An astronomical camera lens

Abstract

The application discloses an astronomical camera lens, which comprises an objective lens seat, an aperture seat and a lens barrel, and is sequentially provided with a front lens group, an independent variable diaphragm and a flat field lens group from the direction of light incidence; the front lens group comprises a lens A, a lens B and a focusing lens; and the flat field lens group comprises a lens C and a lens D. The application is optimized for astronomical photography and also takes into account the function of general camera lens ground scene photography, is high in quality and light in weight, and is simple to use. When the lens is used to shoot deep space and starry sky, the star point aberration of the photo is obviously improved, the peripheral distortion is reduced, and the chromatic aberration control is excellent. The lens can effectively reduce the purchase cost of photographers, and is not only limited to astronomical photography, but also applicable to daily photography, and has the characteristics of high cost performance, portability and the like, so that more people can be attracted to join the ranks of astronomical photography, thereby achieving the purpose of popularizing astronomy.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of optical equipment, and particularly relates to an astronomical camera lens. BACKGROUND

[0002] At present, the lens used by a single-lens reflex camera has many optimizations in terms of structure (focusing speed, portability) and imaging effect (background blur, aberration, etc.) in daily photography, but when the camera lens is directly applied to the field of astronomical photography, especially deep space photography, the effect is often unsatisfactory, which has nothing to do with the price, but because this kind of lens is not optimized for astronomical photography (infinite focus optimization, flat-field lens group, etc.). And the refractive telescope optimized for astronomical photography (called telescope due to the special optical structure, hereinafter uniformly referred to as lens) has a focal length of 300MM-1400MM. When this kind of lens is used with APS-C or full-frame, a relatively narrow angle of view is obtained. When the camera frame size is unchanged, a shorter focal length lens is needed to obtain a wider angle of view. A 150MM-200MM focal length lens can meet such requirements when used with APS-C or full-frame, but at present, there are only two specifications of 180MM and 200MM lenses in this focal length range, and the available manufacturers are very few, and the price is expensive, and the effect obtained is not perfect. The most fatal disadvantage is that the price is expensive and the effect is not perfect, resulting in a low cost performance.

[0003] The above-mentioned 180MM and 200MM lenses can meet the demand for shooting a wider angle of view, but the cost performance is low. Therefore, in order to reduce the cost and achieve the purpose of popularizing astronomical photography, a camera lens suitable for astronomical photography, daily photography, good portability and high cost performance is needed.

[0004] The patent with application number 2022201978312 discloses a new lens structure of a refractive astronomical camera lens that integrates observation and shooting, which includes a main mirror system, a focusing device, a bearing system, an observation interface and a shooting interface. However, the air gap between the lenses is not disclosed, so the optimization effect for astronomical photography cannot be known.

[0005] The patent with application number 2020104438025 discloses a multifunctional APO optical lens barrel, which includes a main lens barrel, a focusing device, a focusing lens, a zenith extension tube, a shooting extension tube, a camera adapter ring, an eyepiece interface and an eyepiece. The components of the lens barrel can be freely combined as a shooting lens barrel or an observation lens barrel. One combination of the shooting lens barrel includes the main lens barrel, the focusing device, the focusing lens, the shooting extension tube and the camera adapter ring connected in sequence. The focal length of the optical lens barrel is less than 200MM, but the air gap between the lenses is not disclosed, and the F4.5 aperture is small, which will affect the imaging quality when shooting at night. SUMMARY

[0006] To solve the above technical problems, the present application provides an astronomical camera lens to solve the problem that SLR camera lens cannot be used for astronomical photography and daily photography at the same time.

[0007] The present application is realized by the following technical solutions.

[0008] The present application provides an astronomical camera lens, which comprises an objective lens seat, an aperture seat, a lens barrel, and is sequentially provided with a front lens group, an independent variable diaphragm and a flat field lens group from the direction of light incidence.

