Internal focusing imaging system and internal focusing telephoto lens including the same

Abstract

The present invention discloses an internal focus imaging system and an internal focus telephoto lens including the same, belonging to the field of optical imaging technology. The system comprises a first fixed group, a focusing group, and a second fixed group, which are sequentially arranged from the object side to the image side. By setting the first fixed group and the second fixed group to remain stationary, focusing is achieved only by moving the focusing group, which can effectively seal the lens and prevent external fog, dust, etc. from entering the interior of the lens. At the same time, by moving only two lenses in the focusing group from infinity to the closest object distance, the breathing effect is effectively reduced, thereby improving the stability of shooting and the consistency of imaging. In addition, by moving only part of the lenses for focusing, the load is small, the focusing process is smoother, and the noise is smaller. The internal focus telephoto lens of the present invention has a compact overall structure and is easy to carry. The focal length is greater than the mechanical barrel length, which is conducive to ensuring the telephoto characteristics of the lens while not causing the barrel length to be too long, thereby reducing the moving load during the focusing process.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical imaging, and in particular relates to an inner-focus imaging system and an inner-focus telephoto lens comprising the same. Background Art

[0002] Photography, especially telephoto and astronomical photography, places higher demands on lens design. For example, astronomical photography places high demands on image quality, including the precision of star imaging and the control of optical system dispersion. Traditional telephoto lenses, due to their long focal length, often come with long barrels, making them bulky and inconvenient to carry and operate.

[0003] Furthermore, existing technologies often struggle to achieve telephoto characteristics while simultaneously maintaining compactness, optical performance, and adaptability to specific applications. Furthermore, telephoto lenses are typically large, and to achieve focus, the drive motor required requires high torque, which increases the overall size of the lens, hindering its miniaturization. Summary of the Invention

[0004] In response to one or more of the above-mentioned defects or improvement needs in the prior art, the present invention provides an inner-focus imaging system and an inner-focus telephoto lens including the same, which can effectively reduce the lens length and improve the imaging quality.

[0005] To achieve the above object, one aspect of the present invention provides an inner focusing imaging system, comprising a first fixed group, a focusing group, and a second fixed group arranged in sequence from the object side to the image side;

[0006] The first fixed group has positive refractive power, and the first fixed group includes a first lens and a second lens arranged in sequence from the object side to the image side; the first lens has positive refractive power, and the second lens has negative refractive power;

[0007] The focusing group realizes focusing at different object distances by moving, and includes a third lens and a fourth lens arranged in sequence from the object side to the image side; the third lens has a positive refractive power, and the fourth lens has a negative refractive power;

[0008] The second fixed group includes a fifth lens and a sixth lens arranged in sequence from the object side to the image side; the fifth lens has negative refractive power, and the sixth lens has positive refractive power.

[0009] As a further improvement of the present invention, the object-side surface and the image-side surface of the first lens are both convex surfaces; the object-side surface and the image-side surface of the second lens are both concave surfaces;

[0010] and / or,

[0011] The object-side surface and the image-side surface of the third lens are both convex; the object-side surface of the fourth lens is concave;

[0012] and / or,

[0013] The object-side surface of the fifth lens is concave; the image-side surface of the sixth lens is convex.

[0014] As a further improvement of the present invention, the first lens and the second lens are cemented to form a first doublet lens, and the fifth lens and the sixth lens are cemented to form a second doublet lens.

[0015] As a further improvement of the present invention, the axial distance TTL from the object side surface to the image plane of the first lens and the effective focal length EFL of the lens satisfy the following relationship: TTL / EFL<0.8;

[0016] and / or,

[0017] The front and rear curvature radii R1 and R2 of the first lens satisfy the following relationship: 0.5<|R1 / R2|<1.

[0018] As a further improvement of the present invention, at least one of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens is made of an ultra-low dispersion material.

[0019] As a further improvement of the present invention, the material of the first lens is an ultra-low dispersion material, and the first lens satisfies nd<1.5, vd>80, where nd is the refractive index and vd is the Abbe number;

[0020] and / or,

[0021] The sixth lens satisfies nd>1.5, vd<50, where nd is the refractive index and vd is the Abbe number.

