A telephoto lens and a telephoto system including the telephoto lens

Abstract

The present invention discloses a telephoto lens and a telephoto system including the telephoto lens, wherein the telephoto lens adopts a method of forming two groups of double-cemented lenses with four spherical lenses, and satisfies the following relationship: 1<f / TTL, 2<|f 34 / f 12 | Among them, f, f 12 、f 34 They are the focal lengths of the entire telephoto lens, the first double-cemented lens, and the second double-cemented lens, respectively. TTL is the distance from the first surface of the lens object side to the image plane. The overall focal length is greater than the mechanical tube length, which is beneficial to ensure the telephoto characteristics of the lens without causing the tube length to be too long, making the overall structure compact. While ensuring high imaging quality, the number of lens assemblies is reduced, making installation easier; on the other hand, the relative position deviation between the two double-cemented lenses has little effect on imaging, reducing the tolerance sensitivity of the lens.

Description

Technical Field

[0001] The present invention belongs to the field of optical telephoto imaging, and in particular relates to a telephoto lens and a telephoto system comprising the telephoto lens. Background Art

[0002] A telephoto lens is a lens that can image distant objects and is characterized by its small relative aperture and field of view.

[0003] Telephoto lenses are often used in telescopes as their objective lenses, and they are used together with eyepieces to allow users to observe distant objects. Telescopes are usually visual systems, so their specific implementation forms are monocular telescopes or binocular telescopes. Since the telephoto lens in a visual telescope must be used in combination with an eyepiece, a prism or a lens-type steering system, the aberration compensation between it and other parts should be considered during design. This adds a certain degree of difficulty to the design. When using a handheld telescope, the picture will shake due to the unstable handholding, and the physical sense will be poor. Long-term observation will cause eye fatigue and dizziness. If you encounter a wonderful view and want to record and shoot it, you have to connect your mobile phone to take pictures through an adapter ring, which causes many inconveniences.

[0004] Currently, telephoto lenses have appeared on smart electronic devices, such as mobile phones, which work with image sensors to directly record and display images, eliminating the process of human eye observation. However, due to the limited space of smart electronic devices, the aperture (about 4mm) and focal length (about 10mm) of telephoto lenses are limited, and the imaging effect of conventional telephoto lenses cannot be achieved. Summary of the invention

[0005] In response to at least one of the above defects or improvement needs in the prior art, the present invention provides a telephoto lens and a telephoto system including the telephoto lens. The telephoto lens adopts a method of forming two groups of double-cemented lenses with four spherical lenses. The overall focal length is greater than the mechanical barrel length. Compared with the mobile phone telephoto lens, both the aperture and the focal length are increased, thereby achieving high-quality telephoto imaging.

[0006] To achieve the above objective, according to one aspect of the present invention, there is provided a telephoto lens, characterized in that it comprises, from the object side to the image side:

[0007] A first lens having positive refractive power, wherein both front and rear surfaces thereof are convex;

[0008] A second lens having negative refractive power, whose object side surface is concave and whose image side surface is convex;

[0009] A third lens element having positive refractive power, wherein both the front and rear surfaces thereof are convex;

[0010] A fourth lens element having negative refractive power, wherein both the front and rear surfaces thereof are concave;

[0011] The first lens and the second lens form a first double-cemented lens and have positive refractive power;

[0012] The third lens and the fourth lens form a second doublet lens having negative refractive power;

[0013] The telephoto lens satisfies the following relationship:

[0014] 1<f / TTL

[0015] 2<|f 34 / f 12 |

[0016] Among them, f, f 12 、f 34 They are the focal lengths of the entire telephoto lens, the first double cemented lens, and the second double cemented lens respectively. TTL is the distance from the first object surface of the lens to the image plane.

[0017] Preferably, the front and rear curvature radii R1 and R2 of the first lens satisfy:

[0018] 0.5<|R1 / R2|<2.

[0019] Preferably, the refractive index of d-light of the first lens material Nd≤1.55, and the Abbe number Vd≥70.

