KR101825708B1

KR101825708B1 - Telephoto single focal point lens system and photographing apparatus having the same

Info

Publication number: KR101825708B1
Application number: KR1020150147546A
Authority: KR
Inventors: 류재명; 이해진; 이정두
Original assignee: 주식회사 삼양옵틱스
Priority date: 2015-10-22
Filing date: 2015-10-22
Publication date: 2018-02-06
Also published as: KR20170047102A

Abstract

A telephoto short-focal lens system and a photographing apparatus including the same are disclosed.
The telephoto short focal length lens system includes a first lens unit having a positive refractive power, a second lens unit including a single lens having a convex meniscus shape on the object side and performing focusing, And a third lens unit having a positive refractive power, and the first lens unit and the third lens unit may be fixed at the time of focusing.

Description

TECHNICAL FIELD [0001] The present invention relates to a telephoto short focal point lens system and a photographing apparatus including the telephoto single focal point lens system.

An exemplary embodiment of the present invention relates to a telescopic short-focal lens system capable of performing focusing with an inner focus method and high-speed focusing, and a photographing apparatus including the same.

In recent years, there has been a demand for miniaturization of a photographing apparatus, a power saving function, and the like, and there is a demand for miniaturization of a photographing apparatus using a solid-state image pickup device such as a CCD (Charge Coupled Devices) type image sensor or CMOS (Complementary Metal-Oxide Semiconductor) type image sensor . Such photographing apparatuses include a digital still camera, a video camera, and an interchangeable lens camera. Still further, a photographing apparatus using a solid-state image sensing device is suitable for miniaturization, and recently it has been applied to a small information terminal including a cellular phone. Users have a demand for high performance such as high resolution and wide angle. In addition, as the consumer's expertise in cameras continues to increase, there is an increasing demand for short-focus lenses such as wide-angle lenses and telephoto lenses.

However, in the case of a telephoto lens system, the number of lenses is increased, which makes miniaturization difficult. In addition, lens processing is becoming increasingly difficult for aberration correction such as spherical aberration and curvature of field.

When the number of lenses of the focusing lens group is large, the focusing speed of the focusing lens group is slow, and the size of the actuator for driving the focusing lens group is large, thereby inhibiting the miniaturization of the photographing apparatus can do.

An exemplary embodiment employs an inner focus method and provides a telephoto short-focal length lens system capable of focusing at a high speed by reducing the weight of the focusing lens unit.

An exemplary embodiment provides an imaging apparatus including an inner focusing system and a telephoto focusing lens system capable of focusing at a high speed by reducing the weight of the focusing lens group.

The telephoto short focal lens system according to the exemplary embodiment,

A first lens group having a positive refracting power and including a first lens and a second lens from the object side, the combined focal length of the first lens and the second lens having a positive value;

A second lens group including a single lens having a convex meniscus shape on the object side and performing focusing; And

And a third lens group having positive refractive power and including a positive refractive lens on its upper side,

The first lens group and the third lens group may be fixed at the time of focusing.

The first lens group may include an aspherical lens having a convex meniscus shape on the object side on the upper side of the second lens.

And the second lens may have a lens having a positive refractive power.

A concave lens may be provided on the nearest upper side of the aspherical lens of the first lens group.

The first lens group may include a diaphragm.

The diaphragm may be provided at the uppermost position of the first lens group.

The telephoto short-focal length lens system can satisfy the following expression.

1.1 ≤f ₁₂ /f≤1.9

₁₂ where f is the combined focal length of the first lens and the second lens, f is from infinity denotes a telephoto focal length of the single focus lens system.

0.2 ≤b _f / _f ₁₂ ≤1.9

Here, b _f is the distance from the image side of the lens at the uppermost side of the telephoto short focal length lens system to the image surface, and f ₁₂ is the combined focal length of the first lens and the second lens.

The telephoto short focal length lens system can satisfy the following expression.

0.6? V _f / v _r? 0.9

Here, v _f is the average of the Abbe numbers of all the lenses located on the object side of the aspherical lens of the first lens group, v _r is the position of the Abbe number of all lenses belonging to the first lens group, Represents the average of the numbers.

