Medium-and-long-focus tilt-shift macro lens

Abstract

The utility model discloses a medium-long focus tilt-shift macro lens, which structurally comprises a first lens group G1, a second lens group G2 with positive diopter and a third lens group G3 with negative diopter in sequence from an object side to an image surface side, the aperture Stop is arranged between the second lens group G2 and the third lens group G3; the first lens group G1 is fixed, the second lens group G2 serves as a main focusing lens group and moves from the image plane side to the object side, the third lens group G3 serves as an auxiliary focusing group and moves from the image plane side to the object side, and aberration caused by movement of the second lens group G2 is corrected. Under the condition that the size is controlled, the medium-and-long-focus macro lens with the maximum field angle smaller than 45 degrees is achieved, the image field of the medium-and-long-focus macro lens is large enough and reaches 65 mm or above, the diameter of the image field of the medium-and-long-focus macro lens exceeds 20 mm of the image field diameter of a full-frame camera, mutual translation of the lens and the camera can be achieved by + / -10 mm or above, tilt shift of the lens and the camera can be achieved by + / -8 degrees or above, and black edge shielding caused by insufficient image fields is avoided.

Description

Technical Field

[0001] The utility model is a medium-long focal length macro lens with a field of view angle of less than 45°, which can well image objects from infinity to a photographic magnification of 1, and has a large imaging frame. It can achieve translation in any direction on a full-frame camera with an image plane diameter of 43.2mm, and the tilt-shift can still cover the entire camera frame, and is particularly applicable to the lens field of full-frame digital exchange cameras. Background Art

[0002] At present, the known cameras use macro lenses that can form good images from infinity to close distances, and the maximum photographic magnification of the closest distance is 1x. For example, in the known Japanese patent JP 2013-104994, when an object moves from infinity to a close distance, the first and fourth lens groups are fixed, and the second and third lens groups move toward each other to achieve focusing. Although good imaging can be achieved, the image field diameter is insufficient. If used for a full-frame camera to achieve a translation of more than 10 mm, or a tilt shift of more than 8°, black edges and incomplete image field coverage will appear. If it is magnified proportionally, the performance will decrease. At the same time, the volume is too large to be miniaturized. There is also the well-known Japanese patent No. JP 2024-29669. The first and fourth lens groups are fixed, and the second and third lens groups move toward each other to achieve focusing. Although good imaging can be achieved, the image field diameter is too small. When used for a full-frame camera to achieve a translation of more than ±10mm, or a tilt shift of more than ±8°, a black edge phenomenon will appear, and the last lens is too close to the image plane. When achieving translation and tilt movement, there is no space for the mechanical structure to achieve it, and interference and other problems will inevitably occur. Utility Model Content

[0003] In order to overcome the problem that the above-mentioned known medium-to-long focal length macro lenses cannot realize the large-range translation of more than ±10mm and the tilt-shift function of more than ±8° on a full-frame camera, the utility model will provide a medium-to-long focal length macro lens with a large screen from infinity to a photographic magnification of about 1.0 times, an imaging circle diameter of more than 65mm, and a long back focal length, which can realize translation of more than ±10mm and tilt shift of more than ±8° on a full-frame camera, and a field of view angle of less than 45° with good imaging.

[0004] In order to achieve the above-mentioned utility model purpose, the utility model adopts the following technical solutions:

[0005] The utility model provides a medium-long focal length axis-shift macro lens, which 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;

[0006] The aperture Stop is disposed between the second lens group G2 and the third lens group G3;

[0007] The first lens group G1 is fixed, the second lens group G2 is used as a main focus lens group, and moves from the image side to the object side. The third lens group G3 is used as an auxiliary focus group, and moves from the image side to the object side to correct the aberration caused by the movement of the second lens group G2.

[0008] The focal lengths of the first lens group G1, the second lens group G2 and the third lens group G3 satisfy the following conditional equations (1) and (2):

[0009] |F1 / F0|≧6.0(1)

[0010] 2.0≤|F3 / F2|≤5.0 (2)

[0011] in,

[0012] F1: focal length of the first lens group G1;

[0013] F2: focal length of the second lens group G2;

[0014] F3: focal length of the third lens group G3;

[0015] F0: The focal length of the entire optical system at infinity.

