An ultra-wide-angle lens

Abstract

The present invention provides an ultra-wide-angle lens, comprising a first lens, a second lens, a third lens, an aperture, a fourth lens, a fifth lens, a sixth lens and a filter arranged in sequence from the object side to the image side along the optical axis direction, wherein the object side surface of the optical axis region of the first lens is a convex surface; the object side surface and the image side surface of the optical axis region of the second lens are concave surfaces; the ultra-wide-angle lens satisfies the following relationship: f1'<0, f2'<0, f3'>0, f4'>0, f5'<0, f6'>0, 0.4

Description

Technical Field

[0001] The present invention relates to the technical field of optical lenses, and in particular to an ultra-wide-angle lens. Background Art

[0002] Ultra-wide-angle lenses have a wider field of view and are therefore widely used in situations where a wide range of imaging is required. As the main component of imaging equipment, the performance of the lens determines the imaging performance of the equipment, and the number of lenses in the lens determines the cost of the lens.

[0003] However, the existing ultra-wide-angle lens has a field of view of only about 120 degrees, which limits the viewing angle. Summary of the invention

[0004] The purpose of the present invention is to provide an ultra-wide-angle lens to solve the problem of small field of view of existing ultra-wide-angle lenses.

[0005] The present invention provides an ultra-wide-angle lens, comprising a first lens, a second lens, a third lens, an aperture, a fourth lens, a fifth lens, a sixth lens and a filter arranged in sequence from the object side to the image side along the optical axis direction, wherein the object side surface of the optical axis region of the first lens is a convex surface; the object side surface and the image side surface of the optical axis region of the second lens are concave surfaces; the ultra-wide-angle lens satisfies the following relationship:

[0006] f1'<0, f2'<0, f3'>0, f4'>0, f5'<0, f6'>0, 0.4 <CT / TTL<0.6,4.2<TTL / ImaH<4.4,10.0<TTL / f’<12.7,0.68<f’ / IH<0.85;

[0007] Wherein, CT is the sum of the thicknesses of the first lens to the sixth lens on the optical axis, TTL is the distance from the object side surface of the first lens to the image plane, IH is half of the image height of the ultra wide-angle lens, ImaH is the image height of the ultra wide-angle lens, f' is the focal length of the ultra wide-angle lens, and the focal lengths of the first lens to the sixth lens are f1', f2', f3', f4', f5', and f6', respectively.

[0008] Furthermore, the ultra wide-angle lens also satisfies the following relationship: f123'<0, f456'>0, wherein f123' is the combined focal length of the first lens, the second lens, and the third lens, and f456' is the combined focal length of the fourth lens, the fifth lens, and the sixth lens.

[0009] Furthermore, the ultra-wide-angle lens also satisfies the following relationship: -0.86 <f456' / f123'<-0.63。

[0010] Furthermore, the ultra-wide-angle lens further satisfies the following relational expression: 1.6 < f1' / f2' < 2.2.

[0011] Furthermore, the ultra-wide-angle lens further satisfies the following relational expression: 3.5 < R1 / R2 < 5.2, where R1 is the curvature radius of the object side surface of the first lens, and R2 is the curvature radius of the image side surface of the first lens.

[0012] Furthermore, the first lens and the fourth lens are made of glass, and the second lens, the third lens, the fifth lens, and the sixth lens are made of plastic.

[0013] Furthermore, the ultra-wide-angle lens further satisfies the following relational expression: 0.1 < (R3 + R4) / (R3 - R4) < 0.75, where R3 is the curvature radius of the object side surface of the second lens, and R4 is the curvature radius of the image side surface of the second lens.

[0014] Furthermore, the ultra-wide-angle lens further satisfies the following relational expression: -0.35 < f’ / f123’ < -0.22, where f123' is the combined focal length of the first lens, the second lens, and the third lens.

[0015] Furthermore, the ultra-wide-angle lens further satisfies the following relational expression: 0.34 < f’ / f456’ < 0.45, where f456' is the combined focal length of the fourth lens, the fifth lens, and the sixth lens.