[0009] Preferably, the air gap between the lens A and the lens B is 1-2mm, and the lens A is arranged on one side of the lens B in the direction of light incidence; the air gap between the lens B and the focusing lens is 25-29mm, and the lens B is arranged on one side of the focusing lens in the direction of light incidence; the air gap between the focusing lens and the lens C is 16-18mm, and the focusing lens is arranged on one side of the lens C in the direction of light incidence; the air gap between the lens C and the lens D is 24-26mm, and the lens C is arranged on one side of the lens D in the direction of light incidence.

[0010] Preferably, the lens further comprises a lens hood, a gasket, a focusing lens pressing ring, an aperture knob, an aperture connecting ring, a flat field lens pressing ring and an adapter socket, the lens A and the lens B are arranged at one end of the objective lens seat in the direction of light incidence, the lens B is connected with the objective lens seat through the gasket, the other end of the objective lens seat is connected with one end of the aperture seat in the direction of light incidence, the focusing lens is fixed in the aperture seat through the focusing lens pressing ring, the aperture seat is provided with a focal length locking system, the independent variable diaphragm is fixed on the aperture connecting ring, one side of the independent variable diaphragm in the direction of light incidence is connected with the aperture seat, the aperture connecting ring is connected with the aperture knob, the aperture connecting ring is arranged on one side of the independent variable diaphragm in the direction of light emission, the aperture connecting ring is connected with the aperture knob, one side of the flat field lens pressing ring in the direction of light incidence is connected with the lens C, the other side of the flat field lens pressing ring is connected with one side of the lens barrel in the direction of light incidence, the lens D is arranged on one side of the lens barrel in the direction of light emission, and one side of the lens barrel in the direction of light emission is threadedly connected with the adapter socket.

[0011] Preferably, the lens A is an achromatic lens with a diameter of 42-46MM and a focal length of 180-210MM, the lens A comprises a lens E and a lens F, and the lens E is connected with the lens F; the lens B is a meniscus lens with a diameter of 41-46MM and a diameter focal length of 180-210MM; and the focusing lens is a lens with a diameter of 25-29MM.

[0012] Preferably, a threaded hole A is arranged on the objective seat, a lens A is connected with the objective seat by penetrating the threaded hole A using a screw, a threaded hole B is arranged on the flat-field mirror pressing ring, a lens C and the flat-field mirror pressing ring are connected with the lens barrel by penetrating the threaded hole B using a screw, a threaded hole C is arranged on the lens barrel, and a lens D is connected with the lens barrel by penetrating the threaded hole C using a screw.

[0013] Preferably, a fixing hole is arranged on the aperture connecting ring, a buckle is arranged on one side of the aperture connecting ring, and the aperture connecting ring is connected with the aperture knob through the buckle.

[0014] Preferably, a slide rod is arranged on one side of the independent variable diaphragm in the light incidence direction, and a plurality of insertion columns are arranged on the other side of the independent variable diaphragm, and the independent variable diaphragm is connected with the aperture connecting ring by being inserted into the fixing hole through the insertion columns.

[0015] Preferably, an aperture guide rail is arranged on the aperture seat, and the independent variable diaphragm is connected with the aperture guide rail on the aperture seat through the slide rod.

[0016] Preferably, a thread A is arranged on the outer wall of one side of the objective seat in the light incidence direction, a thread B is arranged on the outer wall of the other side of the objective seat, the objective seat is connected with the light shield through the thread A, and the objective seat is connected with the aperture seat through the thread B.

[0017] Preferably, the focal length of the lens is 165 mm.

