WO2018078888A1 - Zoom lens, imaging device, moving body, and system - Google Patents

Abstract

The zoom lens according to the present invention is provided with, in order from an object side, a first lens group having negative refractive power, a second lens group having positive refractive power, a third lens group having negative refractive power, a fourth lens group, and a fifth lens group having positive refractive power, and during power variation from a wide-angle end to a telephoto end, the spacing from the first lens group to an imaging element being constant, the spacing between the first lens group and the second lens group decreasing, the spacing between the second lens group and the third lens group increasing, the spacing between the third lens group and the fourth lens group decreasing, and the fifth lens group moving toward the imaging element in a convex arc trajectory.

Description

Zoom lens, imaging device, moving object, and system

The present invention relates to a zoom lens, an imaging device, a moving body, and a system.

A zoom lens having a negative, positive, negative and positive five-group configuration is known (for example, Patent Documents 1 and 2). In the zoom lens, the first lens group located closest to the object moves during zooming.
Patent Document 1 Japanese Patent Laid-Open No. 2015-114625 Patent Document 2 Japanese Patent Laid-Open No. 2016-118658

Challenges to be solved

In a zoom lens that moves the first lens unit at the time of zooming, due to the influence of manufacturing errors, mounting errors, driving errors, etc. of the first lens unit, focus shift and image shift are likely to occur at zooming.

General disclosure

A zoom lens according to an aspect of the present invention includes, in order from the object side, a first lens group having negative refractive power, a second lens group having positive refractive power, a third lens group having negative refractive power, 4 lens groups and a fifth lens group having positive refractive power. At the time of zooming from the wide-angle end to the telephoto end, the distance from the first lens group to the image sensor is constant, the distance between the first lens group and the second lens group decreases, and the second lens group and the third lens group The distance increases, the distance between the third lens group and the fourth lens group decreases, and the fifth lens group moves along a locus of a convex arc toward the image sensor.

Conditional expression −1.8 <f1 / fw <−1.1 where f1 is the focal length of the first lens unit and fw is the focal length of the entire system at the wide angle end.
You may be satisfied.

The first lens group includes four lenses having negative, negative, negative, and positive refractive powers in order from the object side, and the Abbe of the three lenses having the negative refractive power included in the first lens group. If the numbers are v1, v2, and v3, respectively, the conditional expression v1> 60
v2> 60
v3> 60
You may be satisfied.

The first lens group may include four lenses having negative, negative, negative, and positive refractive power in order from the object side. Of the three lenses having negative refractive power included in the first lens group, at least one of the two lenses on the object side may be an aspherical lens.

The second lens group includes at least three convex lenses, and all the convex lenses included in the second lens group satisfy the conditional expression v> 50.
You may be satisfied. Conditional expression 1.0 <f2 / fw <1.8, where f2 is the focal length of the second lens group.
You may be satisfied.

At least one of the fourth lens group and the fifth lens group may be composed of a single lens or a cemented lens. At least one of the fourth lens group and the fifth lens group may have a focus function.

At least one of the fourth lens group and the fifth lens group may be composed of a single lens or a cemented lens. The at least one of the fourth lens group and the fifth lens group may have an anti-vibration function.

The second lens group may include at least one single lens that is an aspheric lens having a positive refractive power.

The first lens group includes four lenses having negative, negative, negative, and positive refractive power in order from the object side, and the refractive index of the lens having the positive refractive power of the first lens group is n4, When the Abbe number is v4, the conditional expression n4> 1.9
v4 <35
You may be satisfied.

The fourth lens group may have a negative refractive power.

The fourth lens group may have a positive refractive power.

An imaging apparatus according to one embodiment of the present invention includes the zoom lens and an imaging element.

The moving body according to one embodiment of the present invention moves with the zoom lens described above.

The moving body may be an unmanned aerial vehicle.

A system according to an aspect of the present invention includes the above zoom lens, a support mechanism that supports the zoom lens so as to be displaceable, and a handle that is attached to the support mechanism.

According to the above zoom lens, it is difficult for focus shift and image shift to occur during zooming.

The above summary of the invention does not enumerate all the features of the present invention. A sub-combination of these feature groups can also be an invention.

