Medium format telephoto autofocus lens and photographic device

Abstract

The present application discloses a medium-format telephoto autofocus lens and a photographic device. The medium-format telephoto autofocus lens includes, from the object side to the image side, a first lens group with positive focal power, a second lens group with negative focal power, a third lens group with positive focal power, and a fourth lens group with negative focal power, and includes an aperture stop arranged on the side of the last lens in the first lens group adjacent to the object side; during the focusing process, the second lens group moves along the optical axis from the object side to the image side, the third lens group moves along the optical axis from the image side to the object side, and the positions of the first lens group and the fourth lens group relative to the image plane remain unchanged; the medium-format telephoto autofocus lens satisfies the following conditional formulas: 0.9≤F1 / F≤1.5, (1); 0.5≤F2 / F≤0.9, (2); 0.4≤R1 / F≤1, (3); 2.5≤F / H≤3.5, (4). The technical solution of the present application can achieve a relatively large aperture while maintaining imaging quality.

Description

Technical Field

[0001] The present application relates to the field of camera technology, and in particular to a medium format telephoto autofocus lens and a photographic device. Background Art

[0002] With the development of the photography industry, users have higher and higher demands on cameras. Even full-frame cameras cannot satisfy high-end users' pursuit of ultimate photography, and they turn to medium-format cameras.

[0003] In the prior art, although medium format focus lenses have high imaging quality characteristics such as high sharpness and low dispersion, they generally have the problem of small lens aperture, which leads to poor adaptability in certain environments.

[0004] Therefore, it is necessary to improve the existing medium format lenses. Summary of the invention

[0005] The present application provides a medium format telephoto autofocus lens and a photographic device, aiming to solve the problem that existing medium format lenses are difficult to adapt to large aperture photography and videography.

[0006] To achieve the above-mentioned purpose, the present application proposes a medium-format telephoto autofocus lens. The medium-format telephoto autofocus lens includes, from the object side to the image side, a first lens group with positive focal power, a second lens group with negative focal power, a third lens group with positive focal power, and a fourth lens group with negative focal power, and includes an aperture stop disposed on the side of the last lens in the first lens group adjacent to the object side; during the focusing process, the second lens group moves along the optical axis from the object side to the image side, the third lens group moves along the optical axis from the image side to the object side, and the first lens group and the fourth lens group remain unchanged relative to the image plane;

[0007] Medium format telephoto autofocus lenses meet the following conditions:

[0008] 0.9≤F1 / F≤1.5, (1);

[0009] 0.5≤F2 / F≤0.9, (2);

[0010] 0.4≤R1 / F≤1, (3);

[0011] 2.5≤F / H≤3.5, (4);

[0012] Among them, F1 represents the composite focal length of the first lens group, F2 represents the composite focal length of the second lens group, R1 represents the radius of curvature of the surface of the first lens in the first lens group close to the object side, F represents the effective focal length of the lens at infinite working distance, and H is the half image height of the medium format telephoto autofocus lens.

[0013] In some embodiments, the first lens group includes, from the object side to the image side, a first lens with positive power, a second lens with positive power, a third lens with negative power, a fourth lens with positive power, a fifth lens with negative power, and a sixth lens with positive power;

[0014] Wherein, the aperture stop is located between the fifth lens and the sixth lens; the fourth lens and the fifth lens are combined into a first cemented lens.

[0015] In some embodiments, the first lens group includes, from the object side to the image side, a first lens with positive power, a second lens with positive power, a third lens with positive power, a fourth lens with negative power, a fifth lens with negative power, a sixth lens with positive power, and a seventh lens with positive power;

[0016] Wherein, the aperture stop is located between the sixth lens and the seventh lens; the third lens and the fourth lens are combined into a second cemented lens, and the fifth lens and the sixth lens are combined into a third cemented lens.

[0017] In some embodiments, the second lens group includes at least one lens with a refractive index Nd≥1.9.

[0018] In some embodiments, the second lens group includes, from the object side to the image side, an eighth lens having positive power and a ninth lens having negative power;

[0019] The refractive index Nd8 of the eighth lens is ≥1.9; and the eighth lens and the ninth lens are combined into a fourth cemented lens.