[0020] Preferably, the curvature radii R4 and R6 of the object-side surface of the third lens and the image-side surface of the fourth lens satisfy:

[0021] 1.2<R4 / R6<1.8

[0022] And R6<60mm.

[0023] Preferably, a filter is placed between the fourth lens and the image plane, and the front and rear surfaces of the filter are both planes.

[0024] Preferably, a stop is provided on the front surface of the first lens.

[0025] To achieve the above object, according to another aspect of the present invention, a telephoto system is provided, characterized in that it comprises:

[0026] The telephoto lens, the fixing ring and spacer for fixing the telephoto lens, the sensor chip and the driving board, and the focusing mechanism;

[0027] The fixing ring is used to sequentially insert the first double-cemented lens, the spacer, and the second double-cemented lens of the telephoto lens to fix the telephoto lens;

[0028] The spacer is used to ensure that the distance between the two doublet lenses meets the design value;

[0029] The sensor chip is located on the image side of the telephoto lens and fixed on the driving board, and is used to detect images;

[0030] The driving board is the main control circuit of the telephoto system, used to drive the sensor chip to acquire images;

[0031] The focusing mechanism is used to change the relative distance between the fixing ring and the driving plate to achieve focusing.

[0032] Preferably, the focusing mechanism moves the fixing ring alone, or moves the driving plate alone.

[0033] Preferably, the focusing mechanism is a manual focusing structure;

[0034] Alternatively, the focusing mechanism is an electric focusing mechanism, and the electric focusing is controlled by the driving board.

[0035] Preferably, the fixing ring is an elastic interference ring;

[0036] The inner diameter of the elastic interference ring is smaller than the diameter of each lens to be installed in the telephoto lens, and an opening is left on the side wall of the elastic interference ring;

[0037] After the telephoto lenses are sequentially mounted into the elastic interference ring, the first double cemented lens, the second double cemented lens and the elastic interference ring interfere with each other, and the optical axes of different lenses and the mechanical axis of the elastic interference ring coincide.

[0038] The above-mentioned preferred technical features can be combined with each other as long as they do not conflict with each other.

[0039] In general, the above technical solution conceived by the present invention has the following beneficial effects compared with the prior art:

[0040] 1. The telephoto lens of the present invention belongs to a typical telephoto optical group, and the overall focal length is greater than the mechanical tube length, which is beneficial to ensure the telephoto characteristics of the lens without causing the tube length to be too long, making the overall structure compact.

[0041] 2. The telephoto lens of the present invention is realized by using four spherical lenses to form two groups of double-cemented lenses, which reduces the number of lens assemblies while ensuring high imaging quality, making installation easier; on the other hand, the relative position deviation between the two double-cemented lenses has little effect on imaging, reducing the tolerance sensitivity of the lens.

[0042] 3. The telephoto system of the present invention has many significant improvements over the above-mentioned telephoto lens, and also has the following outstanding advantages: it uses an image sensor to directly detect signals, eliminating the need for an image transfer prism and an eyepiece system, thereby avoiding the dizziness caused by long-term observation with a visual telescope, and can also solve the problem of real-time display and storage when connected to electronic devices such as mobile phones, tablets, and computers, thereby solving the problem of cumbersome image storage with a visual telescope. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a schematic diagram of a telephoto lens of the present invention;

[0044] Figure 2 is an axial chromatic aberration diagram of the telephoto lens embodiment 1 of the present invention;

[0045] Figure 3a is a field curvature diagram of telephoto lens embodiment 1 of the present invention;

[0046] Figure 3b is a distortion diagram of telephoto lens embodiment 1 of the present invention;

[0047] Figure 4 is a point diagram of a telephoto lens embodiment 1 of the present invention;

[0048] Figure 5 is an MTF curve diagram of telephoto lens embodiment 1 of the present invention;

[0049] Figure 6 is an axial chromatic aberration diagram of telephoto lens embodiment 2 of the present invention;

[0050] Figure 7a is a field curvature diagram of a telephoto lens embodiment 2 of the present invention;