[0018] The present application has the following beneficial effects:

[0019] The present application is optimized for astronomical photography, and also considers the function of general camera lens ground scene photography, is high in quality and light in weight, and is simple to use. When the present lens is used to shoot deep space and starry sky, the star point aberration of the photo is obviously improved, the peripheral distortion is reduced, and the chromatic aberration control is excellent. The lens of the present application can effectively reduce the purchase cost of photographers, and is not limited to astronomical photography in application, but is also applicable in daily photography. The lens has the characteristics of high cost performance, portability and the like, and is convenient for attracting more people to join the ranks of astronomical photography, so as to achieve the purpose of popularizing astronomy. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is the exploded view of the present application;

[0021] Figure 2 is a schematic view of the optical system of the present application;

[0022] Figure 3 is a structural schematic view of the aperture seat of the present application;

[0023] Figure 4 is a structural schematic view of the aperture connecting ring of the present application;

[0024] Figure 5 This is a schematic diagram of the structure of the flat-field mirror pressure ring of the present invention;

[0025] Figure 6 This is the front view of the aperture blade structure of the present invention;

[0026] Figure 7 This is the reverse side of the aperture blade structure of the present invention;

[0027] Figure 8 This is a structural diagram of the aperture knob of the present invention;

[0028] Figure 9 This is a simulation result diagram of the optical path of the present invention;

[0029] In the diagram: 1-Lens hood, 3-Lens A, 31-Lens E, 32-Lens F, 4-Washer, 5-Lens B, 6-Thread A, 7-Objective mount, 8-Threaded hole A, 9-Thread B, 10-Focusing lens retaining ring, 11-Focusing lens, 12-Focal lock system, 13-Aperture mount, 14-Independent variable aperture, 141-Slider, 142-Pin, 15-Aperture knob, 16-Aperture connecting ring, 17-Planing lens retaining ring, 18-Lens C, 19-Lens barrel, 20-Threaded hole C, 21-Lens D, 22-Adapter mount, 23-Fixing hole, 24-Snap, 25-Threaded hole B, 26-Aperture guide rail. Detailed Implementation

[0030] The technical solution of the present invention is further described below, but the scope of protection is not limited to what is described.

[0031] Example 1:

[0032] like Figures 1 to 9 As shown, an astronomical astrophotography lens includes an objective lens mount 7, an aperture mount 13, and a lens barrel 19. The lens, arranged sequentially from the light incident direction, comprises a front lens group, an independent variable aperture 14, and a field-planing lens group. The front lens group, primarily used for imaging and focusing, includes lenses A3, B5, and a focusing lens 11. The field-planing lens group includes lenses C18 and D21. The focusing lens 11 is used for focusing. The field-planing lens group corrects light rays that are not parallel to the optical axis, ensuring that the light rays reaching the camera sensor are parallel to the optical axis, thus optimizing the shooting effect.

[0033] The lens of this invention adopts a five-element lens design with three types of lenses, which has the advantages of convenient optical axis adjustment and easy assembly. It can effectively reduce the error caused by assembling different lenses. Among them, lens A3 is the first type of lens; lens B5 and lens D21 are the second type of lens; and focusing lens 11 and lens C18 are the third type of lens. Lenses of the same type have the same size.

[0034] The air gap between the lens A3 and the lens B5 is 1mm±0.03mm, the lens A3 is arranged on the side of the lens B5 in the light incident direction, the air gap between the lens B5 and the focusing lens 11 is 27.92mm±0.03mm, the lens B5 is arranged on the side of the focusing lens 11 in the light incident direction, the air gap between the focusing lens 11 and the lens C18 is 16.72mm±0.03mm, the focusing lens 11 is arranged on the side of the lens C18 in the light incident direction, the air gap between the lens C18 and the lens D21 is 25.88mm±0.03mm, the lens C18 is arranged on the side of the lens D21 in the light incident direction, and the air gap between the lens D21 and the shooting terminal is 60mm. The air gap between each lens is the optimal solution obtained according to the modeling simulation data, which is the optimal distance of the optical lens and the optical structure, and can effectively improve the image quality. The air gap adopted in the application can effectively reduce the assembly difficulty and can increase the threshold value of the lens shell error.

