points, and the image-side surface 532 has two critical points at an off-axis region.

The fourth lens element 540 with negative refractive power has an object-side surface 541 being convex in a paraxial region thereof and an image-side surface 542 being concave in a paraxial region thereof, and is aspheric, the object-side surface 541 has an inflection point, the image-side surface 542 has an inflection point, the object-side surface 541 has a critical point in an off-axis region thereof, and the image-side surface 542 has a critical point in the off-axis region thereof.

The fifth lens element 550 with positive refractive power has a convex object-side surface 551 at a paraxial region and a convex image-side surface 552 at a paraxial region, and is aspheric, the object-side surface 551 has three inflection points, the image-side surface 552 has an inflection point, and the object-side surface 551 has a critical point at an off-axis region.

The sixth lens element 560 with negative refractive power has a concave object-side surface 561 at a paraxial region, a convex image-side surface 562 at a paraxial region, both surfaces are aspheric, the object-side surface 561 has an inflection point, the image-side surface 562 has two inflection points, the object-side surface 561 has a critical point at an off-axis region, and the image-side surface 562 has a critical point at an off-axis region.

The seventh lens element 570 with positive refractive power has a convex object-side surface 571 at a paraxial region and a concave image-side surface 572 at a paraxial region, which are both aspheric, the object-side surface 571 has two inflection points, the image-side surface 572 has four inflection points, the object-side surface 571 has a critical point at an off-axis region, and the image-side surface 572 has a critical point at an off-axis region.

The eighth lens element 580 with negative refractive power has a convex object-side surface 581 at a paraxial region thereof and a concave image-side surface 582 at a paraxial region thereof, and is aspheric, wherein the object-side surface 581 has three inflection points, the image-side surface 582 has an inflection point, the object-side surface 581 has two off-axis critical points, and the image-side surface 582 has an off-axis critical point.

The filter 590 is made of glass, and is disposed between the eighth lens 580 and the image plane 595, and does not affect the focal length of the imaging optical system.

Please refer to table nine and table ten below.

In the fifth embodiment, the curve equation of the aspherical surface represents the form as in the first embodiment. In addition, the definitions described in the following table are the same as those in the above embodiments, and are not repeated herein.

< sixth embodiment >

Referring to fig. 11 to 12, wherein fig. 11 is a schematic view of an image capturing apparatus according to a sixth embodiment of the invention, and fig. 12 is a graph showing spherical aberration, astigmatism and distortion in the sixth embodiment from left to right. As shown in fig. 11, the image capturing device includes an optical system for image capturing (not labeled) and an electronic photosensitive element 699. The imaging optical system includes, in order from an object side to an image side, an aperture stop 600, a first lens element 610, a second lens element 620, an aperture stop 601, a third lens element 630, an aperture stop 602, a fourth lens element 640, a fifth lens element 650, a sixth lens element 660, a seventh lens element 670, an eighth lens element 680, a filter element 690, and an image plane 695. The electron photosensitive element 699 is disposed on the image forming surface 695. The imaging optical system includes eight lenses (610, 620, 630, 640, 650, 660, 670, 680), and there is no other lens to be inserted between the lenses.

The first lens element 610 with positive refractive power has a convex object-side surface 611 at a paraxial region and a concave image-side surface 612 at a paraxial region, and is made of plastic material.

The second lens element 620 with negative refractive power has a convex object-side surface 621 at a paraxial region and a concave image-side surface 622 at a paraxial region, and is aspheric, the object-side surface 621 has an inflection point, the image-side surface 622 has an inflection point, and the object-side surface 621 has a critical point at an off-axis region.

The third lens element 630 with positive refractive power has a convex object-side surface 631 at a paraxial region and a concave image-side surface 632 at a paraxial region, and is aspheric, the object-side surface 631 has two inflection points, the image-side surface 632 has two inflection points, and the image-side surface 632 has two off-axis critical points.

