Internal focusing macro photography optical system

Abstract

The invention relates to an internal focusing macro photography optical system. The optical system is sequentially provided with a first lens group, a first focusing group, a third lens group, a second focusing group and a fifth lens group from an object side to an image surface side, wherein the first lens group, the first focusing group, the third lens group, the second focusing group and the fifth lens group have positive diopter and are fixed; the optical system is further provided with an aperture, and the aperture is located on the image plane side of the first focusing group and the object side of the second focusing group. And when the shot object is close to the short distance from the infinity, the first focusing group and the second focusing group move towards the object side. According to the invention, miniaturization of an optical system can be realized, and a good macro imaging effect is achieved.

Description

Technical Field

[0001] The present invention relates to the field of optical applications, and in particular to an inner-focus macro photography optical system suitable for optical systems using solid-state imaging optical elements such as digital still cameras and digital video cameras, and an imaging device having the optical system. Background Art

[0002] As solid-state imaging elements have become popular in digital still cameras, digital video cameras and other imaging devices, especially mirrorless digital photography and video recording devices, the demand for high-performance, portable photography and video recording optical systems has been rapidly promoted, and many internal focusing optical systems with macro shooting features have been proposed, for example, refer to patent document CN105785689A.

[0003] At present, the market has put forward requirements for high performance and miniaturization of optical systems, especially for the magnification, imaging performance and ease of use of optical systems. In CN105785689A, the inner focusing optical system is configured from the object side in sequence with a fixed first lens group, a movable first moving group G1, and a second moving group G2 that is also movable and closest to the image plane. However, the inner focusing optical system of this patent has a small magnification (less than 0.5 times), a short focal length (less than 50mm converted to a 35mm camera), and is not conducive to reducing perspective distortion during macro photography. In addition, the number of lenses constituting the third lens group (second moving group G2) of the optical system is large and the volume is large, which is not conducive to achieving fast automatic focusing.

[0004] As described above, in the existing internal focus macro photography optical systems, including the technology described in the above patent document, there is no optical system that has both good macro imaging effect and is compact and portable. Summary of the invention

[0005] In view of the problems existing in the prior art, the object of the present invention is to provide an inner-focus macro photography optical system which has both good macro imaging effect and the characteristics of being small and portable.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] An inner-focus macro photography optical system, wherein the optical system is provided with, from the object side to the image plane side, a first lens group having positive refractive power and being fixed, a first focusing group, a third lens group, a second focusing group and a fifth lens group being fixed; the optical system is also provided with an aperture, which is located on the image plane side of the first focusing group and on the object side of the second focusing group; when the photographed object approaches from infinity to a close distance, the first focusing group and the second focusing group move toward the object side.

[0008] The first focus group and the second focus group meet the following conditions:

[0009] 0.4 <f1 / f0<2.0;0.2<f2 / f0<1.0;

[0010] Here, f1 is the focal length of the first focus group, f2 is the focal length of the second focus group, and f0 is the focal length of the entire optical system.

[0011] The first focus group and the second focus group meet the following conditions:

[0012] M1 / β<16; M2 / β<24;

[0013] Here, M1 is the movable range of the first focus group, M2 is the movable range of the second focus group, and β is the maximum magnification of the optical system.

[0014] The optical system meets the following conditions:

[0015] (T0*Fno) / (β*f0)<4.0;

[0016] Among them, T0 is the total optical length of the optical system from the object side of the first lens group closest to the object side to the imaging surface of the optical system, Fno is the open aperture value of the optical system, β is the maximum magnification of the optical system, and f0 is the focal length of the entire optical system.

