Prime lens

Abstract

The prime lens disclosed by the invention can be used for a full-frame camera. The prime lens sequentially comprises a first lens group with negative refractive power, an aperture diaphragm, a second lens group with positive refractive power and a third lens group with negative refractive power in the direction of an incident optical axis. The first lens in the direction of the incident optical axis is a positive lens, the object side surface is a non-spherical convex surface, and the image side surface is a spherical convex surface. The last lens in the direction of the incident optical axis is a negative lens, the object side face is a non-spherical concave face, and the image side face is a non-spherical concave face. The first lens and the last lens have the same d-line refractive index, d-line Abbe number and object side aspheric surface expression. In a large light flux interval, the prime lens is high in imaging resolution and low in optical distortion.

Description

Technical Field

[0001] The present application belongs to the technical field of photographic lenses, and in particular relates to a fixed-focus lens for a full-frame camera. Background Art

[0002] The photosensitive element area of ​​a full-frame camera is equivalent to that of a 35mm film. The lens of a full-frame camera should have a large aperture and low optical distortion to ensure image quality. The official website of the Sony SEL50F1.4GM fixed-focus lens from Japan has disclosed the lens structure and modulation transfer function (MTF) curve, which can be found at Figure 6 and Figure 7 . Summary of the invention

[0003] The technical problem to be solved by this application is how to improve the fixed-focus lens to improve the imaging quality of the full-frame camera.

[0004] The present application discloses a fixed-focus lens.

[0005] This fixed-focus lens can be used for full-frame cameras. It includes the following components along the incident optical axis: The first lens group is fixed relative to the image plane and has negative refractive power. The first lens along the incident optical axis is a positive lens, the object side surface is a non-spherical convex surface, and the image side surface is a spherical convex surface; Aperture stop; fixed relative to the image plane; The second lens group is movable along the incident optical axis, has positive refractive power, and is close to the imaging surface after focusing on a close object; and The third lens group is fixed relative to the image plane and has negative refractive power, the last lens along the incident optical axis is a negative lens, the object side surface is a non-spherical concave surface, and the image side surface is a non-spherical concave surface; The first lens and the last lens have the same d-line refractive index, d-line Abbe number and object-side aspheric surface expression.

[0006] In some embodiments of the present application, it can be selected that the maximum light flux of the fixed focus lens is F / 1.2~1.3, and the first lens group and the third lens group each include two consecutively arranged biconvex spherical positive lenses. Further, the first lens has a curvature radius of +118.78mm on the object side, a curvature radius of -87.61mm on the image side, an optical axis thickness of 6.60mm, a d-line refractive index of 1.81, and a d-line Abbe number of 40.7; the last lens has a curvature radius of -188.70mm on the object side, a curvature radius of +500.00mm on the image side, an optical axis thickness of 2.00mm, a d-line refractive index of 1.81, and a d-line Abbe number of 40.7.

[0007] By implementing the technical solution of this application, the following beneficial effects can be obtained.

[0008] The fixed-focus lens disclosed in the present application can be used for a full-frame camera. The fixed-focus lens includes a first lens group with negative refractive power, an aperture stop, a second lens group with positive refractive power, and a third lens group with negative refractive power in sequence along the direction of the incident optical axis. The first lens along the direction of the incident optical axis is a positive lens, the object side surface is a non-spherical convex surface, and the image side surface is a spherical convex surface. The last lens along the direction of the incident optical axis is a negative lens, the object side surface is a non-spherical concave surface, and the image side surface is a non-spherical concave surface. The first lens and the last lens have consistent d-line refractive index, d-line Abbe number, and object side surface aspherical expression. In a large light flux range, the fixed-focus lens has high imaging resolution and low optical distortion. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The following drawings should be used in conjunction with the detailed description.

[0010] Figure 1 This is a cross-sectional view of the optical axis of the fixed-focus lens in the first embodiment, and the legends represent: IMG-image plane, FIT-filter protector, STO-aperture stop, Z1-incident optical axis.

[0011] Figure 2a Table 1 shown lists the data and position relationship of each lens in Example 1.

[0012] Figure 2b The even-order binomials f1 of the three aspherical surfaces of the first embodiment and Table 2 recording the aspherical coefficients of the three surfaces are listed.

[0013] Figure 3 This is a light path diagram of the fixed-focus lens in the infinity focus state in the first embodiment.

[0014] Figure 4 This is a light path diagram of the fixed-focus lens in the close-range focusing state in the first embodiment.