[0016] Furthermore, the ultra-wide-angle lens further satisfies the following relational expression: 13.5 < TTL < 14.6, where TTL is the distance from the object side surface of the first lens to the image plane.

[0017] The ultra-wide-angle lens provided by the present invention includes a first lens, a second lens, a third lens, a diaphragm, a fourth lens, a fifth lens, a sixth lens, and a filter arranged in sequence from the object side to the image side along the optical axis direction. It is characterized in that the object side surface in the optical axis region of the first lens is a convex surface; the object side surface and the image side surface in the optical axis region of the second lens are concave surfaces; the ultra-wide-angle lens satisfies the following relational expressions: f1' < 0, f2' < 0, f3' > 0, f4' > 0, f5' < 0, f6' > 0, 0.4 < CT / TTL < 0.6, 4.2 < TTL / ImaH < 4.4, 10.0 < TTL / f’ < 12.7, 0.68 < f’ / IH < 0.85. The field of view angle of the ultra-wide-angle lens reaches 180 - 220 degrees, providing an ultra-wide-angle lens with a large field of view angle. Description of the Drawings

[0018] Figure 1 It is a cross-sectional view of an ultra-wide-angle lens provided in Embodiment 1 of the present invention;

[0019] Figure 2 for Figure 1 Schematic diagram of optical data of each lens in the ultra-wide-angle lens;

[0020] Figure 3 for Figure 1 Schematic diagram of aspherical parameters of ultra-wide-angle lens;

[0021] Figure 4 for Figure 1 Schematic diagram of field curvature and distortion of ultra-wide-angle lens in;

[0022] Figure 5 for Figure 1 Schematic diagram of longitudinal aberration of the ultra-wide-angle lens;

[0023] Figure 6 is a cross-sectional view of an ultra-wide-angle lens provided in Embodiment 2 of the present invention;

[0024] Figure 7 for Figure 6 Schematic diagram of optical data of each lens in the ultra-wide-angle lens;

[0025] Figure 8 for Figure 6 Schematic diagram of aspherical parameters of ultra-wide-angle lens;

[0026] Fig. 9 for Figure 6 Schematic diagram of field curvature and distortion of ultra-wide-angle lens in;

[0027] Fig.10 for Figure 6 Schematic diagram of longitudinal aberration of the ultra-wide-angle lens;

[0028] Fig.11 is a cross-sectional view of an ultra-wide-angle lens provided in Embodiment 3 of the present invention;

[0029] Fig.12 for Fig.11 Schematic diagram of optical data of each lens in the ultra-wide-angle lens;

[0030] Fig.13 for Fig.11 Schematic diagram of aspherical parameters of ultra-wide-angle lens;

[0031] Fig.14 for Fig.11 Schematic diagram of field curvature and distortion of ultra-wide-angle lens in;

[0032] Fig.15 for Fig.11 Schematic diagram of longitudinal aberration of the ultra-wide-angle lens;

[0033] Fig.16 is a cross-sectional view of an ultra-wide-angle lens provided in Embodiment 4 of the present invention;

[0034] Fig.17 for Fig.16 Schematic diagram of optical data of each lens in the ultra-wide-angle lens;

[0035] Fig.18 for Fig.16 Schematic diagram of aspherical parameters of ultra-wide-angle lens;

[0036] Fig.19 for Fig.16 Schematic diagram of field curvature and distortion of ultra-wide-angle lens in;

[0037] Fig. 20 for Fig.16 Schematic diagram of longitudinal aberration of the ultra-wide-angle lens;

[0038] Fig.21 is a cross-sectional view of an ultra-wide-angle lens provided in Embodiment 5 of the present invention;

[0039] Fig. 22 for Fig.21 Schematic diagram of optical data of each lens in the ultra-wide-angle lens;

[0040] Fig.23 for Fig.21 Schematic diagram of aspherical parameters of ultra-wide-angle lens;

[0041] Fig.24 for Fig.21 Schematic diagram of field curvature and distortion of ultra-wide-angle lens in;

[0042] Fig.25 for Fig.21 Schematic diagram of the longitudinal aberration of the ultra-wide-angle lens.