And the second lens group may have a negative refractive power.

The focal length of the telephoto short-focal lens system at an infinite distance may be larger than the rear focal length.

The angle of view of the telescopic short-focal lens system may range from 40 to 60 degrees.

The first lens and the second lens may be a negative lens and a positive lens, respectively.

At least one of the first lens and the second lens may have a plane on an object side or an upper side.

The first lens and the second lens of the first lens group may be bonded. A biconcave lens and two biconvex lenses may be provided on the upper side of the aspherical lens of the first lens group.

The third lens group may include a biconvex lens and a biconcave lens.

An imaging apparatus according to an exemplary embodiment includes a telephoto short-focal lens system and an imaging element that receives light imaged by the telephoto short-focal lens system,

Wherein the telescopic short focal length lens system comprises a first lens group having a positive refractive power and including a first lens and a second lens from the object side, the combined focal length of the first lens and the second lens having a positive value, And a third lens group having positive refractive power, the second lens group including one lens having a convex meniscus shape and performing focusing, and the positive lens having the positive refractive power, The first lens group and the third lens group may be fixed.

The telephoto short-focal length lens system according to the exemplary embodiment can be miniaturized by adopting the inner focus method. In addition, the telephoto short-focal length lens system according to the exemplary embodiment has a small number of focusing lens groups to enable high-speed focusing. Further, the telephoto short-focal length lens system can realize a compact and bright lens. The exemplary embodiment can photograph a high-quality photograph by effectively controlling the aberration generated in implementing a bright lens, and it is possible to provide a compact and inexpensive short-focus lens system. In addition, the telephoto short focal length lens system according to the exemplary embodiment can provide a telephoto type lens system having a standard angle of view.

Fig. 1 shows a telephoto short focal lens system according to the first numerical example.
Fig. 2 is a schematic diagram of the telephoto short focal length lens system shown in Fig.
Fig. 3 shows a telephoto short focal length lens system according to the second numerical embodiment.
Fig. 4 shows an aberration diagram of the telescopic short focal lens system shown in Fig.
Fig. 5 shows a telephoto short focal lens system according to the third numerical example.
FIG. 6 shows an aberration diagram of the telephoto short focal length lens system shown in FIG. 5; FIG.
7 schematically shows a photographing apparatus according to an exemplary embodiment.

Hereinafter, a telescopic short-focal lens system according to an exemplary embodiment and a photographing apparatus including the telephoto short-focal length lens system will be described in detail with reference to the accompanying drawings.

Fig. 1 shows a telephoto short focal length lens system 100-1 according to an exemplary embodiment of the present invention.

The telephoto short focal length lens system 100-1 is arranged in order from the object side O to the image side I and includes a first lens group G1 having a positive refractive power and a second lens group G2 , And a third lens group G3 having a positive refractive power.

Hereinafter, the image side I indicates a direction in which an image plane is formed, and the object side O indicates a direction in which a subject exists. Hereinafter, the object side surface of the lens represents the lens surface on the side of the subject, and the image side surface represents the lens surface on the side of the image surface.

The first lens group G1 may include a first lens L1-1 and a second lens L2-1. The first lens L1-1 may have a negative refractive power, for example, and the second lens L2-1 may have a positive refractive power. The first lens group G1 may include at least one aspherical lens. The first lens group G1 may include, for example, an aspherical third lens L3-1 having a convex meniscus shape on the object side.

The first lens L1-1 may be a meniscus lens convex toward the object side O, for example. At least one of the first lens L1-1 and the second lens L2-1 may include a plane on an object side or an upper side. Meanwhile, the first lens L1-1 and the second lens L2-1 may be bonded. The combined focal length of the first lens L1-1 and the second lens L2-1 may have a positive value. Thereby, the diameter of the lenses disposed after the second lens L2-1 can be reduced.

