Macro photography optical system

Abstract

This invention discloses a macro photography optical system, specifically relating to the field of optical imaging. It comprises, along the optical axis from the object side to the image side, a cemented lens, a focusing lens group, a back-focusing lens group, and an image plane mirror. This invention uses spherical lenses made entirely of glass, placing a variable aperture between the focusing lenses, which moves with the focusing lenses to improve and balance aberration levels at various focusing distances. The combined cemented lens group has aberration elimination function and is relatively fixed to the image plane. It prevents dust and moisture from entering the lens interior during the movement of the focusing lenses. The final lens in the lens group is a convex lens, which reduces the incidence angle of the principal rays in each field of view and increases the back focal length, making it suitable for SLR cameras, mirrorless cameras, and even cinema cameras, achieving excellent imaging results.

Description

Technical Field

[0001] This invention relates to the field of optical imaging technology, and more specifically, to a macro photography optical system. Background Technology

[0002] A digital SLR camera is a single-lens reflex digital camera. This technology involves mounting a mirror at a 45° angle in front of the film plane. Above the mirror are a ground glass, a pentaprism, and an eyepiece. The pentaprism reflects the real image light multiple times, changing the light path and sending the image to the eyepiece. This ensures that the image seen in the viewfinder is always the same as the image on the film, and that the framing and the actual shooting area are essentially identical. This unique prism design allows the photographer to directly observe the image passing through the lens in the viewfinder.

[0003] Fixed-focus lenses can be classified according to their focusing method into two types: screw-out type and internal focusing type.

[0004] Screw-out lenses are relatively easy to design, but during use, because the structure cannot be completely sealed, external dust and moisture can easily enter the lens and contaminate the optical lens.

[0005] Internal focusing can completely prevent external dust and moisture from easily entering the lens, thus providing excellent protection.

[0006] Internal focusing systems are classified according to the number of focusing groups, and are further divided into single-group focusing systems and multi-group focusing systems.

[0007] In single-group focusing, only one lens group moves together during focusing, and the lenses within the group are relatively fixed and cannot move. In multi-group focusing, at least two lens groups move simultaneously during focusing, and the distance between the two lens groups also changes.

[0008] Because lens manufacturers often cannot achieve a high level of precision in machining the cam barrel, coupled with low precision in lens machining and assembly, the yield rate of produced lenses is relatively low. Summary of the Invention

[0009] In order to overcome the above-mentioned defects of the prior art, the embodiments of the present invention provide a macro photography optical system. The technical problem to be solved by the present invention is: how to improve the problem of low lens production yield caused by low lens processing precision and low assembly precision, so as to achieve a good imaging effect.

[0010] To achieve the above objectives, the present invention provides the following technical solution: a macro photography optical system, comprising, along the optical axis from the object side to the image side, a cemented lens, a focusing lens group, a rear focusing lens group, and an image plane mirror, wherein:

[0011] The cemented lens includes, along the optical axis from the object side to the image side, a lens L1 with positive optical power and a lens L2 with positive optical power.

[0012] The focusing lens group, along the optical axis from the object side to the image side, includes, in sequence, a lens L3 with negative optical power, a lens L4 with positive optical power, a lens L5 with negative optical power, a lens L6 with positive optical power, an aperture with infinite radius of curvature, a lens L7 with negative optical power, a lens L8 with positive optical power, a lens L9 with positive optical power, and a lens L10 with negative optical power.

[0013] The rear focusing lens group includes, along the optical axis from the object side to the image side, a lens L11 with negative optical power, a lens L12 with positive optical power, a lens L13 with positive optical power, and a lens L14 with negative optical power.

[0014] The image mirror is configured as a lens L15 with an infinite radius of curvature and an image plane.

[0015] In a preferred embodiment, the lenses L1-L14 are all configured as glass concave / convex spherical lenses, and the aperture is configured as a variable aperture.

[0016] In a preferred embodiment, the lens comprises, in sequence from the object side to the image side along the optical axis, a cemented lens, a focusing group, a back focusing lens group, and an image plane mirror, wherein:

[0017] The cemented lens includes, along the optical axis from the object side to the image side, a lens L1 with positive optical power and a lens L2 with positive optical power.

