KR101026111B1 - Interchangeable lenses for quasi-expert camera - Google Patents

Abstract

The present invention relates to a semi-professional camera interchangeable lens optical system, comprising: a first lens having a convex surface on an object side, a concave surface on an image side, and having positive refractive power as a whole; A second lens having a convex surface on an object side and a concave surface on an image side, and having a negative refractive power as a whole; A third lens having a convex aspherical surface on the object side, a concave aspherical surface on the image side, and having a negative refractive power as a whole; A fourth lens having a concave or convex aspherical surface on the object side and a convex aspherical surface on the image side and having positive refractive power as a whole; A triplet in which convex surfaces are formed on the image side and a fifth lens having a positive refractive power as a whole, a concave surface is formed on the object side, a sixth lens having a negative refractive power as a whole, and a seventh lens having a positive refractive power as a whole. A spherical spherical lens group having a structure; Disclosed is a technical configuration including an aperture disposed between an aspherical third lens and a fourth lens and selectively converging light incident from the third lens.

Camera, DSLR, Interchangeable Lens, High End, Ultra Wide, Bright Lens, Aspheric, Triplet, Apochromat

Description

INTERCHANGEABLE LENSES FOR QUASI-EXPERT CAMERA}

The present invention relates to a semi-professional camera interchangeable lens optical system, and more particularly, ultra wide angles of which the use of the same lens array is completely different by maximizing the characteristics of the spherical triplet structure and the use of a large degree of freedom aspherical surface. The present invention relates to a semi-professional camera interchangeable lens optical system that enables the use of an optical system and a standard optical system with good brightness to realize an economical optical engine.

In general, digital cameras are DSLR (exchangeable lens type) cameras that exchange lenses, high-end digital cameras (more than 10 million pixels) that enhance the manual function and zoom performance with appearance similar to the DSLR cameras, and are easy to carry and operate. It is largely divided into the most popular compact digital camera, and there is a combination of high-end and DSLR.

At this time, DSLR (lens interchangeable) camera using interchangeable lens is for professional use. There are wide angle, standard, semi-telephoto, telephoto, zoom, and converter optical system according to the type of lens. In recent years, as the price of the product has changed more economically, CMOS cameras using CMOS imagers are being introduced one after another.

In addition, the interchangeable lens optical system used in the existing digital cameras was very complicated and the price range was formed very high due to the characteristics of the market, but as the market became larger, the range of users is expanding from the experts to the general public. We are trying to diversify and miniaturizing to make it more portable.

In addition, many companies in the market are making numerous attempts to break down the realm of professional DSLR cameras that can exchange lenses and the common compact digital cameras that are popular.

Unfortunately, the development of interchangeable lenses that are simple and high in performance with their small size and small size has not been achieved yet, and users of the general public as well as camera suppliers also want to use the interchangeable lenses. It is required.

The present invention has been made to solve the above-described problems, to provide an interchangeable lens that can be used by non-professional general public, but also compact and good performance, the use of aspherical surface with large degree of freedom and spherical triplet structure The object of the present invention is to provide a semi-professional camera interchangeable lens optical system that can be used as a standard optical system with good brightness and a very wide-angle optical system that is completely used in the same lens array by maximizing the characteristics of

That is, the present invention is a very bright standard lens having an angle of view of about 40 to 60 degrees of the field of view commonly used in the related art and having an aperture ratio (F / #) of 2.0 or less, and an angle of view of more than 110 degrees, but a fisheye type ( The ultra wide-angle lens that does not have any optical distortion such as fisheye-type can be used in both areas with the same lens array configuration, and economical optical engine can be implemented. To provide a semi-professional camera interchangeable lens optical system.

The present invention provides a light emitting device comprising: a first lens having a convex surface on an object side and a concave surface on an image side and having positive refractive power as a whole; A second lens having a convex surface on an object side and a concave surface on an image side, and having a negative refractive power as a whole; A third lens having a convex aspherical surface on the object side, a concave aspherical surface on the image side, and having a negative refractive power as a whole; A fourth lens having a concave or convex aspherical surface on the object side and a convex aspherical surface on the image side and having positive refractive power as a whole; A triplet in which convex surfaces are formed on the image side and a fifth lens having a positive refractive power as a whole, a concave surface is formed on the object side, a sixth lens having a negative refractive power as a whole, and a seventh lens having a positive refractive power as a whole. A spherical spherical lens group having a structure; It is disposed between the third lens and the fourth lens consisting of an aspherical surface, characterized in that it comprises an aperture for selectively converging the light incident from the third lens.

