A high magnification macro lens

Abstract

The application discloses a high-magnification macro lens, which comprises a first lens group G1, a second lens group G2 with positive refractive power and a third lens group G3 with negative refractive power from the object side to the image plane side in sequence; when the object is from infinity to a close distance and is focused, the first lens group G1 is fixed, the second lens group G2 is moved from the image side to the object side, and the third lens group G3 is moved in cooperation with the second lens group G2, thereby playing a role of assisting focusing. The application is convenient and fast to use, can realize good imaging from infinity to 2 times of photographic magnification, and realizes a macro lens with small size, low cost and high performance.

Description

Technical Field

[0001] This invention relates to the field of interchangeable camera lens technology, and in particular to a high-magnification macro lens. Background Technology

[0002] Currently, there are many types of interchangeable macro lenses used in cameras and camcorders, ranging from infinity to equivalent magnification. For example, Japanese Patent Application Publication Nos. 2006-153942 and 2012-53260 describe a structure where, starting from the object side, the refractive power of each lens group is positive, negative, positive, negative in sequence. During the focusing process from infinity to equivalent magnification, focusing is achieved by the movement of the second and third lens groups, while the first and fourth groups remain fixed. While this achieves excellent imaging results, the large number of lenses and the mutual cancellation and interference between the movement of the second and third groups make it difficult to achieve higher magnification macro effects. Furthermore, miniaturization and low-cost production are challenging.

[0003] Furthermore, for example, the publicly known Japanese Patent Application Publication No. 2012-63403 describes a structure where, starting from the object side, the refractive power of each lens group is positive, negative, positive, negative, negative, positive in sequence. As the object moves from infinity to the point of equal magnification, the second and third lens groups move to focus, while the first, fourth, fifth, and sixth groups remain fixed. While this achieves excellent imaging results, the large number of lenses hinders low-cost miniaturization. Additionally, the shared movement space between the second and third lens groups limits the range of motion, preventing the achievement of higher magnification macro effects. Summary of the Invention

[0004] The main objective of this invention is to provide a high-magnification macro lens that can effectively solve the problems of macro lenses being unable to achieve higher magnification, being bulky, and costly.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A high-magnification macro lens comprises, from the object side to the image side, a first lens group G1, a second lens group G2 with positive refractive power, and a third lens group G3 with negative refractive power. When the object moves from infinity to near, and the focus is achieved, the first lens group G1 remains fixed, the second lens group G2 moves from the image side to the object side, and the third lens group G3 moves in coordination with the second lens group G2 to assist in focusing, and satisfies the following condition (1):

[0007] 2.0≤|L / DL2|≤3.5 (1);

[0008] in,

[0009] L: Total length of the optical system;

[0010] DL2: At infinity, the distance from the image side of the first lens group G1 to the object side of the second lens group G2 is measured.

[0011] Preferably, condition (2) is satisfied:

[0012] 1.4≤|S2 / S1|≤2.1 (2);

[0013] in,

[0014] S1: The amount of movement of the second lens group G2 from infinity to 1x magnification;

[0015] S2: The amount of movement of the second lens group G2 from infinity to when the magnification is at its maximum.

[0016] Preferably, condition (3) is satisfied:

[0017] 0.3≤Ymax / F2≤0.8 (3);

[0018] in,

[0019] Ymax: The maximum paraxial image height of the optical system, Ymax = FL × tanω, where FL is the focal length of the optical system at infinity and ω is the half-angle of the image.

[0020] F2: Focal length of the second lens group G2.

[0021] Preferably, condition (4) is satisfied:

[0022] 0.2≤|F2 / F3|≤1.5 (3);

[0023] in,

[0024] F2: Focal length of the second lens group G2;

[0025] F3: Focal length of the third lens group G3.

[0026] [Explanation of conditional expressions]

[0027] If the upper limit of condition (1) is exceeded, the distance between the first lens group G1 and the second lens group G2 will be too small. When focusing, this will limit the movement of the second lens group G2, making it difficult to achieve high-magnification macro functionality. Alternatively, the total optical length L will be too large, resulting in a bulky optical system when achieving magnification of 1.5x or higher, making it difficult to achieve the goal of miniaturization. If the lower limit of condition (1) is exceeded, although the distance DL between the first lens group G1 and the second lens group G2 is large enough to easily achieve high-magnification macro requirements, the distance DL2 between the first lens group G1 and the second lens group G2 will be too large, resulting in a larger outer diameter of the first lens group G1. The entire optical system will also become bulky, making it difficult to achieve the design requirement of miniaturization.

[0028] If the upper limit of condition (2) is exceeded, the amount of movement at the maximum magnification is large enough, and although it is easy to meet the requirements of high magnification photography, the excessive amount of movement will make the entire optical system too large, making it difficult to achieve the design goal of miniaturization. If the lower limit of condition (2) is exceeded, although it is easy to meet the design requirements of miniaturization, the amount of movement of the second lens group G2 at the maximum magnification is too small, making it difficult to meet the requirements of high magnification macro photography.

[0029] If the upper limit of condition (3) is exceeded, the refractive power of the second lens group G2 is too strong. Although it is easy to achieve miniaturization and high-magnification macro requirements, the strong refractive power will make it difficult to correct various aberrations, thus failing to achieve high-performance photographic effects. If the lower limit of condition (3) is exceeded, although performance is easy to guarantee, the refractive power of the second lens group G2 is too weak. To achieve high-magnification photographic effects, the amount of movement will be large, resulting in a large optical system size, making miniaturization and low cost impossible.