1 schematically illustrates an example of a mobile system 10 that includes an unmanned aerial vehicle (UAV) 100 and a controller 50. An example of the functional block of UAV100 is shown. 1 shows a lens configuration of a lens system 300 in a first example. The movement locus of each lens unit at the time of zooming from the wide angle end to the telephoto end is schematically shown. It shows spherical aberration, astigmatism and distortion at the wide angle end. Spherical aberration, astigmatism, and distortion are shown at an intermediate angle of view. Spherical aberration, astigmatism and distortion at the telephoto end are shown. The spherical aberration diagram of the lens system 300 for three wavelengths of light is shown. The lens structure of the lens system 900 in 2nd Example is shown. The movement locus of each lens unit at the time of zooming from the wide angle end to the telephoto end is schematically shown. It shows spherical aberration, astigmatism and distortion at the wide angle end. Spherical aberration, astigmatism, and distortion are shown at an intermediate angle of view. Spherical aberration, astigmatism and distortion at the telephoto end are shown. The spherical aberration figure about the light of 3 wavelengths of the lens system 900 is shown. 2 is an external perspective view showing an example of a stabilizer 800. FIG.

Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

The claims, the description, the drawings, and the abstract include matters that are subject to copyright protection. The copyright owner will not object to any number of copies of these documents as they appear in the JPO file or record. However, in other cases, all copyrights are reserved.

FIG. 1 schematically shows an example of a mobile system 10 including an unmanned aerial vehicle (UAV) 100 and a controller 50. The UAV 100 includes a UAV main body 101, a gimbal 110, a plurality of imaging devices 230, and an imaging device 220. The imaging device 220 includes a lens device 160 and an imaging unit 140. The UAV 100 is an example of a moving body that includes an imaging device and moves. The moving body is a concept including, in addition to UAV, other aircraft that moves in the air, vehicles that move on the ground, ships that move on the water, and the like.

The UAV main body 101 includes a plurality of rotor blades. The UAV main body 101 flies the UAV 100 by controlling the rotation of a plurality of rotor blades. For example, the UAV main body 101 causes the UAV 100 to fly using four rotary wings. The number of rotor blades is not limited to four. The UAV 100 may be a fixed wing aircraft that does not have rotating blades.

The imaging device 230 is an imaging camera that images a subject included in a desired imaging range. The plurality of imaging devices 230 are sensing cameras that image the surroundings of the UAV 100 in order to control the flight of the UAV 100. The imaging device 230 may be fixed to the UAV main body 101.

Two imaging devices 230 may be provided on the front surface which is the nose of the UAV 100. Two other imaging devices 230 may be provided on the bottom surface of the UAV 100. The two imaging devices 230 on the front side may be paired and function as a so-called stereo camera. The two imaging devices 230 on the bottom side may also be paired and function as a stereo camera. Three-dimensional spatial data around the UAV 100 may be generated based on images captured by the plurality of imaging devices 230. The distance to the subject imaged by the imaging device 230 can be specified by a stereo camera using a plurality of imaging devices 230.

The number of imaging devices 230 provided in the UAV 100 is not limited to four. The UAV 100 only needs to include at least one imaging device 230. The UAV 100 may include at least one imaging device 230 on each of the nose, the tail, the side surface, the bottom surface, and the ceiling surface of the UAV 100. The imaging device 230 may have a single focus lens or a fisheye lens. In the description related to the UAV 100, the plurality of imaging devices 230 may be collectively referred to simply as the imaging device 230.

The controller 50 includes a display unit 54 and an operation unit 52. The operation unit 52 receives an input operation for controlling the attitude of the UAV 100 from the user. The controller 50 transmits a signal for controlling the UAV 100 based on a user operation received by the operation unit 52. For example, the operation unit 52 receives an operation for changing the magnification of the lens device 160. The controller 50 transmits a signal instructing the change of the magnification to the UAV 100.

The controller 50 receives an image captured by at least one of the imaging device 230 and the imaging device 220. The display unit 54 displays an image received by the controller 50. The display unit 54 may be a touch panel. The controller 50 may accept an input operation from the user through the display unit 54. The display unit 54 may accept a user operation or the like in which the user specifies the position of the subject to be imaged by the imaging device 220.