[0022] As a further improvement of the present invention, the focal length F1 of the first fixed group and the effective focal length EFL of the lens satisfy the following relationship: F1 / EFL>0.95;

[0023] and / or,

[0024] The focal length F2 of the focusing group and the effective focal length EFL of the lens satisfy the following relationship: |F2 / EFL|>3;

[0025] and / or,

[0026] The focal length F3 of the second fixed group and the effective focal length EFL of the lens satisfy the following relationship: 5>|F3 / EFL|>0.3;

[0027] and / or,

[0028] The air interval T23 between the second lens and the third lens and the air interval T45 between the fourth lens and the fifth lens satisfy the following conditions: 8>T45 / T23>2.5;

[0029] and / or,

[0030] The distance between the image side surface of the sixth lens and the image plane is 5 mm to 30 mm.

[0031] As a further improvement of the present invention, a plurality of filters are further arranged between the image plane and the sixth lens.

[0032] Another aspect of the present invention provides an inner focusing telephoto lens, comprising any one of the inner focusing imaging systems described above.

[0033] As a further improvement of the present invention, a stop is provided on the object side of the first lens.

[0034] The above-mentioned improved technical features can be combined with each other as long as they do not conflict with each other.

[0035] In general, the above technical solutions conceived by the present invention have the following beneficial effects compared with the prior art:

[0036] (1) The internal focusing imaging system of the present invention realizes focusing only by moving the focusing group, by setting the first fixed group and the second fixed group to remain stationary, so that the lens installed on the outermost side of the lens can remain unchanged, which is convenient for sealing the lens and preventing external fog, dust, etc. from entering the interior of the lens; at the same time, only by moving the two lenses in the focusing group, the change in the lens field angle during focusing from infinity to the closest object distance, that is, the breathing effect, is effectively reduced, thereby improving the shooting stability and imaging consistency. In addition, compared with the solution of focusing by moving the entire lens, the focus is achieved by moving only part of the lens, which has a small load, a smoother focusing process, and less noise.

[0037] (2) The internal focusing imaging system of the present invention limits the distance between the image side surface of the sixth lens and the image plane to 5 mm to 30 mm to ensure a longer optical back focus, thereby reducing the impact of dirt on the filter on the imaging. When the lens is used in a scene requiring long exposure shooting, it is convenient for subsequent image superposition and stretching processing, greatly reducing the requirements for filter cleanliness, thereby ensuring the quality of the final image.

[0038] (3) The internal focusing imaging system of the present invention uses ultra-low dispersion material for at least one lens to effectively optimize the system to near the diffraction limit, so that when imaging a star point at infinity, the image spot is smaller, thereby helping to improve the clarity and contrast of the imaging.

[0039] (4) The internal focusing imaging system and the internal focusing telephoto lens including the same of the present invention have a compact overall structure and are easy to carry. The focal length is greater than the mechanical barrel length, which is beneficial for ensuring the telephoto characteristics of the lens while not causing the barrel length to be too long, thereby reducing the moving load during the focusing process, and has good application prospects and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0041] Figure 1 This is a schematic diagram of Example 1 of the present invention when the object distance is infinite;

[0042] Figure 2 1 is an axial aberration diagram when the object distance is infinite in Example 1 of the present invention;

[0043] Figure 3 1 is a diagram of field curvature and distortion when the object distance is infinite in Example 1 of the present invention;

[0044] Figure 4 This is a point diagram when the object distance is infinite in Example 1 of the present invention;

[0045] Figure 5 1 is an MTF curve diagram when the object distance is infinite in Example 1 of the present invention;

[0046] Figure 6 This is a schematic diagram of Example 1 when the object distance is 5m;

[0047] Figure 7 This is an axial aberration diagram of Example 1 of the present invention when the object distance is 5m;

[0048] Figure 8 This is a diagram of field curvature and distortion when the object distance is 5 meters in Example 1 of the present invention;