[0016] If the lower limit of the conditional expression |F1 / F0|≧6.0(1) is exceeded, the refractive power of the front part G1 of the first lens group is too strong. If the refractive power of the first lens group G1 is negative, in the entire optical system, the positive refractive power of the second lens group G2 will be offset. For balance, the refractive power of the second lens group G2 will become very strong, and the focusing movement amount will tend to be small. Although it is easy to achieve a miniaturized effect, it will cause the field angle to become larger, and it will be difficult to achieve the medium and long focal length design requirement of an angle of view of less than 45°. If the refractive power of the first lens group G1 is positive, although it is easy to achieve a medium and long focal length design requirement of a field angle of less than 45°, the strength of the positive refractive power of the second lens group G2 will be weakened. If a 1x macro effect is achieved, the focusing movement amount will become very large because the refractive power of G2 as a focusing group is too weak, which will cause the entire optical system to become bulky, making miniaturization difficult.

[0017] If the upper limit of the conditional expression 2.0≤|F3 / F2|≤5.0(2) is exceeded, the positive refractive power of the second lens group G2 will be too strong and the negative refractive power of the third lens group G3 will be too weak. Therefore, although the focusing movement of the second lens group G2 is very small, the aberration increases sharply due to the excessive positive refractive power of the second lens group G2, and the negative refractive power of the third lens group G3 is too weak to be well corrected, making it difficult to achieve high performance throughout the entire process. If the lower limit of the conditional expression (2) is exceeded, the positive refractive power of the second lens group G2 is too weak. During the focusing process, the negative refractive power of the third lens group G3 can easily correct the aberration caused by the focusing of the second lens group G2. However, if a 1x macro effect is to be achieved, the movement of the second lens group G2 will become very large, making it difficult to achieve the design goal of miniaturization.

[0018] Further technology of the utility model:

[0019] Preferably, the interval between the first lens group G1 and the second lens group G2 satisfies conditional equations (3) and (4);

[0020] 0.3≤LS / F0≤0.6 (3)

[0021] 1.5≤|F0 / D12|≤3.0 (4)

[0022] in,

[0023] LS: The distance from the aperture stop to the rearmost surface of the image side of the optical system at infinity;

[0024] D12: The distance between the first lens group G1 and the second lens group G2 at infinity.

[0025] If the upper limit of the conditional expression 0.3≤LS / F0≤0.6(3) is exceeded, the distance from the aperture to the rear face of the optical system is too far, which will cause the outer diameter of the third lens group G3 to be too large, resulting in interference between the shift mechanism and the camera, making it difficult to achieve the pan and tilt shift functions. If the lower limit of the conditional expression (3) is exceeded, the distance from the aperture to the rear face of the optical system is too close. Although the exit pupil is very close and the volume of the third lens group G3 is small, the entrance pupil distance is very far, which will cause the outer diameter of the first lens group G1 to become large, resulting in the volume of the entire optical system becoming very large.

[0026] If the upper limit of the conditional expression 1.5≤|F0 / D12|≤3.0(4) is exceeded, the interval between the first lens group G1 and the second lens group G2 at infinity is large enough, and when focusing, the second lens group G2 has sufficient space to move, and it is easy to achieve a macro effect of equal magnification. However, because the interval is too large, the entire optical system may become huge, the manufacturing cost is too high, and the volume is too large to be applicable. If the lower limit of the conditional expression (4) is exceeded, the focus movement space of the main focus group G2 is very small, and the diopter strength must be increased, which will cause a sharp deterioration of aberrations due to the diopter being too strong, and it is difficult to achieve the effect of 1x macro and high performance.

[0027] Preferably, the movement amounts of the second lens group G2 and the third lens group G3 satisfy conditional expressions (5) and (6);

[0028] 1.2≤|S2_A / S3_A|≤4.0 (5)

[0029] 1.2≤|S2_B / SB_|≤5.0 (6)

[0030] in,

[0031] S2_A: the focus movement amount of the second lens group G2 when the photographic distance is from infinity to the photographic magnification of 0.5 times;

[0032] S3_A: the focus movement amount of the third lens group G3 when the photographic distance is from infinity to the photographic magnification of 0.5 times;

[0033] S2_B: the focus movement amount of the second lens group G2 when the photographic distance is from infinity to the photographic magnification of 1.0 times;

[0034] S3_B: The focus movement amount of the third lens group G3 when the photographic distance is from infinity to the photographic magnification of 1.0.

[0035] If the upper limit of the conditional expression 1.2≤|S2_A / S3_A|≤4.0(5) is exceeded, the movement of the second lens group G2 of the main focus group is too large, and the spherical aberration and image curvature generated during the focusing process are insufficiently corrected by the third lens group G3 of the auxiliary focus group, resulting in a decrease in performance around 0.5 times, especially the image curvature is difficult to correct. If the lower limit of the conditional expression (5) is exceeded, although the third lens group G3 of the auxiliary focus group provides sufficient aberration correction, it will offset the movement effect of the second lens group G2 of the main focus group, and the focusing movement will increase, causing the entire optical system to become very large, making miniaturization very difficult.