The astigmatism can be easily corrected by the aspherical surface third lens L3-1 of the first lens group G1. Here, the second lens L2-1 having a positive refractive power is disposed on the object side O closest to the aspherical surface third lens L3-1, and the light incident on the aspherical surface third lens L3-1 It is possible to reduce the aperture of the aspherical surface third lens L3-1. If the diameter of the aspherical surface third lens L3-1 is small, the manufacturing cost can be reduced.

And at least one lens may be provided on the upper side (I) of the aspherical surface third lens L3-1. For example, a fourth lens L4-1 having a negative refractive power, a fifth lens L5-1 having a positive refractive power, and a fourth lens L4-1 having a positive refractive power are arranged on the image side I of the aspherical surface third lens L3-1. A sixth lens L6-1 may be provided. For example, the fourth lens L4-1 may be a biconcave lens, the fifth lens L5-1 may be a biconvex lens, and the sixth lens L6-1 may be a biconvex lens. For example, the fourth lens L4-1 and the fifth lens L5-1 may be joined.

The first lens group G1 may include a diaphragm ST. A diaphragm may be provided between the third lens L3-1 of the first lens group and the object side of the second lens group G2. For example, a diaphragm ST may be provided on the uppermost portion I of the first lens group G1. However, it is not limited thereto. By providing the diaphragm in the first lens group, it is possible to correct the distortion well.

The second lens group G2 includes a single lens, and can perform focusing of the telephoto lens system. When focusing, the first lens group G1 and the third lens group G3 are fixed, and focusing can be performed with the inner focus type.

And the second lens group G2 may have a negative refractive power. The second lens group G2 may include, for example, one seventh lens L7-1 of meniscus type convex on the object side (O). Since the second lens group G2 is made up of a small number of lenses, focusing can be performed at a high speed, and the volume of the actuator for driving the second lens group G2 can be reduced, contributing to miniaturization of the telephoto lens system . The seventh lens L7-1 may be an aspherical lens.

The third lens group G3 may include, for example, an eighth lens L8-1 having a positive refractive power and a ninth lens L9-1 having a negative refractive power. The eighth lens L8-1 may be, for example, a biconvex lens, and the ninth lens L9-1 may be a bi-concave lens. For example, the eighth lens L8-1 may be an aspherical lens.

The telephoto short-focal lens system according to the exemplary embodiment may be employed in a photographing apparatus that is mirrorless. In this case, in a photographing apparatus without a mirror, there is a flange-back more than a lens system for SLR (Single Lens Reflex), so that a ninth lens L9-1 of both concave field flattener. The lens on the uppermost side of the large lens system is composed of a double concave lens and acts as a field flattener, so that the curvature of the image can be easily corrected.

The telephoto short-focal lens system according to the exemplary embodiment can arrange the lenses in a double-gauss type so as to realize stable optical performance. For example, as shown in FIG. 1, the first lens group G1 may have a double-gauss shape. For example, the double Gauss type lens may include first, second, and third lenses L1-1, L2-1, L3-1, and fourth, fifth, and sixth lenses L4-1, L5- 1) < / RTI > (L6-1) are arranged symmetrically. Further, the upper surface of the third lens L3-1 is concave, and the object-side surface of the fourth lens L4-1 can be concave. The generation of aberration in the first lens group G1 can be reduced by configuring the first lens group G1 as a double Gauss type. For example, the diaphragm ST is provided between the first lens group G1 and the second lens group G2 for performing focusing, so that the distortion aberration can be effectively corrected.

Particularly, in a moving picture shooting, a contrast auto-focus method of focusing a group of focusing lenses while moving a small distance is required. In this case, it is advantageous to use a stepping motor as a driving source . However, this stepping motor has a low torque of the driving source and is very disadvantageous when moving a heavy lens group. Therefore, the weight of the focusing lens group needs to be minimized. Therefore, the second lens group G2 for performing focusing may be composed of one lens.

In the exemplary embodiment, a double-gauss type lens is modified so that high-speed autofocusing can be achieved while achieving sufficient performance with only one lens.

On the other hand, in a large-diameter lens optical system that performs focusing only with one lens, various aberrations occur. Therefore, an aspherical lens may be employed to correct the aberration. At this time, the size of the aspherical lens tends to increase due to the physical limitation of the large lens optical system. As a result, the manufacturing cost of the aspherical lens is increased, and the product weight may increase. To solve this problem, it is required to appropriately distribute the refractive power of each lens.