The fourth lens element 640 with negative refractive power has a convex object-side surface 641 at a paraxial region and a concave image-side surface 642 at a paraxial region, and is aspheric, the object-side surface 641 has an inflection point, the image-side surface 642 has an inflection point, the object-side surface 641 has a critical point at an off-axis region, and the image-side surface 642 has a critical point at an off-axis region.

The fifth lens element 650 with positive refractive power has a convex object-side surface 651 at a paraxial region thereof and a convex image-side surface 652 at a paraxial region thereof, and is aspheric, the object-side surface 651 has two inflection points, the image-side surface 652 has an inflection point, and the object-side surface 651 has a critical point at an off-axis region thereof.

The sixth lens element 660 with negative refractive power has a concave object-side surface 661 at a paraxial region, a convex image-side surface 662 at a paraxial region, both surfaces being aspheric, the object-side surface 661 has two inflection points, the image-side surface 662 has an inflection point, and the image-side surface 662 has a critical point at an off-axis region.

The seventh lens element 670 with positive refractive power has a convex object-side surface 671 at a paraxial region and a concave image-side surface 672 at a paraxial region, and is aspheric, wherein the object-side surface 671 has two inflection points, the image-side surface 672 has two inflection points, the object-side surface 671 has a critical point at an off-axis region, and the image-side surface 672 has a critical point at an off-axis region.

The eighth lens element 680 with negative refractive power has a convex object-side surface 681 at a paraxial region thereof and a concave image-side surface 682 at a paraxial region thereof, wherein both surfaces are aspheric, the object-side surface 681 has three inflection points, the image-side surface 682 has three inflection points, the object-side surface 681 has two critical points at an off-axis region thereof, and the image-side surface 682 has a critical point at the off-axis region thereof.

The filter 690 is made of glass, is disposed between the eighth lens 680 and the image forming surface 695, and does not affect the focal length of the imaging optical system.

Please refer to the following table eleven and table twelve.

In the sixth embodiment, the curve equation of the aspherical surface represents the form as in the first embodiment. In addition, the definitions described in the following table are the same as those in the above embodiments, and are not repeated herein.

< seventh embodiment >

Referring to fig. 13 to 14, wherein fig. 13 is a schematic view of an image capturing apparatus according to a seventh embodiment of the invention, and fig. 14 is a graph showing spherical aberration, astigmatism and distortion in the seventh embodiment from left to right. As shown in fig. 13, the image capturing device includes an optical system (not shown) for capturing images and an electronic photosensitive element 799. The imaging optical system includes, in order from an object side to an image side, an aperture stop 700, a first lens element 710, a second lens element 720, a third lens element 730, a stop 701, a fourth lens element 740, a fifth lens element 750, a sixth lens element 760, a seventh lens element 770, an eighth lens element 780, a filter element 790 and an image plane 795. Wherein, the electron photosensitive element 799 is disposed on the image forming surface 795. The imaging optical system includes eight lenses (710, 720, 730, 740, 750, 760, 770, 780), and there is no other lens to be inserted between the lenses.

The first lens element 710 with positive refractive power has a convex object-side surface 711 at a paraxial region and a concave image-side surface 712 at a paraxial region, and is aspheric, the object-side surface 711 has an inflection point, the image-side surface 712 has an inflection point, and the image-side surface 712 has a critical point at an off-axis region.

The second lens element 720 with negative refractive power has a convex object-side surface 721 at a paraxial region and a concave image-side surface 722 at a paraxial region, and is aspheric, wherein the object-side surface 721 has two inflection points and the image-side surface 722 has one inflection point.

The third lens element 730 with negative refractive power has a convex object-side surface 731 at a paraxial region and a concave image-side surface 732 at a paraxial region, and is aspheric, wherein the object-side surface 731 has an inflection point, the image-side surface 732 has an inflection point, the object-side surface 731 has a critical point on an off-axis region, and the image-side surface 732 has a critical point on an off-axis region.