The imaging unit 140 generates and records image data of an optical image formed by the lens device 160. The lens device 160 may be provided integrally with the imaging unit 140. The lens device 160 may be a so-called interchangeable lens. The lens device 160 may be provided so as to be detachable from the imaging unit 140.

The gimbal 110 has a support mechanism that movably supports the imaging device 220. The imaging device 220 is attached to the UAV main body 101 via the gimbal 110. The gimbal 110 supports the imaging device 220 so as to be rotatable about the pitch axis. The gimbal 110 supports the imaging device 220 so as to be rotatable around a roll axis. The gimbal 110 supports the imaging device 220 so as to be rotatable about the yaw axis. The gimbal 110 may support the imaging device 220 rotatably around at least one of a pitch axis, a roll axis, and a yaw axis. The gimbal 110 may support the imaging device 220 rotatably about each of the pitch axis, the roll axis, and the yaw axis. The gimbal 110 may hold the imaging unit 140. The gimbal 110 may hold the lens device 160. The gimbal 110 may change the imaging direction of the imaging device 220 by rotating the imaging unit 140 and the lens device 160 about at least one of the yaw axis, the pitch axis, and the roll axis.

FIG. 2 shows an example of functional blocks of the UAV100. The UAV 100 includes an interface 102, a control unit 104, a memory 106, a gimbal 110, an imaging unit 140, and a lens device 160.

The interface 102 communicates with the controller 50. The interface 102 receives various commands from the controller 50. The control unit 104 controls the flight of the UAV 100 according to the command received from the controller 50. The control unit 104 controls the gimbal 110, the imaging unit 140, and the lens device 160. The control unit 104 may be configured by a microprocessor such as a CPU or MPU, a microcontroller such as an MCU, or the like. The memory 106 stores a program necessary for the control unit 104 to control the gimbal 110, the imaging unit 140, and the lens device 160.

The memory 106 may be a computer-readable recording medium. The memory 106 may include at least one of flash memory such as SRAM, DRAM, EPROM, EEPROM, and USB memory. The memory 106 may be provided in the housing of the UAV 100. It may be provided so as to be removable from the housing of the UAV 100.

The gimbal 110 includes a control unit 112, a driver 114, a driver 116, a driver 118, a drive unit 124, a drive unit 126, a drive unit 128, and a support mechanism 130. The drive unit 124, the drive unit 126, and the drive unit 128 may be motors.

The support mechanism 130 supports the imaging device 220. The support mechanism 130 movably supports the imaging direction of the imaging device 220. The support mechanism 130 supports the imaging unit 140 and the lens device 160 so as to be rotatable about the yaw axis, the pitch axis, and the roll axis. The support mechanism 130 includes a rotation mechanism 134, a rotation mechanism 136, and a rotation mechanism 138. The rotation mechanism 134 rotates the imaging unit 140 and the lens device 160 around the yaw axis using the drive unit 124. The rotation mechanism 136 rotates the imaging unit 140 and the lens device 160 around the pitch axis using the driving unit 126. The rotation mechanism 138 uses the drive unit 128 to rotate the imaging unit 140 and the lens device 160 around the roll axis.

The control unit 112 outputs an operation command indicating each rotation angle to the driver 114, the driver 116, and the driver 118 according to the operation command of the gimbal 110 from the control unit 104. The driver 114, the driver 116, and the driver 118 drive the drive unit 124, the drive unit 126, and the drive unit 128 in accordance with an operation command that indicates a rotation angle. The rotation mechanism 134, the rotation mechanism 136, and the rotation mechanism 138 are driven and rotated by the drive unit 124, the drive unit 126, and the drive unit 128, respectively, and change the postures of the imaging unit 140 and the lens device 160.

The imaging unit 140 captures an image with light that has passed through the lens system 300. The imaging unit 140 includes a control unit 222, an imaging element 221, and a memory 223. The control unit 222 may be configured by a microprocessor such as a CPU or MPU, a microcontroller such as an MCU, or the like. The control unit 222 controls the imaging unit 140 and the lens device 160 in accordance with an operation command for the imaging unit 140 and the lens device 160 from the control unit 104. Based on the signal received from the controller 50, the controller 222 outputs to the lens device 160 a control command that instructs the lens device 160 to change the magnification.