The present invention is not only able to implement an ultra-wide optical system suitable for urban buildings or landscape photography by constructing a very compact interchangeable lens with the same lens array and forming an ultra-wide angle, but also sometimes a very bright lens, suitable for portrait shooting anytime, anywhere, indoor or outdoor. It can be applied to two completely different areas, such as realizing a standard optical system with high brightness, and can realize an economical optical engine, and can provide interchangeable lenses that can be used by non-professional users while improving optical performance.

When described in detail with reference to the accompanying drawings and the present invention.

As shown in FIG. 1, the semi-professional camera interchangeable lens optical system according to an exemplary embodiment of the present invention has a lens array for forming an ultra wide angle, and includes two aspherical lenses 30 and 40 and three sheets. The lens system includes seven spherical contact lenses 50, 60, and 70 having a triplet structure, and a diaphragm 80.

The lens system includes a first lens 10 having a convex surface R1 on the object side, a concave surface R2 on the image side, and having a positive refractive power as a whole; A second lens 20 having a convex surface R3 on the object side and a concave surface R4 on the image side and having negative refractive power as a whole; A third lens 30 having a convex aspherical surface R5 on the object side and a concave aspherical surface R6 on the image side and having negative refractive power as a whole; A fourth lens 40 having convex aspherical surfaces R7 and R8 on both the object side and the image side and having positive refractive power as a whole; A fifth lens 50 having a positive refractive power as a whole, a concave surface R11 is formed on the object side, and a plane R on the image side. And a sixth lens 60 having a generally negative refractive power, and a flat R13 on the object side, a convex surface R14 on the image side, and a seventh lens having positive refractive power. 70) is composed of a spherical splicing lens group having a triplet structure which is sequentially arranged from the object side to the image side and bonded to each other.

The first lens 10 is a lens that is disposed at the outermost side and is preferably applied to a strong lens suitable for use by a semi-expert who can be easily used by the general public. It is preferable to use or use a flint-crown type lens having excellent strength.

Preferably, the third lens 30 and the fourth lens 40 formed as the aspherical surface may be formed by using a glass molding press (GMP; a method of forming glass by applying heat to glass). The lens system may be formed through such glass molding. The overall thickness of the lens can be reduced, miniaturization can be achieved, high-quality optical performance can be achieved, and the molding at a very low temperature can be adopted to minimize the problems such as deformation and stress during mass production of the lens. Can be increased.

Here, it is preferable that the third lens 30 is composed of an ultra low dispersion lens, but it is preferable to use a PG325 model of Sumita Glass Co., Ltd. of Japan, and the fourth lens 40 is Sumita Glass of Japan. It is preferable to use PSK100 model of glass company.

The spherical splicing lens group of the triplet structure by the fifth lens 50 to the seventh lens 70 combines three lenses to remove chromatic aberration for three wavelengths of light, thereby enabling high pixels. In this case, the sixth lens 60 has an apochromat shape capable of simultaneously adjusting chromatic dispersion and spherical aberration of various light sources. The sixth lens 60 is formed very thin and has a soft characteristic, and thus the fifth lens 50 and the seventh lens 70 which are bonded back and forth to have a high intensity. It is preferable that the sixth lens 60 is formed so as to completely protect the sixth lens 60 by forming a material having no thermal deformation and chemical deformation. Through this, it is possible to prevent the parts loss that occurred during the parts production and assembly process.

Here, the spherical joint lens group of the fifth lens 50 to the seventh lens 70 is further improved by spherical aberration, chromatic aberration and axle by combining a triplet structure and a suitable radius of curvature (R). To enable a high pixel.

The diaphragm 80 is disposed between the third lens 30 and the fourth lens 40, which are composed of aspherical lenses, and arranged so as to be as close as possible to the fourth lens 40 side, and the third lens 30 Allows selective convergence of light incident from it.

In addition, the semi-professional camera interchangeable lens optical system of the exemplary embodiment described with reference to FIG. 1 provides a viewing angle by appropriately adjusting respective curvature radii and mutual spacing of the first to seventh lenses 10 to 70 constituting the lens system. The wide-angle optical system can be configured to be suitable for shooting urban buildings or landscape photographs.

On the other hand, as shown in Figure 5, the semi-professional camera interchangeable lens optical system according to another embodiment of the present invention has a lens arrangement for improving the brightness, such as to secure the amount of ambient light, two aspherical lenses 130 ( The lens system includes a lens system formed of seven elements including a spherical contact lens 150, 160, and 170 having a triplet structure and a triplet structure, and an aperture 180.