The fourth lens element 740 with positive refractive power has a convex object-side surface 741 in a paraxial region and a concave image-side surface 742 in a paraxial region, and is aspheric, the object-side surface 741 has an inflection point, the image-side surface 742 has an inflection point, the object-side surface 741 has a critical point in an off-axis region, and the image-side surface 742 has a critical point in the off-axis region.

The fifth lens element 750 with positive refractive power has a convex object-side surface 751 at a paraxial region thereof and a convex image-side surface 752 at a paraxial region thereof, and is aspheric, the fifth lens element 750 has an object-side surface 751 having two inflection points, the image-side surface 752 having an inflection point, and the object-side surface 751 having a critical point at an off-axis region thereof.

The sixth lens element 760 with negative refractive power has a concave object-side surface 761 at a paraxial region and a convex image-side surface 762 at a paraxial region, wherein both surfaces are aspheric, the object-side surface 761 has two inflection points, the image-side surface 762 has an inflection point, and the image-side surface 762 has a critical point at an off-axis region.

The seventh lens element 770 with positive refractive power has a convex object-side surface 771 at a paraxial region and a concave image-side surface 772 at a paraxial region, and is made of plastic material, wherein both surfaces are aspheric, the object-side surface 771 has two inflection points, the image-side surface 772 has two inflection points, the object-side surface 771 has a critical point at an off-axis region, and the image-side surface 772 has a critical point at the off-axis region.

The eighth lens element 780 with negative refractive power has a convex object-side surface 781 at a paraxial region thereof and a concave image-side surface 782 at a paraxial region thereof, and is aspheric, wherein the object-side surface 781 has four inflection points, the image-side surface 782 has three inflection points, the object-side surface 781 has a critical point at an off-axis region thereof, and the image-side surface 782 has a critical point at an off-axis region thereof.

The filter 790 is made of glass, is disposed between the eighth lens 780 and the image plane 795, and does not affect the focal length of the imaging optical system.

Please refer to the following thirteen tables and fourteen tables.

In the seventh embodiment, the curve equation of the aspherical surface represents the form as in the first embodiment. In addition, the definitions described in the following table are the same as those in the above embodiments, and are not repeated herein.

< eighth embodiment >

Referring to fig. 15 to 16, wherein fig. 15 is a schematic view of an image capturing apparatus according to an eighth embodiment of the invention, and fig. 16 is a graph showing spherical aberration, astigmatism and distortion in the eighth embodiment from left to right. As shown in fig. 15, the image capturing device includes an optical system (not shown) for capturing images and an electronic photosensitive element 899. The imaging optical system includes, in order from an object side to an image side, an aperture stop 800, a first lens element 810, a second lens element 820, a third lens element 830, a stop 801, a fourth lens element 840, a fifth lens element 850, a sixth lens element 860, a seventh lens element 870, an eighth lens element 880, a filter element 890 and an image plane 895. The electrophotographic photosensitive member 899 is disposed on an image forming surface 895. The imaging optical system includes eight lenses (810, 820, 830, 840, 850, 860, 870, 880), and there is no other lens to be interpolated between the lenses.

The first lens element 810 with positive refractive power has a convex object-side surface 811 at a paraxial region and a concave image-side surface 812 at a paraxial region, and is aspheric, the object-side surface 811 has an inflection point, the image-side surface 812 has an inflection point, and the image-side surface 812 has a critical point at an off-axis region.

The second lens element 820 with negative refractive power has a convex object-side surface 821 at a paraxial region and a concave image-side surface 822 at a paraxial region, and is made of plastic material, wherein both surfaces are aspheric, and the object-side surface 821 has two inflection points and the image-side surface 822 has one inflection point.

The third lens element 830 with negative refractive power has a convex object-side surface 831 at a paraxial region and a concave image-side surface 832 at a paraxial region, both surfaces are aspheric, the object-side surface 831 has an inflection point, the image-side surface 832 has an inflection point, the object-side surface 831 has a critical point at an off-axis region, and the image-side surface 832 has a critical point at an off-axis region.