[0015] Figure 5a and Figure 5b is a modulation transfer function (MTF) curve of the fixed focus lens at the maximum light flux F / 1.25 in the first embodiment, Figure 5b The 4 curve codes are Figure 7 The meaning is consistent; Figure 5a The method of obtaining it is to set the maximum frequency to 30 line pairs in ZEMAX optical software / Analysis / MTF curve / FFT MTF; Figure 5b The method to obtain it is to set the *1 and *2 curves to 10 line pairs and the *3 and *4 curves to 30 line pairs in ZEMAX Optical Software / Analysis / MTF Curve / FFT MTF VS. Field of View.

[0016] Figure 6 and Figure 7Selected from the official website of Japan's SONY SEL50F1.4GM fixed-focus lens https: / / www.sonystyle.com.cn / products / lenses / sel50f14gm / sel50f14gm_feature.html , Figure 6 is a structural diagram, Figure 7 The specific method of obtaining the modulation transfer function curve is unknown. DETAILED DESCRIPTION

[0017] The embodiments are described below with reference to the accompanying drawings.

[0018] In this specification, unless otherwise specified, one embodiment, some embodiments and other embodiments are used to distinguish different embodiments and do not refer to all embodiments; directions / positions indicated by top, bottom, center, edge, inside, outside, far, near, length, width, vertical, horizontal, up, down, front, back, left, right, etc. are based on the observation angle of the drawings and cannot be understood as a component / device being located at a specific position or facing a specific direction.

[0019] In this specification, the light-transmitting surface of the lens may be referred to as the "surface", the side of the lens facing the photographed object is called the "object side", and the side of the lens facing the image plane inside the camera is called the "image side"; the aperture stop may be referred to as the "stop", and the plane on which it is located is numbered together with the light-transmitting surface of the lens.

[0020] Embodiment 1 A fixed-focus lens is disclosed.

[0021] This fixed-focus lens is used for full-frame cameras with autofocus. It has a focal length of 49mm, a maximum light transmittance of F / 1.2~1.3, and an imaging surface of 42~44mm.

[0022] See also Figure 1 , Figure 2a and Figure 2b , Figure 1 is the optical axis cross-section diagram of the fixed-focus lens, Figure 1 The incident light axis Z1 points to the image plane IMG from left to right, and a filter protector FIT is provided in front of the image plane IMG; Figure 2a and Figure 2b In the figure, the lens data and position relationship of the fixed-focus lens are listed in Table 1, Table 2 and Formula f1.

[0023] exist Figure 2a In Table 1, the object side surface of the first lens L1 is represented as surface S1, and the other light-transmitting surfaces (including the plane where the aperture stop STO is located) are numbered in ascending order along the incident optical axis Z1. "Curvature radius R" represents the paraxial curvature radius value of the vertex of a surface. i and the i+1th surface S i+1Lenses between: their "thickness" is the optical axis thickness, and their "refractive index Nd" and "Abbe number Nd" are the measured values ​​of d line (wavelength 587.6nm). In two adjacent lenses, the distance between the image side of the front lens and the object side of the rear lens on the incident optical axis Z1 is called the optical axis distance between the two.

[0024] The fixed-focus lens essentially includes three lens groups. Figure 1 In the lens element (not shown), along the incident optical axis Z1, the first lens group G1, the aperture stop STO, the second lens group G2 and the third lens group G3 are arranged in sequence from the object side to the image side.

[0025] In the process of focusing, only the second lens group G2 can be driven by the stepping motor to move forward and backward along the incident optical axis Z1, and the first lens group G1, the aperture stop STO and the third lens group G3 are all fixed relative to the image plane IMG. The optical axis spacing between the aperture stop STO and the first lens group G1 (i.e., surface S10) is about 6.0mm, the optical axis spacing between the aperture stop STO and the third lens group G2 (i.e., surface S17) is about 31.1mm, and the optical axis spacing between the image plane IMG and the third lens group G3 (i.e., surface S26) is about 14.9mm.

[0026] The first lens group G1 has negative refractive power and is composed of six glass lenses. The six glass lenses are the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5 and the sixth lens L6 along the incident optical axis Z1. The first lens L1 is cemented with the second lens L2, and the third lens L3 is cemented with the fourth lens L4. The fourth lens L4 and the fifth lens L5 are both biconvex spherical positive lenses.

[0027] The second lens group G2 has positive refractive power and is composed of three glass lenses. The three glass lenses are a seventh lens L7, an eighth lens L8 and a ninth lens L9 in sequence along the incident optical axis Z1. The eighth lens L8 is cemented with the ninth lens L8.