[0020] In some embodiments, the third lens group includes, from the object side to the image side, a tenth lens having positive power, an eleventh lens having negative power, and a twelfth lens having positive power;

[0021] The tenth lens and the eleventh lens are combined into a fifth cemented lens; and the tenth lens and the eleventh lens satisfy:

[0022] |Vd10-Vd11|≥25, (5);

[0023] Wherein, Vd10 is the Abbe number of the tenth lens in the third lens group with respect to the light with a wavelength of 587.6 nm; Vd11 is the Abbe number of the eleventh lens in the third lens group with respect to the light with a wavelength of 587.6 nm.

[0024] In some embodiments, the fourth lens group includes at least one lens with an Abbe number Vd≥60.

[0025] In some embodiments, the fourth lens group includes, from the object side to the image side, a thirteenth lens having negative power, a fourteenth lens having positive power, a fifteenth lens having negative power, a sixteenth lens having positive power, and a seventeenth lens having negative power;

[0026] The Abbe number Vd16 of the sixteenth lens is ≥60; the thirteenth lens and the fourteenth lens are combined into a sixth cemented lens, and the fifteenth lens and the sixteenth lens are combined into a seventh cemented lens.

[0027] In some embodiments, the fourth lens group includes, from the object side to the image side, a thirteenth lens having positive power, a fourteenth lens having negative power, and a fifteenth lens having negative power;

[0028] The Abbe number Vd14 of the fourteenth lens is ≥60; the thirteenth lens and the fourteenth lens are combined into a sixth cemented lens.

[0029] The present application also provides a photographic device, which includes an image sensor and the medium format telephoto autofocus lens as described above, wherein the image sensor and the medium format telephoto autofocus lens are detachably connected.

[0030] The technical solution of the present application proposes a medium-format telephoto autofocus lens. The medium-format telephoto autofocus lens includes, from the object side to the image side, a first lens group with positive focal power, a second lens group with negative focal power, a third lens group with positive focal power, and a fourth lens group with negative focal power, and includes an aperture stop arranged on the side of the last lens in the first lens group adjacent to the object side; during the focusing process, the second lens group moves along the optical axis from the object side to the image side, and the third lens group moves along the optical axis from the image side to the object side, and the first lens group and the fourth lens group remain unchanged relative to the image plane; the medium-format telephoto autofocus lens includes, from the object side to the image side, a first lens group and a fourth lens group, and a second lens group. The telephoto autofocus lens satisfies the following conditions: 0.9≤F1 / F≤1.5, (1); 0.5≤F2 / F≤0.9, (2); 0.4≤R1 / F≤1, (3); 2.5≤F / H≤3.5, (4); wherein F1 represents the composite focal length of the first lens group, F2 represents the composite focal length of the second lens group, R1 represents the radius of curvature of the surface of the first lens in the first lens group close to the object side, F represents the effective focal length of the lens at infinite working distance, and H represents the half image height of the medium format telephoto autofocus lens. The technical solution of the present application can effectively correct aberrations by alternating positive and negative optical powers of four lens groups, thereby improving image sharpness, and optimizing the focal length ratio of each lens group and the position of the aperture stop, so as to achieve a relatively large aperture while maintaining image quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work, among which:

[0032] Figure 1 A schematic diagram showing the structure of Embodiment 1 of the present application is shown;

[0033] Figure 2 A schematic diagram showing axial chromatic aberration of Example 1 of the present application when in focus at infinity is shown;

[0034] Figure 3 A schematic diagram showing field curvature and distortion of Example 1 of the present application when focusing at infinity is shown;

[0035] Figure 4 A schematic diagram showing axial chromatic aberration of Example 1 of the present application at the minimum focusing distance is shown;

[0036] Figure 5 A schematic diagram showing field curvature and distortion of Example 1 of the present application at the closest focusing distance is shown;

[0037] Figure 6 A schematic diagram showing the structure of Embodiment 2 of the present application is shown;

[0038] Figure 7 A schematic diagram showing axial chromatic aberration of Example 2 of the present application when in focus at infinity is shown;

[0039] Figure 8 A schematic diagram showing field curvature and distortion of Example 2 of the present application when focusing at infinity;