The fourth lens element 840 with negative refractive power has a convex object-side surface 841 at a paraxial region and a concave image-side surface 842 at a paraxial region, both surfaces of the fourth lens element being aspheric, the object-side surface 841 has an inflection point, the image-side surface 842 has an inflection point, the object-side surface 841 has a critical point at an off-axis region, and the image-side surface 842 has a critical point at an off-axis region.

The fifth lens element 850 with positive refractive power has an object-side surface 851 being convex in a paraxial region thereof and an image-side surface 852 being convex in a paraxial region thereof, wherein both surfaces are aspheric, the object-side surface 851 has two inflection points, the image-side surface 852 has an inflection point, and the object-side surface 851 has a critical point in an off-axis region thereof.

The sixth lens element 860 with negative refractive power has a concave object-side surface 861 at a paraxial region and a convex image-side surface 862 at a paraxial region, wherein both surfaces are aspheric, the object-side surface 861 has two inflection points, the image-side surface 862 has an inflection point, and the image-side surface 862 has a critical point at an off-axis region.

The seventh lens element 870 with positive refractive power has a convex object-side surface 871 in a paraxial region thereof and a concave image-side surface 872 in a paraxial region thereof, wherein both surfaces are aspheric, the object-side surface 871 has two inflection points, the image-side surface 872 has two inflection points, the object-side surface 871 has a critical point in an off-axis region thereof, and the image-side surface 872 has a critical point in the off-axis region thereof.

The eighth lens element 880 with negative refractive power has a convex object-side surface 881 at a paraxial region and a concave image-side surface 882 at a paraxial region, and is aspheric, wherein the object-side surface 881 has four inflection points, the image-side surface 882 has four inflection points, the object-side surface 881 has a critical point at an off-axis region, and the image-side surface 882 has a critical point at an off-axis region.

The filter element 890 is made of glass, and is disposed between the eighth lens 880 and the image plane 895, and does not affect the focal length of the imaging optical system.

Please refer to table fifteen and table sixteen below.

In the eighth embodiment, the curve equation of the aspherical surface represents the form as in the first embodiment. In addition, the definitions described in the following table are the same as those of the above embodiments, and are not repeated herein.

< ninth embodiment >

Referring to fig. 17 to fig. 18, wherein fig. 17 is a schematic view of an image capturing apparatus according to a ninth embodiment of the invention, and fig. 18 is a graph showing spherical aberration, astigmatism and distortion in the ninth embodiment from left to right. As shown in fig. 17, the image capturing device includes an optical system (not shown) for image capturing and an electronic photosensitive element 999. The imaging optical system includes, in order from an object side to an image side, an aperture stop 900, a first lens element 910, a second lens element 920, a stop 901, a third lens element 930, a fourth lens element 940, a stop 902, a fifth lens element 950, a sixth lens element 960, a seventh lens element 970, an eighth lens element 980, a filter element 990, and an image plane 995. The electronic photosensitive element 999 is disposed on the image plane 995. The imaging optical system includes eight lenses (910, 920, 930, 940, 950, 960, 970, 980), and there is no other lens to be inserted between the lenses.

The first lens element 910 with positive refractive power has a convex object-side surface 911 at a paraxial region and a concave image-side surface 912 at a paraxial region, and both surfaces are aspheric, and the image-side surface 912 has three inflection points.

The second lens element 920 with positive refractive power has an object-side surface 921 being convex in a paraxial region thereof and an image-side surface 922 being concave in a paraxial region thereof, and both surfaces are aspheric, the image-side surface 922 has an inflection point, and the image-side surface 922 has a critical point in an off-axis region thereof.

The third lens element 930 with positive refractive power has a concave object-side surface 931 at a paraxial region and a convex image-side surface 932 at a paraxial region, and is made of plastic material, wherein both surfaces are aspheric, the object-side surface 931 has two inflection points, the image-side surface 932 has three inflection points, and the image-side surface 932 has three critical points at an off-axis region.