[0049] Figure 9 This is the spot diagram of Example 1 of the present invention when the object distance is 5m;

[0050] Figure 10 This is an MTF curve diagram of Example 1 of the present invention when the object distance is 5 meters;

[0051] Figure 11 is a schematic diagram of Example 2 of the present invention when the object distance is infinite;

[0052] Figure 12 This is an axial aberration diagram when the object distance is infinite in Example 2 of the present invention;

[0053] Figure 13 1 is a diagram of field curvature and distortion when the object distance is infinite in Example 2 of the present invention;

[0054] Figure 14 This is a point diagram when the object distance is infinite in Example 2 of the present invention;

[0055] Figure 15 This is an MTF curve diagram of Example 2 of the present invention when the object distance is infinite;

[0056] Figure 16 is a schematic diagram of Example 3 of the present invention when the object distance is infinite;

[0057] Figure 17 This is an axial aberration diagram when the object distance is infinite in Example 3 of the present invention;

[0058] Figure 18 1 is a diagram of field curvature and distortion when the object distance is infinite in Example 3 of the present invention;

[0059] Figure 19 This is a point diagram when the object distance is infinite in Example 3 of the present invention;

[0060] Figure 20 This is an MTF curve diagram of Example 3 of the present invention when the object distance is infinite;

[0061] Figure 21 is a schematic diagram of Example 4 of the present invention when the object distance is infinite;

[0062] Figure 22 1 is an axial aberration diagram when the object distance is infinite in Example 4 of the present invention;

[0063] Figure 23 1 is a diagram of field curvature and distortion when the object distance is infinite according to Example 4 of the present invention;

[0064] Figure 24 This is a point diagram when the object distance is infinite in Example 4 of the present invention;

[0065] Figure 25 This is an MTF curve diagram of Example 4 of the present invention when the object distance is infinite;

[0066] Figure 26 is a schematic diagram of Example 5 of the present invention when the object distance is infinite;

[0067] Figure 27 This is an axial aberration diagram when the object distance is infinite in Example 5 of the present invention;

[0068] Figure 28 1 is a diagram of field curvature and distortion when the object distance is infinite in Example 5 of the present invention;

[0069] Figure 29This is a point diagram when the object distance is infinite in Example 5 of the present invention;

[0070] Figure 30 This is an MTF curve diagram of Example 5 of the present invention when the object distance is infinite;

[0071] In all the drawings, the same reference numerals represent the same technical features, specifically: 1. First fixed group; 101. First lens; 102. Second lens; 2. Focusing group; 201. Third lens; 202. Fourth lens; 3. Second fixed group; 301. Fifth lens; 302. Sixth lens; 4. Aperture; 5. Filter; 6. Image plane. DETAILED DESCRIPTION

[0072] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to illustrate the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0073] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0074] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0075] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediate medium; internal communication between two components, or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0076] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0077] Example:

[0078] See also Figures 1 to 30 The internal focusing imaging system in a preferred embodiment of the present invention includes a first fixed group 1, a focusing group 2, and a second fixed group 3, arranged sequentially from the object side to the image side. The first fixed group 1 and the second fixed group 3 are fixed in position, and focusing at different object distances is achieved solely through the movement of the focusing group 2. This reduces the impact of focusing group movement on aberrations and ensures balanced image quality at various working distances.

[0079] Specifically, the first fixing group 1 in the preferred embodiment of the present invention has a positive bending force, such as Figure 1 As shown in the figure, the left side of the imaging system is the object side and the right side is the image side. The first fixed group 1 specifically includes a first lens 101 and a second lens 102 arranged in sequence from the object side to the image side, and the first lens 101 and the second lens 102 are glued together to form a first doublet lens; wherein the first lens 101 has positive refractive power, and preferably both the object side surface and the image side surface thereof are convex; the second lens 102 has negative refractive power, and preferably both the object side surface and the image side surface thereof are concave.

