CN213365168U - Telephoto lens and telephoto system comprising same - Google Patents

Abstract

The utility model discloses a telephoto lens and a telephoto system including the telephoto lens. The utility model is characterized in that the telephoto lens adopts four spherical lenses to form two groups of doublet lenses, and satisfies the following relational formula: 1<f /TTL, 2<|f ₃₄ /f ₁₂ | Among them, f, f ₁₂ , and f ₃₄ are the focal lengths of the entire telephoto lens, the first doublet lens, and the second doublet lens, respectively, and TTL is the first lens on the object side of the lens The distance from the surface to the image plane. The overall focal length is longer than the length of the mechanical barrel, which is conducive to ensuring the telephoto characteristics of the lens without causing the barrel length to be too long, making the overall structure compact. While ensuring high imaging quality, the number of lens assemblies is reduced, which is convenient for installation; on the other hand, the relative positional deviation between the two doublet lenses has little effect on imaging, reducing the tolerance sensitivity of the lens.

Description

Telephoto lens and telephoto system comprising same

Technical Field

The utility model belongs to optics telephoto imaging field, concretely relates to telephoto lens and contain telephoto system of this telephoto lens.

Background

The telephoto lens is a lens for imaging a distant object and is characterized by a small relative aperture and a small angle of view.

Telephoto lenses are often used in telescopes as their objective lenses, in conjunction with eyepieces, for users to view distant objects. Telescopes are usually visual systems, so they are embodied in monocular telescopes or binoculars. Since the telephoto lens in the visual telescope is used in combination with the eyepiece, the prism, or the lens steering system, aberration compensation between it and other parts should be considered at the time of design. This adds a certain difficulty to the design. When the handheld telescope is used, due to the fact that the handheld telescope is unstable, the picture can shake, physical examination feeling is poor, people can feel eyestrain after long-time observation, and vertigo feeling is caused. If a wonderful visual field is met, the user wants to record and take a picture, and needs to connect the mobile phone through the adapter ring to take a picture, so that inconvenience is caused.

At present, a telephoto lens appears on an intelligent electronic device, such as a mobile phone, and is matched with an image sensor to directly record and display images, so that the process of human eye observation is omitted. However, the space of the intelligent electronic device is limited, so that the aperture (about 4 mm) and the focal length (about 10 mm) of the telephoto lens are limited, and the imaging effect of the conventional telescopic objective lens cannot be realized.

SUMMERY OF THE UTILITY MODEL

At least one in defect or improvement demand more than prior art, the utility model provides a telephoto system of telephoto lens and containing this telephoto lens, telephoto lens adopt 4 sphere lens to constitute two sets of double-cemented lens's mode, and whole focus is greater than mechanical barrel length, compares in the telephoto lens of cell-phone, can all increase in clear aperture and focus two aspects, has realized the high quality telephoto formation of image.

To achieve the above object, according to an aspect of the present invention, there is provided a telephoto lens, which includes, in order from an object side to an image side:

a first lens having positive bending force, the front and rear surfaces of which are convex surfaces;

the second lens with negative bending force has a concave object-side surface and a convex image-side surface;

a third lens having positive refractive power, both front and rear surfaces of which are convex surfaces;

a fourth lens having a negative refracting power, the front and rear surfaces of which are concave surfaces;

the first lens and the second lens form a first cemented doublet lens with positive bending force;

the third lens and the fourth lens form a second double cemented lens with negative bending force;

the telephoto lens satisfies the following relation:

1＜f/TTL

2＜|f₃₄/f₁₂|

wherein, f₁₂、f₃₄The focal lengths of the whole telephoto lens, the first doublet and the second doublet are respectively, and TTL is the distance from the first surface of the lens object space to the image plane.

Preferably, the first lens front-rear curvature radii R1, R2 satisfy:

0.5＜|R1/R2|＜2。

preferably, the refractive index Nd of the d light of the first lens material is less than or equal to 1.55, and the Abbe number Vd is greater than or equal to 70.

Preferably, the third and fourth lens object side surfaces have radii of curvature R4, R6 that satisfy:

1.2＜R4/R6＜1.8

and R6 is less than 60 mm.

Preferably, an optical filter is also placed between the fourth lens and the image plane, and the front surface and the rear surface of the optical filter are both flat.

Preferably, the front surface of the first lens is provided with a diaphragm.