[0040] Fig. 9 A schematic diagram showing axial chromatic aberration of Example 2 of the present application at the minimum focusing distance is shown;

[0041] Fig.10 A schematic diagram showing field curvature and distortion of Example 2 of the present application at the closest focusing distance is shown. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0043] See also Figure 1As shown, the present application proposes a medium-format telephoto autofocus lens, which includes, from the object side to the image side, a first lens group G1 with positive focal power, a second lens group G2 with negative focal power, a third lens group G3 with positive focal power, and a fourth lens group G4 with negative focal power, and includes an aperture stop STP arranged on the side of the last lens in the first lens group G1 adjacent to the object side; in the focusing process, the second lens group G2 moves along the optical axis from the object side to the image side, the third lens group G3 moves along the optical axis from the image side to the object side, and the positions of the first lens group G1 and the fourth lens group G4 relative to the image plane remain unchanged;

[0044] Medium format telephoto autofocus lenses meet the following conditions:

[0045] 0.9≤F1 / F≤1.5, (1);

[0046] 0.5≤F2 / F≤0.9, (2);

[0047] 0.4≤R1 / F≤1, (3);

[0048] 2.5≤F / H≤3.5, (4);

[0049] Among them, F1 represents the composite focal length of the first lens group G1, F2 represents the composite focal length of the second lens group G2, R1 represents the curvature radius of the surface of the first lens L01 in the first lens group G1 close to the object side, F represents the effective focal length of the lens at infinite working distance, and H is the half image height of the medium format telephoto autofocus lens.

[0050] The technical solution of the present application sets the aperture stop STP on the side of the last lens in the first lens group G1 adjacent to the object, which is conducive to controlling the amount of light entering. By adjusting the size of the aperture stop STP, the aperture value of the lens can be controlled, thereby achieving large aperture shooting.

[0051] The lens is configured with a combination of lens groups with positive, negative, positive and negative optical focal lengths, so that the lens can effectively correct various aberrations, such as spherical aberration, chromatic aberration and distortion, improve imaging quality, and ensure picture clarity and sharpness while maintaining a larger aperture.

[0052] Furthermore, during the focusing process, the second lens group G2 is designed to move from the object side to the image side along the optical axis, and the third lens group G3 moves from the image side to the object side. This "inner focus" mechanism reduces the change in the total length of the lens during the focusing process, making the focusing speed faster and smoother. At the same time, since the first lens group G1 and the fourth lens group G4 remain relatively fixed during the focusing process, it helps to maintain the overall stability of the lens and the consistency of imaging.

[0053] In addition, by satisfying specific conditional expressions (1), (2), (3) and (4), the proportional relationship between the focal length, the radius of curvature and the overall focal length of each component of the lens is limited, thereby improving the imaging quality and focusing performance of the lens.

[0054] Specifically, conditional expression (1) defines the relationship between the focal length F1 of the first lens group G1 and the effective focal length F of the lens at infinite working distance. If the value exceeds the upper limit of the range, the length of the entire first lens group G1 will be longer, which will reduce the tolerance sensitivity, but will be disadvantageous for miniaturization of the lens; if the value is below the lower limit of the range, it will be beneficial to reduce the size and weight of the first lens group G1, but will be disadvantageous for correcting the chromatic aberration of the lens system and improving the resolution.

[0055] Condition (2) defines the relationship between the focal length F2 of the second lens group G2 and the effective focal length F of the lens at infinite working distance. If the upper limit of the range is exceeded, the movement stroke of the second lens group G2 will be longer, which will increase the autofocus time; if the lower limit of the range is lower than the lower limit, it will be detrimental to the correction of chromatic aberration of the lens system and the improvement of resolution.

[0056] Condition (3) defines the ratio of the curvature radius R1 of the surface of the first lens L01 in the first lens group G1 close to the object side to the effective focal length F of the lens at the infinite working distance. If the curvature radius R1 exceeds the upper limit of the range, it is not conducive to the correction of off-axis aberrations; if the curvature radius R1 is below the lower limit of the range, the lens system will be sensitive to decentering and spherical aberration will be easily generated.