[0051] Figure 7b is a distortion diagram of telephoto lens embodiment 2 of the present invention;

[0052] Figure 8 is a point diagram of a telephoto lens embodiment 2 of the present invention;

[0053] Fig. 9 is an MTF curve diagram of telephoto lens embodiment 2 of the present invention;

[0054] Fig.10 is an axial chromatic aberration diagram of the telephoto lens embodiment 3 of the present invention;

[0055] Fig.11a is a field curvature diagram of a telephoto lens embodiment 3 of the present invention;

[0056] Fig.11b is a distortion diagram of telephoto lens embodiment 3 of the present invention;

[0057] Fig.12 is a point diagram of a telephoto lens embodiment 3 of the present invention;

[0058] Fig.13 is an MTF curve diagram of telephoto lens embodiment 3 of the present invention;

[0059] Fig.14is a schematic diagram of a telephoto system embodiment 1 including a telephoto lens according to the present invention;

[0060] Fig.15 is a schematic diagram of a telephoto system embodiment 2 including a telephoto lens according to the present invention;

[0061] Fig.16 is a schematic diagram of a telephoto system embodiment 3 including a telephoto lens according to the present invention;

[0062] Fig.17 Schematic diagram of telephoto system embodiment 4 including a telephoto lens in the present invention. DETAILED DESCRIPTION

[0063] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other. The present invention is further described in detail below in conjunction with specific embodiments.

[0064] like Figure 1 FIG. 1 is a schematic diagram of a specific implementation of the telephoto lens of the present invention. The telephoto lens includes, from the object side to the image side, the following components:

[0065] A stop STOP located at the front surface of the first lens L1;

[0066] A first lens L1 having positive refractive power, wherein both the front and rear surfaces thereof are convex;

[0067] The second lens L2 has a negative refractive power, and its object side surface is concave and its image side surface is convex;

[0068] A third lens L3 having positive refractive power, whose front and rear surfaces are both convex;

[0069] A fourth lens L4 having negative refractive power, whose front and rear surfaces are both concave;

[0070] The first lens L1 and the second lens L2 form a first doublet lens having positive refractive power;

[0071] The third lens L3 and the fourth lens L4 form a second doublet lens having negative refractive power;

[0072] The telephoto lens satisfies the following relationship:

[0073] 1<f / TTL

[0074] 2<|f 34 / f 12 |

[0075] Among them, f, f 12 、f 34 They are the focal lengths of the entire telephoto lens, the first double cemented lens, and the second double cemented lens respectively. TTL is the distance from the first object surface of the lens to the image plane.

[0076] Preferably, the front and rear curvature radii R1 and R2 of the first lens satisfy:

[0077] 0.5<|R1 / R2|<2.

[0078] Preferably, the refractive index of d-light of the first lens material is Nd≤1.52, and the Abbe number Vd≥70. Such an arrangement can effectively correct chromatic aberration and improve imaging quality.

[0079] Preferably, the radii of curvature R4 and R6 of the object surface of the third lens and the image surface of the fourth lens satisfy:

[0080] 1.2<R4 / R6<1.8

[0081] And R6<60mm.

[0082] Furthermore, when there is a requirement for wavelength selection, a filter L5 is also included in front of the image plane.

[0083] Figure 1 Among them, S1 is the front surface of the first lens L1, S2 is the cemented surface of the first lens L1 and the second lens L2, S3 is the back surface of the second lens L2, S4 is the front surface of the third lens L3, S5 is the cemented surface of the third lens L3 and the fourth lens L4, S6 is the back surface of the fourth lens L4, S7 and S8 are the front and back surfaces of the filter L5, and S9 is the image plane.

[0084] In all the following embodiments, the lens parameters satisfy the aforementioned conditions.