[0080] Furthermore, the focusing group 2 in the preferred embodiment of the present invention includes a third lens 201 and a fourth lens 202 arranged in sequence from the object side to the image side; wherein the third lens 201 has positive refractive power, and preferably both its object-side surface and its image-side surface are convex; the fourth lens 202 has negative refractive power, and preferably its object-side surface is concave.

[0081] Furthermore, in the preferred embodiment, the second fixed group 3 includes a fifth lens 301 and a sixth lens 302 arranged in sequence from the object side to the image side, and the fifth lens 301 and the sixth lens 302 are cemented together to form a second doublet lens; wherein the fifth lens 301 has negative refractive power, and preferably its object-side surface is concave; and the sixth lens 302 has positive refractive power, and preferably its object-side surface is convex.

[0082] Preferably, the axial distance from the first lens 101 to the image plane 6 is TTL, and the effective focal length of the lens is EFL, which satisfies: TTL / EFL<0.8; so that the tube length is smaller than the focal length, which is conducive to miniaturization of the lens size.

[0083] Preferably, the front and rear curvature radii R1 and R2 of the first lens 101 satisfy the relationship: 0.5<|R1 / R2|<1, so as to achieve appropriate refractive power, maintain the aberration balance of the telephoto lens, and keep a good processed shape.

[0084] Preferably, the focal length of the first fixed group 1 is F1, the focal length of the focusing group 2 is F2, and the focal length of the second fixed group 3 is F3, then:

[0085] F1 / EFL>0.95;

[0086] |F2 / EFL|>3;

[0087] 5>|F3 / EFL|>0.3;

[0088] This arrangement is designed to allow the first fixed group 1 and the second fixed group 3 to take on more optical power and more aberration correction functions, and the focusing group 2 to take on more focusing functions, so that the focusing group 3 deflects less light during movement, which is beneficial to the balance of aberrations at different object distances.

[0089] Further preferably, 2>F1 / EFL>0.95;

[0090] Preferably, the air interval between the second lens 102 and the third lens 201 is T23, and the air interval between the fourth lens 202 and the fifth lens 301 is T45, and the following conditions are satisfied: 8>T45 / T23>2.5;

[0091] Preferably, a plurality of filters 5 are provided between the image side surface of the sixth lens 302 and the image plane 6 to meet the requirements of wavelength selection; and the distance between the image side surface of the sixth lens 302 and the image plane 6 is preferably controlled within a range of 5 mm to 30 mm to ensure a longer optical back focus and reduce the impact of dirt on the filter 5 on imaging. This facilitates subsequent image superposition and stretching processing when the lens is used in scenes requiring long exposure shooting, greatly reducing the requirements for the cleanliness of the filter 5, thereby ensuring the quality of the final image.

[0092] Preferably, at least one of the first lens 101, the second lens 102, the third lens 201, the fourth lens 202, the fifth lens 301, and the sixth lens 302 is made of an ultra-low dispersion material, effectively optimizing the system to near the diffraction limit. This results in a smaller spot size on the image plane 6 when imaging stars at infinity, thereby improving image clarity and contrast, which are extremely important parameters in astronomical photography applications.

[0093] Preferably, first lens 101 is made of an ultra-low dispersion material. Furthermore, first lens 101 preferably satisfies the following conditions: nd < 1.5, vd > 80, where nd is the refractive index and vd is the Abbe number. This configuration allows for more effective control of the dispersion characteristics of the entire optical system, resulting in a more compact lens system with improved performance while maintaining high-quality imaging.

[0094] At the same time, the sixth lens 302 satisfies: nd>1.5, vd<50, where nd is the refractive index and vd is the Abbe number, so as to cooperate with the first lens 101 in the first fixed group 1 to better achieve the balance of aberrations when the focusing group 2 moves.

[0095] Furthermore, the present invention arranges the inner focusing imaging system inside the lens to form an inner focusing telephoto lens, and arranges a stop 4 corresponding to the object side of the first lens 101 .