The fourth lens element 940 with negative refractive power has a concave object-side surface 941 at a paraxial region and a concave image-side surface 942 at a paraxial region, and is made of plastic material, wherein both surfaces are aspheric, the object-side surface 941 has three inflection points, the image-side surface 942 has three inflection points, and the image-side surface 942 has a critical point at an off-axis region.

The fifth lens element 950 with positive refractive power has an object-side surface 951 being convex in a paraxial region thereof and an image-side surface 952 being concave in a paraxial region thereof, both surfaces being aspheric, the image-side surface 952 having two inflection points, and the image-side surface 952 having a critical point in an off-axis region thereof.

The sixth lens element 960 with negative refractive power has a convex object-side surface 961 at a paraxial region and a concave image-side surface 962 at a paraxial region, both surfaces are aspheric, the object-side surface 961 has an inflection point, the image-side surface 962 has two inflection points, the object-side surface 961 has a critical point at an off-axis region, and the image-side surface 962 has a critical point at an off-axis region.

The seventh lens element 970 with positive refractive power has a convex object-side surface 971 at a paraxial region and a convex image-side surface 972 at a paraxial region, both surfaces are aspheric, the object-side surface 971 has two inflection points, the image-side surface 972 has four inflection points, the object-side surface 971 has a critical point at an off-axis region, and the image-side surface 972 has two critical points at the off-axis region.

The eighth lens element 980 with negative refractive power has a concave object-side surface 981 at a paraxial region and a concave image-side surface 982 at a paraxial region, wherein both surfaces are aspheric, the object-side surface 981 has an inflection point, the image-side surface 982 has an inflection point, and the image-side surface 982 has a critical point at an off-axis region.

The filter 990 is made of glass, and is disposed between the eighth lens element 980 and the image plane 995, and does not affect the focal length of the imaging optical system.

Please refer to the following seventeen and eighteen tables.

In the ninth embodiment, the curve equation of the aspherical surface represents the form as in the first embodiment. In addition, the definitions described in the following table are the same as those in the above embodiments, and are not repeated herein.

< tenth embodiment >

Referring to fig. 19 to fig. 20, in which fig. 19 is a schematic view of an image capturing device according to a tenth embodiment of the invention, and fig. 20 is a graph showing spherical aberration, astigmatism and distortion curves in the tenth embodiment in order from left to right. As shown in fig. 19, the image capturing device includes an optical system (not labeled) for capturing images and an electronic photosensitive element 1099. The imaging optical system includes, in order from an object side to an image side, an aperture stop 1000, a first lens element 1010, a second lens element 1020, a third lens element 1030, a stop 1001, a fourth lens element 1040, a fifth lens element 1050, a sixth lens element 1060, a seventh lens element 1070, an eighth lens element 1080, a filter element 1090, and an image plane 1095. The electron sensor 1099 is disposed on the image plane 1095. The imaging optical system includes eight lenses (1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080), and there is no other lens to be interpolated between the lenses.

The first lens element 1010 with positive refractive power has a convex object-side surface 1011 at a paraxial region and a concave image-side surface 1012 at a paraxial region, and is aspheric, the object-side surface 1011 has an inflection point, and the image-side surface 1012 has an inflection point.

The second lens element 1020 with positive refractive power has an object-side surface 1021 being convex in a paraxial region thereof and an image-side surface 1022 being concave in the paraxial region thereof, and is made of plastic material.

The third lens element 1030 with negative refractive power has a convex object-side surface 1031 at a paraxial region and a concave image-side surface 1032 at a paraxial region, and is made of plastic material.

The fourth lens element 1040 with negative refractive power has a convex object-side surface 1041 at a paraxial region and a concave image-side surface 1042 at a paraxial region, which are both aspheric, wherein the object-side surface 1041 has an inflection point, the image-side surface 1042 has two inflection points, the object-side surface 1041 has a critical point at an off-axis region, and the image-side surface 1042 has two critical points at the off-axis region.