The telephoto short-focal lens system according to the exemplary embodiment may have a standard angle of view with an angle of view ranging from 40 to 60 degrees. In order to realize stable optical performance, a telephoto type lens system having a double-gauss type lens system and having a focal length greater than a back focal length (BFL) . Thereby, the aberration can be effectively corrected in the first lens unit. The back focal length represents the distance from the upper surface of the lens at the uppermost side to the upper surface.

The exemplary embodiment has a standard focusing angle having a range of 40 to 60 degrees in the angle of view, a small focusing lens having a small F number and light weight to achieve high-speed autofocusing, and low manufacturing cost. Further, in the exemplary embodiment, a double gauss type having excellent optical performance and a telephoto type applicable in a standard angle of view range can be employed.

Also, the first lens group G1 may include at least one aspherical lens to correct the astigmatism and the surface curvature. It is preferable that the aspherical lens employs a meniscus shape so as to be advantageous for aspherical surface molding. The lens positioned immediately before the object side of the aspheric lens may have a positive refractive power so that the aspherical lens does not become large.

The telephoto short focal length lens system according to the exemplary embodiment can satisfy the following expression.

1.1 ≤f ₁₂ /f≤1.9 <formula 1>

Where f ₁₂ is the total focal length of all the lenses located on the object side of the aspherical third lens of the first lens group, for example, the first lens and the second lens, f is the focal point of the telephoto short- Represents the distance. The focal length of the lens located on the object side of the aspherical lens of the first lens group must be short to reduce the aperture of the aspherical lens. However, if the focal length of the lens positioned immediately in front of the aspheric lens is too short, the assembly sensitivity can be increased. (f ₁₂ / f) satisfies the formula (1), the assembly sensitivity of the lens can be lowered while reducing the size of the aspherical lens.

0.2 ≤b _f / _f ₁₂ ≤0.35 <Equation 2>

Here, b _f is the distance from the image side to the image plane of the lens at the uppermost side of the telephoto short focal length lens system, and f ₁₂ is all the lenses located on the object side of the aspherical third lens of the first lens group, Represents the combined focal length of the first lens and the second lens.

In the exemplary embodiment, the lens on the uppermost side may act as a field flattener. For example, in the present invention, a concave field flattener can be used. Such a field flattener is advantageous for correction of surface curvature as it is located closer to the image plane. (b _f / f ₁₂ ) satisfies the formula (2), the distance from the field flattener to the image plane can be shortened, and the effect of correcting the field curvature through the field flattener can be enhanced. (b _f / f ₁₂ ) deviates from the lower limit value of the equation (2), the ninth lens which is positioned at the uppermost position and operates as a field flattener is disposed too close to the upper surface, so that it may be difficult to use in a lens interchangeable camera product.

0.6 ≤v _f / v _r ≤0.9 <formula 3>

Where v _f is the average of the Abbe numbers of all the lenses located on the object side of the third aspheric lens of the first lens group and v _r is the position of the third aspherical lens of the first lens group, Represents the average Abbe number of all lenses.

The total aberration of the telescopic short focal length lens system can be satisfactorily corrected by minimizing the aberration of each lens group and chromatic aberration can be reduced by selecting an appropriate material for each lens group. The first lens close to the object side may be formed of a high refractive index material for the purpose of image surface curvature correction. Abbe number of lenses of high refractive index material may not be large. In order to correct the chromatic aberration of the first lens group, a lens having a large Abbe number may be used for lenses near the image side of the first lens group. The Abbe number of the lenses located on the object side of the aspherical surface third lens with respect to the aspheric surface lens in the first lens group is smaller than the Abbe number of the lenses located above the aspherical surface third lens. (v _f / v _r ) satisfies the formula (3), the chromatic aberration of the first lens unit can be reduced to realize good optical performance.

Next, definition of an aspherical surface used in a telephoto short focal length lens system according to an exemplary embodiment is as follows.