[0017] After adopting the above scheme, when the photographed object approaches from infinity to a close distance, the first focus group on the object side and the second focus group on the image side move from the position close to the image plane toward the object side respectively, and the lens groups closest to the object side and the image side are fixed. This structure can extend its focus range as much as possible while keeping the total length of the optical system unchanged, thereby achieving a larger magnification and good focusing performance while keeping the entire optical system small. At the same time, in the present invention, the first lens group has a positive optical focal length, and the first focus group and the second focus group are distributed on both sides of the aperture, which is conducive to extending its focal distance while maintaining the magnification of the optical system, thereby obtaining a longer working distance during macro shooting and reducing perspective distortion during macro shooting. In short, the present invention can achieve a good macro imaging effect while achieving a small optical system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the optical system structure of the first embodiment of the present invention;

[0019] Figure 2 INF (infinity) spherical aberration, astigmatism and distortion diagram of Example 1;

[0020] Figure 3Schematic diagram of MOD (closest point) spherical aberration, astigmatism and distortion of Example 1;

[0021] Figure 4 is a schematic diagram of the optical system structure of the second embodiment of the present invention;

[0022] Figure 5 INF (infinity) spherical aberration, astigmatism and distortion diagram of Example 2;

[0023] Figure 6 The MOD (closest point) spherical aberration, astigmatism and distortion diagram of Example 2;

[0024] Figure 7 This is a schematic diagram of the optical system structure of Embodiment 3 of the present invention;

[0025] Figure 8 INF (infinity) spherical aberration, astigmatism and distortion diagram of Example 3;

[0026] Fig. 9 The MOD (closest point) spherical aberration, astigmatism and distortion diagram of Example 3;

[0027] Fig.10 Schematic diagram of the optical system structure of the fourth embodiment of the present invention;

[0028] Fig.11 INF (infinity) spherical aberration, astigmatism and distortion diagram of Example 4;

[0029] Fig.12 The MOD (closest point) spherical aberration, astigmatism and distortion diagram of Example 4. DETAILED DESCRIPTION

[0030] like Figure 1 , 4 As shown in Figures 7 and 10, the present invention discloses an inner-focus macro photography optical system, which is provided with: a first lens group G1 with positive refractive power and fixed, a first focusing group G2, a third lens group G3, a second focusing group G4 and a fixed fifth lens group G5 in sequence from the object side to the image plane side; the optical system is also provided with an aperture S, which is located on the image plane side of the first focusing group G2 and the object side of the second focusing group G4; when the photographed object approaches from infinity to a close distance, the first focusing group G2 and the second focusing group G4 move toward the object side.

[0031] When the photographed object approaches from infinity to a close distance, the first focus group G2 on the object side and the second focus group G4 on the image plane side move from a position close to the image plane toward the object side, respectively, and the lens groups closest to the object side and the image plane side are fixed. This structure can extend the focus range as much as possible while keeping the total length of the optical system unchanged, thereby achieving a larger magnification and good focusing performance while keeping the entire optical system small. At the same time, in the present invention, the first lens group G1 has a positive optical focal length, and the first focus group G2 and the second focus group G4 are distributed on both sides of the aperture S, which is conducive to extending the focal distance while maintaining the magnification of the optical system, thereby obtaining a longer working distance during macro shooting and reducing perspective distortion during macro shooting.

[0032] On the basis of the above, the first focus group G2 and the second focus group G4 satisfy the conditions (1) and (2), which is beneficial to reduce the number and volume of lenses of the two focus groups while maintaining the magnification of the optical system, thereby facilitating the realization of fast automatic focusing. The conditional equations (1) and (2) are as follows:

[0033] 0.4 < f1 / f0 < 2.0 (1)

[0034] 0.2 < f2 / f0 < 1.0 (2)

[0035] Here, f1 is the focal length of the first focusing group G2, f2 is the focal length of the second focusing group G4, and f0 is the focal length of the entire optical system.

[0036] On the basis of the above, the first focus group G2 and the second focus group G4 satisfy conditional expressions (3) and (4), and can control the movement range of the focus group to be reduced under the same magnification condition, thereby facilitating the miniaturization of the optical system. Conditional expressions (3) and (4) are as follows:

[0037] M1 / β < 16 (3)

[0038] M2 / β < 24 (4)

[0039] Here, M1 is the movable range of the first focusing group G2, M2 is the movable range of the second focusing group G4, and β is the maximum magnification of the optical system.