[0057] Conditional equation (4) specifies the ratio range of the effective focal length F and the half image height H of the lens at infinite working distance. If the upper limit of the range is exceeded, the field of view angle becomes smaller, limiting the shooting range; if the lower limit of the range is lower than the lower limit, the field of view angle becomes larger, which is not conducive to the correction of lens distortion and will cause the captured image to be distorted.

[0058] In summary, the lens provided by the technical solution of the present application can ensure image quality while maintaining large aperture photography.

[0059] In some embodiments, the first lens group G1 includes, from the object side to the image side, a first lens L01 with positive power, a second lens L02 with positive power, a third lens L03 with negative power, a fourth lens L04 with positive power, a fifth lens L05 with negative power, and a sixth lens L06 with positive power; wherein an aperture stop STP is located between the fifth lens L05 and the sixth lens L06; the fourth lens L04 and the fifth lens L05 are combined into a first cemented lens.

[0060] And in some embodiments, the first lens group G1 includes, from the object side to the image side, a first lens L01 with positive power, a second lens L02 with positive power, a third lens L03 with positive power, a fourth lens L04 with negative power, a fifth lens L05 with negative power, a sixth lens L06 with positive power, and a seventh lens L07 with positive power; wherein the aperture stop STP is located between the sixth lens L06 and the seventh lens L07; the third lens L03 and the fourth lens group G4 are combined into a second cemented lens, and the fifth lens L05 and the sixth lens L06 are combined into a third cemented lens.

[0061] Two specific structural settings of the first lens group G1 are proposed above. By combining multiple lenses into the first lens group G1, accurately matching the optical power of the lenses and combining cemented lenses, the first lens group G1 can achieve high-quality imaging effects, including high definition, low aberration, low distortion and low dispersion. Based on the cemented lens setting, the size and weight of the lens are reduced, making the lens more compact and portable.

[0062] In some embodiments, the second lens group G2 includes at least one lens with a refractive index Nd≥1.9.

[0063] Refractive index is a physical quantity that describes the ability of optical materials to refract light. Materials with high refractive index can achieve the same optical power at a shorter distance, thus helping to reduce the size and weight of the lens.

[0064] Therefore, in this embodiment, the second lens group G2 includes at least one high refractive index lens, which can achieve a smaller volume and higher imaging quality of the second lens group G2.

[0065] In some embodiments, the second lens group G2 includes, from the object side to the image side, an eighth lens L08 with positive refractive power and a ninth lens L09 with negative refractive power; wherein the refractive index Nd8 of the eighth lens L08 is ≥ 1.9; and the eighth lens L08 and the ninth lens L09 are combined into a fourth cemented lens.

[0066] In this embodiment, a specific structural arrangement of the second lens group G2 is proposed. From the object side to the image side, it includes an eighth lens L08 with positive power and a ninth lens L09 with negative power. The aberration is corrected by the combination of positive and negative power to improve the image quality. The eighth lens L08 and the ninth lens L09 are further combined into a cemented lens to further reduce the number of lenses and simplify the lens structure.

[0067] In some embodiments, the third lens group G3 includes, from the object side to the image side, a tenth lens L10 having positive refractive power, an eleventh lens L11 having negative refractive power, and a twelfth lens L12 having positive refractive power; wherein the tenth lens L10 and the eleventh lens L11 are combined into a fifth cemented lens.

[0068] In this embodiment, a specific structural arrangement of the third lens group G3 is proposed. Similarly, through the alternating arrangement of positive and negative optical powers and the use of cemented lenses, the third lens group G3 can effectively correct various aberrations, ensure that the image can maintain high imaging quality in the entire field of view and achieve a more compact structure.

[0069] Furthermore, the tenth lens L10 and the eleventh lens L11 satisfy:

[0070] |Vd10-Vd11|≥25, (5);

[0071] Wherein, Vd10 is the Abbe number of the tenth lens L10 in the third lens group G3 with respect to the light with a wavelength of 587.6 nm; Vd11 is the Abbe number of the eleventh lens L11 in the third lens group G3 with respect to the light with a wavelength of 587.6 nm.