[0035] The lens further comprises a light shield 1, a gasket 4, a focusing lens pressing ring 10, an aperture knob 15, an aperture connecting ring 16, a flat field lens pressing ring 17, and an adapter socket 22. The lens A3 and the lens B5 are arranged at one end of the objective lens seat 7 in the light incident direction, the lens B5 is connected with the objective lens seat 7 through the gasket 4, and the gasket 4 plays a role in limiting the air gap between the lens A3 and the lens B5. The other end of the objective lens seat 7 is connected with one end of the aperture seat 13 in the light incident direction, the focusing lens 11 is fixed in the aperture seat 13 through the focusing lens pressing ring 10, the aperture seat 13 is provided with a focal length locking system 12, which plays a limiting role, by rotating the objective lens seat 7, the distance between the objective lens seat 7 and the aperture seat 13 can be changed to achieve the purpose of focusing, and the focal length locking system 12 ensures that the focal length does not change, which is convenient for long-time shooting. The independent variable diaphragm 14 is fixed on the aperture connecting ring 16, one side of the independent variable diaphragm 14 in the light incident direction is connected with the aperture seat 13, the aperture connecting ring 16 is connected with the aperture knob 15, and the aperture connecting ring 16 is arranged on the side of the independent variable diaphragm 14 in the light emitting direction. The aperture connecting ring 16 is connected with the aperture knob 15, one side of the flat field lens pressing ring 17 in the light incident direction is connected with the lens C18, the other side of the flat field lens pressing ring 17 is connected with one side of the lens barrel 19 in the light incident direction, the lens D21 is arranged on the side of the lens barrel 19 in the light emitting direction, and one side of the lens barrel 19 in the light emitting direction is screw-connected with the adapter socket 22.

[0036] The lens A3 is a cemented lens with a diameter of 44MM and a focal length of 200MM, and the lens A3 is an ED ultra-low dispersion cemented glass, so that the lens has more advantages than conventional lenses in reducing chromatic aberration and image clarity; the cemented lens includes a lens E31 and a lens F32, which can effectively reduce the influence of spherical aberration and chromatic aberration, the lens E31 is connected with the lens F32, and the lens E31 is arranged on one side of the light incidence direction of the lens F32; since the selection of the lens group needs to ensure that the focal lengths are as same as possible, the lens B5 is a meniscus lens with a diameter of 44MM and a focal length of 199MM, and the positive and negative focal lengths of the meniscus lens can effectively reduce the spherical aberration; the focusing lens 11 is a lens with a diameter of 27MM and a focal length of -185MM (the selection criteria of the lens B5 and the focusing lens 11 are the optimal solution obtained through ZEMAX simulation, which has the smallest chromatic aberration, the lowest aberration and coma, and is the optimal solution of the lens group). Figure 9 By using the simulated light spot diagram, it can be seen that when the image surface is within 9mm, the RMS (diffraction spot caused by aberration) is approximately less than or equal to the lens Airy (Airy spot radius), so when the image surface is within 9mm, a relatively ideal optical system design can be obtained, and when the image surface is greater than 9mm, the RMS radius increases, but it is within a controllable range, and the influence on the picture quality can be ignored.

[0037] The objective holder 7 is provided with a threaded hole A8, the lens A3 is connected with the objective holder 7 by penetrating the threaded hole A8 through the use of an m4 machine screw, the flat-field lens compression ring 17 is provided with an m3 threaded hole B25, the lens C18 and the flat-field lens compression ring 17 are connected with the lens barrel 19 by penetrating the threaded hole B25 through the use of a screw, and the lens barrel 19 is provided with an m3 threaded hole C20, and the lens D21 is connected with the lens barrel 19 by penetrating the threaded hole C20 through the use of a screw.

[0038] The aperture connecting ring 16 is provided with a fixing hole 23, and one side of the aperture connecting ring 16 is provided with a buckle 24, and the aperture connecting ring 16 is connected with the aperture knob 15 through the buckle 24.

[0039] One side of the independent variable diaphragm 14 is provided with a sliding rod 141, and the other side of the independent variable diaphragm 14 is provided with a plug column 142, and the independent variable diaphragm 14 is connected with the aperture connecting ring 16 by inserting a plurality of plug columns 142 into the fixing hole 23.