[0028] The third lens group G3 has negative refractive power and is composed of six glass lenses. The six glass lenses are the tenth lens L10, the eleventh lens L11, the twelfth lens L12, the thirteenth lens L13, the fourteenth lens L14 and the fifteenth lens L15 along the incident optical axis Z1. The tenth lens L10 is cemented with the eleventh lens L11, and the thirteenth lens L13 is cemented with the fourteenth lens L14. The eleventh lens L11 and the twelfth lens L12 are both biconvex spherical positive lenses.

[0029] All 15 glass lenses are distributed in sequence along the incident light axis to form three lens groups, which are installed in the lens barrel. The lens barrel is equipped with a stepper motor and a power supply interface.

[0030] Figure 1, the second lens group G2 is in the middle of its moving range.

[0031] See also Figure 3 The optical path diagram of the fixed-focus lens in the infinity focus state is shown in FIG. Figure 3 In the figure, the second lens group G2 is at the object side (left side) boundary of its moving range, and the optical axis spacing with the first lens group G1 is 7.35 mm.

[0032] See also Figure 4 The optical path diagram of the fixed-focus lens in the close-range focusing state is shown in FIG. Figure 4 In the figure, the second lens group G2 is at the image side (right side) boundary of its moving range, and the optical axis distance between it and the third lens group G3 is about 1.0 mm.

[0033] The main parameters of each glass lens are detailed below.

[0034] The first lens L1 is a positive lens, with an object side surface being a non-spherical convex surface with a curvature radius of +118.78 mm, an image side surface being a spherical convex surface with a curvature radius of -87.61 mm, an optical axis thickness of 6.60 mm, a d-line refractive index of 1.81, and a d-line Abbe number of 40.7.

[0035] The second lens L2 is a double concave spherical negative lens with a curvature radius of -87.61 mm on the object side, a curvature radius of +41.01 mm on the image side, an optical axis thickness of 1.50 mm, a d-line refractive index of 1.49, and a d-line Abbe number of 70.4. It is cemented with the first lens L1.

[0036] The third lens L3 is a biconcave spherical negative lens, with a curvature radius of -36.00 mm on the object side, a curvature radius of +122.30 mm on the image side, an optical axis thickness of 1.50 mm, a d-line refractive index of 1.78, a d-line Abbe number of 29.7, and an optical axis spacing of 10.39 mm from the second lens L2.

[0037] The fourth lens L4 is a biconvex spherical positive lens with a curvature radius of +122.30mm on the object side, a curvature radius of +41.20mm on the image side, an optical axis thickness of 10.40mm, a d-line refractive index of 1.59, and a d-line Abbe number of 68.3. It is cemented with the third lens L3.

[0038] The fifth lens L5 is a biconvex spherical positive lens, with a curvature radius of +197.32mm on the object side, a curvature radius of -77.81mm on the image side, an optical axis thickness of 7.30mm, a d-line refractive index of 2.00, a d-line Abbe number of 29.1, and an optical axis spacing of 0.15mm from the fourth lens L4 The sixth lens L6 is a negative lens. The object side surface is a convex spherical surface with a curvature radius of +95.68mm, the image side surface is a concave spherical surface with a curvature radius of +45.51mm, the optical axis thickness is 1.00mm, the d-line refractive index is 1.65, the d-line Abbe number is 33.8, the optical axis spacing between it and the fifth lens L5 is 0.15mm, and the optical axis spacing between it and the aperture stop STO is about 6.0mm.

[0039] The seventh lens L7 is a negative lens. The object side surface is a convex spherical surface with a curvature radius of +46.63mm, the image side surface is a concave spherical surface with a curvature radius of +76.03mm, the optical axis thickness is 4.00mm, the d-line refractive index is 1.88, the d-line Abbe number is 40.8, and the minimum optical axis spacing between it and the sixth lens L6 when focusing at infinity is 7.35mm.

[0040] The eighth lens L8 is a double concave spherical negative lens, with a curvature radius of -72.26mm on the object side, a curvature radius of +44.76mm on the image side, an optical axis thickness of 1.50mm, a d-line refractive index of 1.61, a d-line Abbe number of 37.0, and an optical axis spacing of 5.49mm from the seventh lens L7 The ninth lens L9 is a biconvex spherical positive lens with a curvature radius of +44.76mm on the object side, a curvature radius of -57.00mm on the image side, an optical axis thickness of 9.70mm, a d-line refractive index of 1.59, and a d-line Abbe number of 68.3. It is cemented with the eighth lens L8.