The memory 223 may be a computer-readable recording medium, and may include at least one of flash memory such as SRAM, DRAM, EPROM, EEPROM, and USB memory. The memory 223 may be provided inside the housing of the imaging unit 140. It may be provided so as to be removable from the housing of the imaging unit 140.

The imaging element 221 generates image data of an optical image that is held inside the housing of the imaging unit 140 and is formed via the lens device 160, and outputs the image data to the control unit 222. The control unit 222 stores the image data output from the image sensor 221 in the memory 223. The control unit 222 may output the image data to the memory 106 via the control unit 104 and store it.

The lens device 160 is a zoom lens. The lens device 160 is a full length fixed zoom lens. The lens device 160 is a five-group zoom lens. The lens device 160 includes a control unit 162, a memory 163, a drive mechanism 161, and a lens system 300. The lens system 300 includes a first lens group 301, a second lens group 302, a third lens group 303, a fourth lens group 304, and a fifth lens group 305 in order from the object side. The first lens group 301 does not move in the optical axis direction of the lens system 300 when the lens device 160 is zoomed. The first lens group 301 may be a lens fixed in the optical axis direction of the lens system 300. Among the plurality of lens groups included in the lens device 160, the lens group located closest to the object side that is involved in the image plane movement at the time of zooming does not move at the time of zooming of the lens device 160. Therefore, it is difficult for focus shift, image shift, and the like to occur during zooming. In the description of the present embodiment, the optical axis of the lens system 300 may be simply referred to as “optical axis”. The “lens group” refers to a group of one or more lenses. The “lens group” may be composed of a single lens. The “lens group” is a concept including a lens composed of a single lens.

The control unit 162 moves at least one of the second lens group 302, the third lens group 303, the fourth lens group 304, and the fifth lens group 305 along the optical axis in accordance with a control command from the control unit 222. For example, the second control unit 162 moves the second lens group 302, the third lens group 303, the fourth lens group 304, and the fifth lens group 305 along the optical axis during zooming. This prevents the movement of the focus position during zooming. An image formed by the lens system 300 of the lens device 160 is captured by the imaging unit 140.

The driving mechanism 161 drives the second lens group 302, the third lens group 303, the fourth lens group 304, and the fifth lens group 305. The drive mechanism 161 includes, for example, an actuator and a holding member that holds the second lens group 302, the third lens group 303, the fourth lens group 304, and the fifth lens group 305. Driving pulses are supplied from the control unit 162 to the actuator. The actuator is displaced by a driving amount corresponding to the supplied pulse. When the holding member is displaced according to the displacement of the actuator, the second lens group 302, the third lens group 303, the fourth lens group 304, and the fifth lens group 305 are displaced.

The lens device 160 may be provided integrally with the imaging unit 140. The lens device 160 may be a so-called interchangeable lens. The lens device 160 may be provided so as to be detachable from the imaging unit 140.

The imaging device 230 includes a control unit 232, a control unit 234, an imaging device 231, a memory 233, and a lens 235. The control unit 232 may be configured by a microprocessor such as a CPU or MPU, a microcontroller such as an MCU, or the like. The control unit 232 controls the image sensor 231 in accordance with an operation command for the image sensor 231 from the control unit 104.

The control unit 234 may be configured by a microprocessor such as a CPU or MPU, a microcontroller such as an MCU, or the like. The control unit 234 controls the focal length of the lens 235 in accordance with an operation command for the lens 235 from the control unit 104. The control unit 234 may control the focal point of the lens 235 in accordance with an operation command for the lens 235. The control unit 234 may control a diaphragm included in the lens 235 in accordance with an operation command for the lens 235.

The memory 233 may be a computer-readable recording medium. The memory 233 may include at least one of flash memory such as SRAM, DRAM, EPROM, EEPROM, and USB memory.

The image sensor 231 generates image data of an optical image formed through the lens 235 and outputs the image data to the control unit 232. The control unit 232 stores the image data output from the image sensor 231 in the memory 233.