To achieve the above object, according to another aspect of the present invention, there is also provided a telephoto system, which includes:

the long-focus lens, a fixing ring and a space ring for fixing the long-focus lens, a sensor chip, a driving plate and a focusing mechanism are arranged on the long-focus lens;

the fixing ring is used for sequentially plugging a first doubly-cemented lens, a spacing ring and a second doubly-cemented lens of the telephoto lens so as to fix the telephoto lens;

the space ring is used for ensuring that the distance between the two double-cemented lenses meets a design value;

the sensor chip is positioned on the image side of the telephoto lens, fixed on the driving plate and used for detecting an image;

the driving board is a main control circuit of the telephoto system and is used for driving the sensor chip to acquire an image;

the focusing mechanism is used for changing the relative distance between the fixing ring and the driving plate to realize focusing.

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

Preferably, the focusing mechanism is a manual focusing structure;

or the focusing mechanism is an electric focusing mechanism, and electric focusing is controlled by the driving plate.

Preferably, 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 seam is reserved on the side wall of the elastic interference ring;

after the telephoto lens is sequentially arranged in the elastic interference ring, the first doubly-cemented lens, the second doubly-cemented lens and the elastic interference ring are in interference fit with each other, and the optical axes of different lenses and the mechanical axis of the elastic interference ring are overlapped.

The above-described preferred features may be combined with each other as long as they do not conflict with each other.

Generally, through the utility model discloses above technical scheme who conceives compares with prior art, has following beneficial effect:

1. the utility model discloses a telephoto lens belongs to typical telephoto type optical group, and whole focus is greater than mechanical tube length, is favorable to guaranteeing the telephoto characteristic of camera lens can not cause the tube length overlength again for overall structure is small and exquisite.

2. The telephoto lens of the utility model is realized by adopting a mode that 4 spherical lenses form two groups of double cemented lenses, thereby reducing the lens assembly quantity while ensuring higher imaging quality and being convenient for installation; on the other hand, the relative position deviation between the two double-cemented lenses has small influence on imaging, and the tolerance sensitivity of the lens is reduced.

3. The utility model discloses a telephoto system when possessing the progress that above-mentioned telephoto lens is a great deal of to show, still has following outstanding advantage: the image sensor is adopted to directly detect signals, a relay prism and an ocular lens system are omitted, the vertigo feeling of long-time observation by using the visual telescope is avoided, real-time display and storage of connecting electronic equipment such as a mobile phone, a tablet, a computer and the like can be solved, and the problem of complicated image storage of the visual telescope is solved.

Drawings

Fig. 1 is a schematic view of a telephoto lens of the present invention;

fig. 2 is an on-axis aberration diagram according to embodiment 1 of the telephoto lens system of the present invention;

fig. 3a is a field curvature diagram of the telephoto lens embodiment 1 according to the present invention;

fig. 3b is a distortion diagram of the telephoto lens according to embodiment 1 of the present invention;

fig. 4 is a point diagram of the telephoto lens according to embodiment 1 of the present invention;

fig. 5 is an MTF graph of the telephoto lens embodiment 1 according to the present invention;

fig. 6 is an on-axis aberration diagram according to embodiment 2 of the telephoto lens system of the present invention;

fig. 7a is a field curvature diagram of the telephoto lens embodiment 2 according to the present invention;

fig. 7b is a distortion diagram of the telephoto lens according to embodiment 2 of the present invention;

fig. 8 is a point diagram of a telephoto lens according to embodiment 2 of the present invention;

fig. 9 is an MTF graph of telephoto lens embodiment 2 according to the present invention;

fig. 10 is an on-axis chromatic aberration diagram of embodiment 3 of the telephoto lens according to the present invention;

fig. 11a is a field curvature diagram of telephoto lens according to embodiment 3 of the present invention;

fig. 11b is a distortion diagram of the telephoto lens according to embodiment 3 of the present invention;

fig. 12 is a point diagram of a telephoto lens according to embodiment 3 of the present invention;

fig. 13 is an MTF graph of telephoto lens embodiment 3 according to the present invention;

fig. 14 is a schematic view of a telephoto system embodiment 1 according to the present invention including a telephoto lens;

fig. 15 is a schematic view of the telephoto system embodiment 2 according to the present invention including a telephoto lens;

fig. 16 is a schematic view of the telephoto system embodiment 3 according to the present invention including a telephoto lens;

fig. 17 is a schematic diagram of a telephoto system embodiment 4 according to the present invention including a telephoto lens.