[0096] In actual use, the first fixed group 1 and the second fixed group 3 remain stationary, and focusing is achieved only by moving the focusing group 2, so that the lens installed on the outermost side of the lens can remain unchanged, which is convenient for sealing the lens and preventing external fog, dust, etc. from entering the interior of the lens; at the same time, compared with the overall focusing solution of the lens, the present invention only moves the focusing group 2, and the change in the lens field angle during focusing, that is, the breathing effect, is effectively reduced from infinity to the closest object distance, thereby improving the shooting stability and imaging consistency. In addition, compared with the solution of focusing by moving the entire lens, the focus is achieved by moving only part of the lens, which has a small load, a smoother focusing process, and less noise.

[0097] According to the above-mentioned implementation manner, a detailed description will be given below in combination with specific embodiments and with reference to the accompanying drawings.

[0098] Example 1:

[0099] The main parameters of the imaging system are shown in Tables 1 and 2.

[0100] Table 1 Imaging system parameters in Example 1

[0101] parameter Value parameter Value parameter Value Focal length f(mm) 150.021 BFL 7.3 First lens 1.437 Net aperture EPD (mm) 30 |R1 / R2| 0.68 First lens vd 95.123 TTL(mm) 109.000 F1 / EFL 1.77 Sixth lens nd 1.625 Field of view FOV 1.679° |F2 / EFL| 10.31 Sixth lens vd 35.578 Image height (mm) 4.41 |F3 / EFL| 3.15 TTL / EFL 0.73 T45 / T23 3.62

[0102] Table 2 Imaging system parameters in Example 1

[0103]

[0104] Figure 1 Schematic diagram showing the positions of the lenses in the imaging system when the object distance is infinite and under the setting parameters in Table 1 and Table 2;

[0105] Figure 2 It shows the axial aberration diagram of the image when the object distance is infinite, which shows the axial aberration of light at different pupil heights at different wavelengths, that is, the distance between the intersection of light from different annular bands on the axis and the image plane. The more concentrated the curves at different wavelengths are, the better it is, indicating that the spherical aberration and chromatic aberration are controlled within a relatively good range, and the better the imaging effect.

[0106] Figure 3 The field curvature and distortion diagram when the object distance is infinite is shown. Among them, the more the field curvature curves of each wavelength are closer together, the better the imaging effect. The smaller the separation between the field curvature and the curve, the smaller the astigmatism. When the distortion is controlled within 1%, it is considered that the object and the image are almost completely similar and cannot be perceived by the human eye.

[0107] Figure 4 The spot diagram shows the object distance at infinity. This is a diagram of the light distribution on a specific surface by tracing a light beam in an optical system. The black circle represents the Airy disk. When the spot diagram is optimized to the size of the Airy disk, it can be considered to be optimized to the diffraction limit.

[0108] Figure 5 This graph shows the MTF curve at infinite object distance. This curve describes the imaging quality of an optical system and indicates its ability to transmit contrast. The horizontal axis represents spatial frequency, and the vertical axis represents the MTF value, with a maximum value of 1. The top curve in the graph is the ideal MTF curve, also known as the diffraction limit. The other curves are actual MTF curves for different fields of view. The closer these curves are to the diffraction limit, the better the imaging performance.

[0109] It is known that the above content is also applicable to other specific embodiments and will not be repeated below.

[0110] according to Figures 4 and 5 From the parameters in the figure, we can see that the internal focusing telephoto lens can form images at infinity and maintain good results.

[0111] Figure 6 The following is a schematic diagram showing the positions of the lenses in the imaging system when the object distance is 5m and the parameters in Table 1 and Table 2 are set.

[0112] Figures 7 to 10The system shows the parameter performance of object imaging when the object distance is 5m and under the setting parameters of Table 1 and Table 2. It can image objects 5m away and maintain good effects. The subsequent embodiments can also image objects 5m away and maintain good effects, which will not be shown one by one later.

[0113] Example 2:

[0114] The main parameters of the imaging system are shown in Table 3 and Table 4, and the system imaging parameter diagram is shown in Figures 11 to 15 .