At this time, the lens system composed of the seven sheets is made of the same material and arrangement as the configuration of the lens system of the embodiment described with reference to FIG. 1, and shall be used mutatis mutandis.

However, in the fourth lens 140, the object side is formed as the concave surface R7, and in the fifth lens 150, the object side is formed as the convex surface R9, and the sixth lens 160 is formed. ) Has a difference in forming an image side of the concave surface R12 and the object side of the seventh lens 170 in contact with the concave surface R13.

In addition, the curvature radius and the distance between each of the first lens 110 to the seventh lens 170 has a different difference, the semi-professional camera interchangeable lens optical system of another embodiment described with reference to FIG. By appropriately adjusting the radius of curvature and the mutual spacing of the first lens 110 to the seventh lens 170, the optical distortion is eliminated and the center brightness and the amount of ambient light are increased so that the brightness is higher than the ultra wide angle so as to be suitable for portrait photography regardless of indoors or outdoors. It is to make a good standard optical system.

Here, the non-explained symbols W1 and W11 serve as a window glass to protect the image pickup device and prevent foreign substances from entering, and the unexplained symbols C1 and C11 convert image light into an electrical signal to input image information. To perform the function.

Furthermore, optical filters F1 (F11) such as a brightness adjusting filter and a color correction filter are arranged between the seventh lens 70, 170 and the window glass W1 and W11 to improve optical performance. The optical filter may not particularly affect the optical length.

In addition, the optical system according to the embodiment of the present invention having the above-described configuration may be suitably multiplied with respect to the first lens 10, 110, and seventh lens 70, 170, and the productive curvature radius R and It was configured to satisfy the mass productivity by configuring to have a distance (d), an embodiment with reference to Figure 1 is configured by selecting the optical length 48mm ± 2mm, aperture ratio F / #: 2.8 and angle of view (clock angle) 114 degrees 2 is configured by selecting an optical field of 117 mm ± 5 mm, an aperture ratio F / #: 1.4, and an angle of view of 57 degrees, and the optical system of one embodiment and the other embodiment has the following conditions 1, It was designed to satisfy the same 2,3.

[Condition 1]

1.3 ≤ B / f ≤ 1.6

Here, the focal length of the entire lens system is f, and the back focal length from the fourteenth surface R14 of the seventh lens 70 and 170 to the focal point B is referred to as f.

[Condition 2]

4.0 ≤ T / f ≤ 6.0

Here, the distance from the first first lens 10, 110 to the last seventh lens 70, 170 of the optical system is referred to as the optical field length T, and the focal length of the entire lens system is f.

[Condition 3]

1.43≤n≤1.80, 30≤v≤95 [Third Lens]

1.43≤n≤1.80, 30≤v≤95 [Fourth Lens]

1.80≤n≤2.01, 18≤v≤30 [Sixth Lens]

Where n is the refractive index of the lens and v is the dispersion of the lens.

Next, Table 1 and Table 2 below show the optical system analysis data in the appropriately magnified state with respect to each embodiment of the present invention having the above-described configuration and conditions, the radius of curvature and the center interval, the refractive index of the lens and the lens The results of analyzing the dispersion rate and the like are shown.

[Table 1] Interchangeable lens analysis data of ultra-wide angle configuration according to an embodiment of the present invention

Lens surface Bending Radius (R) Interval (d) Refractive index (n) Dispersion rate (v) Remarks First side (R1) 81.70 3.600 1.5688 56.04 2nd side (R2) 174.0 0.300 Page 3 (R3) 26.00 1.500 1.4875 70.44 Fourth side (R4) 8.040 1.286 Page 5 (R5) * 20.32 2.200 1.5067 70.50 Aspheric surface Page 6 (R6) * 5.721 7.950 Aspheric surface iris - 0.200 Page 7 (R7) * 12.32 11.30 1.5938 61.38 Aspheric surface Page 8 (R8) * -8.956 0.500 Aspheric surface Page 9 (R9) ∞ 4.300 1.7725 49.62 Page 10 (R10) -10.80 - join Page 11 (R11) -10.80 0.800 1.9229 20.88 join Page 12 (R12) ∞ - join Page 13 (R13) ∞ 4.000 1.6968 55.46 join Page 14 (R14) -19.20 5.870 Optical filter - 1.800 1.5168 64.20 Brightness Filter
or
Color correction filter Window glass - 0.750 1.5168 64.20 Image pickup device - 1.200