Detailed Description

In order to make the objects, 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 merely illustrative of the invention and are not intended to limit the invention. Furthermore, the technical features mentioned in the embodiments 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 will be described in further detail with reference to the following embodiments.

As shown in fig. 1, for the utility model discloses a long-focus lens embodies the sketch map, and long-focus lens includes from the object space to the image space in proper order:

a STOP located at a front surface position of the first lens L1;

a first lens L1 having a positive bending force, the front and rear surfaces of which are convex surfaces;

the second lens element L2 with negative refractive power has a concave object-side surface and a convex image-side surface;

a third lens L3 having a positive bending force, the front and rear surfaces of which are convex surfaces;

a fourth lens L4 having a negative bending force, the front and rear surfaces of which are concave;

wherein the first lens L1 and the second lens L2 form a first cemented doublet with positive refractive power;

the third lens L3 and the fourth lens L4 constitute a second cemented doublet having a negative refracting power;

the telephoto lens satisfies the following relation:

1＜f/TTL

2＜|f₃₄/f₁₂|

wherein, f₁₂、f₃₄The focal lengths of the whole telephoto lens, the first doublet and the second doublet are respectively, and TTL is the distance from the first surface of the lens object space to the image plane.

Preferably, the first lens front-rear curvature radii R1, R2 satisfy:

0.5＜|R1/R2|＜2。

preferably, the refractive index Nd of the d light of the first lens material is less than or equal to 1.52, and the Abbe number Vd is greater than or equal to 70. By the arrangement, chromatic aberration can be effectively corrected, and imaging quality is improved.

Preferably, the third lens object side surface and the fourth lens image side surface have radii of curvature R4, R6 that satisfy:

1.2＜R4/R6＜1.8

and R6 is less than 60 mm.

Further, when there is a wavelength selection requirement, a filter L5 is further included in front of the image plane.

In fig. 1, S1 is a front surface of the first lens L1, S2 is a cemented surface of the first lens L1 and the second lens L2, S3 is a rear surface of the second lens L2, S4 is a front surface of the third lens L3, S5 is a cemented surface of the third lens L3 and the fourth lens L4, S6 is a rear surface of the fourth lens L4, S7 and S8 are front and rear surfaces of the filter L5, and S9 is an image plane.

In all the following embodiments, the lens parameters satisfy the foregoing conditions.

< telephoto lens embodiment 1>

Table 1 is a parameter table for telephoto lens embodiment 1, the main parameters are as follows:

100.001mm, 24mm EPD (clear aperture), 94.95803mm TTL, 2.228 ° FOV (field angle), 4.000mm Image light

TABLE 1 parameter Table for telephoto lens embodiment 1

Surface numbering	Surface type	Radius of curvature (mm)	Thickness (mm)	Refractive index/Abbe number
					OBJ (goal)	Spherical surface	All-round	All-round	——
Stop	Spherical surface	All-round	0	——
					S1	Spherical surface	47.478	5	1.497/81.595
S2	Spherical surface	-46.524	4.5	1.750/35.021
					S3	Spherical surface	-191.468	8.14	——
S4	Spherical surface	21.838	5.50	1.720/43.683
					S5	Spherical surface	-398.552	3	1.612/44.093
S6	Spherical surface	14.944	67	——
					S7	Spherical surface	All-round	0.5	1.517/64.212
S8	Spherical surface	All-round	1.30	——
					S9	Spherical surface	All-round	——	——

An on-axis chromatic aberration diagram of the telephoto lens embodiment 1 is shown in fig. 2;

the field curvature diagram of telephoto lens embodiment 1 is shown in fig. 3 a;

the distortion diagram of the telephoto lens in embodiment 1 is shown in fig. 3 b;

the dot diagram of telephoto lens embodiment 1 is shown in fig. 4;

the MTF graph of telephoto lens embodiment 1 is shown in fig. 5.

< telephoto lens embodiment 2>

Table 2 is a parameter table for telephoto lens embodiment 2, the main parameters are as follows:

108.288mm, 24mm EPD, 100.000mm TTL, 2.110 ° FOV (field of view), 4.000mm Image light.