[0040] The aperture seat 13 is provided with an aperture guide rail 26, and the independent variable diaphragm 14 is connected with the aperture guide rail 26 on the aperture seat 13 through the sliding rod 141.

[0041] The outer wall of the objective seat 7 on the side of the light incidence direction is provided with a thread A6, the other side of the objective seat 7 is provided with a thread B9, the objective seat 7 is threadedly connected with the light shield 1 through the thread A6, and the objective seat 7 is threadedly connected with the aperture seat 13 through the thread B9.

[0042] The focal length of the astronomical camera lens is 165MM.

[0043] The optical indicators that can be reached by the optical system are as follows: focal length f' = 165mm; relative aperture D / f' = 1 / 3.75; applicable spectral frequency: 300-700nm; the lens is adapted to a 1-inch cmos camera, an APS-C camera and a full-frame camera; a manual aperture setting is adopted; a manual focusing is set, the focusing mechanism (comprising the objective seat 7 and the aperture seat 13) adopts positive and negative screw threads for focusing, the focusing action of the lens is accurate and reliable, the screw thread structure increases the contact surface pressure of the focusing mechanism, thereby increasing the friction force, the setting of the focal length locking system 12 is also convenient for the locking of the focal length and long-time shooting.

[0044] Compared with a daily photography lens, the lens is optimized for astronomical photography - the flat field mirror structure is added to correct the light rays that are not parallel to the optical axis, so that the light rays reaching the sensor are parallel to the optical axis; the lengthened light shield effectively reduces the influence of ambient stray light on the shooting image; the manual aperture accurately controls the high-quality image; the manual focusing structure can be locked after accurate focusing. And the structure is simplified - the automatic focusing is removed (because astronomical photography is in a dark environment, the effect of automatic focusing is not as good as that of manual focusing); the manual aperture can find the most suitable aperture size. Through the optimization of astronomical photography and the optimization of the structure, the lens is more suitable for astronomical photography; compared with similar lenses, the lens has higher cost performance (through the selection of lenses and the optimization of the mechanical structure of the lens shell, the cost is effectively reduced), and because of the modularization (objective seat 7, aperture seat 13, lens barrel 19), the installation and debugging are facilitated.

[0045] The present application is modularized for different components to facilitate the assembly and debugging of the lens, and a threaded hole suitable for machine screws is arranged at the lens assembly position to facilitate the adjustment of the optical axis of the lens. Because the astronomical photography needs to be precisely focused at infinity in the dark environment at night, the effect of automatic focusing is not as good as that of manual focusing, so the lens adopts a manual focusing mode, the relative positions between the objective lens group, the lens A3, the lens B5 and the focusing lens 11 are changed by rotating the objective holder 7 to achieve focusing. The focusing is performed by rotating the threaded B9, and the aperture is also manually controlled. The aperture can be controlled by manually rotating the aperture knob 15 to drive the aperture connecting ring 16 and the aperture blade group 14, so as to realize the aperture blade zooming, thereby achieving the purpose of manually controlling the aperture, and the optimal effect can be obtained by manually controlling the aperture size. In order to further improve the stability of the optical axis of the lens, the focusing lens pressing ring 10 is arranged in front of the focusing lens 11 and the flat field lens group to ensure the stability.