[0043] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0044] In order to facilitate understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Several embodiments of the present invention are provided in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0045] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0047] Embodiment 1

[0048] See also Figures 1 to 5 The first embodiment of the present invention provides an ultra-wide-angle lens, comprising a first lens 11, a second lens 12, a third lens 13, an aperture 18, a fourth lens 14, a fifth lens 15, a sixth lens 16 and a filter 17 arranged in sequence from the object side to the image side along the optical axis direction, wherein the object side surface of the optical axis region of the first lens 11 is a convex surface; the object side surface and the image side surface of the optical axis region of the second lens 12 are concave surfaces; the ultra-wide-angle lens satisfies the following relationship:

[0049] f1'<0, f2'<0, f3'>0, f4'>0, f5'<0, f6'>0, 0.4 <CT / TTL<0.6,4.2<TTL / ImaH<4.4,10.0<TTL / f’<12.7,0.68<f’ / IH<0.85;

[0050] Wherein, CT is the sum of the thicknesses of the first lens 11 to the sixth lens 16 on the optical axis, TTL is the distance from the object side of the first lens 11 to the image plane, IH is half of the image height of the ultra wide-angle lens, ImaH is the image height of the ultra wide-angle lens, f' is the focal length of the ultra wide-angle lens, and the focal lengths of the first lens 11 to the sixth lens 16 are f1', f2', f3', f4', f5', and f6', respectively.

[0051] In this embodiment, the first lens 11 includes an object side surface 111 and an image side surface 112. The object side surface 111 in the optical axis region of the first lens 11 is a convex surface, and the image side surface 112 in the optical axis region is a concave surface. The material of the first lens 11 is glass. The first lens 11 is conducive to focusing light of the ultra-wide-angle lens 200 and is conducive to expanding the field of view of the ultra-wide-angle lens.

[0052] The second lens 12 includes an object side surface 121 and an image side surface 122. The object side surface 121 of the optical axis region of the second lens 12 is a concave surface, and the image side surface 122 of the optical axis region is a concave surface. The material of the second lens 12 is plastic. The second lens 12 is used to correct the aberration of the ultra-wide-angle lens.

[0053] The third lens 13 includes an object side surface 131 and an image side surface 132. The object side surface 131 of the optical axis region of the third lens 13 is a convex surface, and the image side surface 132 of the optical axis region is a convex surface. The material of the third lens 13 is plastic. The third lens 13 is used to correct the aberration of the ultra-wide-angle lens 200.

[0054] The fourth lens 14 includes an object side surface 141 and an image side surface 142. The object side surface 141 in the optical axis region of the fourth lens 14 is a convex surface, and the image side surface 142 in the optical axis region is a convex surface. The material of the fourth lens 14 is glass. The fourth lens 14 is used to correct the aberration of the ultra-wide-angle lens 200.

[0055] The fifth lens 15 includes an object side surface 151 and an image side surface 152. The object side surface 151 in the optical axis region of the fifth lens 15 is a concave surface, and the image side surface 152 in the optical axis region is a concave surface. The material of the fifth lens 15 is plastic. The fifth lens 15 is used to correct the aberration of the ultra-wide-angle lens.

[0056] The sixth lens 16 includes an object side surface 161 and an image side surface 162. The object side surface 161 in the optical axis region of the sixth lens 16 is a convex surface, and the image side surface 162 in the optical axis region is a convex surface. The sixth lens 16 is made of plastic. The sixth lens 16 is used to correct the aberration of the ultra-wide-angle lens.

[0057] In this embodiment, the system parameters of the ultra-wide-angle lens are set as follows: Figure 2 As shown, the field of view can reach 190 degrees, which greatly improves the field of view.

[0058] It should be noted that in this embodiment Figure 2 , and in other embodiments Figure 7 , Fig.12 , Fig.17 , Fig. 22 In the datasheet, except for material and field of view, all other parameters are in millimeters.