[0018] The focusing lens group, along the optical axis from the object side to the image side, includes, in sequence, a lens L3 with positive optical power, a lens L4 with positive optical power, a lens L5 with negative optical power, a lens L6 with positive optical power, an aperture with infinite radius of curvature, a lens L7 with negative optical power, a lens L8 with negative optical power, a lens L9 with positive optical power, and a lens L10 with negative optical power.

[0019] The rear focusing lens group includes, along the optical axis from the object side to the image side, a lens L11 with positive optical power, a lens L12 with negative optical power, a lens L13 with positive optical power, and a lens L14 with positive optical power.

[0020] The image mirror is configured as a lens L15 with an infinite radius of curvature and an image plane.

[0021] In a preferred embodiment, the lenses L1-L14 are all configured as glass concave / convex spherical lenses, and the aperture is configured as a variable aperture.

[0022] In a preferred embodiment, the lens comprises, in sequence from the object side to the image side along the optical axis, a front focusing lens, a focusing group, a rear focusing lens group, and an image plane mirror, wherein:

[0023] The front focusing lens is set as a lens L1 with positive optical power;

[0024] The focusing lens group, along the optical axis from the object side to the image side, includes, in sequence, a lens L2 with positive optical power, a lens L3 with negative optical power, a lens L4 with positive optical power, a lens L5 with positive optical power, a lens L6 with positive optical power, an aperture with negative optical power, a lens L7 with positive optical power, a lens L8 with positive optical power, a lens L9 with negative optical power, and a lens L10 with positive optical power.

[0025] The rear focusing lens group includes, along the optical axis from the object side to the image side, a lens L11 with negative optical power, a lens L12 with positive optical power, and a lens L13 with positive optical power.

[0026] The image mirror is configured as a lens L14 with an infinite radius of curvature and an image plane.

[0027] In a preferred embodiment, the lenses L1-L13 are all configured as glass concave / convex spherical lenses, and the aperture is configured as a variable aperture.

[0028] The technical effects and advantages of this invention are as follows:

[0029] This invention employs an all-glass spherical lens, placing the variable aperture between the focusing groups. The aperture moves with the focusing groups, improving and balancing aberration levels at various focusing distances. The composite cemented lens eliminates aberrations and remains relatively fixed to the imaging plane. It prevents dust and moisture from entering the lens during focusing group movement. The final lens in the lens group is a convex lens, which reduces the principal ray incident angle in each field of view and increases the back focal length, making it suitable for SLR cameras, mirrorless cameras, and even cinema cameras, achieving excellent imaging results. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the lens in Embodiment 1 of the present invention.

[0031] Figure 2 This is a schematic diagram of the lens in Embodiment 2 of the present invention.

[0032] Figure 3 This is a schematic diagram of the lens in Embodiment 3 of the present invention. Detailed Implementation

[0033] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0034] Example 1:

[0035] This invention provides, for example Figure 1 The macro photography optical system shown includes, along the optical axis from the object side to the image side, a cemented lens, a focusing lens group, a rear focusing lens group, and an image plane mirror, wherein:

[0036] The cemented lens includes, along the optical axis from the object side to the image side, a lens L1 with positive optical power and a lens L2 with positive optical power.

[0037] The focusing lens group, along the optical axis from the object side to the image side, includes, in sequence, a lens L3 with negative optical power, a lens L4 with positive optical power, a lens L5 with negative optical power, a lens L6 with positive optical power, an aperture with infinite radius of curvature, a lens L7 with negative optical power, a lens L8 with positive optical power, a lens L9 with positive optical power, and a lens L10 with negative optical power.

[0038] The rear focusing lens group includes, along the optical axis from the object side to the image side, a lens L11 with negative optical power, a lens L12 with positive optical power, a lens L13 with positive optical power, and a lens L14 with negative optical power.

[0039] The image mirror is configured as a lens L15 with an infinite radius of curvature and an image plane;

[0040] The specific surface coefficients are shown in the table below (unit: mm).