Claims

1. An astronomical camera lens, characterized by: The lens comprises an objective seat (7), an aperture seat (13), a lens barrel (19), and the lens is sequentially provided with a front lens group, an independent variable diaphragm (14) and a flat field lens group from the light incident direction, the front lens group comprises a lens A (3), a lens B (5) and a focusing lens (11), the flat field lens group comprises a lens C (18) and a lens D (21); The air gap between the lens A (3) and the lens B (5) is 1-2mm, the lens A (3) is arranged on the side of the lens B (5) in the light incident direction; the air gap between the lens B (5) and the focusing lens (11) is 25-29mm, the lens B (5) is arranged on the side of the focusing lens (11) in the light incident direction; the air gap between the focusing lens (11) and the lens C (18) is 16-18mm, the focusing lens (11) is arranged on the side of the lens C (18) in the light incident direction; the air gap between the lens C (18) and the lens D (21) is 24-26mm, the lens C (18) is arranged on the side of the lens D (21) in the light incident direction; The lens further comprises a lens hood (1), a gasket (4), a focusing lens pressing ring (10), an aperture knob (15), an aperture connecting ring (16), a flat field lens pressing ring (17) and an adapter socket (22); the lens A (3) and the lens B (5) are arranged at one end of the objective seat (7) in the light incident direction, the lens B (5) is connected with the objective seat (7) through the gasket (4); the other end of the objective seat (7) is connected with one end of the aperture seat (13) in the light incident direction; the focusing lens (11) is fixed in the aperture seat (13) through the focusing lens pressing ring (10), the aperture seat (13) is provided with a focal length locking system (12); the independent variable diaphragm (14) is fixed on the aperture connecting ring (16), one side of the independent variable diaphragm (14) in the light incident direction is connected with the aperture seat (13), the aperture connecting ring (16) is connected with the aperture knob (15), the aperture connecting ring (16) is arranged on the side of the independent variable diaphragm (14) in the light emitting direction, the aperture connecting ring (16) is connected with the aperture knob (15); one side of the flat field lens pressing ring (17) in the light incident direction is connected with the lens C (18), the other side of the flat field lens pressing ring (17) is connected with one side of the lens barrel (19) in the light incident direction, the lens D (21) is arranged on the side of the lens barrel (19) in the light emitting direction, one side of the lens barrel (19) in the light emitting direction is threadedly connected with the adapter socket (22); One side of the outer wall of the objective seat (7) in the light incident direction is provided with a thread A (6), the other side of the outer wall of the objective seat (7) is provided with a thread B (9), the objective seat (7) is threadedly connected with the lens hood (1) through the thread A (6), and the objective seat (7) is threadedly connected with the aperture seat (13) through the thread B (9).

2. An astronomical camera lens as claimed in claim 1, characterized in that: The lens A (3) is a cemented lens with a diameter of 42-46MM and a focal length of 180-210MM, the cemented lens comprises a lens E (31) and a lens F (32), the lens E (31) is connected with the lens F (32); the lens B (5) is a meniscus lens with a diameter of 41-46MM and a focal length of 180-210MM; the focusing lens (11) is a lens with a diameter of 25-29MM.

3. An astronomical camera lens as claimed in claim 1, characterized in that: The objective holder (7) is provided with a threaded hole A (8), the lens A (3) is connected with the objective holder (7) by penetrating the threaded hole A (8) with a screw; the flat-field mirror pressing ring (17) is provided with a threaded hole B (25), the lens C (18) and the flat-field mirror pressing ring (17) are connected with the lens barrel (19) by penetrating the threaded hole B (25) with a screw; the lens barrel (19) is provided with a threaded hole C (20), the lens D (21) is connected with the lens barrel (19) by penetrating the threaded hole C (20) with a screw.

4. An astronomical camera lens as claimed in claim 1, characterized in that: The aperture connecting ring (16) is provided with a fixing hole (23), one side of the aperture connecting ring (16) is provided with a buckle (24), the aperture connecting ring (16) is connected with the aperture knob (15) through the buckle (24).

5. An astronomical camera lens as claimed in claim 1, characterized in that: The independent variable diaphragm (14) is provided with a slide rod (141) on one side of the light incidence direction, the other side of the independent variable diaphragm (14) is provided with a plug column (142), the independent variable diaphragm (14) is connected with the aperture connecting ring (16) by inserting the plug column (142) into the fixing hole (23).

6. An astronomical camera lens as claimed in claim 1, characterized in that: The aperture seat (13) is provided with an aperture guide rail (26), the independent variable diaphragm (14) is connected with the aperture guide rail (26) on the aperture seat (13) through the slide rod (141).

7. An astronomical camera lens as claimed in claim 1, characterized in that: The lens focal length is 165MM.

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