[0072] It is understandable that when light passes through lenses with different Abbe numbers, their correction effects on chromatic aberration will complement each other, thereby achieving better dispersion control in the entire system. Therefore, in further design optimization, a specific conditional formula is proposed for the tenth lens L10 and the eleventh lens L11 in the third lens group G3 to ensure that the dispersion performance difference between them is large enough.

[0073] Conditional formula (5) |Vd10-Vd11|≥25 indicates that the difference (absolute value) between the Abbe numbers of the tenth lens L10 and the eleventh lens L11 should be greater than or equal to 25. This ensures that the difference between the Abbe numbers of the tenth lens L10 and the eleventh lens L11 is large enough to further reduce the chromatic aberration of the entire system.

[0074] In some embodiments, the fourth lens group G4 includes at least one lens with an Abbe number Vd≥60.

[0075] The Abbe number is a physical quantity that describes the dispersion ability of optical materials, indicating the rate of change of the material's refractive index for light of different wavelengths. The higher the Abbe number, the smaller the dispersion of the material for light of different wavelengths, which means that the imaging consistency of the lens under different colors is better and chromatic aberration can be reduced.

[0076] Therefore, in this embodiment, by providing at least one high Abbe number lens in the fourth lens group G4, chromatic aberration can be reduced, blur and color distortion caused by chromatic aberration can be avoided, and the imaging quality of the lens can be further improved.

[0077] In some embodiments, the fourth lens group G4 includes, from the object side to the image side, a thirteenth lens L13 with negative power, a fourteenth lens L14 with positive power, a fifteenth lens L15 with negative power, a sixteenth lens L16 with positive power, and a seventeenth lens L17 with negative power; wherein the Abbe number Vd16 of the sixteenth lens L16 is ≥ 60; the thirteenth lens L13 and the fourteenth lens L14 are combined into a sixth cemented lens, and the fifteenth lens L15 and the sixteenth lens L16 are combined into a seventh cemented lens.

[0078] And in some embodiments, the fourth lens group G4 includes, from the object side to the image side, a thirteenth lens L13 with positive refractive power, a fourteenth lens L14 with negative refractive power and a fifteenth lens L15 with negative refractive power; wherein the Abbe number Vd14 of the fourteenth lens L14 is ≥60; the thirteenth lens L13 and the fourteenth lens L14 are combined into a sixth cemented lens.

[0079] Two specific structural settings of the fourth lens group G4 are proposed above. They are also based on the combination of multiple lenses, and by accurately matching the focal length of the lenses, combining cemented lenses, and using high Abbe number lenses, the fourth lens group G4 can achieve high-quality imaging effects, and based on high refractive index materials and cemented lens settings, the size and weight of the lens can be reduced, making the lens more compact and portable.

[0080] In the present application, a parallel glass plate GL configured by a filter is arranged between the last lens of the fourth lens group G4 and the image plane IMG. The parallel glass plate GL is used to filter light to improve the image quality. Specifically, the parallel glass plate GL can absorb or reflect light of certain wavelengths to eliminate or reduce interference factors such as chromatic aberration and stray light, thereby improving the contrast and clarity of the image.

[0081] Specific embodiments of the medium format telephoto autofocus lens of the present application are presented below.

[0082] Example 1

[0083] Figure 1 FIG. 1 is a schematic diagram of the structure of a medium format telephoto autofocus lens according to Example 1. Figure 1As shown, in this embodiment, the first lens group G1 includes, from the object side to the image side, a first lens L01 with positive power, a second lens L02 with positive power, a third lens L03 with negative power, a fourth lens L04 with positive power, a fifth lens L05 with negative power, and a sixth lens L06 with positive power; wherein the aperture stop STP is located between the fifth lens L05 and the sixth lens L06; the fourth lens L04 and the fifth lens L05 are combined into a first cemented lens. The second lens group G2 includes, from the object side to the image side, an eighth lens L08 with positive power and a ninth lens L09 with negative power; wherein the refractive index Nd8 of the eighth lens L08 is 2.00; the eighth lens L08 and the ninth lens L09 are combined into a fourth cemented lens. The third lens group G3 includes, from the object side to the image side, a tenth lens L10 with positive refractive power, an eleventh lens L11 with negative refractive power and a twelfth lens L12 with positive refractive power; wherein, the Abbe number Vd10 of the tenth lens L10 is 52.32, the Abbe number Vd11 of the eleventh lens L11 is 22.70, and the tenth lens L10 and the eleventh lens L11 are combined into a fifth cemented lens. The fourth lens group G4 includes, from the object side to the image side, a thirteenth lens L13 with negative power, a fourteenth lens L14 with positive power, a fifteenth lens L15 with negative power, a sixteenth lens L16 with positive power and a seventeenth lens L17 with negative power; wherein, the Abbe number Vd16 of the sixteenth lens L16 is 95.10; the thirteenth lens L13 and the fourteenth lens L14 are combined into a sixth cemented lens, and the fifteenth lens L15 and the sixteenth lens L16 are combined into a seventh cemented lens.