[0040] On the basis of the above, the optical system satisfies conditional formula (5), which can make the overall optical system achieve a better balance between magnification, total length, aperture value and focal distance, thus facilitating the realization of an optical system with high magnification (macro), compact size (miniaturization), long focal distance (small perspective distortion), and large aperture S (small impact by ambient illumination). Conditional formula (5) is as follows:

[0041] (T0*Fno) / (β*f0) < 4.0 (5)

[0042] Among them, T0 is the total optical length of the optical system from the object side of the first lens group G1 closest to the object side to the imaging surface of the optical system, Fno is the open aperture value of the optical system, β is the maximum magnification of the optical system, and f0 is the focal length of the entire optical system.

[0043] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0044] Embodiment 1

[0045] Figure 1 Schematic diagram of the structure of the inner focus macro photography optical system according to the first embodiment of the present invention. Figure 2 The spherical aberration, astigmatism and distortion diagram under INF of Example 1 are shown below. Figure 3 : spherical aberration, aberration and distortion diagram of Example 1 under MOD. Figure 1 As shown, the inner-focus macro photography optical system of the first embodiment includes a first lens group G1, a first focusing group G2, a third lens group G3, a second focusing group G4 and a fifth lens group G5. The inner-focus macro photography optical system also includes an aperture S. The first focusing group G2 and the second focusing group G4 are located on the object side and the image side of the aperture S, respectively.

[0046] The first lens group G1 includes a first lens L1 which is a meniscus lens convex toward the object side, has positive refractive power, and is fixedly arranged.

[0047] The first focus group G2 is arranged on the image side of the first lens group G1. The first focus group G2 is provided with a second lens L2, a third lens L3 and a fourth lens L4 in sequence from the object side to the image side. The second lens L2 is a meniscus lens convex to the object side; the third lens L3 is a meniscus lens convex to the object side, and the object side surface of the third lens L3 is attached to the image side surface of the second lens L2; ​​the fourth lens L4 is a double convex lens. When the object to be photographed approaches from infinity to a close distance, the first focus group G2 can move toward the object side as a whole.

[0048] The third lens group G3 is arranged on the image side of the first focus group G2, and includes a fifth lens L5 and a sixth lens L6 in sequence from the object side to the image side, and an aperture S is arranged between the fifth lens L5 and the sixth lens L6. The fifth lens L5 is a meniscus lens convex to the object side, and the sixth lens L6 is a double concave lens.

[0049] The second focusing group G4 is arranged on the image side of the third lens group G3, and is provided with a seventh lens L7, an eighth lens L8 and a ninth lens L9 in order from the object side to the image side. The seventh lens L7 is a meniscus lens convex to the object side, the eighth lens L8 is a meniscus lens convex to the object side, and the ninth lens L9 is a double convex lens, and the object side surface of the ninth lens L9 is attached to the image side surface of the eighth lens L8. When the object to be photographed approaches from infinity to a close distance, the second focusing group G4 can move toward the object side as a whole.

[0050] The fifth lens group G5 is arranged on the image side of the second focus group G4, and includes a tenth lens L10, an eleventh lens L11, and a twelfth lens L12 in order from the object side to the image side. The tenth lens L10 is a biconcave lens, the eleventh lens L11 is a biconcave lens, the twelfth lens L12 is a biconvex lens, and the object side surface of the twelfth lens L12 is bonded to the image side surface of the eleventh lens L11.