[0115] Table 3 Imaging system parameters in Example 2

[0116] parameter Value parameter Value parameter Value Focal length f(mm) 149.928 BFL 13.309 First lens nd 1.438 Net aperture EPD (mm) 30 |R1 / R2| 0.68 First lens vd 94.577 TTL(mm) 105 F1 / EFL 1.02 Sixth lens nd 1.617 Field of view FOV 1.674° |F2 / EFL| 3.76 Sixth lens vd 36.627 Image height (mm) 4.41 |F3 / EFL| 0.32 TTL / EFL 0.70 T45 / T23 5.85

[0117] Table 4 Imaging system parameters in Example 2

[0118]

[0119]

[0120] Figure 11 The following is a schematic diagram illustrating the positions of the lenses when the object distance is infinite and under the setting parameters of Table 3 and Table 4;

[0121] Figures 12 to 15 The system's imaging performance is shown when the object distance is infinite and under the setting parameters in Tables 3 and 4. It is capable of imaging objects at infinity and maintaining good results.

[0122] Example 3:

[0123] The main parameters of the imaging system are shown in Table 5 and Table 6, and the system imaging parameter diagram is shown in Figures 16 to 20 .

[0124] Table 5 Imaging system parameters in Example 3

[0125] parameter Value parameter Value parameter Value Focal length f(mm) 149.005 BFL 11.766 First lens nd 1.456 Net aperture EPD (mm) 29.68 |R1 / R2| 0.63 First lens vd 90.270 TTL(mm) 108 F1 / EFL 1.75 Sixth lens nd 1.597 Field of view FOV 1.694° |F2 / EFL| 806684.34 Sixth lens vd 39.891 Image height (mm) 4.41 |F3 / EFL| 3.43 TTL / EFL 0.72 T45 / T23 2.51

[0126] Table 6 Imaging system parameters 2 in Example 3

[0127]

[0128]

[0129] Figure 16 The following is a schematic diagram illustrating the position of each lens when the object distance is infinite and the setting parameters in Table 5 and Table 6;

[0130] Figures 17 to 20The system's imaging performance is shown when the object distance is infinite and under the parameters set in Tables 5 and 6. It is capable of imaging objects at infinity and maintaining good results.

[0131] Example 4:

[0132] The main parameters of the imaging system are shown in Table 7 and Table 8, and the system imaging parameter diagram is shown in Figures 21 to 25 .

[0133] Table 7 Imaging system parameters in Example 4

[0134] parameter Value parameter Value parameter Value Focal length f(mm) 149.391 BFL 22.015 First lens nd 1.437 Net aperture EPD (mm) 29.68 |R1 / R2| 0.63 First lens vd 95.123 TTL(mm) 110.265 F1 / EFL 1.24 Sixth lens nd 1.673 Field of view FOV 1.686° |F2 / EFL| 46.15 Sixth lens vd 32.179 Image height (mm) 4.41 |F3 / EFL| 0.88 TTL / EFL 0.74 T45 / T23 2.92

[0135] Table 8 Imaging system parameters 2 in Example 4

[0136]

[0137]

[0138] Figure 21 The following illustrates the position of each lens when the object distance is infinite and the setting parameters in Table 7 and Table 8;

[0139] Figures 22 to 25 The system's imaging performance is shown when the object distance is infinite and under the parameters shown in Tables 7 and 8. The system is capable of imaging objects at infinity and maintaining good imaging quality.

[0140] Example 5:

[0141] The main parameters of the imaging system are shown in Tables 9 and 10, and the system imaging parameter diagram is shown in Figures 26 to 30 .

[0142] Table 9 Imaging system parameters in Example 5

[0143] parameter Value parameter Value parameter Value Focal length f(mm) 149.970 BFL 25.301 First lens nd 1.438 Net aperture EPD (mm) 30 |R1 / R2| 0.66 First lens vd 94.577 TTL(mm) 109 F1 / EFL 0.95 Sixth lens nd 1.847 Field of view FOV 1.681° |F2 / EFL| 3.93 Sixth lens vd 23.787 Image height (mm) 4.41 |F3 / EFL| 0.47 TTL / EFL 0.73 T45 / T23 4.48

[0144] Table 10 Imaging system parameters 2 in Example 5

[0145]

[0146]

[0147] Figure 26 The following illustrates the position of each lens when the object distance is infinite and the setting parameters in Table 9 and Table 10;

[0148] Figures 27 to 30The system's imaging performance is shown when the object distance is infinite and under the parameters listed in Tables 9 and 10. The system is capable of imaging objects at infinity and maintaining good imaging quality.