[0084] In this embodiment, the numerical data of the medium format telephoto autofocus lens are shown in Table 1 and Table 2:

[0085] Table 1

[0086]

[0087] Table 2

[0088]

[0089] The surface number indicates the surface number of each lens from the object side to the image side.

[0090] Figure 2 and Figure 3 The axial chromatic aberration, field curvature and distortion curves of Example 1 when in infinity focus are shown. Figure 4 and Figure 5 The graphs show the axial chromatic aberration, field curvature and distortion of Example 1 when the lens is in focus at the closest distance.

[0091] The axial chromatic aberration curve diagram represents the axial chromatic aberration curve when the aperture number is 1.47, wherein the F line, D line, and C line represent the axial chromatic aberration at a wavelength of 486nm, a wavelength of 587nm, and a wavelength of 656nm, respectively, the horizontal axis represents the spherical aberration value, and the vertical axis represents the field of view. The field curvature curve diagram represents the field curvature curve when the half field angle ω is 14.02°, wherein the dotted line S represents the value of the chief ray D line on the sagittal image plane, the solid line T represents the value of the chief ray D line on the meridional image plane, the horizontal axis represents the field curvature value, and the vertical axis represents the field of view. The distortion curve diagram represents the distortion curve when the half field angle ω is 14.02°, wherein the horizontal axis represents the distortion value, and the vertical axis represents the field of view. The above description of various spherical aberrations, field curvatures, and distortion curve diagrams is the same as that of other embodiments, and will not be repeated below.

[0092] As can be seen from Figures 2-5, the lens of this embodiment 1 has a good imaging effect.

[0093] Example 2

[0094] Figure 6 FIG. 2 is a schematic diagram of the structure of a medium format telephoto autofocus lens according to Example 2. Figure 6As shown, in this embodiment, the first lens group G1 includes, from the object side to the image side, a first lens L01 with positive power, a second lens L02 with positive power, a third lens L03 with positive power, a fourth lens L04 with negative power, a fifth lens L05 with negative power, a sixth lens L06 with positive power, and a seventh lens L07 with positive power; wherein the aperture stop STP is located between the sixth lens L06 and the seventh lens L07; the third lens L03 and the fourth lens L04 are combined into a second cemented lens, and the fifth lens L05 and the sixth lens L06 are combined into a third cemented lens. The second lens group G2 includes, from the object side to the image side, an eighth lens L08 with positive power and a ninth lens L09 with negative power; wherein the refractive index Nd8 of the eighth lens L08 is 1.92; and the eighth lens L08 and the ninth lens L09 are combined into a fourth cemented lens. The third lens group G3 includes, from the object side to the image side, a tenth lens L10 with positive power, an eleventh lens L11 with negative power, and a twelfth lens L12 with positive power; wherein the Abbe number Vd10 of the tenth lens L10 is 55.53, the Abbe number Vd11 of the eleventh lens L11 is 23.79, and the tenth lens L10 and the eleventh lens L11 are combined into a fifth cemented lens. The fourth lens group G4 includes, from the object side to the image side, a thirteenth lens L13 with positive power, a fourteenth lens L14 with negative power, and a fifteenth lens L15 with negative power; wherein the Abbe number Vd14 of the fourteenth lens L14 is 68.35; the thirteenth lens L13 and the fourteenth lens L14 are combined into a sixth cemented lens.