[0051] In this embodiment, the lens data of the optical system are set as follows:

[0052] Optical parameters

[0053]

[0054]

[0055] Aspheric surface data

[0056] Page 6

[0057] K=0.00000E+00 A4=-1.93000E-05 A6=1.37000E-08 A8=-1.01000E-10 A10=1.82000E-13

[0058] Page 7

[0059] K=0.00000E+00 A4=-1.43000E-05 A6=3.08000E-08 A8=-1.50000E-10 A10=2.10000E-13

[0060] Page 11

[0061] K=0.00000E+00 A4=4.89000E-05 A6=-3.72000E-07 A8=1.45000E-09 A10=-2.00000E-12 A12=-3.50000E-15

[0062] Page 12

[0063] K=0.00000E+00 A4=4.87000E-05 A6=-3.39000E-07 A8=5.98000E-10 A10=6.19000E-12 A12=-3.00000E-14

[0064] Page 15

[0065] K=0.00000E+00 A4=-1.07000E-06 A6=-8.03000E-09 A8=1.67000E-10 A10=-2.47000E-13

[0066] Page 17

[0067] K=0.00000E+00 A4=7.00000E-06 A6=-2.24000E-08 A8=2.86000E-10 A10=-3.98000E-13

[0068]

[0069]

[0070] According to the above lens parameters, the optical system of this embodiment satisfies the conditions (1)-(5), the maximum magnification β is 1.0000, and the focal length f0 is 96.9999 mm. Figure 2 and Figure 3 It can be seen that this embodiment has a good macro imaging effect. Specifically, INF refers to the object distance being infinite, MOD refers to the object distance being the shortest (maximum magnification), Figure 2 is the spherical aberration, aberration and distortion diagram when the object is infinitely far away. Figure 3 The spherical aberration, aberration and distortion diagrams are when the object is closest. Figure 2 and Figure 3 In the figure, the horizontal coordinate of spherical aberration (SA) is the amount of aberration, with the unit of mm, and the top of the vertical coordinate is the half picture angle, which is equivalent to the maximum viewing angle. In this embodiment, the spherical aberration is controlled within the range of ±0.15mm when the object is at infinity, and within the range of ±0.25mm when the object is at the closest distance. The horizontal coordinate of astigmatism (AST) is the amount of aberration, with the unit of mm, and the top of the vertical coordinate is the half picture angle, which is equivalent to the maximum viewing angle. X (solid line) represents the sagittal direction, and Y (dashed line) represents the meridian direction. The two curves in the figure represent aberrations in different directions, respectively. In this embodiment, the aberration is controlled within the range of ±0.25mm when the object is at infinity, and within the range of ±0.25mm when the object is at the closest distance. The horizontal coordinate of distortion (DIST) is the distortion amount, with the unit of %, and the top of the vertical coordinate is the half picture angle, which is equivalent to the maximum viewing angle. In this embodiment, the distortion is controlled within the range of 10% when the object is at infinity and when the object is at the closest distance.

[0071] Embodiment 2

[0072] Figure 4 FIG. 2 is a schematic diagram of the structure of an inner-focus macro photography optical system according to a second embodiment of the present invention. Figure 5 The spherical aberration, astigmatism and distortion diagram under INF of Example 2 are shown below: Figure 6 : spherical aberration, aberration and distortion diagram of Example 2 under MOD. Figure 4 As shown, the inner-focus macro photography optical system of the second embodiment includes a first lens group G1, a first focusing group G2, a third lens group G3, a second focusing group G4 and a fifth lens group G5. The inner-focus macro photography optical system also includes an aperture S. The first focusing group G2 and the second focusing group G4 are located on the object side and the image side of the aperture S, respectively.

[0073] The first lens group G1 includes a first lens L1 which is a meniscus lens convex toward the object side, has positive refractive power, and is fixedly arranged.

[0074] The first focus group G2 is arranged on the image side of the first lens group G1, and the first focus group G2 is provided with a second lens L2, a third lens L3 and a fourth lens L4 in sequence from the object side to the image side. The second lens L2 is a meniscus lens convex to the object side; the third lens L3 is a double convex lens, and the object side surface of the third lens L3 is attached to the image side surface of the second lens L2; ​​the fourth lens L4 is a meniscus lens convex to the image side. When the object to be photographed approaches from infinity to a close distance, the first focus group G2 can move toward the object side as a whole.