[0041] The tenth lens L10 is a double concave spherical negative lens with a curvature radius of -109.27mm on the object side, a curvature radius of +46.00mm on the image side, an optical axis thickness of 1.50mm, a d-line refractive index of 1.77, a d-line Abbe number of 29.7, an optical axis spacing of approximately 31.1mm from the aperture stop STO, and a minimum optical axis spacing of approximately 1.0mm from the ninth lens L9 when focusing at close distances.

[0042] The eleventh lens L11 is a biconvex spherical positive lens, with a curvature radius of +46.00 mm on the object side, a curvature radius of -88.76 mm on the image side, an optical axis thickness of 9.00 mm, a d-line refractive index of 1.59, and a d-line Abbe number of 68.3, and is cemented with the tenth lens L10.

[0043] The twelfth lens L12 is a biconvex spherical positive lens, with a curvature radius of +61.32 mm on the object side, a curvature radius of -343.14 mm on the image side, an optical axis thickness of 7.11 mm, a d-line refractive index of 1.92, a d-line Abbe number of 20.9, and an optical axis spacing of 0.15 mm from the eleventh lens L11.

[0044] The thirteenth lens L13 is a positive lens, with a spherical convex surface on the object side with a curvature radius of +42.03 mm, a spherical concave surface on the image side with a curvature radius of +184.08 mm, an optical axis thickness of 6.10 mm, a d-line refractive index of 1.88, a d-line Abbe number of 40.8, and an optical axis spacing of 0.15 mm from the twelfth lens L12.

[0045] The fourteenth lens L14 is a negative lens, with a spherical convex surface on the object side with a curvature radius of +184.08 mm, a spherical concave surface on the image side with a curvature radius of +26.47 mm, an optical axis thickness of 1.50 mm, a d-line refractive index of 1.85, and a d-line Abbe number of 23.8. It is cemented with the thirteenth lens L13.

[0046] The fifteenth lens L15 (i.e. the last lens) is a negative lens. Both the object side and the image side are aspherical concave surfaces. The curvature radius of the object side is -188.70 mm, the curvature radius of the image side is +500.00 mm, the optical axis thickness is 2.00 mm, the d-line refractive index is 1.81, the d-line Abbe number is 40.7, the optical axis spacing between it and the fourteenth lens L14 is 7.92 mm, and the optical axis spacing between it and the image plane IMG is about 14.9 mm.

[0047] The fixed-focus lens has two continuously arranged biconvex spherical lenses before and after the aperture stop STO, which can control the main light path and reduce the edge vignetting.

[0048] The five pairs of cemented lenses of this fixed-focus lens have large differences in the dispersion coefficients of the positive and negative lenses, which can correct chromatic aberration, off-axis aberration and astigmatism, reduce the tolerance sensitivity of imaging quality, and facilitate process control.

[0049] The first lens L1 and the fifteenth lens L15 of the fixed focus lens have the same d-line refractive index, d-line Abbe number and object-side aspheric surface expression. Specifically, the first lens L1 and the fifteenth lens L15 can be made of the same optical glass.

[0050] The specific shapes of the three aspheric surfaces S1, S25 and S26 in Table 1 are Figure 2b The even binomial f1 and the coefficients in Table 2 are used to characterize the surface of the lens. In the even binomial f1, Y is the radial coordinate, that is, the distance from the optical axis in the direction perpendicular to the optical axis; Z(Y) is the axial coordinate, that is, the distance from the vertex of the lens surface in the direction parallel to the optical axis; R is the paraxial curvature radius at the vertex of the lens surface; K is the cone constant; Ai is the i-th order aspheric coefficient. For surfaces S1 and S25, the values ​​of K, A4, A6, A8 and A12 in the even binomial f1 are consistent.

[0051] See also Figure 5a and Figure 5b The modulation transfer function (MTF) curve of the fixed focus lens at a light transmission of F / 1.25 is shown in the figure. Figure 5aIt can be seen that the MTF values ​​of the six representative curves decrease basically evenly in the frequency range of 0~30lp / mm. The four curves on the top almost overlap with each other, and only the 21mm-sagittal curve finally drops below 0.5. Figure 5b and Figure 7 It can be seen that at a light transmission of F / 1.25, the imaging quality of this fixed-focus lens is equivalent to or close to the maximum light transmission of F / 1.4 of the SEL50F1.4GM fixed-focus lens of Japan's SONY company. Therefore, this fixed-focus lens can be used for full-frame cameras, and the maximum light transmission it is adapted to reaches F / 1.2~1.3.