[0085] <Telephoto lens example 1>

[0086] Table 1 is a parameter table of telephoto lens embodiment 1, and the main parameters are as follows:

[0087] f=100.001mm,EPD(clear aperture)=24mm,TTL=94.95803mm,FOV(field of view)=2.228°,Image height=4.000mm

[0088] Table 1. Parameters of telephoto lens embodiment 1

[0089] Surface number Surface type Curvature radius (mm) Thickness(mm) Refractive Index / Abbe Number OBJ Spherical endless endless —— STOP Spherical endless 0 —— S1 Spherical 47.478 5 1.497 / 81.595 S2 Spherical -46.524 4.5 1.750 / 35.021 S3 Spherical -191.468 8.14 —— S4 Spherical 21.838 5.50 1.720 / 43.683 S5 Spherical -398.552 3 1.612 / 44.093 S6 Spherical 14.944 67 —— S7 Spherical endless 0.5 1.517 / 64.212 S8 Spherical endless 1.30 —— S9 Spherical endless —— ——

[0090] The axial chromatic aberration diagram of telephoto lens Example 1 is shown in FIG. Figure 2As shown;

[0091] The field curvature diagram of telephoto lens embodiment 1 is as follows: Figure 3a As shown;

[0092] The distortion diagram of telephoto lens embodiment 1 is shown in FIG. Figure 3b As shown;

[0093] The point diagram of telephoto lens embodiment 1 is shown in FIG. Figure 4 As shown;

[0094] The MTF curve of telephoto lens example 1 is as follows: Figure 5 shown.

[0095] <Telephoto lens example 2>

[0096] Table 2 is a parameter table of telephoto lens embodiment 2, and the main parameters are as follows:

[0097] f=108.288mm,EPD=24mm,TTL=100.000mm,FOV(field of view)=2.110°,Image height=4.000mm.

[0098] Table 2. Parameters of telephoto lens embodiment 2

[0099] Surface number Surface type Curvature radius (mm) Thickness(mm) Refractive Index / Abbe Number OBJ Spherical endless endless —— STOP Spherical endless 0 —— S1 Spherical 45.203 4.99 1.497 / 81.595 S2 Spherical -41.614 4.5 1.626 / 35.714 S3 Spherical -1016.18 4.99 —— S4 Spherical 21.778 5.50 1.702 / 41.141 S5 Spherical -420.519 2.80 1.612 / 44.093 S6 Spherical 15.310 75 —— S7 Spherical endless 0.5 1.517 / 64.212 S8 Spherical endless 1.71 —— S9 Spherical endless —— ——

[0100] The axial chromatic aberration diagram of telephoto lens Example 2 is shown in FIG. Figure 6 As shown;

[0101] The field curvature diagram of telephoto lens embodiment 2 is as follows: Figure 7a As shown;

[0102] The distortion diagram of telephoto lens embodiment 2 is shown in FIG. Figure 7b As shown;

[0103] The point diagram of telephoto lens embodiment 2 is shown in FIG. Figure 8 As shown;

[0104] The MTF curve of telephoto lens embodiment 2 is as follows: Fig. 9 shown.

[0105] <Telephoto lens example 3>

[0106] Table 3 is a parameter table of telephoto lens embodiment 3, and the main parameters are as follows:

[0107] f=419.911mm,EPD=90mm,TTL=404.680mm,FOV(field of view)=0.546°,Image height=4.000mm.

[0108] Table 3. Parameters of telephoto lens embodiment 3

[0109]

[0110]

[0111] The axial chromatic aberration diagram of telephoto lens Example 3 is as follows: Fig.10 As shown;

[0112] The field curvature diagram of telephoto lens embodiment 3 is as follows: Fig.11a As shown;

[0113] The distortion diagram of telephoto lens embodiment 3 is shown in FIG. Fig.11b As shown;

[0114] The point diagram of telephoto lens embodiment 3 is as follows: Fig.12 As shown;

[0115] The MTF curve of telephoto lens Example 3 is as follows: Fig.13 shown.

[0116] The present invention also provides a telephoto system including the telephoto lens, which is specifically implemented as follows:

[0117] <Telephoto System Example 1>

[0118] Fig.14 It is a specific embodiment 1 of the telephoto system, comprising a telephoto lens (including a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and preferably also including a filter L5), a housing 1, a fixing ring 2, a spacer 3, a focusing knob 40, a sensor chip 5, a driving board 6, and a power and data interface 7.