TABLE 2 parameter Table of telephoto lens embodiment 2

Surface numbering	Surface type	Radius of curvature (mm)	Thickness (mm)	Refractive index/Abbe number
					OBJ	Spherical surface	All-round	All-round	——
Stop	Spherical surface	All-round	0	——
					S1	Spherical surface	45.203	4.99	1.497/81.595
S2	Spherical surface	-41.614	4.5	1.626/35.714
					S3	Spherical surface	-1016.18	4.99	——
S4	Spherical surface	21.778	5.50	1.702/41.141
					S5	Spherical surface	-420.519	2.80	1.612/44.093
S6	Spherical surface	15.310	75	——
					S7	Spherical surface	All-round	0.5	1.517/64.212
S8	Spherical surface	All-round	1.71	——
					S9	Spherical surface	All-round	——	——

The on-axis aberration diagram of telephoto lens embodiment 2 is shown in fig. 6;

the field curvature diagram of telephoto lens embodiment 2 is shown in fig. 7 a;

the distortion diagram of telephoto lens embodiment 2 is shown in fig. 7 b;

the dot diagram of telephoto lens embodiment 2 is shown in fig. 8;

the MTF graph of telephoto lens embodiment 2 is shown in fig. 9.

< telephoto lens embodiment 3>

Table 3 is a parameter table for telephoto lens embodiment 3, the main parameters are as follows:

419.911mm, 90mm EPD, 404.680mm TTL, 0.546 ° FOV (field of view), 4.000mm Image light.

TABLE 3 parameter Table of telephoto lens embodiment 3

An on-axis chromatic aberration diagram of the telephoto lens embodiment 3 is shown in fig. 10;

the field curvature diagram of telephoto lens embodiment 3 is shown in fig. 11 a;

the distortion diagram of the telephoto lens embodiment 3 is shown in fig. 11 b;

the dot diagram of telephoto lens embodiment 3 is shown in fig. 12;

the MTF graph of telephoto lens embodiment 3 is shown in fig. 13.

The utility model also provides a contain telephoto system of telephoto lens, its concrete implementation is as follows:

< telephoto System embodiment 1>

Fig. 14 shows a telephoto system according to embodiment 1, which includes a telephoto lens (including a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and preferably further including an optical filter L5), a housing 1, a fixed ring 2, a spacer 3, a focus knob 40, a sensor chip 5, a driving board 6, and a power and data interface 7.

An imaging lens composed of a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4 is mounted in the fixed ring 2; the fixing ring 2 is a hollow cylindrical structure, one end of the fixing ring is provided with a mounting step, and a double-cemented lens consisting of a first lens L1, a second lens L2, a spacer 3 and a third lens L3, a fourth lens L4 are sequentially plugged in from the other end of the fixing ring during mounting. The outer wall of the fixing ring is provided with a groove, and a focusing rod of the focusing knob 40 is just embedded into the groove. The focus lever is in an eccentric state, and when the focus knob 40 is rotated, the focus lever eccentrically rotates about the central shaft to drive the fixing ring 2 to move in the axial direction (optical axis direction), thereby realizing focusing.

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

The detection surface of the sensor chip 5 is located at an image focal plane during infinity imaging, and when close-range imaging is performed, the lens is moved in a direction away from the sensor chip 5 by the focusing knob 40. The sensor chip is directly soldered on the driving board 6, and the driving board 6 has electronic elements such as isp (image Signal processor) chip, etc., which can process and output image information in real time.

The power and data interface 7 can be but not limited to Type-C or Micro-USB, and the interface can be directly connected with devices such as a computer and a mobile phone (the mobile phone needs to support an OTG function), and can supply power and transmit data in real time.

Preferably, the fixing ring is an elastic interference ring for centering installation of the 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 opening seam is reserved on the side wall of the elastic interference ring; after the telephoto lens is sequentially arranged in the elastic interference ring, the first doubly-cemented lens, the second doubly-cemented lens and the elastic interference ring are in interference fit with each other, and the optical axes of different lenses and the mechanical axis of the elastic interference ring are overlapped.

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 lenses to be installed, the elastic interference ring is not closed, a straight line slit is reserved on the side wall of the elastic interference ring 11, after the elastic interference ring is installed in each lens of the telephoto lens, the slit is opened except radial deformation, and the slit can receive force from the elastic interference ring to contract inwards, so that each lens of the telephoto lens is clamped by the elastic interference ring, the lenses of the telephoto lens are in interference fit with the elastic interference ring, and the optical axis of each lens of the telephoto lens is superposed with the mechanical axis of the elastic interference ring, thereby achieving the effect of centering installation.

Preferably, the elastic interference ring is made of materials with certain hardness, strength and rigidity, such as POM plastics, PC plastics, ABS plastics, aluminum alloy and the like, and the elastic interference ring is not easy to deform axially, so that the centering effect of the lens after installation is ensured.