[0052] In this fixed-focus lens, there are five pairs of lenses cemented together. The first lens L1 and the last lens (i.e., the fifteenth lens L15) are large-aperture aspherical lenses and are complementary in optical design. The first lens group G1 and the third lens group G2 both include two continuously arranged double-convex spherical positive lenses, so that the resolution is good and the optical distortion is low under the condition of light transmission F / 1.2~1.3, which can improve the lens vignetting problem of large aperture lenses.

[0053] The fixed-focus lens is a replaceable component of a full-frame camera. For other aspects of its structure and function, please refer to paragraphs 0110 to 0122 on pages 10 to 11 of the specification of patent CN10847825A, or refer to commercially available fixed-focus lenses for cameras.

[0054] In other embodiments, the above-mentioned lens may be made of other types of lens materials, specifically: The d-line refractive index of the first lens L1 is 1.75 to 1.85, and the d-line Abbe number is 35 to 45. The d-line refractive index of the second lens L2 is 1.45 to 1.55, and the d-line Abbe number is 65 to 75. The d-line refractive index of the third lens L3 is 1.75-1.85, and the d-line Abbe number is 25-35. The d-line refractive index of the fourth lens L4 is 1.55 to 1.65, and the d-line Abbe number is 35 to 45. The d-line refractive index of the fifth lens L5 is 1.95 to 2.05, and the d-line Abbe number is 25 to 35. The d-line refractive index of the sixth lens L6 is 1.65 to 1.75, and the d-line Abbe number is 30 to 50. The d-line refractive index of the seventh lens L7 is 1.85 to 1.95, and the d-line Abbe number is 35 to 45. The d-line refractive index of the eighth lens L8 is 1.55 to 1.65, and the d-line Abbe number is 35 to 45. The d-line refractive index of the ninth lens L9 is 1.55 to 1.65, and the d-line Abbe number is 65 to 75. The d-line refractive index of the tenth lens L10 is 1.75 to 1.85, and the d-line Abbe number is 25 to 35. The d-line refractive index of the eleventh lens L11 is 1.55 to 1.65, and the d-line Abbe number is 65 to 75. The d-line refractive index of the twelfth lens L12 is 1.85 to 1.95, and the d-line Abbe number is 15 to 25. The d-line refractive index of the thirteenth lens L13 is 1.85 to 1.95, and the d-line Abbe number is 35 to 45. The d-line refractive index of the fourteenth lens L14 is 1.80 to 1.90, and the d-line Abbe number is 20 to 30. The d-line refractive index of the fifteenth lens L15 is 1.75 to 1.85, and the d-line Abbe number is 35 to 45; Based on the lens data of the first embodiment, the surface shape, optical axis thickness and optical axis spacing of each lens need to be adaptively adjusted to achieve clear imaging and other technical requirements of the camera.

[0055] All the above embodiments, application examples and technical analysis are intended to introduce the technical concept and features of the present application so that those skilled in the art can implement the technical solution of the present application, and do not constitute any limitation on the protection scope of the present application. Simple modifications and equivalent transformations of the above embodiments are within the protection scope of the claims of the present application.

Claims

1. A fixed-focus lens, which can be used for a full-frame camera, characterized in that: It includes along the incident light axis direction: The first lens group is fixed relative to the image plane and has negative refractive power. The first lens along the incident optical axis is a positive lens, the object side surface is a non-spherical convex surface, and the image side surface is a spherical convex surface; Aperture stop; fixed relative to the image plane; The second lens group is movable along the incident optical axis, has positive refractive power, and is close to the imaging surface after focusing on a close object; and The third lens group is fixed relative to the image plane and has negative refractive power. The last lens along the incident optical axis is a negative lens, the object side surface is a non-spherical concave surface, and the image side surface is a non-spherical concave surface. The first lens and the last lens have the same d-line refractive index, d-line Abbe number and object-side aspheric surface expression.

2. The fixed-focus lens according to claim 1, characterized in that: The maximum light flux adapted by the fixed-focus lens is F / 1.2-1.3, and the first lens group and the third lens group each include two consecutively arranged biconvex spherical positive lenses.