The aspheric surface shape can be expressed by the following equation with the optical axis direction as the z-axis and the direction perpendicular to the optical axis direction as the y-axis, with the traveling direction of the light beam as a normal. Where Z is the distance from the apex of the lens in the direction of the optical axis, Y is the distance in the direction perpendicular to the optical axis, K is the conic constant, A, B, C, D, E, F. (1 / R) of the radius of curvature at the apex of the lens, respectively.

In the present invention, the telephoto short-focal length lens system can be implemented through numerical embodiments according to various designs as follows. Hereinafter, the total effective focal length f is expressed in mm units, the half angle of view (HFOV) is expressed in degrees, * denotes an aspherical surface, and F denotes an F number.

At least one optical filter (OF) may be provided on the uppermost side (I) in each of the drawings. The optical filter OF may include at least one of, for example, a low pass filter, an IR-cut filter, and a cover glass. However, it is also possible to construct a lens system without an optical filter. The image of the object can be incident on the image plane (IMG) through the lenses. The upper surface IMG may be, for example, an imaging element surface or an imaging element surface. The imaging device may comprise, for example, a CCD or CMOS.

In each numerical embodiment, the lens surface numbers (S1, S2, S3 ... Sn; n is a natural number) are sequentially aligned from the object side (O) to the image side (I). In the drawing, the lens surface number is written only for the object side surface of the lens closest to the object side of each lens group and the upper side surface of the lens at the uppermost side of the lens group for convenience.

&Lt; First Numerical Embodiment >

Fig. 1 shows a telephoto short-focal length lens system 100-1 according to the first numerical example, and the following shows design data of the first numerical example.

f = 51.038 mm, F / 1.44, HFOV = 23.50 DEG

Lens face Radius of curvature Thickness or spacing between lenses Refractive index Abe number Object inf. D0 S1 206.778 2 1.64769 33.84 S2 37.927 0.2 S3 36.117 10.5 2.00069 25.46 S4 inf. 0.1 S5 * 59.625 3 1.68400 31.30 S6 * 25.094 10.781 S7 -39.174 2.0 1.72825 28.32 S8 29.583 12.45 1.69680 55.46 S9 -48.431 0.1 S10 50,000 7.4 1.88300 40.80 S11 -131.895 0.6 S12 (ST) inf. D1 S13 * 38,000 2.5 1.68400 31.30 S14 * 18.133 D2 S15 * 65.226 7.5 1.68970 52.70 S16 * -36.632 7.539 S17 -123.030 1.5 1.56883 56.04 S18 50,000 D3 S19 inf. 2.5 1.51680 64.20 S20 inf. D4 IMG inf. D5

The following shows the variable spacing between infinite distance and near distance in the first numerical example.

No. Object (DO) D1 D2 D3 D4 D5 Infinite distance
m = 0 inf. 2.00178 18.32783 19.5 1.02158 0.00192 Nearest street
m = -0.15 337.165 8.70009 11.62951 19.5 1.15459 -0.08455

In Table 2, m represents the magnification.

The following shows the aspherical surface coefficients in the first numerical example.

S5 S6 S13 S14 S15 S16 K -1.0 -1.0 -1.0 -1.0 -1.0 -1.0 A -3.638351e-6 8.780333e-6 -5.688391e-5 -5.606567e-5 -5.079978e-7 2.189271e-6 B -3.191320e-9 6.142542e-9 2.633654e-7 3.230809e-7 -1.413043e-9 -5.682527e-9 C -4.204817e-12 1.134598e-11 -9.029458e-10 -1.207755e-9 1.094572e-11 1.737121e-11 D 6.048832e-15 -1.127929e-14 1.808817e-12 2.733286e-12 -1.561120e-14 -2.077513e-14 E -1.590491e-15 -2.838987e-15

Fig. 2 shows a ray fan for the first numerical example. Fig. Here, the dotted line represents the C-line, the solid line represents the d-line, and the one dotted line represents the transverse aberration for the F-line. The C-line shows a wavelength of 656.2700 nm, the d-line shows 587.5600 nm, and the F-line shows a wavelength of 486.1300 nm.