[0041]

[0042]

[0043] Focusing at infinity Focusing at closest distance M 0 1 EFL 85.061 76.782 S0 Infinity 150.053 S4 52.516 2.000 S19 3.009 53.530

[0044] Wherein: aperture value (Fno) = 2.8, effective focal length (EFL) = 85mm, magnification M = 0-1;

[0045] The optical system in this embodiment satisfies the following conditions:

[0046] -2000 <f1-2<-500;

[0047] 20 <f3-10<200;

[0048] -900 <f11-14<-200;

[0049] 0.1 <f / TTL<0.3;

[0050] WL>150

[0051] f1-2 is the combined focal length of lenses L1 to L2, f3-10 is the combined focal length of lenses L3 to L10, f11-14 is the combined focal length of lenses L11 to L14, f is the combined focal length of the entire system, TTL is the distance from the object to the center of the image plane, WL is the distance from the object to the front end of the first lens, and all lenses use spherical glass lenses.

[0052] The variable aperture is located between the focus groups (lens L3-lens L10) and moves as the focus groups move, thereby improving and balancing the aberration levels at various focusing distances.

[0053] The cemented lens composed of lens L1 and lens L2, in addition to its aberration-eliminating function, is fixed relative to the imaging plane; when the focusing group moves, it also prevents dust, water vapor and other substances from entering the lens and contaminating the internal optical structure.

[0054] The last lens, L14, is a convex lens. It serves to reduce the incidence angle of the principal rays in each field of view and increase the back focal length, making this optical model suitable for SLR cameras, mirrorless cameras, and even movie cameras.

[0055] Example 2:

[0056] This invention provides, for example Figure 2 The macro photography optical system shown includes, along the optical axis from the object side to the image side, a cemented lens, a focusing lens group, a rear focusing lens group, and an image plane mirror, wherein:

[0057] The cemented lens includes, along the optical axis from the object side to the image side, a lens L1 with positive optical power and a lens L2 with positive optical power.

[0058] The focusing lens group, along the optical axis from the object side to the image side, includes, in sequence, a lens L3 with positive optical power, a lens L4 with positive optical power, a lens L5 with negative optical power, a lens L6 with positive optical power, an aperture with infinite radius of curvature, a lens L7 with negative optical power, a lens L8 with negative optical power, a lens L9 with positive optical power, and a lens L10 with negative optical power.

[0059] The rear focusing lens group includes, along the optical axis from the object side to the image side, a lens L11 with positive optical power, a lens L12 with negative optical power, a lens L13 with positive optical power, and a lens L14 with positive optical power.

[0060] The image mirror is configured as a lens L15 with an infinite radius of curvature and an image plane;

[0061] The specific surface coefficients are shown in the table below (unit: mm).

[0062]

[0063]

[0064] Focusing at infinity Focusing at closest distance M 0 1 EFL 105.026 65.846 S0 Infinity 153.299 S4 41.080 2.000 S19 2.924 42.006

[0065] Wherein: aperture value (Fno) = 2.8, effective focal length (EFL) = 105mm, magnification M = 0-1; the optical system of this embodiment satisfies the following conditions:

[0066] 500 <f1-2<1500;

[0067] 20 <f3-10<150;

[0068] -500 <f11-14<-50;

[0069] 0.1 <f / TTL<0.3;

[0070] WL>153

[0071] f1-2 is the combined focal length of lenses L1 to L2, f3-10 is the combined focal length of lenses L3 to L10, f11-14 is the combined focal length of lenses L11 to L14, f is the combined focal length of the entire system, TTL is the distance from the object to the center of the image plane, WL is the distance from the object to the front end of the first lens, and all lenses use spherical glass lenses.

[0072] The variable aperture is located between the focus groups (lens L3-lens L10) and moves as the focus groups move, thereby improving and balancing the aberration levels at various focusing distances.

[0073] The cemented lens composed of lens L1 and lens L2, in addition to its aberration-eliminating function, is fixed relative to the imaging plane; when the focusing group moves, it also prevents dust, water vapor and other substances from entering the lens and contaminating the internal optical structure.