3. The fixed-focus lens according to claim 2, characterized in that: The first lens has a curvature radius of +118.78 mm on the object side, a curvature radius of -87.61 mm on the image side, an optical axis thickness of 6.60 mm, a d-line refractive index of 1.81, and a d-line Abbe number of 40.7; The final lens has a curvature radius of -188.70 mm on the object side, a curvature radius of +500.00 mm on the image side, an optical axis thickness of 2.00 mm, a d-line refractive index of 1.81, and a d-line Abbe number of 40.

7.

4. The fixed-focus lens according to claim 3, characterized in that: The lenses constituting the first lens group are as follows along the incident optical axis: the first lens; The second lens is a biconcave spherical negative lens, with a curvature radius of -87.61 mm on the object side, a curvature radius of +41.01 mm on the image side, an optical axis thickness of 1.50 mm, a d-line refractive index of 1.49, and a d-line Abbe number of 70.4, cemented with the first lens; The third lens is a double concave spherical negative lens, with a curvature radius of -36.00mm on the object side, a curvature radius of +122.30mm on the image side, an optical axis thickness of 1.50mm, a d-line refractive index of 1.78, and a d-line Abbe number of 29.7; The fourth lens is a biconvex spherical positive lens, with a curvature radius of +122.30mm on the object side, a curvature radius of +41.20mm on the image side, an optical axis thickness of 10.40mm, a d-line refractive index of 1.59, and a d-line Abbe number of 68.3, cemented with the third lens; The fifth lens is a biconvex spherical positive lens, with a curvature radius of +197.32 mm on the object side, a curvature radius of -77.81 mm on the image side, an optical axis thickness of 7.30 mm, a d-line refractive index of 2.00, and a d-line Abbe number of 29.1; and The sixth lens is a negative lens, with a convex spherical surface on the object side and a curvature radius of +95.68mm, a concave spherical surface on the image side and a curvature radius of +45.51mm, an optical axis thickness of 1.00mm, a d-line refractive index of 1.65, and a d-line Abbe number of 33.

8.

5. The fixed-focus lens according to claim 4, characterized in that: The distance between the aperture stop and the optical axis of the sixth lens is 6.0 mm.

6. The fixed-focus lens according to claim 4, characterized in that: The lenses constituting the second lens group are as follows along the incident optical axis: The seventh lens is a negative lens, with a convex spherical surface on the object side and a curvature radius of +46.63mm, a concave spherical surface on the image side and a curvature radius of +76.03mm, an optical axis thickness of 4.00mm, a d-line refractive index of 1.88, and a d-line Abbe number of 40.8; The eighth lens is a biconcave spherical negative lens, with a curvature radius of -72.26 mm on the object side, a curvature radius of +44.76 mm on the image side, an optical axis thickness of 1.50 mm, a d-line refractive index of 1.61, and a d-line Abbe number of 37.0; and The ninth lens is a double convex spherical positive lens with a curvature radius of +44.76mm on the object side, a curvature radius of -57.00mm on the image side, an optical axis thickness of 9.70mm, a d-line refractive index of 1.59, and a d-line Abbe number of 68.

3. It is cemented with the eighth lens.

7. The fixed-focus lens according to claim 6, wherein: The lenses constituting the third lens group are as follows along the incident optical axis: The tenth lens is a double concave spherical negative lens, with a curvature radius of -109.27mm on the object side, a curvature radius of +46.00mm on the image side, an optical axis thickness of 1.50mm, a d-line refractive index of 1.77, and a d-line Abbe number of 29.7; The eleventh lens is a biconvex spherical positive lens, with a curvature radius of +46.00mm on the object side, a curvature radius of -88.76mm on the image side, an optical axis thickness of 9.00mm, a d-line refractive index of 1.59, and a d-line Abbe number of 68.3, cemented with the tenth lens; The twelfth lens is a biconvex spherical positive lens, with a curvature radius of +61.32mm on the object side, a curvature radius of -343.14mm on the image side, an optical axis thickness of 7.11mm, a d-line refractive index of 1.92, and a d-line Abbe number of 20.9; The thirteenth lens is a positive lens, with a spherical convex surface on the object side and a curvature radius of +42.03mm, a spherical concave surface on the image side and a curvature radius of +184.08mm, an optical axis thickness of 6.10mm, a d-line refractive index of 1.88, and a d-line Abbe number of 40.8; The fourteenth lens is a negative lens, with a spherical convex surface on the object side and a curvature radius of +184.08 mm, a spherical concave surface on the image side and a curvature radius of +26.47 mm, an optical axis thickness of 1.50 mm, a d-line refractive index of 1.85, and a d-line Abbe number of 23.8, cemented with the thirteenth lens; and The last lens.

Images