[0075] The third lens group G3 is arranged on the image side of the first focus group G2, and is provided with a fifth lens L5 and a sixth lens L6 in sequence from the object side to the image side, and an aperture S is arranged between the fifth lens L5 and the sixth lens L6. The fifth lens L5 is a biconcave lens, and the sixth lens L6 is a meniscus lens convex toward the object side.

[0076] The second focusing group G4 is arranged on the image side of the third lens group G3, and is provided with a seventh lens L7, an eighth lens L8 and a ninth lens L9 in sequence from the object side to the image side. The seventh lens L7 is a biconvex lens, the eighth lens L8 is a meniscus lens convex to the object side, and the ninth lens L9 is a biconvex lens, and the object side surface of the ninth lens L9 is bonded to the image side surface of the eighth lens L8. When the object to be photographed approaches from infinity to a close distance, the second focusing group G4 can move toward the object side as a whole.

[0077] The fifth lens group G5 is arranged on the image side of the second focus group G4, and includes a tenth lens L10, an eleventh lens L11, a twelfth lens L12, and a thirteenth lens L13 in order from the object side to the image side. The tenth lens L10 is a biconcave lens, the eleventh lens L11 is a biconvex lens, the twelfth lens L12 is a biconcave lens, and the thirteenth lens L13 is a biconvex lens.

[0078] In this embodiment, the lens data of the optical system are set as follows:

[0079] Optical parameters

[0080]

[0081]

[0082] Aspheric surface data

[0083] Page 6

[0084] K=0.00000E+00A4=-1.27947E-05A6=5.38823E-08A8=2.54575E-11A10=-2.20615E-13Page 7

[0085] K=0.00000E+00A4=-2.85253E-06A6=5.70248E-08A8=3.20279E-11A10=-2.55271E-13Page 11

[0086] K=0.00000E+00A4=4.63456E-05A6=-5.36365E-08A8=-2.34122E-11A10=3.68590E-13Page 12

[0087] K=0.00000E+00A4=4.40906E-05A6=-4.86721E-08A8=-4.75660E-11A10=5.31424E-13Page 20

[0088] K=0.00000E+00A4=-9.73757E-06A6=-1.78975E-08A8=3.72869E-10A10=-2.36677E-12A12=-1.46272E-15

[0089] Page 21

[0090] K=0.00000E+00A4=-2.46010E-05A6=8.29180E-09A8=-4.00070E-10A10=2.94214E-12A12=-1.42361E-14

[0091]

[0092]

[0093] According to the above lens parameters, the optical system of this embodiment satisfies the conditional formulas (1) to (5), the maximum magnification β is 0.9904, and the focal length f0 is 97.0660 mm. Figure 5 and Figure 6 It can be seen that this embodiment has a good macro imaging effect. Specifically, Figure 5 is the spherical aberration, aberration and distortion diagram when the object is infinitely far away. Figure 6 The spherical aberration, aberration and distortion diagrams are when the object is closest. Figure 5 and Figure 6 In the figure, the horizontal coordinate of spherical aberration (SA) is the amount of aberration, with the unit of mm, and the top of the vertical coordinate is the half picture angle, which is equivalent to the maximum viewing angle. In this embodiment, the spherical aberration is controlled within the range of ±0.1mm when the object is infinitely far away, and the spherical aberration is controlled within the range of ±0.1 when the object is closest. The horizontal coordinate of astigmatism (AST) is the amount of aberration, with the unit of mm, and the top of the vertical coordinate is the half picture angle, which is equivalent to the maximum viewing angle. X (solid line) represents the sagittal direction, and Y (dashed line) represents the meridian direction. The two curves in the figure represent aberrations in different directions, respectively. In this embodiment, the aberration is controlled within the range of ±0.25mm when the object is infinitely far away and when the object is closest. The horizontal coordinate of distortion (DIST) is the distortion amount, with the unit of %, and the top of the vertical coordinate is the half picture angle, which is equivalent to the maximum viewing angle. In this embodiment, the distortion is controlled within the range of 5% when the object is farthest away and when the object is closest.