[0074] The last lens, L14, is a convex lens. It serves to reduce the incidence angle of the principal rays in each field of view and increase the back focal length, making this optical model suitable for SLR cameras, mirrorless cameras, and even movie cameras.

[0075] Example 3:

[0076] This invention provides, for example Figure 3The macro photography optical system shown includes, along the optical axis from the object side to the image side, a front focusing lens, a focusing group of lenses, a rear focusing lens group, and an image plane mirror, wherein:

[0077] The front focusing lens is set as a lens L1 with positive optical power;

[0078] The focusing lens group, along the optical axis from the object side to the image side, includes, in sequence, a lens L2 with positive optical power, a lens L3 with negative optical power, a lens L4 with positive optical power, a lens L5 with positive optical power, a lens L6 with positive optical power, an aperture with negative optical power, a lens L7 with positive optical power, a lens L8 with positive optical power, a lens L9 with negative optical power, and a lens L10 with positive optical power.

[0079] The rear focusing lens group includes, along the optical axis from the object side to the image side, a lens L11 with negative optical power, a lens L12 with positive optical power, and a lens L13 with positive optical power.

[0080] The image mirror is configured as a lens L14 with an infinite radius of curvature and an image plane;

[0081] The specific surface coefficients are shown in the table below (unit: mm).

[0082]

[0083]

[0084] Wherein: aperture (Fno) = 2.8, effective focal length (EFL) = 150mm, magnification M = 0-1;

[0085] The optical system in this embodiment satisfies the following conditions:

[0086] 100 <f1<1000;

[0087] 20 <f2-10<150;

[0088] -200 <f11-13<-20;

[0089] 0.1 <f / TTL<0.3;

[0090] WL>207

[0091] f1 is the focal length of lens L1, f2-10 is the combined focal length of lenses L2 to L10, f10-13 is the combined focal length of lenses L10 to L13, f is the overall focal length of the entire system, TTL is the distance from the object to the center of the image plane, WL is the distance from the object to the front end of the first lens, and all lenses use spherical glass lenses.

[0092] The variable aperture is located between the focus groups (lenses L2-L9) and moves as the focus groups move, thereby improving and balancing the aberration levels at various focusing distances.

[0093] In addition to its aberration-eliminating function, lens L1 is fixed relative to the imaging plane. When the focusing group moves, it also prevents dust, water vapor, etc. from entering the lens and contaminating the internal optical structure.

[0094] The last lens, L13, is a convex lens. It serves to reduce the incidence angle of the principal rays in each field of view and increase the back focal length, making this optical model suitable for SLR cameras, mirrorless cameras, and even movie cameras.

[0095] Finally, the following points should be noted: First, in the description of this application, it should be noted that, unless otherwise specified and limited, the terms "installation", "connection", and "linkage" should be interpreted broadly, and can be mechanical or electrical connections, or internal connections between two components, or direct connections. "Up", "down", "left", "right", etc. are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may change.

[0096] Secondly: The accompanying drawings of the embodiments disclosed in this invention only involve the structures involved in the embodiments disclosed in this invention. Other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of this invention can be combined with each other.

[0097] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A macro photography optical system, characterized in that: It includes, from the object side to the image side along the optical axis direction in sequence, a cemented lens, a focusing lens group, a rear focusing lens group, and an image plane mirror, where: The cemented lens includes, from the object side to the image side along the optical axis direction in sequence, a lens L1 with positive optical power and a lens L2 with positive optical power; The focusing lens group includes, from the object side to the image side along the optical axis direction in sequence, a lens L3 with negative optical power, a lens L4 with positive optical power, a lens L5 with negative optical power, a lens L6 with positive optical power, an aperture with an infinite radius of curvature, a lens L7 with negative optical power, a lens L8 with positive optical power, a lens L9 with positive optical power, and a lens L10 with negative optical power; The rear focusing lens group includes, from the object side to the image side along the optical axis direction in sequence, a lens L11 with negative optical power, a lens L12 with positive optical power, a lens L13 with positive optical power, and a lens L14 with negative optical power; The image plane mirror is set as a lens L15 with an infinite radius of curvature and an image plane; Among them, the optical system satisfies the following conditions: -2000 < f1-2 < -500, where f1-2 is the combined focal length of lenses L1 and L2; 20 < f3-10 < 200, where f3-10 is the combined focal length of lenses L3 to L10; -900 < f11-14 < -200, where f11-14 is the combined focal length of lenses L11 to L14; 0.1 < f / TTL < 0.3, where f is the overall combined focal length of the system and TTL is the object distance; WL > 150, where WL is the object distance.