The transverse aberration shows the aberrations for the Zango (Tangential) and Sagittal (Sagittal) surfaces.

&Lt; Second Numerical Embodiment >

FIG. 3 shows a telephoto short-focal length lens system 100-2 according to the second numerical example, and the following shows design data of the second numerical example.

f = 51.026 mm, F / 1.44, HFOV = 23.63 DEG

Lens face Radius of curvature Thickness or spacing between lenses Refractive index Abe number Object inf. D0 One 247.203 2.0 1.48749 70.44 2 34.770 11.5 1.90043 37.37 3 inf. 0.1 4* 50,000 3.0 1.68475 31.21 5 22.910 11.217 6 -37.517 2.0 1.67270 32.17 7 30.679 12.0 1.69680 55.46 8 -49.082 0.1 9 49.082 6.8 1.88300 40.80 10 -187.495 0.6 11 (Stop) inf. D1 12 * 38.548 2.5 1.68475 31.21 13 * 19.235 D2 14 * 71.010 7.5 1.68997 53.00 15 * -36.463 6.363 16 -101.185 1.5 1.60342 38.01 17 50,000 D3 18 inf. 2.5 1.51680 64.20 19 inf. D4 Image inf. D5

The telescopic short focal length lens system 100-2 according to the second numerical example is configured such that the first lens group G1 includes the first lens L1-2, the second lens L2-2, the third lens L3- 2, a fourth lens L4-2, and a fifth lens L5-2. The second lens L2-2 may be an aspherical lens.

And the second lens group G2 may include a sixth lens L6-2. The third lens group G3 may include a seventh lens L7-2 and an eighth lens L8-2.

The following shows the variable spacing between infinite distance and near distance in the second numerical example.

No. Object (D0) D1 D2 D3 D4 D5 m = 0 inf. 2.015800 17.323642 19.5 1.00000 0 m = -1 / 8 405.82465 7.997714 11.341729 19.5 1.00000 0

The following is the aspherical surface coefficient in the second numerical example.

S3 S4 S11 S12 S13 S14 K -1.0 -1.0 -1.0 -1.0 -1.0 -1.0 A -9.023876e-6 -2.830766e-6 -5.627926e-5 -5.552434e-5 -6.029809e-7 3.010915e-6 B 1.207160e-8 2.304456e-8 2.749052e-7 3.348469e-7 -3.430307e-9 -1.042985e-8 C -2.551480e-11 -5.920545e-12 -1.006104e-9 -1.320955e-9 3.177667e-11 5.513514e-11 D 1.780914e-14 3.755034e-15 2.149463e-12 3.119317e-12 -1.031973e-13 -1.593297e-13 E -2.014094e-15 -3.351480e-15 1.358607e-16 1.950152e-16

Fig. 4 shows a ray fan for the second numerical embodiment. Fig. Here, the dotted line represents the C-line, the solid line represents the d-line, and the one dotted line represents the transverse aberration for the F-line. The C-line shows a wavelength of 656.2700 nm, the d-line shows 587.5600 nm, and the F-line shows a wavelength of 486.1300 nm.

&Lt; Third Numerical Embodiment >

Fig. 5 shows a telephoto short-focal lens system according to the third numerical example, and the following shows design data of the third numerical example.

f = 51.035 mm, F / 1.44, HFOV = 23.54

Lens face Radius of curvature Thickness or spacing between lenses Refractive index Abe number Object inf. D0 S1 603.360 2.5 1.64769 33.84 S2 34.014 11.5 2.00069 25.46 S3 inf. 0.1 S4 * 98.891 3.450 1.68475 31.21 S5 * 33.248 9.887 S6 -42.196 2.2 1.72825 28.32 S7 29.351 12.5 1.69680 55.46 S8 -55.038 0.1 S9 55.038 7.58 1.88300 40.80 S10 -101.185 0.7 S11 (ST) inf. D1 S12 * 38.548 2.5 1.68475 31.21 S13 * 19.235 D2 S14 * 71.010 7.5 1.68997 53.00 S15 * -36.463 7.436 S16 -101.185 1.5 1.54072 47.20 S17 50,000 D3 S18 inf. 2.5 1.51680 64.20 S19 inf. D4 IMG inf. D5

The telescopic short focal length lens system 100-3 according to the third numerical example is configured such that the first lens group G1 includes the first lens L1-3, the second lens L2-3, the third lens L3- 3, a fourth lens L4-3, a fifth lens L5-3, and a sixth lens L6-3. The third lens L3-3 may be an aspherical lens.