[0119] The imaging lens composed of the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 is installed in the fixing ring 2; the fixing ring 2 is a hollow cylindrical structure with a mounting step at one end. When installing, the doublet lens composed of the first lens L1 and the second lens L2, the spacer 3, and the doublet lens composed of the third lens L3 and the fourth lens L4 are inserted from the other end in sequence. A groove is provided on the outer wall of the fixing ring, and the focusing rod of the focusing knob 40 is just embedded in the groove. The focusing rod is in an eccentric state. When the focusing knob 40 is rotated, the focusing rod rotates eccentrically around the central axis, driving the fixing ring 2 to move in the axial direction (optical axis direction), thereby achieving focusing.

[0120] The filter L5 has a thickness of 0.5 mm and can be directly fixed in front of the sensor chip 5 by dispensing glue, or can be installed on a filter holder in front of the sensor chip 5 (not shown).

[0121] The detection surface of the sensor chip 5 is located at the image focal plane when imaging at infinity. When imaging at close range, the lens can be moved away from the sensor chip 5 by the focus knob 40. The sensor chip is directly welded on the driving board 6, and the driving board 6 has electronic components such as ISP (Image Signal Processor) chip, which can process and output image information in real time.

[0122] The power and data interface 7 can be but is not limited to Type-C or Micro-USB. This interface can be directly connected to devices such as computers and mobile phones (the mobile phone must support the OTG function), which can provide power and transmit data in real time.

[0123] Preferably, the fixing ring is an elastic interference ring used for centering installation of multiple lenses; the inner diameter of the elastic interference ring is smaller than the diameter of each lens to be installed in the telephoto lens, and an open slit is left on the side wall of the elastic interference ring; after the telephoto lenses are sequentially installed in the elastic interference ring, the first double-cemented lens, the second double-cemented lens and the elastic interference ring interfere with each other, and the optical axes of different lenses and the mechanical axis of the elastic interference ring coincide.

[0124] The inner diameter of the elastic interference ring is slightly smaller than the diameter of each lens of the telephoto lens. The elastic interference ring has radial elasticity to allow the lens to be installed, and the elastic interference ring is not closed. A straight line slit is left on the side wall of the elastic interference ring 11. After the lenses of the telephoto lens are installed in the elastic interference ring, in addition to radial deformation, the slit opens and is subjected to the inward contraction force of the elastic interference ring, so that the elastic interference ring clamps the lenses of the telephoto lens, and the lenses of the telephoto lens and the elastic interference ring achieve interference fit. The optical axis of the lenses of the telephoto lens coincides with the mechanical axis of the elastic interference ring, thereby achieving the effect of centering installation.

[0125] Preferably, the elastic interference ring is made of POM plastic, PC plastic, ABS plastic, aluminum alloy or other materials with certain hardness, strength and rigidity. The elastic interference ring is not easily deformed axially, thus ensuring the centering effect of the lens after installation.

[0126] Preferably, the middle of the elastic interference ring is a through hole with a uniform diameter.

[0127] Preferably, the inner surfaces of the elastic interference rings are subjected to a matte treatment to avoid the influence of stray light and ensure the imaging quality of the optical system.

[0128] Preferably, as for the straightness or curvature of the opening slit of the elastic interference ring, the opening slit of the elastic interference ring is a straight line or a curve, or a combination of a straight line and a curve.

[0129] Preferably, for the discontinuity of the opening slit of the elastic interference ring, the opening slit of the elastic interference ring is continuous, and the side wall of the elastic interference ring is not closed, or the opening slit of the elastic interference ring is discontinuous and segmented. The width of the slit can be changed accordingly according to the diameter of the elastic interference ring to ensure the interference fit effect between the lens and the elastic interference ring.