2. The macro photography optical system according to claim 1, characterized in that: The lenses L1-L14 are all set as glass concave / convex spherical lenses, and the aperture is set as a variable aperture.

3. The macro photography optical system according to claim 1, characterized in that: It includes, from the object side to the image side along the optical axis direction in sequence, a cemented lens, a focusing lens group, a rear focusing lens group, and an image plane mirror, where: The cemented lens includes, from the object side to the image side along the optical axis direction in sequence, a lens L1 with positive optical power and a lens L2 with positive optical power; The focusing lens group includes, from the object side to the image side along the optical axis direction in sequence, a lens L3 with positive optical power, a lens L4 with positive optical power, a lens L5 with negative optical power, a lens L6 with positive optical power, an aperture with an infinite radius of curvature, a lens L7 with negative optical power, a lens L8 with negative optical power, a lens L9 with positive optical power, and a lens L10 with negative optical power; The rear focusing lens group includes, from the object side to the image side along the optical axis direction in sequence, a lens L11 with positive optical power, a lens L12 with negative optical power, a lens L13 with positive optical power, and a lens L14 with positive optical power; The image plane mirror is set as a lens L15 with an infinite radius of curvature and an image plane; Among them, the optical system satisfies the following conditions: 500 < f1-2 < 1500, where f1-2 is the combined focal length of lenses L1 and L2; 20 < f3-10 < 150, where f3-10 is the combined focal length of lenses L3 to L10; -500 < f11-14 < -50, where f11-14 is the combined focal length of lenses L11 to L14; 0.1 < f / TTL < 0.3, where f is the overall combined focal length of the system and TTL is the object distance; WL > 153, where WL is the object distance.

4. A macro photography optical system according to claim 3, characterized in that: The lenses L1 - L14 are all set as glass concave / convex spherical lenses, and the aperture is set as a variable aperture.

5. A macro photography optical system according to claim 1, characterized in that: It includes a front focusing lens, a focusing group lens, a rear focusing lens group, and an image plane lens in sequence from the object side to the image side along the optical axis direction, where: The front focusing lens is set as the lens L1 with a positive optical power; The focusing group lens includes, in sequence from the object side to the image side along the optical axis direction, the lens L2 with a positive optical power, the lens L3 with a negative optical power, the lens L4 with a positive optical power, the lens L5 with a positive optical power, the lens L6 with a positive optical power, an aperture with a negative optical power, the lens L7 with a positive optical power, the lens L8 with a positive optical power, the lens L9 with a negative optical power, and the lens L10 with a positive optical power; The rear focusing lens group includes, in sequence from the object side to the image side along the optical axis direction, the lens L11 with a negative optical power, the lens L12 with a positive optical power, and the lens L13 with a positive optical power; The image plane lens is set as the lens L14 with an infinite radius of curvature and the image plane; Among them, the optical system satisfies the following conditions: 100 < f1 < 1000, where f1 is the focal length of the lens L1; 20 < f2 - 10 < 150, where f2 - 10 is the combined focal length of the lenses L2 to L10; -200 < f11 - 13 < -20, where f11 - 13 is the combined focal length of the lenses L11 to L13; 0.1 < f / TTL < 0.3, where f is the combined focal length of the entire system and TTL is the object distance; WL > 207, where WL is the object distance.

6. A macro photography optical system according to claim 5, characterized in that: The lenses L1 - L13 are all set as glass concave / convex spherical lenses, and the aperture is set as a variable aperture.

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