And the second lens group G2 may include a seventh lens L7-2. The third lens group G3 may include an eighth lens L8-2 and a ninth lens L9-2.

The following shows the variable spacing between infinite distance and near distance in the third numerical example.

No. Object (D0) D1 D2 D3 D4 D5 Infinite distance
m = 0 inf. 2.00305 19.48734 20.556 1.01829 0.00307 Nearest street
m = -1 / 8 405.341 7.93772 13.55267 20.556 1.14082 -0.07880

The following is an aspherical surface coefficient in the third numerical example.

S4 S5 S12 S13 S14 S15 K -1.0 -1.0 -1.0 -1.0 -1.0 -1.0 A 1.236707e-5 2.586066e-5 -4.530373e-5 -4.436886e-5 -1.150420e-6 2.074281e-6 B -3.491325e-8 -2.571488e-8 1.815732e-7 2.350419e-7 7.938806e-9 -3.966589e-9 C 3.090885e-11 4.344931e-11 -5.479711e-10 -8.216668e-10 -4.145196e-11 1.528777e-11 D -1.279195e-14 -4.318453e-14 9.848773e-13 1.840289e-12 1.069932e-13 -5.493679e-14 E -8.106077e-16 -1.988827e-15 -7.480417e-17 1.090201e-16

As described above, the telescopic short focal length lens system according to the exemplary embodiment can realize a telephoto type lens system having an angle of view in the range of about 40 to 60 degrees and a focal length that is longer than the focal length. In addition, the telescopic short-focal length lens system is light in weight because the F number is small and the focusing lens group can be lightened to realize high-speed auto focusing (AF), and the manufacturing cost can be reduced.

Next, it is shown that the first to third numerical embodiments described above satisfy the above-mentioned formulas 1 to 3, respectively.

Example 1 Example 2 Example 3 f 51.0384 51.0263 51.0350 f ₁₂ 72.4715 72.3748 87.4526 b _f 23.0235 22.1482 24.0774 f _last -62.3038 -58.0055 -61.6730 v _f 29.6490 35.2201 29.6490 v _r 41.5279 42.8112 41.5279 Equation (1) 1.42 1.42 1.71 Equation (2) 0.31 0.31 -0.39 Equation (3) 0.71 1.26 0.71

FIG. 7 shows a photographing apparatus having a telephoto short-focal length lens system 100 according to an exemplary embodiment. The telephoto short focal length lens system 100 is substantially the same as that described with reference to Figs. 1, 3, and 5. The photographing apparatus includes an imaging element 112 that receives the light imaged by the telephoto short-focal length lens system 100. The photographing apparatus may include a recording means 113 recording information corresponding to the photoelectrically-converted object from the imaging element 112, and a finder 114 for observing a subject image. In addition, a display unit 115 for displaying a subject image may be provided. Here, an example in which the viewfinder 114 and the display unit 115 are separately provided is shown, but only the display unit can be provided without a viewfinder. Further, the photographing apparatus can be applied not only to the SLR but also to the mirrorless camera.

The photographing apparatus shown in FIG. 7 is merely an example, and the present invention is not limited thereto, but can be applied to various optical apparatuses other than a camera. Thus, by applying the telephoto short-focal lens system according to the exemplary embodiment to a photographing apparatus such as a digital camera, it is possible to realize an optical apparatus capable of fast auto focusing. Further, the telephoto short-focal lens system according to the exemplary embodiment can be applied to a mirrorless type optical apparatus.

The telephoto short-focal length lens system according to the exemplary embodiment adopts the inner focus method and can realize miniaturization. In this embodiment, by using the inner focusing method in which some lenses in the lens system are moved by focusing rather than the front focusing method in which the lens closest to the object side of the telescopic short focal lens system performs focusing, You can carry it.