[0059] It can be understood that in the embodiment of the present invention, the Nth lens mn includes an object-side surface mn1 and an image-side surface mn2, wherein N=(1, 2, 3, 4, 5, 6); m=(1, 2, 3, 4, 5, 6); n=(1, 2, 3, 4, 5, 6); when N is 1, n=1; when N is 2, n=2; when N is 3, n=3; when N is 4, n=4; when N is 5, n=5; when N is 6, n=6.

[0060] Embodiment 2

[0061] Please refer to Figures 6 to 10 , an ultra-wide-angle lens provided by the second embodiment of the present invention includes a first lens 21, a second lens 22, a third lens 23, a diaphragm 28, a fourth lens 24, a fifth lens 25, a sixth lens 26, and a filter 27 arranged in sequence from the object side to the image side and along the optical axis direction. The object side surface of the optical axis region of the first lens 21 is convex; the object side surface and the image side surface of the optical axis region of the second lens 22 are concave; the ultra-wide-angle lens satisfies the following relational expressions: f1'<0, f2'<0, f3'>0, f4'>0, f5'<0, f6'>0, 0.4<CT / TTL<0.6, 4.2<TTL / ImaH<4.4, 10.0<TTL / f’<12.7, 0.68<f’ / IH<0.85; where CT is the total thickness of the first lens 21 to the sixth lens 26 on the optical axis, TTL is the distance between the object side surface of the first lens 21 and the image surface, IH is half of the image height of the ultra-wide-angle lens, ImaH is the image height of the ultra-wide-angle lens, f' is the focal length of the ultra-wide-angle lens, and the focal lengths of the first lens 21 to the sixth lens 26 are f1', f2', f3', f4', f5', and f6' respectively.

[0062] In this embodiment, the system parameters of the ultra-wide-angle lens are set as shown in Figure 7 , which can make the field of view reach 200 degrees, greatly improving the field of view.

[0063] Embodiment 3

[0064] Please refer to Figure Figures 11 to 15, an ultra-wide-angle lens provided by the third embodiment of the present invention includes a first lens 31, a second lens 32, a third lens 33, a diaphragm 38, a fourth lens 34, a fifth lens 35, a sixth lens 36, and a filter 37 arranged in sequence from the object side to the image side and along the optical axis direction. The object side surface of the optical axis region of the first lens 31 is convex; the object side surface and the image side surface of the optical axis region of the second lens 32 are concave; the ultra-wide-angle lens satisfies the following relational expressions: f1'<0, f2'<0, f3'>0, f4'>0, f5'<0, f6'>0, 0.4<CT / TTL<0.6, 4.2<TTL / ImaH<4.4, 10.0<TTL / f’<12.7, 0.68<f’ / IH<0.85; where CT is the total thickness of the first lens 31 to the sixth lens 36 on the optical axis, TTL is the distance from the object side surface of the first lens 31 to the image surface, IH is half of the image height of the ultra-wide-angle lens, ImaH is the image height of the ultra-wide-angle lens, f' is the focal length of the ultra-wide-angle lens, and the focal lengths of the first lens 31 to the sixth lens 36 are f1', f2', f3', f4', f5', f6' respectively.

[0065] In this embodiment, the system parameters of the ultra-wide-angle lens are set as Fig.12 shown, which can make the field of view reach 220 degrees, greatly improving the field of view.

[0066] Embodiment Four

[0067] Please refer to Figures 16 to 20 , an ultra-wide-angle lens provided by the fourth embodiment of the present invention includes a first lens 41, a second lens 42, a third lens 43, a diaphragm 48, a fourth lens 44, a fifth lens 45, a sixth lens 46, and a filter 47 arranged in sequence from the object side to the image side and along the optical axis direction. The object side surface of the optical axis region of the first lens 41 is convex; the object side surface and the image side surface of the optical axis region of the second lens 42 are concave; the ultra-wide-angle lens satisfies the following relational expressions: f1'<0, f2'<0, f3'>0, f4'>0, f5'<0, f6'>0, 0.4<CT / TTL<0.6, 4.2<TTL / ImaH<4.4, 10.0<TTL / f’<12.7, 0.68<f’ / IH<0.85; where CT is the total thickness of the first lens 41 to the sixth lens 46 on the optical axis, TTL is the distance from the object side surface of the first lens 41 to the image surface, IH is half of the image height of the ultra-wide-angle lens, ImaH is the image height of the ultra-wide-angle lens, f' is the focal length of the ultra-wide-angle lens, and the focal lengths of the first lens 41 to the sixth lens 46 are f1', f2', f3', f4', f5', f6' respectively. Specifically, in this embodiment, the system parameters of the ultra-wide-angle lens system are as Fig.17 as shown in