The fifth lens element 1050 with positive refractive power has a convex object-side surface 1051 and a convex image-side surface 1052 at a paraxial region, wherein both surfaces are aspheric, the object-side surface 1051 has two inflection points, the image-side surface 1052 has one inflection point, and the object-side surface 1051 has two critical points at an off-axis region.

The sixth lens element 1060 with positive refractive power has a convex object-side surface 1061 in a paraxial region thereof, and a convex image-side surface 1062 in a paraxial region thereof, wherein both surfaces are aspheric, the object-side surface 1061 has two inflection points, the image-side surface 1062 has two inflection points, and the object-side surface 1061 has a critical point in an off-axis region thereof.

The seventh lens element 1070 with positive refractive power has a convex object-side surface 1071 at a paraxial region thereof and a convex image-side surface 1072 at a paraxial region thereof, both surfaces thereof being aspheric, the object-side surface 1071 thereof having two inflection points, the image-side surface 1072 thereof having three inflection points, the object-side surface 1071 thereof having a critical point at an off-axis region thereof, and the image-side surface 1072 thereof having two critical points at the off-axis region thereof.

The eighth lens element 1080 with negative refractive power has an object-side surface 1081 being concave at a paraxial region thereof and an image-side surface 1082 being concave at a paraxial region thereof, and both surfaces thereof are aspheric, the object-side surface 1081 has an inflection point, the image-side surface 1082 has two inflection points, the object-side surface 1081 has a critical point at an off-axis region thereof, and the image-side surface 1082 has a critical point at the off-axis region thereof.

The filter element 1090 is made of glass, and is disposed between the eighth lens 1080 and the image plane 1095, and does not affect the focal length of the imaging optical system.

Please refer to the nineteen and twenty tables below.

In the tenth embodiment, the curve equation of the aspherical surface represents the form as in the first embodiment. In addition, the definitions described in the following table are the same as those in the above embodiments, and are not repeated herein.

< eleventh embodiment >

Referring to fig. 21, a perspective view of an image capturing apparatus according to an eleventh embodiment of the invention is shown. In the present embodiment, the image capturing device 10 is a camera module. The image capturing device 10 includes an imaging lens 11, a driving device 12, an electronic sensor 13, and an image stabilizing module 14. The imaging lens 11 includes the imaging optical system of the first embodiment, a lens barrel (not shown) for carrying the imaging optical system, and a support device (not shown), and the imaging lens 11 may be configured with the imaging optical system of another embodiment, which is not limited to this. The image capturing device 10 uses the imaging lens 11 to focus light to generate an image, and performs image focusing in cooperation with the driving device 12, and finally images on the electronic sensor 13 and can output the image data.

The driving device 12 may have an Auto-Focus (Auto-Focus) function, and the driving method thereof may use a driving system such as a Voice Coil Motor (VCM), a Micro Electro-Mechanical Systems (MEMS), a Piezoelectric system (piezo-electric), and a Memory Alloy (Shape Memory Alloy). The driving device 12 can make the imaging lens 11 obtain a better imaging position, and can provide a clear image for the subject in the state of different object distances. In addition, the image capturing device 10 carries an electronic photosensitive element 13 (such as CMOS, CCD) with good brightness and low noise to be disposed on the image plane of the image capturing optical system, so as to truly present the good image quality of the image capturing optical system.

The image stabilization module 14 is, for example, an accelerometer, a gyroscope or a Hall Effect Sensor. The driving device 12 can be used as an Optical Image Stabilization (OIS) device in combination with the Image Stabilization module 14, and compensate for a blur Image generated by shaking at the moment of shooting by adjusting the variation of the imaging lens 11 in different axial directions, or provide an Electronic anti-shake function (EIS) by using an Image compensation technique in Image software, so as to further improve the imaging quality of shooting dynamic and low-illumination scenes.