[0094] Embodiment 3

[0095] Figure 7 Schematic diagram of the structure of the inner-focus macro photography optical system according to the third embodiment of the present invention. Figure 8 The spherical aberration, astigmatism and distortion diagram under INF of Example 3 are shown below. Fig. 9 : spherical aberration, aberration and distortion diagram of Example 3 under MOD. Figure 7 As shown, the inner-focus macro photography optical system of the third embodiment includes a first lens group G1, a first focusing group G2, a third lens group G3, a second focusing group G4 and a fifth lens group G5. The inner-focus macro photography optical system also includes an aperture S. The first focusing group G2 and the second focusing group G4 are located on the object side and the image side of the aperture S, respectively.

[0096] The first lens group G1 includes a first lens L1 which is a meniscus lens convex toward the object side, has positive refractive power, and is fixedly arranged.

[0097] The first focus group G2 is arranged on the image side of the first lens group G1. The first focus group G2 is provided with a second lens L2, a third lens L3 and a fourth lens L4 in sequence from the object side to the image side. The second lens L2 is a meniscus lens convex to the object side; the third lens L3 is a double convex lens, the object side surface of the third lens L3 is attached to the image side surface of the second lens L2; ​​the fourth lens L4 is a meniscus lens convex to the object side. When the object to be photographed approaches from infinity to a close distance, the first focus group G2 as a whole can move toward the object side.

[0098] The third lens group G3 is arranged on the image side of the first focus group G2, and includes a fifth lens L5 and a sixth lens L6 in sequence from the object side to the image side, and an aperture S is arranged between the fifth lens L5 and the sixth lens L6. The fifth lens L5 is a meniscus lens convex to the object side, and the sixth lens L6 is a double concave lens.

[0099] The second focusing group G4 is arranged on the image side of the third lens group G3, and is provided with a seventh lens L7, an eighth lens L8 and a ninth lens L9 in order from the object side to the image side. The seventh lens L7 is a biconvex lens, the eighth lens L8 is a meniscus lens convex to the object side, and the ninth lens L9 is a biconvex lens, and the object side surface of the ninth lens L9 is bonded to the image side surface of the eighth lens L8.

[0100] The fifth lens group G5 is arranged on the image side of the second focus group G4, and includes a tenth lens L10, an eleventh lens L11, a twelfth lens L12, and a thirteenth lens L13 in order from the object side to the image side. The tenth lens L10 is a meniscus lens convex to the image side, the eleventh lens L11 is a biconcave lens, the twelfth lens L12 is a meniscus lens convex to the object side, and the object side surface of the twelfth lens L12 is bonded to the image side surface of the eleventh lens L11, and the thirteenth lens L13 is a meniscus lens convex to the image side.

[0101] In this embodiment, the lens data of the optical system are set as follows: Optical parameters

[0102]

[0103] According to the above lens parameters, the optical system of this embodiment satisfies the conditions (1)-(5), the maximum magnification β is 1.0000, and the focal length f0 is 97.0004 mm. Figure 8 and Fig. 9 It can be seen that this embodiment has a good macro imaging effect. Specifically, Figure 8is the spherical aberration, aberration and distortion diagram when the object is infinitely far away. Fig. 9 The spherical aberration, aberration and distortion diagrams are when the object is closest. Figure 8 and Fig. 9 In the figure, the horizontal coordinate of spherical aberration (SA) is the amount of aberration, with the unit of mm, and the top of the vertical coordinate is the half picture angle, which is equivalent to the maximum viewing angle. In this embodiment, the spherical aberration is controlled within the range of ±0.05mm when the object is infinitely far away, and the spherical aberration is controlled within the range of ±0.25mm when the object is closest. The horizontal coordinate of astigmatism (AST) is the amount of aberration, with the unit of mm, and the top of the vertical coordinate is the half picture angle, which is equivalent to the maximum viewing angle. X (solid line) represents the sagittal direction, and Y (dashed line) represents the meridian direction. The two curves in the figure represent aberrations in different directions, respectively. In this embodiment, the aberration is controlled within the range of ±0.15mm when the object is infinitely far away, and the aberration is controlled within the range of ±0.25mm when the object is closest. The horizontal coordinate of distortion (DIST) is the distortion amount, with the unit of %, and the top of the vertical coordinate is the half picture angle, which is equivalent to the maximum viewing angle. In this embodiment, the distortion is controlled within the range of 5% when the object is infinitely far away and when the body is closest.