[0130] By using a specially constructed elastic interference ring, the lens and the elastic interference ring are installed in interference fit, so as to realize the centering installation of multiple lenses. The elastic interference ring in the present invention has low requirements on processing accuracy. After ensuring the processing accuracy of the lens, there is no need to consider the installation tolerance of the lens, and there is no need to repeatedly debug and modify the installation barrel. The lens can be installed in the elastic interference ring to realize centering installation. The lens is easy to install and disassemble, and the overall installation process is short. It is suitable for most optical systems and is conducive to wide promotion and use.

[0131] <Telephoto System Example 2>

[0132] Fig.15 Detailed description of the embodiment 2 of the telephoto system. Compared with the embodiment 1, the focusing mechanism is replaced by a stepping screw motor 41 instead of a focusing knob 40. The stepping screw motor is fixed inside the housing 1, and a slider 411 connects a screw 412 and a light rod 413. One end of the slider is embedded in the groove of the fixing ring 2. During electric focusing, the reduction stepping motor 414 drives the screw to rotate, thereby causing the slider to move along the axial direction of the light rod, driving the fixing ring 2 to move.

[0133] <Telephoto System Example 3>

[0134] Fig.16 3 is a schematic diagram of a specific embodiment of a telephoto system. Compared with the specific embodiment 1, the moving object during focusing is replaced by the driving plate 6 from the fixed ring 2, and the focusing structure 42 adopts a gear rack transmission for focusing. The gear 421 is relatively fixed to the housing 1, and the driving plate 6 is fixed to the rack 422. During focusing, the gear 421 rotates, and the rack 422 meshing with the gear 421 also moves accordingly, so as to realize the axial movement of the detection surface of the sensor chip 5.

[0135] <Telephoto System Example 4>

[0136] Fig.17 It is a schematic diagram of specific embodiment 4 of the telephoto system. Compared with specific embodiment 1, the figure does not show the housing 1, filter L5, sensor chip 5, drive board 6, power supply and data interface 7, and focuses on showing a new focusing method.

[0137] The new focusing mechanism comprises a focusing rod 21, a guide sleeve 22 with a guide bevel groove, a gear sleeve 23 with a groove opened along the axial direction on the inner wall, and a stepping motor 24 with a gear.

[0138] A telephoto lens is installed in the fixing ring 2, and a circular groove is formed on the outer wall thereof. A focus rod 21 is fixed in the groove, and the other end of the focus rod 21 passes through the guide bevel groove on the guide sleeve 22 and is inserted into the groove of the gear sleeve 23. The stepper motor 24 is fixed on the guide sleeve 22. When focusing, the stepper motor 24 rotates to drive the gear sleeve 23 meshing therewith to rotate. Since one end of the focus rod is inserted into the groove on the inner wall of the gear sleeve 23, the focus rod moves axially along the guide sleeve bevel groove. The focus rod 21 is connected to the fixing ring 2, so the fixing ring 2 will also move axially.

[0139] The power source of the focusing solution can be changed to manual rotation of the gear sleeve 23 in addition to the motor.

[0140] In summary, compared with the prior art, the solution of the present invention has the following significant advantages:

[0141] 1. The telephoto lens of the present invention belongs to a typical telephoto optical group, and the overall focal length is greater than the mechanical tube length, which is beneficial to ensure the telephoto characteristics of the lens without causing the tube length to be too long, making the overall structure compact.

[0142] 2. The telephoto lens of the present invention is realized by using four spherical lenses to form two groups of double-cemented lenses, which reduces the number of lens assemblies while ensuring high imaging quality, making installation easier; on the other hand, the relative position deviation between the two double-cemented lenses has little effect on imaging, reducing the tolerance sensitivity of the lens.

[0143] 3. The telephoto system of the present invention has many significant improvements over the above-mentioned telephoto lens, and also has the following outstanding advantages: it uses an image sensor to directly detect signals, eliminating the need for an image transfer prism and an eyepiece system, thereby avoiding the dizziness caused by long-term observation with a visual telescope, and can also solve the problem of real-time display and storage when connected to electronic devices such as mobile phones, tablets, and computers, thereby solving the problem of cumbersome image storage with a visual telescope.