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

Preferably, the inner surfaces of the elastic interference rings are subjected to extinction treatment, so that the influence of stray light is avoided, and the imaging quality of the optical system is ensured.

Preferably, for the straight curve of the opening seam of the elastic interference ring, the opening seam of the elastic interference ring is a straight line or a curved line, or a combination of the straight line and the curved line.

Preferably, for the discontinuity of the open seam of the elastic interference ring, the open seam of the elastic interference ring is continuous when the side wall of the elastic interference ring is not closed, or the open seam of the elastic interference ring is discontinuous and segmented. The width of the slit can be correspondingly changed according to the diameter of the elastic interference ring, so that the interference fit effect of the lens and the elastic interference ring is ensured.

The multi-lens centering installation is realized by using the specially-structured elastic interference ring to enable the lens to be installed with the elastic interference ring in an interference fit mode. The utility model provides an elastic interference ring is low to the machining precision requirement, after guaranteeing the machining precision of lens, need not consider the installation tolerance of lens again, also need not debug repeatedly and revise the installation lens cone, and the centering installation can be realized in the elastic interference ring is packed into to lens. The lens is convenient to mount and dismount, short in overall mounting flow time, suitable for most optical systems and beneficial to wide popularization and use.

< telephoto System example 2>

Fig. 15 is a schematic diagram of embodiment 2 of the telephoto system, in which the focus adjustment mechanism is replaced with a stepping screw motor 41 by a focus adjustment knob 40, as compared with embodiment 1. The stepping screw motor is fixed inside the shell 1, the sliding block 411 is connected with the screw 412 and the polished rod 413, and one end of the sliding block is embedded into the groove of the fixing ring 2. When the focusing is performed electrically, the speed reduction stepping motor 414 drives the screw rod to rotate, so that the slide block moves along the axial direction of the polished rod to drive the fixing ring 2 to move.

< telephoto System embodiment 3>

Fig. 16 is a schematic diagram of embodiment 3 of the telephoto system, in which a moving object in focusing is replaced with a drive plate 6 by a fixed ring 2, and a focusing structure 42 performs focusing by rack and pinion drive, as compared with embodiment 1. The gear 421 is fixed relative to the housing 1, and the drive plate 6 is fixed to the rack 422. During focusing, the gear 421 rotates, and the rack 422 meshed with the gear 421 moves along with the gear, so that the detection surface of the sensor chip 5 moves axially.

< telephoto System example 4>

Fig. 17 is a schematic diagram of embodiment 4 of the telephoto system, and compared with embodiment 1, the housing 1, the optical filter L5, the sensor chip 5, the driving board 6, the power supply and data interface 7 are not shown in the diagram, so that a new focusing manner is emphasized.

The new focus mechanism comprises a focus lever 21, a guide sleeve 22 with a guide chute, a gear sleeve 23 with a groove on the inner wall in the axial direction, and a stepping motor 24 with a gear.

The fixed ring 2 is provided with a telephoto lens, the outer wall of the fixed ring is provided with a circular groove, a focusing rod 21 is fixed in the groove, and the other end of the focusing rod 21 is clamped into the groove of the gear sleeve 23 after passing through a guide chute on the guide sleeve 22. Step motor 24 is fixed on guide sleeve 22, and during the focusing, step motor 24 rotates and drives gear sleeve 23 of meshing with it rotatory, because the one end card of focusing pole is in the recess of gear sleeve 23 inner wall, and the focusing pole is followed together along guide sleeve chute at axial displacement, and focusing pole 21 links together with solid fixed ring 2, so solid fixed ring 2 also can be along with along axial displacement.

The power source of the focusing scheme can be realized by manually rotating the gear sleeve 23 in a slightly changed way besides a motor.

To sum up, compare with prior art, the utility model discloses a scheme exists following apparent advantage:

1. the utility model discloses a telephoto lens belongs to typical telephoto type optical group, and whole focus is greater than mechanical tube length, is favorable to guaranteeing the telephoto characteristic of camera lens can not cause the tube length overlength again for overall structure is small and exquisite.

2. The telephoto lens of the utility model is realized by adopting a mode that 4 spherical lenses form two groups of double cemented lenses, thereby reducing the lens assembly quantity while ensuring higher imaging quality and being convenient for installation; on the other hand, the relative position deviation between the two double-cemented lenses has small influence on imaging, and the tolerance sensitivity of the lens is reduced.