[0104] Embodiment 4

[0105] Fig.10 FIG. 4 is a schematic diagram of the structure of an inner-focus macro photography optical system according to a fourth embodiment of the present invention. Fig.11 The spherical aberration, astigmatism and distortion diagram of Example 4 under INF are shown below: Fig.12 Graphs of spherical aberration, aberration and distortion under MOD of Example 4 are shown below. Fig.10 As shown, the inner-focus macro photography optical system of the fourth embodiment includes a first lens group G1, a first focusing group G2, a third lens group G3, a second focusing group G4 and a fifth lens group G5. The inner-focus macro photography optical system also includes an aperture S. The first focusing group G2 and the second focusing group G4 are located on the object side and the image side of the aperture S, respectively.

[0106] The first lens group G1 includes a first lens L1 which is a meniscus lens convex toward the object side, has positive refractive power, and is fixedly arranged.

[0107] The first focus group G2 is arranged on the image side of the first lens group G1, and the first focus group G2 is provided with a second lens L2, a third lens L3 and a fourth lens L4 in sequence from the object side to the image side. The second lens L2 is a meniscus lens convex to the object side; the third lens L3 is a double convex lens, and the object side surface of the third lens L3 is attached to the image side surface of the second lens L2; ​​the fourth lens L4 is a meniscus lens convex to the image side. When the object to be photographed approaches from infinity to a close distance, the first focus group G2 can move toward the object side as a whole.

[0108] The third lens group G3 is arranged on the image side of the first focus group G2, and the aperture S is arranged between the first focus group G2 and the third lens group G3. The third lens group G3 is provided with a fifth lens L5 and a sixth lens L6 in sequence from the object side to the image side. The fifth lens L5 is a meniscus lens convex to the object side, and the sixth lens L6 is a meniscus lens convex to the object side.

[0109] The second focusing group G4 is arranged on the image side of the third lens group G3, and is provided with a seventh lens L7, an eighth lens L8 and a ninth lens L9 in order from the object side to the image side. The seventh lens L7 is a biconvex lens, the eighth lens L8 is a meniscus lens convex to the object side, and the ninth lens L9 is a biconvex lens, and the object side surface of the ninth lens L9 is bonded to the image side surface of the eighth lens L8.

[0110] The fifth lens group G5 is arranged on the image side of the second focus group G4, and includes a tenth lens L10, an eleventh lens L11, a twelfth lens L12, and a thirteenth lens L13 in order from the object side to the image side. The tenth lens L10 is a biconcave lens, the eleventh lens L11 is a meniscus lens convex to the image side, the twelfth lens L12 is a meniscus lens convex to the image side, and the thirteenth lens L13 is a meniscus lens convex to the image side, and the object side surface of the thirteenth lens L13 is bonded to the image side of the twelfth lens L12.