Where K = 0.0, AD = 0.124E-02, AE = -0.17765E-04, AF = 0.31245E-06, AG = -0.17098E-08 on the fifth surface R5;

K = 0.0, AD = 0.1883E-02, AE = -0.18126E-04, AF = 0.19302E-05, AG = -0.73702E-08 of the sixth surface R6;

K = 0.0, AD = 0.31593E-04, AE = 0.31142E-05, AF = 0.000000E-00, AG = 0.000000E-00 of the seventh surface R7;

K = 0.0, AD = 0.435E-03, AE = -0.2856E-05, AF = 0.53642E-06, AG = -0.14987E-07, AH = 0.21747E-09, AI = -0.10635E-11.

[Table 2] Interchangeable lens analysis data for brightness according to another embodiment of the present invention

Lens surface Bending Radius (R) Interval (d) Refractive index (n) Dispersion rate (v) Remarks First side (R1) 52.58 9.200 1.5688 56.04 2nd side (R2) 126.8 0.300 Page 3 (R3) 35.80 6.560 1.4875 70.44 Fourth side (R4) 18.18 7.350 Page 5 (R5) * 618.4 6.000 1.5067 70.50 Aspheric surface Page 6 (R6) * 20.46 23.08 Aspheric surface iris - 4.110 Page 7 (R7) * -458.1 12.40 1.5938 61.38 Aspheric surface Page 8 (R8) * -21.40 0.500 Aspheric surface Page 9 (R9) 109.8 10.96 1.7725 49.62 Page 10 (R10) -39.83 - join Page 11 (R11) -39.83 1,000 1.9229 20.88 join Page 12 (R12) 253.8 - join Page 13 (R13) 253.8 6.500 1.6968 55.46 join Page 14 (R14) -43.80 24.93 Optical filter - 1.800 1.5168 64.20 Color correction filter Window glass - 0.750 1.5168 64.20 Image pickup device - 1.200

Wherein K = 0.0, AD = 0.76796E-04, AE = -0.22051E-06, AF = 0.48221E-09, AG = -0.47265E-12 on the fifth surface R5;

K = 0.0, AD = 0.12E-03, AE = 0.34672E-06, AF = -0.33165E-08, AG = 0.23067E-10 of the sixth surface R6;

K = 0.0, AD = -0.16478E-04, AE = -0.11352E-07, AF = 0.000000E-00, AG = 0.000000E-00 of the seventh surface R7;

K = 0.0, AD = 0.47438E-05, AE = 0.31609E-08, AF = 0.000000E-00, and AG = 0.000000E-00 on the eighth surface R8.

Furthermore, the present invention measures the focal length of the entire lens system with an effective diameter (dl: mm) and a spherometer measuring the inner diameter with a PROFELE PROJECTOR, a rear focal length B, and a first first lens of the optical system. (10) (110) is the distance from the last seventh lens (70, 170) T, the angle of view measurement θ by the projection tester, the aperture ratio of the center (CR) and the peripheral (PR) of the resolution measurement (f / dl = F / 1.4 or F / 2.8), it can be seen that the lens shape and lens arrangement of the optical system according to the embodiment of the present invention satisfy all of the conditions 1, 2, and 3 described above.

That is, [condition 1]

1.3 ≤ B / f ≤ 1.6,

[Condition 2]

4.0 ≤ T / f ≤ 6.0,

[Condition 3]

1.43≤n≤1.80, 30≤v≤95 [Third Lens]

1.43≤n≤1.80, 30≤v≤95 [Fourth Lens]

1.80≤n≤2.01 and 18≤v≤30 [sixth lens] are satisfied.

In other words, the semi-professional camera interchangeable lens optical system having an ultra wide angle according to an embodiment of the present invention exhibits an optical performance capable of widening the viewing angle while being compact and high pixel, and the brightness priority standard according to another embodiment of the present invention. Semi-professional camera interchangeable lens optical system for optical system can increase the central brightness and the amount of ambient light without optical distortion.

2 and 6 are analytical graphs showing aberration characteristics of a semi-professional camera interchangeable lens optical system according to an embodiment of the present invention and another embodiment. Astigmatism and Percent Distortion of Tangential Field Curvature (T) and Curved Field Curvature (X) And, Lateral Color Aberration, and Ray Diagram.

As shown in the analysis graphs of FIGS. 2 and 6, each interchangeable lens optical system according to an embodiment of the present invention and the other embodiment shows spherical aberration or aberration in which values of images are shown adjacent to an axis in almost all fields. It is shown that the correction state of top aberration, percent distortion, and chromatic aberration is good.