3. The utility model discloses a telephoto system when possessing the progress that above-mentioned telephoto lens is a great deal of to show, still has following outstanding advantage: the image sensor is adopted to directly detect signals, a relay prism and an ocular lens system are omitted, the vertigo feeling of long-time observation by using the visual telescope is avoided, real-time display and storage of connecting electronic equipment such as a mobile phone, a tablet, a computer and the like can be solved, and the problem of complicated image storage of the visual telescope is solved.

It will be appreciated that the embodiments of the system described above are merely illustrative, in that elements illustrated as separate components may or may not be physically separate, may be located in one place, or may be distributed over different network elements. Some or all of the modules can be selected according to actual needs to achieve the purpose of the scheme of the embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.

In addition, it should be understood by those skilled in the art that in the specification of the embodiments of the present invention, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

In the description of the embodiments of the present invention, a large number of specific details are explained. It is understood, however, that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description. Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the invention, various features of the embodiments of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects.

However, the disclosed method should not be interpreted as reflecting an intention that: rather, the claimed embodiments of the invention require more features than are expressly recited in each claim. Rather, as the following 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 this invention. Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention, and not to limit the same; although the embodiments of the present invention have been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims (10)

1. A telephoto lens comprising, in order from an object side to an image side:

a first lens having positive bending force, the front and rear surfaces of which are convex surfaces;

the second lens with negative bending force has a concave object-side surface and a convex image-side surface;

a third lens having positive refractive power, both front and rear surfaces of which are convex surfaces;

a fourth lens having a negative refracting power, the front and rear surfaces of which are concave surfaces;

the first lens and the second lens form a first cemented doublet lens with positive bending force;

the third lens and the fourth lens form a second double cemented lens with negative bending force;

the telephoto lens satisfies the following relation:

1＜f/TTL

2＜|f₃₄/f₁₂|

wherein, f₁₂、f₃₄The focal lengths of the whole telephoto lens, the first doublet and the second doublet are respectively, and TTL is the distance from the first surface of the lens object space to the image plane.

2. The telephoto lens as recited in claim 1, wherein:

the first lens front-rear curvature radii R1, R2 satisfy:

0.5＜|R1/R2|＜2。

3. the telephoto lens as recited in claim 1, wherein:

the refractive index Nd of d light of the first lens material is less than or equal to 1.55, and the Abbe number Vd is greater than or equal to 70.

4. The telephoto lens as recited in claim 1, wherein:

the third and fourth lens object side and image side surface radii of curvature R4, R6 satisfy:

1.2＜R4/R6＜1.8

and R6 is less than 60 mm.

5. The telephoto lens as recited in claim 1, wherein:

an optical filter is also arranged between the fourth lens and the image surface, and the front surface and the rear surface of the optical filter are both planes.

6. The telephoto lens as recited in claim 1, wherein:

the front surface of the first lens is provided with a diaphragm.

7. A telephoto system, comprising:

the telephoto lens, the fixing ring and the spacer for fixing the telephoto lens, the sensor chip and the driving plate, and the focusing mechanism as claimed in any one of claims 1 to 6;

the fixing ring is used for sequentially plugging a first doubly-cemented lens, a spacing ring and a second doubly-cemented lens of the telephoto lens so as to fix the telephoto lens;

the space ring is used for ensuring that the distance between the two double-cemented lenses meets a design value;

the sensor chip is positioned on the image side of the telephoto lens, fixed on the driving plate and used for detecting an image;

the driving board is a main control circuit of the telephoto system and is used for driving the sensor chip to acquire an image;

the focusing mechanism is used for changing the relative distance between the fixing ring and the driving plate to realize focusing.

8. The telephoto system as set forth in claim 7, wherein:

the focusing mechanism moves the fixing ring alone or moves the driving plate alone.

9. The telephoto system as set forth in claim 7, wherein:

the focusing mechanism is a manual focusing structure;

or the focusing mechanism is an electric focusing mechanism, and electric focusing is controlled by the driving plate.

10. The telephoto system as set forth in claim 7, 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 seam is reserved on the side wall of the elastic interference ring;

after the telephoto lens is sequentially arranged in the elastic interference ring, the first doubly-cemented lens, the second doubly-cemented lens and the elastic interference ring are in interference fit with each other, and the optical axes of different lenses and the mechanical axis of the elastic interference ring are overlapped.

Images