[0036] If the upper limit of the conditional expression 1.2≤|S2_B / S3_B|≤5.0(6) is exceeded, the movement of the second lens group G2 of the main focus group is too large, and the spherical aberration and image curvature generated during the focusing process are insufficiently corrected by the third lens group G3 of the auxiliary focus group, resulting in a decrease in performance at 1.0 times, especially the image curvature is difficult to correct. If the lower limit of the conditional expression (6) is exceeded, although the third lens group G3 of the auxiliary focus group provides sufficient aberration correction, it will offset the movement effect of the second lens group G2 of the main focus group, and the focusing movement will increase, causing the entire optical system to become very large, making it difficult to miniaturize.

[0037] The beneficial effects of the utility model are:

[0038] The utility model provides a medium-long focal length shift macro lens, which realizes a medium-long focal length macro lens with a maximum field angle of less than 45° while controlling the volume. The image field is large enough to reach more than 65mm, which exceeds the image field diameter of 20mm of a full-frame camera. The lens and the camera can be shifted relative to each other by more than ±10mm and tilted by more than ±8°, and there will be no black edge occlusion caused by insufficient image field. It can be widely used in professional photography fields such as commodity photography, architecture, and landscape. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is an optical structure diagram of the first embodiment of the utility model;

[0040] Figure 2 The spherical aberration, field curvature aberration, distortion aberration and lateral chromatic aberration at infinity, 0.5-times photographic magnification and 1.0-times photographic magnification of the first embodiment;

[0041] Figure 3 This is an optical structure diagram of the second embodiment of the utility model;

[0042] Figure 4 The spherical aberration, field curvature aberration, distortion aberration and lateral chromatic aberration at infinity, 0.5-times photographic magnification and 1.0-times photographic magnification of the second embodiment;

[0043] Figure 5 This is an optical structure diagram of the third embodiment of the utility model;

[0044] Figure 6 The spherical aberration, field curvature aberration, distortion aberration, and lateral chromatic aberration at infinity, 0.5-times magnification, and 1.0-times magnification of the third embodiment are shown. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution in the embodiment of the utility model will be further described in detail below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model but not all. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the utility model.

[0046] First embodiment:

[0047] like Figure 1 As shown, the macro lens of the first embodiment includes, from the object side, a first lens group G1 with positive refractive power, a positive refractive power G2 and a third lens group G3 with negative refractive power. The image field diameter reaches Φ67mm, which is 23.8mm larger than the full-frame image field diameter of 43.2mm. It can achieve a vertical and horizontal translation of more than ±10mm. At the same time, BF_I NF is long enough, and the distance between the optical system and the image plane is large enough, so the shift mechanism of translation and shaking of the head can be easily realized without causing interference.

[0048] The spherical aberration, field curvature aberration, distortion aberration and lateral chromatic aberration at infinity, 0.5x magnification and 1.0x magnification of the first embodiment are as follows: Figure 2 shown.

[0049] The data of the first embodiment are as follows.

[0050] R (mm): The radius of curvature of each surface.

[0051] D(mm): The distance between each lens and the thickness of the lens.

[0052] Nd: The refractive index of each glass at the d line.

[0053] Vd: Abbe number of glass.

[0054] Focal length:101.9933.

[0055] FNO:2.87.

[0056] Half-frame angle ω: 18.058.

[0057] Surface number R D Nd Vd 1 -419.2264 1.5000 1.53031 67.42 2 419.2264 1.7626 3 -988.9355 4.5000 1.87510 45.25 4 -237.8220 D(4) 5 49.5786 4.7304 1.89141 33.77 6 701.9177 6.8233 7 -74.3590 1.0000 1.78737 23.92 8 31.1489 6.8677 1.92286 20.88 9 -74.2786 0.9579 10 -91.0272 4.9298 1.91392 23.35 11 29.9253 5.3509 1.49700 81.61 12 -89.6049 0.1500 13 96.4295 2.6436 1.88100 40.15 14 -320.0818 0.8500 15STOP inf D(15) 16 131.5759 1.0000 1.88564 21.55 17 41.6690 9.7523 18 -38.7618 1.0000 1.68893 31.16 19 70.3932 9.0476 1.90326 27.29 20 -44.8924 16.6161 21 -32.7269 1.0000 1.49700 81.61 22 0.0000 0.1500 23 218.2766 5.9427 1.87156 41.46 24 -80.7375 BF

[0058] focal length 101.9933 0.5 times 1.0 times D(4) 49.3020 22.8415 1.0000 D(15) 1.9000 15.0845 27.2633 BF 40.3171 53.5931 63.2558

[0059] Second embodiment:

[0060] like Figure 3As shown, the macro lens of the second embodiment includes, from the object side, a first lens group G1 with positive refractive power, a positive refractive power G2 and a third lens group G3 with negative refractive power. The image field diameter reaches Φ67mm, which is 23.8mm larger than the full-frame image field diameter of 43.2mm. It can achieve a vertical and horizontal translation of more than ±10mm. At the same time, BF_I NF is long enough, and the distance between the optical system and the image plane is large enough, so the shift mechanism of translation and shaking of the head is easy to achieve without causing interference.