[0068] In this embodiment, the system parameters of the ultra-wide-angle lens are set as shown in Fig.17 , so that the field of view can reach 180 degrees, greatly improving the field of view.

[0069] Embodiment Five

[0070] Please refer to Figure 21 to Figure 25 , an ultra-wide-angle lens provided by the fourth embodiment of the present invention includes a first lens 51, a second lens 52, a third lens 53, a diaphragm 58, a fourth lens 54, a fifth lens 55, a sixth lens 56 and a filter 57 arranged in sequence from the object side to the image side and along the optical axis direction. The object side surface of the optical axis region of the first lens 51 is convex; the object side surface and the image side surface of the optical axis region of the second lens 52 are concave; the ultra-wide-angle lens satisfies the following relational expressions: f1'<0, f2'<0, f3'>0, f4'>0, f5'<0, f6'>0, 0.4 < CT / TTL < 0.6, 4.2 < TTL / ImaH < 4.4, 10.0 < TTL / f’ < 12.7, 0.68 < f’ / IH < 0.85; where CT is the total thickness of the first lens 51 to the sixth lens 56 on the optical axis, TTL is the distance from the object side surface of the first lens 51 to the image surface, IH is half of the image height of the ultra-wide-angle lens, ImaH is the image height of the ultra-wide-angle lens, f' is the focal length of the ultra-wide-angle lens, and the focal lengths of the first lens 51 to the sixth lens 56 are f1', f2', f3', f4', f5', f6' respectively. Specifically, in this embodiment, the system parameters of the ultra-wide-angle lens are as shown in Fig. 22 as shown in

[0071] In this embodiment, the system parameters of the ultra-wide-angle lens are set as shown in Fig. 22 , so that the field of view can reach 190, greatly improving the field of view.

[0072] The ultra-wide-angle lens provided by the present invention includes a first lens, a second lens, a third lens, a diaphragm, a fourth lens, a fifth lens, a sixth lens and a filter arranged in sequence from the object side to the image side and along the optical axis direction. The object side surface of the optical axis region of the first lens is convex; the object side surface and the image side surface of the optical axis region of the second lens are concave; the ultra-wide-angle lens satisfies the following relational expressions: f1'<0, f2'<0, f3'>0, f4'>0, f5'<0, f6'>0, 0.4 < CT / TTL < 0.6, 4.2 < TTL / ImaH < 4.4, 10.0 < TTL / f’ < 12.7, 0.68 < f’ / IH < 0.85. The field of view of the ultra-wide-angle lens can reach 180 - 220 degrees, providing an ultra-wide-angle lens with a large field of view.

[0073] In some embodiments, the ultra-wide-angle lens further satisfies the following relational expressions:

[0074] 1. The ultra-wide-angle lens further satisfies the following relational expression: -0.86 < f456' / f123' < -0.63.

[0075] 2. The ultra-wide-angle lens further satisfies the following relational expression: 1.6 < f1' / f2' < 2.2.

[0076] 3. The ultra-wide-angle lens further satisfies the following relational expression: 3.5 < R1 / R2 < 5.2, where R1 is the curvature radius of the object side surface of the first lens, and R2 is the curvature radius of the image side surface of the first lens.

[0077] 4. The first lens and the fourth lens are made of glass, and the second lens, the third lens, the fifth lens, and the sixth lens are made of plastic.

[0078] 5. The ultra-wide-angle lens further satisfies the following relational expression: 0.1 < (R3 + R4) / (R3 - R4) < 0.75, where R3 is the curvature radius of the object side surface of the second lens, and R4 is the curvature radius of the image side surface of the second lens.