[0095] In this embodiment, the numerical data of the medium format telephoto autofocus lens are shown in Table 3 and Table 4:

[0096] Table 3

[0097]

[0098] Table 4

[0099]

[0100] Figure 7 and Figure 8 The axial chromatic aberration, field curvature and distortion curves of Example 2 when in infinity focus are shown. Fig. 9 and Fig.10 The graphs show the axial chromatic aberration, field curvature and distortion of Example 2 when the lens is in focus at the closest distance.

[0101] As can be seen from Figures 7-10, the lens of this embodiment 2 has a good imaging effect.

[0102] The present application also provides a photographic device. The photographic device includes an image sensor and the above medium-format telephoto autofocus lens, wherein the image sensor and the medium-format telephoto autofocus lens are detachably connected. The image sensor is a camera.

[0103] In this embodiment, the photographic device includes all technical solutions of all embodiments of the above-mentioned medium format telephoto autofocus lens, and therefore has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described one by one here.

[0104] The above description is only a partial or preferred embodiment of the present application. Neither the text nor the drawings can limit the scope of protection of the present application. All equivalent structural changes made using the contents of the present application specification and drawings under the overall concept of the present application, or direct / indirect application in other related technical fields are included in the scope of protection of the present application.

Claims

1. A medium format telephoto autofocus lens, characterized in that: The lens comprises, from the object side to the image side, a first lens group having positive power, a second lens group having negative power, a third lens group having positive power, and a fourth lens group having negative power, and an aperture stop disposed on a side of the last lens in the first lens group adjacent to the object side; During the focusing process, the second lens group moves along the optical axis from the object side to the image side, the third lens group moves along the optical axis from the image side to the object side, and the positions of the first lens group and the fourth lens group relative to the image plane remain unchanged; The first lens group includes, from the object side to the image side, a first lens with positive power, a second lens with positive power, a third lens with negative power, a fourth lens with positive power, a fifth lens with negative power, and a sixth lens with positive power; the second lens group includes, from the object side to the image side, an eighth lens with positive power and a ninth lens with negative power; the third lens group includes, from the object side to the image side, a tenth lens with positive power, an eleventh lens with negative power, and a twelfth lens with positive power; the fourth lens group includes, from the object side to the image side, a thirteenth lens with negative power, a fourteenth lens with positive power, a fifteenth lens with negative power, a sixteenth lens with positive power, and a seventeenth lens with negative power; The medium format telephoto autofocus lens meets the numerical data in Table 1 and Table 2 below: Table 1 The surface number indicates the surface number of each lens from the object side to the image side; Table 2 。 2. A medium format telephoto autofocus lens, characterized in that: The lens comprises, from the object side to the image side, a first lens group having positive power, a second lens group having negative power, a third lens group having positive power, and a fourth lens group having negative power, and an aperture stop disposed on a side of the last lens in the first lens group adjacent to the object side; During the focusing process, the second lens group moves along the optical axis from the object side to the image side, the third lens group moves along the optical axis from the image side to the object side, and the positions of the first lens group and the fourth lens group relative to the image plane remain unchanged; The first lens group includes, from the object side to the image side, a first lens with positive power, a second lens with positive power, a third lens with positive power, a fourth lens with negative power, a fifth lens with negative power, a sixth lens with positive power and a seventh lens with positive power; the second lens group includes, from the object side to the image side, an eighth lens with positive power and a ninth lens with negative power; the third lens group includes, from the object side to the image side, a tenth lens with positive power, an eleventh lens with negative power and a twelfth lens with positive power; the fourth lens group includes, from the object side to the image side, a thirteenth lens with positive power, a fourteenth lens with negative power and a fifteenth lens with negative power; The medium format telephoto autofocus lens meets the numerical data in Table 3 and Table 4 below: Table 3 Among them, the surface number represents the surface number of each lens from the object side to the image side; Table 4 。 3. A photographic device, characterized in that: It comprises an image sensor and the medium format telephoto autofocus lens as claimed in claim 1 or 2, wherein the image sensor is detachably connected to the medium format telephoto autofocus lens.

Images