[0061] The spherical aberration, field curvature aberration, distortion aberration and lateral chromatic aberration at infinity, 0.5x magnification and 1.0x magnification of the second embodiment are as follows: Figure 4 shown.

[0062] The data of the second embodiment are as follows.

[0063] R (mm): The radius of curvature of each surface.

[0064] D(mm): The distance between each lens and the thickness of the lens.

[0065] Nd: The refractive index of each glass at the d line.

[0066] Vd: Abbe number of glass.

[0067] Focal length:117.00.

[0068] FNO:2.87.

[0069] Half-frame angle ω: 15.860.

[0070]

[0071]

[0072]

[0073] Third embodiment:

[0074] like Figure 5 As shown, Figure 5 As shown, the macro lens of the second embodiment includes, from the object side, a first lens group G1 with negative refractive power, a positive refractive power G2 and a third lens group G3 with negative refractive power. The image field diameter reaches Φ67mm, which is 23.8mm larger than the full-frame image field diameter of 43.2mm. It can achieve a vertical and horizontal translation of more than ±10mm. At the same time, BF_I NF is long enough, and the distance between the optical system and the image plane is large enough, so the shift mechanism of translation and shaking of the head can be easily realized without causing interference.

[0075] The spherical aberration, field curvature aberration, distortion aberration and lateral chromatic aberration at infinity, 0.5x magnification and 1.0x magnification of the third embodiment are as follows: Figure 6 shown.

[0076] The data of the third embodiment are as follows.

[0077] R (mm): The radius of curvature of each surface.

[0078] D(mm): The distance between each lens and the thickness of the lens.

[0079] Nd: The refractive index of each glass at the d line.

[0080] Vd: Abbe number of glass. Focal length: 86.0098. FNO: 2.87. Half-frame angle ω: 21.242.

[0081]

[0082]

[0083]

[0084] (Conditional summary table)

[0085]

[0086] The above contents are merely examples and explanations of the structure of the utility model. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the utility model or exceed the scope defined in the claims, they should all fall within the protection scope of the utility model.

Claims

1. A medium-to-long focal length shift macro lens, characterized in that: The lens group includes, 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. The aperture Stop is disposed between the second lens group G2 and the third lens group G3; The first lens group G1 is fixed, the second lens group G2 is used as a main focus lens group, and moves from the image side to the object side. The third lens group G3 is used as an auxiliary focus group, and moves from the image side to the object side to correct the aberration caused by the movement of the second lens group G2. The focal lengths of the first lens group G1, the second lens group G2 and the third lens group G3 satisfy the following conditional equations (1) and (2): |F1 / F0|≧6.0(1) 2.0≤|F3 / F2|≤5.0 (2) in, F1: focal length of the first lens group G1; F2: focal length of the second lens group G2; F3: focal length of the third lens group G3; F0: The focal length of the entire optical system at infinity.

2. The medium-to-long focal length shift macro lens according to claim 1, characterized in that: The interval between the first lens group G1 and the second lens group G2 satisfies conditional expressions (3) and (4); 0.3≤LS / F0≤0.6 (3) 1.5≤|F0 / D12|≤3.0 (4) in, LS: The distance from the aperture stop to the rearmost surface of the image side of the optical system at infinity; D12: The distance between the first lens group G1 and the second lens group G2 at infinity.

3. The medium-to-long focal length shift macro lens according to claim 1, characterized in that: The movement amounts of the second lens group G2 and the third lens group G3 satisfy conditional expressions (5) and (6); 1.2≤|S2_A / S3_A|≤4.0 (5) 1.2≤|S2_B / SB_|≤5.0 (6) in, S2_A: the focus movement amount of the second lens group G2 when the photographic distance is from infinity to the photographic magnification of 0.5 times; S3_A: the focus movement amount of the third lens group G3 when the photographic distance is from infinity to the photographic magnification of 0.5 times; S2_B: the focus movement amount of the second lens group G2 when the photographic distance is from infinity to the photographic magnification of 1.0 times; S3_B: The focus movement amount of the third lens group G3 when the photographic distance is from infinity to the photographic magnification of 1.0.

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