[0111] In this embodiment, the lens data of the optical system are set as follows:

[0112] Optical parameters

[0113]

[0114] Aspheric surface data

[0115] Page 6

[0116] K=0.00000E+00 A4=-1.07389E-05 A6=3.87800E-08 A8=3.93108E-11 A10=-1.60155E-13

[0117] Page 7

[0118] K=0.00000E+00 A4=-3.39099E-06 A6=3.91430E-08 A8=4.10854E-11 A10=-1.57911E-13

[0119] Page 15

[0120] K=0.00000E+00 A4=3.56948E-05 A6=1.48739E-07 A8=9.61907E-11 A10=1.46882E-12

[0121] Page 16

[0122] K=0.00000E+00 A4=3.19739E-05 A6=2.07028E-07 A8=-4.65911E-10 A10=5.64457E-12

[0123] Page 22

[0124] K=0.00000E+00 A4=9.62725E-06 A6=3.09619E-07 A8=-1.60533E-09 A10=3.21207E-12

[0125] Page 23

[0126] K=0.00000E+00 A4=9.73852E-08 A6=2.22685E-07 A8=-8.48193E-10 A10=1.06057E-12

[0127]

[0128] According to the above lens parameters, the optical system of this embodiment satisfies the conditional formulas (1) to (5), the maximum magnification β is 0.9900, and the focal length f0 is 97.0566 mm. Fig.11 and Fig.12 It can be seen that this embodiment has a good macro imaging effect. Specifically, Fig.11 is the spherical aberration, aberration and distortion diagram when the object is infinitely far away. Fig.12 The spherical aberration, aberration and distortion diagrams are when the object is closest. Fig.11 and Fig.12In the figure, the horizontal coordinate of spherical aberration (SA) is the amount of aberration, with the unit of mm, and the top of the vertical coordinate is the half-angle, which is equivalent to the maximum viewing angle. In this embodiment, the spherical aberration when the object is infinitely far away and the object is closest is controlled within the range of ±0.1mm. The horizontal coordinate of astigmatism (AST) is the amount of aberration, with the unit of mm, and the top of the vertical coordinate is the half-angle, which is equivalent to the maximum viewing angle. X (solid line) represents the sagittal direction, and Y (dashed line) represents the meridian direction. The two curves in the figure represent aberrations in different directions, respectively. In this embodiment, the aberration when the object is infinitely far away and the object is closest is controlled within the range of ±0.25mm. The horizontal coordinate of distortion (DIST) is the distortion amount, with the unit of %, and the top of the vertical coordinate is the half-angle, which is equivalent to the maximum viewing angle. In this embodiment, the distortion when the object is infinitely far away and the object is closest is controlled within the range of 5%.

[0129] Based on the first to fourth embodiments, it can be seen that the present invention can achieve a larger magnification and good focusing performance, the perspective distortion during macro shooting is small, a medium and long focal length (greater than 80mm) can be achieved, and a good macro imaging effect is achieved.

[0130] The above description is merely an embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any minor modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. An internal focusing macro photography optical system, characterized in that: The optical system is provided with: a first lens group with positive refractive power and fixed, a first focusing group, a third lens group, a second focusing group and a fifth lens group which are fixed in sequence from the object side to the image plane side; the optical system is also provided with an aperture, which is located on the image plane side of the first focusing group and on the object side of the second focusing group; when the photographed object approaches from infinity to a close distance, the first focusing group and the second focusing group move toward the object side.

2. The inner focus macro photography optical system according to claim 1, characterized in that: The first focus group and the second focus group meet the following conditions: 0.4 <f1 / f0<2.0;0.2<f2 / f0<1.0; Here, f1 is the focal length of the first focus group, f2 is the focal length of the second focus group, and f0 is the focal length of the entire optical system.

3. The inner focus macro photography optical system according to claim 1, characterized in that: The first focus group and the second focus group meet the following conditions: M1 / β<16; M2 / β<24; Here, M1 is the movable range of the first focus group, M2 is the movable range of the second focus group, and β is the maximum magnification of the optical system.

4. The inner focus macro photography optical system according to claim 1, characterized in that: The optical system meets the following conditions: (T0*Fno) / (β*f0)<4.0; Among them, T0 is the total optical length of the optical system from the object side of the first lens group closest to the object side to the imaging surface of the optical system, Fno is the open aperture value of the optical system, β is the maximum magnification of the optical system, and f0 is the focal length of the entire optical system.

Images