The above-described embodiments are merely illustrative, and various modifications and equivalent other embodiments are possible without departing from the scope of the present invention. Therefore, the scope of the true technical protection according to the embodiment of the present invention should be determined by the technical idea of the invention described in the following claims.

G1: first lens group, G2: second lens group
G3: third lens group, OF: optical filter
IMG: Top

Claims

A first lens group having a positive refracting power and including a first lens and a second lens from the object side, the combined focal length of the first lens and the second lens having a positive value;
A second lens group including a single lens having a convex meniscus shape on the object side and performing focusing; And
And a third lens group having positive refractive power and including a positive refractive lens on its upper side,
Wherein the first lens group includes an aspherical lens having a convex meniscus shape on the object side on the upper side of the second lens, and the first lens group and the third lens group are fixed with a telephoto short focal lens system .

delete

The method according to claim 1,
Wherein the second lens is provided with a lens having a positive refractive power.

The method according to claim 1,
And a positive concave lens is provided on the nearest upper side of the aspherical lens of the first lens group.

A first lens group having a positive refracting power and including a first lens and a second lens from the object side, the combined focal length of the first lens and the second lens having a positive value;
A second lens group including a single lens having a convex meniscus shape on the object side and performing focusing; And
And a third lens group having positive refractive power and including a positive refractive lens on its upper side,
The first lens group and the third lens group are fixed at the time of focusing,
Wherein the first lens group includes a diaphragm.

6. The method of claim 5,
And the diaphragm is provided on the uppermost side of the first lens group.

A first lens group having a positive refracting power and including a first lens and a second lens from the object side, the combined focal length of the first lens and the second lens having a positive value;
A second lens group including a single lens having a convex meniscus shape on the object side and performing focusing; And
And a third lens group having positive refractive power and including a positive refractive lens on its upper side,
The first lens group and the third lens group are fixed at the time of focusing,
Telephoto short focal length lens system satisfying the following equation.
<Expression>
1.1 ≤f ₁₂ /f≤1.9
₁₂ where f is the combined focal length of the first lens and the second lens, f is from infinity denotes a telephoto focal length of the single focus lens system.

8. The method according to any one of claims 1 to 7,
Telephoto short focal length lens system satisfying the following equation.
<Expression>
0.2 ≤b _f / _f12 ≤1.9
Here, b _f is the distance from the image side of the lens at the uppermost side of the telephoto short focal length lens system to the image surface, and f ₁₂ is the combined focal length of the first lens and the second lens.

The method according to claim 1,
Telephoto short focal length lens system satisfying the following equation.
<Expression>
0.6? V _f / v _r? 0.9
Here, v _f is the average of the Abbe numbers of all the lenses located on the object side of the aspherical lens of the first lens group, v _r is the position of the Abbe number of all lenses belonging to the first lens group, Represents the average of the numbers.

8. The method according to any one of claims 1 to 7,
And the second lens group has a negative refracting power.

8. The method according to any one of claims 1 to 7,
Wherein the telescopic short focal length lens system has a focal length greater than an after focal length at an infinite distance.

8. The method according to any one of claims 1 to 7,
Wherein the telescopic short focal length lens system has an angle of view of 40-60 degrees.

The method according to claim 1,
Wherein the first lens and the second lens are a negative lens and a positive lens, respectively.

The method according to claim 1,
Wherein at least one of the first lens and the second lens has a plane on an object side or an upper side.

The method according to claim 13 or 14,
Wherein the first lens and the second lens of the first lens group are bonded to each other.

The method according to claim 13 or 14,
A telephoto short focal length lens system in which two positive lens elements and two positive lens elements are provided on the aspherical surface of the first lens group;

8. The method according to any one of claims 1 to 7,
And the third lens group includes a biconvex lens and a biconcave lens.

A telephoto short-focal lens system according to any one of claims 1 and 3 to 7; And
And an imaging element for receiving light formed by said telephoto short-focal lens system.