3 and 7 are graphs illustrating a performance transfer function (MTF) curve of a semi-professional camera interchangeable lens optical system according to an embodiment of the present invention, and the center and spatial frequency are The average of all fields is over 60% as the center is over 80% at 40 l / mm , which shows that a clear image can be obtained based on the general sharpness (40% line).

4 and 8 are diagrams showing simulated screen distortion states for each of the semi-professional camera interchangeable lens optical systems according to one or more embodiments of the present invention. The image is located in this image with respect to the vertical and horizontal center lines, and the image captured in the shape of a roughly rhombus is formed. This shows that there is no distortion of the screen, which is the shape of the object located on the left side and the image on the right image captured by the optical system. Appears in almost the same shape, indicating no distortion.

On the other hand, Figure 9 shows the per-field ambient light data for the semi-professional camera interchangeable lens optical system according to another embodiment of the present invention, showing that the total amount of ambient light is 97% or more, which is a very bright lens.

Accordingly, the present invention can realize an ultra-wide optical system suitable for urban buildings and landscape photographs by constructing a very compact interchangeable lens having an optical length of 48 mm and adjusting ultra-wide angle by appropriately adjusting the curvature radius, spacing and magnification with the same lens array. In addition, the very bright lens with a ratio of F / # 1.4 sometimes makes it possible to realize standard optical system with high brightness suitable for portrait shooting regardless of use anytime, anywhere and indoors, and economical optical engine.

1 is a view showing a lens array for an ultra-wide angle as showing a semi-professional camera interchangeable lens optical system according to an embodiment of the present invention.

2 is a view showing aberration characteristics of the configuration of FIG. 1 in the present invention.

3 is a view showing the MTF characteristics for the configuration of Figure 1 in the present invention.

4 is a view showing the results of screen distortion simulation for the configuration of Figure 1 in the present invention.

FIG. 5 is a view illustrating a lens arrangement for a standard optical system having high brightness, showing a semi-professional camera interchangeable lens optical system according to another embodiment of the present invention; FIG.

6 is a view showing aberration characteristics of the configuration of FIG. 5 in the present invention.

7 is a view showing the MTF characteristics for the configuration of Figure 5 in the present invention.

8 is a view showing the results of screen distortion simulation for the configuration of FIG. 5 in the present invention.

FIG. 9 is a view showing field-specific ambient light data for the configuration of FIG. 5 in the present invention; FIG.

Explanation of symbols on the main parts of the drawings

10,110: first lens 20,120: second lens

30,130: third lens 40,140: fourth lens

50,150: fifth lens 60,160: sixth lens

70, 170: seventh lens 80, 180: aperture

Claims (4)

A first lens having a convex surface on an object side and a concave surface on an image side, and having a positive refractive power as a whole; A second lens having a convex surface on an object side and a concave surface on an image side, and having a negative refractive power as a whole; A third lens having a convex aspherical surface on the object side, a concave aspherical surface on the image side, and having a negative refractive power as a whole; A fourth lens having a concave or convex aspherical surface on the object side and a convex aspherical surface on the image side and having positive refractive power as a whole; A triplet in which convex surfaces are formed on the image side and a fifth lens having a positive refractive power as a whole, a concave surface is formed on the object side, a sixth lens having a negative refractive power as a whole, and a seventh lens having a positive refractive power as a whole. A spherical spherical lens group having a structure; A semi-professional camera interchangeable lens optical system, which is disposed between an aspherical third lens and a fourth lens, and comprises an aperture for selectively converging light incident from the third lens. The method of claim 1, The third and fourth lenses, the aspherical lenses, are semi-professional camera interchangeable lenses optical system, characterized in that the lens shape is structured by GMP molding. The method of claim 1, If f is the focal length of the entire lens system, B is the rear focal length, and T is the distance from the first lens surface to the last lens surface, 1.3 ≤ B / f ≤ 1.6 4.0 ≤ T / f ≤ 6.0 Semi-professional camera interchangeable lens optical system characterized by satisfying the conditions. The method of claim 1, The third and fourth lenses satisfy a refractive index n condition in the range of 1.43 ≦ n ≦ 1.80 and a dispersion rate v in the range of 30 ≦ v ≦ 95; And the sixth lens satisfies a refractive index (n) range of 1.80 ≦ n ≦ 2.01 and a dispersion ratio (v) of 18 ≦ v ≦ 30.

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