[0079] 6. The ultra-wide-angle lens further satisfies the following relational expression: -0.35 < f’ / f123’ < -0.22, where f123' is the combined focal length of the first lens, the second lens, and the third lens.

[0080] 7. The ultra-wide-angle lens further satisfies the following relational expression: 0.34 < f’ / f456’ < 0.45, where f456' is the combined focal length of the fourth lens, the fifth lens, and the sixth lens.

[0081] 8. The ultra-wide-angle lens further satisfies the following relational expression: 13.5 < TTL < 14.6, where the distance TTL from the object side surface to the image side surface is the distance from the object side surface of the first lens to the image side surface. The relational expressions defined in the above various embodiments can be arbitrarily combined to adjust the physical and optical properties of each lens.

[0082] In other embodiments of the present invention, an electronic device is further provided, including the above ultra-wide-angle lens, and further including a housing. The ultra-wide-angle lens is received in the housing to provide an electronic device with a large field of view.

[0083] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An ultra-wide-angle lens, comprising a first lens, a second lens, a third lens, a stop, a fourth lens, a fifth lens, a sixth lens and a filter arranged in sequence from the object side to the image side and along the optical axis, characterized in that: The object side surface of the optical axis region of the first lens is convex; the object side surface and the image side surface of the optical axis region of the second lens are concave; the ultra-wide-angle lens satisfies the following relational expressions: f1'<0, f2'<0, f3'>0, f4'>0, f5'<0, f6'>0, 0.4 < CT / TTL < 0.6, 4.2 < TTL / ImaH < 4.4, 10.0 < TTL / f’ < 12.7, 0.68 < f’ / IH < 0.85; Wherein, CT is the total thickness of the first lens to the sixth lens on the optical axis, TTL is the distance between the object side surface of the first lens and the image surface, IH is half of the image height of the ultra-wide-angle lens, ImaH is the image height of the ultra-wide-angle lens, f' is the focal length of the ultra-wide-angle lens, and the focal lengths of the first lens to the sixth lens are f1', f2', f3', f4', f5', f6' respectively; The ultra-wide-angle lens also satisfies the following relational expressions: -0.86 < f456' / f123' < -0.63, 1.6 < f1' / f2' < 2.

2.

2. The ultra-wide-angle lens according to claim 1, characterized in that: The ultra-wide-angle lens also satisfies the following relational expressions: f123' < 0, f456' > 0, where f123' is the combined focal length of the first lens, the second lens, and the third lens, and f456' is the combined focal length of the fourth lens, the fifth lens, and the sixth lens.

3. The ultra-wide-angle lens according to claim 1, characterized in that: The ultra-wide-angle lens also satisfies the following relational expressions: 3.5 < R1 / R2 < 5.2, where R1 is the curvature radius of the object side surface of the first lens, and R2 is the curvature radius of the image side surface of the first lens.

4. The ultra-wide-angle lens according to claim 1, characterized in that: The first lens and the fourth lens are made of glass, and the second lens, the third lens, the fifth lens, and the sixth lens are made of plastic.

5. The ultra-wide-angle lens according to claim 1, characterized in that: The ultra-wide-angle lens also satisfies the following relational expressions: 0.1 < (R3 + R4) / (R3 - R4) < 0.75, where R3 is the curvature radius of the object side surface of the second lens, and R4 is the curvature radius of the image side surface of the second lens.

6. The ultra-wide-angle lens according to claim 1, characterized in that: The ultra-wide-angle lens also satisfies the following relational expressions: -0.35 < f’ / f123’ < -0.22, where f123' is the combined focal length of the first lens, the second lens, and the third lens.

7. The ultra-wide-angle lens according to claim 1, characterized in that: The ultra-wide-angle lens also satisfies the following relational expressions: 0.34 < f’ / f456’ < 0.45, where f456' is the combined focal length of the fourth lens, the fifth lens, and the sixth lens.

8. The ultra-wide-angle lens according to claim 1, characterized in that: The ultra-wide-angle lens also satisfies the following relational expressions: 13.5 < TTL < 14.6, where TTL is the distance between the object side surface of the first lens and the image surface.

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