< twelfth embodiment >

Referring to fig. 22 to 24, wherein fig. 22 is a perspective view of one side of an electronic device according to a twelfth embodiment of the disclosure, fig. 23 is a perspective view of the other side of the electronic device of fig. 22, and fig. 24 is a system block diagram of the electronic device of fig. 22.

In this embodiment, the electronic device 20 is a smart phone. The electronic device 20 includes the Image capturing device 10, the Image capturing device 10a, the Image capturing device 10b, the flash module 21, the focusing auxiliary module 22, an Image Signal Processor 23 (Image Signal Processor), a user interface 24 and an Image software Processor 25 of the eleventh embodiment. The image capturing device 10, the image capturing device 10a and the image capturing device 10b face the same direction and are all single focus. The

image capturing devices

10a and 10b have similar configurations as the image capturing device 10. In detail, the image capturing device 10a and the image capturing device 10b each include an imaging lens, a driving device, an electronic sensor and an image stabilizing module. The imaging lenses of the image capturing device 10a and the image capturing device 10b each include a lens system group, a lens barrel for carrying the lens system group, and a supporting device.

The image capturing device 10, the image capturing device 10a and the image capturing device 10b of the present embodiment have different viewing angles. In detail, the image capturing device 10 is a wide-angle image capturing device, the image capturing device 10a is a telescopic image capturing device, and the image capturing device 10b is an ultra-wide-angle image capturing device, and the maximum viewing angle of the image capturing device 10 is between the maximum viewing angles of the image capturing device 10a and the image capturing device 10 b. The image capturing device 10, the image capturing device 10a and the image capturing device 10b of the present embodiment have different viewing angles, so that the electronic device 20 can provide different magnifications to achieve the photographing effect of optical zooming. The electronic device 20 includes a plurality of

image capturing devices

10, 10a, 10b as an example, but the number and arrangement of the image capturing devices are not intended to limit the present invention.

When a user shoots a subject 26, the electronic device 20 utilizes the image capturing device 10, the image capturing device 10a, or the image capturing device 10b to collect light for image capturing, starts the flash module 21 to supplement light, performs fast focusing using the object distance information of the subject 26 provided by the focusing auxiliary module 22, and performs image optimization processing by the image signal processor 23 to further improve the quality of an image generated by the image capturing optical system. The focus aid module 22 may employ an infrared or laser focus aid system to achieve rapid focus. The user interface 24 may employ a touch screen or a physical camera button, and perform image capturing and image processing in cooperation with various functions of the image software processor 25. The images processed by the image software processor 25 may be displayed on the user interface 24.

The image capturing device 10 of the present invention is not limited to be applied to a smart phone. The image capturing device 10 can be applied to a mobile focusing system according to the requirement, and has the characteristics of excellent aberration correction and good imaging quality. For example, the image capturing device 10 can be applied to electronic devices such as three-dimensional (3D) image capturing, digital cameras, mobile devices, tablet computers, smart televisions, network monitoring equipment, driving recorders, back-up developing devices, multi-lens devices, identification systems, motion sensing game machines, wearable devices, and the like. The electronic device is only an exemplary embodiment of the present invention, and is not intended to limit the scope of the image capturing device of the present invention.

Although the present invention has been described with reference to the above embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention.

Claims

1. An optical system for image capture, comprising eight lenses, in order from an object side to an image side, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens, wherein the eight lenses respectively have an object side surface facing the object side direction and an image side surface facing the image side direction, and the total number of the lenses of the optical system for image capture is eight;

the first lens element with positive refractive power has a convex object-side surface at a paraxial region, the fifth lens element with positive refractive power has a negative refractive power, the sixth lens element with negative refractive power has a positive refractive power, the seventh lens element with positive refractive power has a convex object-side surface at a paraxial region, the eighth lens element with negative refractive power has a convex object-side surface at a paraxial region, the eighth lens element with a concave image-side surface at a paraxial region, and at least one surface of at least one lens element in the imaging optical system has at least one critical point at an off-axis region;

wherein an abbe number of the second lens element is V2, a curvature radius of the object-side surface of the second lens element is R3, a focal length of the image pickup optical system is f, a focal length of the first lens element is f1, a focal length of the fifth lens element is f5, a focal length of the seventh lens element is f7, and a focal length of the eighth lens element is f8, and the following conditions are satisfied:

10.0<V2<50.0；

0<R3/f<2.0；

0-and-f 5/f1<9.5; and

-7.5<f8/f7<-0.55；

wherein an abbe number of the first lens is V1, an abbe number of the third lens is V3, an abbe number of the fourth lens is V4, an abbe number of the fifth lens is V5, an abbe number of the sixth lens is V6, an abbe number of the seventh lens is V7, an abbe number of the eighth lens is V8, an abbe number of the ith lens is Vi, a refractive index of the first lens is N1, a refractive index of the second lens is N2, a refractive index of the third lens is N3, a refractive index of the fourth lens is N4, a refractive index of the fifth lens is N5, a refractive index of the sixth lens is N6, a refractive index of the seventh lens is N7, a refractive index of the eighth lens is N8, a refractive index of the ith lens is Ni, and a minimum value of Vi/Ni is (Vi/Ni) min, which satisfies the following conditions:

6.0< (Vi/Ni) min <12.0, wherein i =1, 2, 3, 4, 5, 6, 7 or 8.

2. The imaging optical system according to claim 1, wherein the abbe number of the second lens is V2, and the following condition is satisfied:

12.0<V2<30.0。

3. the imaging optical system according to claim 1, wherein a radius of curvature of the object-side surface of the second lens element is R3, and a focal length of the imaging optical system is f, and the following conditions are satisfied:

0.15<R3/f<1.4。

4. the imaging optical system according to claim 1, wherein an optical thickness of the first lens element is CT1, an optical thickness of the second lens element is CT2, an optical thickness of the third lens element is CT3, an optical thickness of the fourth lens element is CT4, and an optical thickness of the fifth lens element is CT5, and the following conditions are satisfied:

0.20<(CT2+CT3+CT4)/(CT1+CT5)<0.75。

5. the imaging optical system according to claim 1, wherein a thickness of the fifth lens element on the optical axis is CT5, and a thickness of the seventh lens element on the optical axis is CT7, and the following conditions are satisfied:

0.10<CT7/CT5<1.3。

6. the imaging optical system according to claim 1, wherein a radius of curvature of the object-side surface of the fifth lens element is R9, and a radius of curvature of the image-side surface of the fifth lens element is R10, and the following conditions are satisfied:

-1.5<(R9+R10)/(R9-R10)<1.5。

7. the imaging optical system according to claim 1, wherein a focal length of the imaging optical system is f, and a focal length of the third lens is f3, and the following conditions are satisfied:

-0.40<f/f3<0.40。

8. the imaging optical system according to claim 1, wherein a focal length of the imaging optical system is f, and a combined focal length of the second lens and the third lens is f23, and the following conditions are satisfied:

-0.40<f/f23<0.20。

9. the imaging optical system according to claim 1, wherein an aperture value of the imaging optical system is Fno, a maximum effective radius of the object-side surface of the first lens element is Y11, and a maximum effective radius of the image-side surface of the eighth lens element is Y82, and the following conditions are satisfied:

1.2-Fno-1.8; and

1.8<Y82/Y11<3.0。

10. the imaging optical system according to claim 1, wherein a distance between the seventh lens element and the eighth lens element on the optical axis is a maximum one of distances between two adjacent lens elements on the optical axis in the imaging optical system;

wherein a vertical distance between a critical point of the object-side surface of the seventh lens element and the optical axis is Yc71, a vertical distance between a critical point of the image-side surface of the seventh lens element and the optical axis is Yc72, and at least one of the critical points of the object-side surface and the image-side surface of the seventh lens element at off-axis respectively satisfies the following conditions:

0.80<Yc72/Yc71<1.5。