[0144] It is to be understood that the embodiments of the system described above are merely illustrative, and the units described as separate components may or may not be physically separated, and may be located in one place, or may be distributed on different network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art may understand and implement the solution without creative effort.

[0145] In addition, it should be understood by those skilled in the art that, in the application documents of the embodiments of the present invention, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0146] In the description of the embodiment of the present invention, a large number of specific details are described. However, it should be understood that the embodiment of the embodiment of the present invention can be practiced without these specific details. In some examples, known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this specification. Similarly, it should be understood that in order to streamline the disclosure of the embodiment of the present invention and help understand one or more of the various inventive aspects, in the above description of the exemplary embodiments of the embodiment of the present invention, the various features of the embodiment of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof.

[0147] This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed embodiments of the invention require more features than are expressly recited in each claim. Rather, as the claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment of an embodiment of the invention.

[0148] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention, rather than to limit them. Although the embodiments of the present invention have been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the embodiments of the present invention.

Claims

1. A telephoto lens, characterized in that: This telephoto lens has four lenses, including the following from the object side to the image side: a first lens element having positive refractive power, wherein both front and rear surfaces thereof are convex; a second lens element having negative refractive power, the object-side surface of which is concave and the image-side surface of which is convex; a third lens element having positive refractive power, whose front and rear surfaces are both convex; a fourth lens element having negative refractive power, the front and rear surfaces of which are both concave; The first lens has a front surface with an aperture, the first lens and the second lens form a first doublet lens with positive refractive power, and the third lens and the fourth lens form a second doublet lens with negative refractive power. The curvature radii R4 and R6 of the object-side surface of the third lens and the image-side surface of the fourth lens satisfy: 1.2<R4 / R6<1.8 And R6<60mm; The telephoto lens also satisfies the following relationship: 1<f / TTL<1.08288 2<|f 34 / f 12 | Among them, f, f 12 、f 34 They are the focal lengths of the entire telephoto lens, the first doublet, and the second doublet, respectively. TTL is the distance from the first object surface of the lens to the image plane.

2. The telephoto lens according to claim 1, wherein: The front and rear curvature radii R1 and R2 of the first lens satisfy: 0.5<|R1 / R2|<2.

3. The telephoto lens according to claim 1, wherein: The first lens material has a refractive index Nd of d-light ≤ 1.55 and an Abbe number Vd ≥ 70.

4. The telephoto lens according to claim 1, wherein: A filter is placed between the fourth lens and the image plane, and the front and rear surfaces of the filter are both flat.

5. A telephoto system, characterized in that: include: The telephoto lens, the fixing ring and spacer for fixing the telephoto lens, the sensor chip and the drive board, and the focusing mechanism according to any one of claims 1 to 4; The fixing ring is used to sequentially insert the first doublet lens, the spacer, and the second doublet lens of the telephoto lens to fix the telephoto lens; The spacer is used to ensure that the distance between the two doublet lenses meets the design value; The sensor chip is located on the image side of the telephoto lens and fixed to the driving board, and is used to detect images; The driving board is the main control circuit of the telephoto system, used to drive the sensor chip to acquire images; The focusing mechanism is used to change the relative distance between the fixing ring and the driving plate to achieve focusing.

6. The telephoto system according to claim 5, wherein: The focusing mechanism moves the fixing ring alone, or moves the driving plate alone.

7. The telephoto system according to claim 5, wherein: The focusing mechanism is a manual focusing structure; Alternatively, the focusing mechanism is an electric focusing mechanism, and the electric focusing is controlled by the driving board.

8. The telephoto system according to claim 5, wherein: The fixing ring is an elastic interference ring; The inner diameter of the elastic interference ring is smaller than the diameter of each lens to be installed in the telephoto lens, and an opening is left on the side wall of the elastic interference ring; After the telephoto lenses are sequentially mounted into the elastic interference ring, the first doublet lens, the second doublet lens and the elastic interference ring interfere with each other, and the optical axes of the different lenses and the mechanical axis of the elastic interference ring coincide.

Images