[0030] If the upper limit of condition (4) is exceeded, the refractive power of the second lens group G2 is too strong. As the main focusing group, if high magnification photography is required, the amount of movement will be large, making it difficult to achieve miniaturization of the optical system. At the same time, if the refractive power of the auxiliary focusing group third lens group G3 is too strong, it will cause the image field to rise rapidly, which is difficult to correct, making it difficult to achieve high performance. If the lower limit of condition (4) is exceeded, the refractive power of the auxiliary focusing group third lens group G3 is too weak, and its corrective effect during focusing will be too weak, making it difficult to achieve miniaturization and high performance requirements.

[0031] Compared with the prior art, the present invention has the following beneficial effects: the high-magnification macro lens provides excellent imaging from infinity to 2x magnification, and achieves small size, low cost and high performance. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the high-magnification macro lens provided in Embodiment 1 of the present invention.

[0033] Figure 2 This is a schematic diagram of spherical aberration, field curvature aberration, distortion aberration, and chromatic aberration at infinity and constant magnification in Example 1.

[0034] Figure 3 This is a schematic diagram of the high-magnification macro lens provided in Embodiment 2 of the invention.

[0035] Figure 4 This is a schematic diagram of spherical aberration, field curvature aberration, distortion aberration, and chromatic aberration at infinity and constant magnification in Example 2. Detailed Implementation

[0036] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0037] Example 1

[0038] like Figure 1 As shown, from the object side to the image plane side, the lens group consists of a first lens group G1, a second lens group G2 with positive refractive power, and a third lens group G3 with negative refractive power. When the object moves from infinity to near, the first lens group G1 remains fixed, the second lens group G2 moves from the image side to the object side, and the third lens group G3 moves in coordination with the second lens group G2 to assist in focusing.

[0039] Example 1: spherical aberration, field curvature aberration, distortion aberration, and chromatic aberration at infinity and constant magnification, as shown below. Figure 2 As shown.

[0040] Focal distance: 87.1;

[0041] Fno: 2.9;

[0042] Half-angle ω: 13.5°;

[0043]

[0044]

[0045]

[0046]

[0047] R(mm): Radius of curvature of each surface;

[0048] D (mm): Spacing between lenses and lens thickness;

[0049] Nd: The refractive index of each glass along the d-line;

[0050] Vd: Abbe number of glass.

[0051] Example 2

[0052] like Figure 3 As shown, from the object side to the image plane side, the lens group consists of a first lens group G1, a second lens group G2 with positive refractive power, and a third lens group G3 with negative refractive power. When the object moves from infinity to near, the first lens group G1 remains fixed, the second lens group G2 moves from the image side to the object side, and the third lens group G3 moves in coordination with the second lens group G2 to assist in focusing.

[0053] Example 2: Spherical aberration, field curvature aberration, distortion aberration, and magnification chromatic aberration at infinity, 1x magnification, and 2x magnification, as follows: Figure 4 As shown.

[0054] Focal distance: 59.21;

[0055] Fno: 2.9;

[0056] Half-angle ω: 19.95;

[0057]

[0058]

[0059]

[0060]

[0061] R(mm): Radius of curvature of each surface;

[0062] D (mm): Spacing between lenses and lens thickness;

[0063] Nd: The refractive index of each glass along the d-line;

[0064] Vd: Abbe number of glass.

[0065] Conditional summary table:

[0066] Example 1 Example 2 Condition (1): 2.0 ≤ |L / DL2| ≤ 3.5 2.940 2.613 Condition (2): 1.4 ≤ |S2 / S1| ≤ 2.1 1.690 1.891 Conditional expression (3): 0.3≤Ymax / F2≤0.8 0.479 0.580 Condition (4): 0.2 ≤ |F2 / F3| ≤ 1.5 0.928 0.568

[0067] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A high-magnification macro lens, characterized in that, From the object side to the image plane side, the lens consists of a first lens group G1, a second lens group G2 with positive refractive power, and a third lens group G3 with negative refractive power. When the object moves from infinity to near, the first lens group G1 remains fixed, the second lens group G2 moves from the image side to the object side, and the third lens group G3 moves in coordination with the second lens group G2 to assist in focusing, and satisfies the following condition (1): 2.0≤|L / DL2|≤3.5 (1); in, L: Total length of the optical system; DL2: The distance from the image side of the first lens group G1 to the object side of the second lens group G2 at infinity.

2. A high-magnification macro lens according to claim 1, characterized in that... Satisfying condition (2): 1.4≤|S2 / S1|≤2.1 (2); in, S1: The amount of movement of the second lens group G2 from infinity to 1x magnification; S2: The amount of movement of the second lens group G2 from infinity to when the magnification is at its maximum.

3. A high-magnification macro lens according to claim 1 or 2, characterized in that, Satisfy condition (3): 0.3≤Ymax / F2≤0.8 (3; in, Ymax: The maximum paraxial image height of the optical system, Ymax=FL×tanω, where FL is the focal length of the optical system at infinity, and ω is the half-angle of the image. F2: Focal length of the second lens group G2.

4. A high-magnification macro lens according to claim 1 or 2, characterized in that, Satisfy condition (4): 0.2≤|F2 / F3|≤1.5 (3); in, F2: Focal length of the second lens group G2; F3: Focal length of the third lens group G3.

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