[0149] The internal focusing imaging system and the internal focusing telephoto lens including the same in the present invention have a compact overall structure and are easy to carry. The focal length is greater than the mechanical barrel length, which is beneficial for ensuring the telephoto characteristics of the lens while not causing the barrel length to be excessively long, thereby reducing the moving load during the focusing process, and has good application prospects and promotion value.

[0150] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An internal focusing imaging system, characterized in that: It includes a first fixed group, a focusing group and a second fixed group arranged in sequence from the object side to the image side; The first fixed group has positive refractive power, and the first fixed group includes a first lens and a second lens arranged in sequence from the object side to the image side; the first lens has positive refractive power, and the second lens has negative refractive power; The focusing group realizes focusing at different object distances by moving, and includes a third lens and a fourth lens arranged in sequence from the object side to the image side; the third lens has a positive refractive power, and the fourth lens has a negative refractive power; The second fixed group includes a fifth lens and a sixth lens arranged in sequence from the object side to the image side; the fifth lens has negative refractive power, and the sixth lens has positive refractive power.

2. The internal focusing imaging system according to claim 1, wherein: The object-side surface and the image-side surface of the first lens are both convex; the object-side surface and the image-side surface of the second lens are both concave; and / or, The object-side surface and the image-side surface of the third lens are both convex; the object-side surface of the fourth lens is concave; and / or, The object-side surface of the fifth lens is concave; the image-side surface of the sixth lens is convex.

3. The internal focusing imaging system according to claim 1, wherein: The first lens and the second lens are cemented to form a first doublet lens, and the fifth lens and the sixth lens are cemented to form a second doublet lens.

4. The internal focusing imaging system according to any one of claims 1 to 3, characterized in that: The axial distance TTL from the object side surface to the image plane of the first lens and the effective focal length EFL of the lens satisfy the following: TTL / EFL<0.8; and / or, The front and rear curvature radii R1 and R2 of the first lens satisfy the following relationship: 0.5<|R1 / R2|<1.

5. The internal focusing imaging system according to claim 4, wherein: The focal length F1 of the first fixed group and the effective focal length EFL of the lens satisfy the following relationship: F1 / EFL>0.95; and / or, The focal length F2 of the focusing group and the effective focal length EFL of the lens satisfy the following relationship: |F2 / EFL|>3; and / or, The focal length F3 of the second fixed group and the effective focal length EFL of the lens satisfy the following relationship: 5>|F3 / EFL|>0.3; and / or, The air interval T23 between the second lens and the third lens and the air interval T45 between the fourth lens and the fifth lens satisfy the following conditions: 8>T45 / T23>2.5; and / or, The distance between the image side surface of the sixth lens and the image plane is 5 mm to 30 mm.

6. The internal focusing imaging system according to claim 5, wherein: At least one of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens is made of an ultra-low dispersion material.

7. The internal focusing imaging system according to claim 6, wherein: The material of the first lens is an ultra-low dispersion material, and the first lens satisfies nd<1.5, vd>80, where nd is the refractive index and vd is the Abbe number; and / or, The sixth lens satisfies nd>1.5, vd<50, where nd is the refractive index and vd is the Abbe number.

8. The internal focusing imaging system according to any one of claims 1 to 3 and 5 to 7, characterized in that: A plurality of filters are also arranged between the image plane and the sixth lens.

9. An inner-focus telephoto lens, characterized in that: The invention comprises the internal focusing imaging system according to any one of claims 1 to 8.

10. The inner focus telephoto lens according to claim 9, wherein: An aperture stop is provided on the object side of the first lens.

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