In this embodiment, an example in which the UAV 100 includes the control unit 104, the control unit 112, the control unit 222, the control unit 232, the control unit 234, and the control unit 162 will be described. However, any one of the control units 104, the control unit 112, the control unit 222, the control unit 232, the control unit 234, and the process executed by a plurality of the control units 162 may be executed by any one control unit. Processing executed by the control unit 104, the control unit 112, the control unit 222, the control unit 232, the control unit 234, and the control unit 162 may be executed by one control unit. In the present embodiment, an example in which the UAV 100 includes the memory 106, the memory 223, and the memory 233 will be described. Information stored in at least one of the memory 106, the memory 223, and the memory 233 may be stored in one or more other memories of the memory 106, the memory 223, and the memory 233.

In the lens system 300, the first lens group 301 has negative refractive power. The second lens group 302 has a positive refractive power. The third lens group 303 has negative refractive power. The fifth lens group 305 has positive refractive power. The first lens group 301, the second lens group 302, the third lens group 303, the fourth lens group 304, and the fifth lens group 305 are, from the object side, the first lens group 301, the second lens group 302, and the third lens. A group 303, a fourth lens group 304, and a fifth lens group 305 are provided in this order. In the description of the present embodiment, when the behavior of the lens system 300 at the time of zooming is described, the behavior when the lens device 160 functions as a zoom lens with respect to an object at infinity is shown.

The distance from the first lens group 301 to the image sensor 221 is constant during zooming from the wide-angle end to the telephoto end. At the time of zooming from the wide-angle end to the telephoto end, the distance between the first lens group 301 and the second lens group 302 decreases. At the time of zooming from the wide-angle end to the telephoto end, the distance between the second lens group 302 and the third lens group 303 increases. At the time of zooming from the wide angle end to the telephoto end, the distance between the third lens group 303 and the fourth lens group 304 decreases. At the time of zooming from the wide-angle end to the telephoto end, the fifth lens group 305 moves along a locus of a convex arc toward the image sensor 221. The movement along the locus of the convex arc means, for example, that the fifth lens group 305 moves along a locus that moves away from the image sensor 221 after approaching the image sensor 221.

In the lens system 300, the first lens group 301 does not move with respect to the image sensor 221 at the time of zooming, and moves along a locus that leaves the image sensor 221 after the fifth lens group 305 approaches the image sensor 221 side. Accordingly, it is possible to correct the image plane deviation due to the movement of the second lens group 302 mainly responsible for zooming. By preventing the first lens group 301 from moving during zooming, the lens group drive mechanism can be simplified. Further, the eccentricity of the first lens group 301 can be suppressed when disturbance such as vibration occurs. For this reason, it is possible to suppress defocusing and resolution degradation during vibration. In addition, the image pickup apparatus 220 can be reduced in size and performance.

The distance between the fourth lens group 304 and the fifth lens group 305 increases during zooming from the wide-angle end to the telephoto end. Note that, at the time of zooming from the wide-angle end to the telephoto end, the distance between the fourth lens group 304 and the fifth lens group 305 increases between the angle of view at the wide-angle end and a predetermined angle of view. On the other hand, the distance between the fourth lens group 304 and the fifth lens group 305 can be constant or decreased between the angle of view larger than the predetermined angle of view and the angle of view at the telephoto end.

The first lens group 301 may include four lenses having negative, negative, negative, and positive refractive power in order from the object side. When the Abbe numbers of the three lenses having negative refractive power included in the first lens group 301 are v1, v2, and v3, the following three conditional expressions v1> 60 (conditional expression 1)
v2> 60 (conditional expression 2)
v3> 60 (conditional expression 3)
Is preferably satisfied.

In the first lens group 301, since the negative refractive power can be shared by the three lenses having negative refractive power, the overall negative refractive power of the first lens group 301 can be increased. Further, the overall length of the lens system 300 can be shortened. In addition, imaging characteristics can be improved. Since the three lenses having negative refractive power share the negative power of the first lens group 301, a lens having negative refractive power can be formed using a low dispersion material. Thereby, chromatic aberration can be suppressed more strongly.

Conditional expression −1.8 <f1 / fw <−1.1 (conditional expression 4) where f1 is the focal length of the first lens group 301 and fw is the focal length of the entire system (lens system 300) at the wide angle end.
Is preferably satisfied. The lens system 300 can be reduced in size by satisfying the lower limit of conditional expression 4, that is, by making the refractive power of the first lens group 301 higher than a predetermined lower limit threshold. By satisfying the upper limit of conditional expression 4, that is, by making the refractive power of the first lens group 301 not higher than a predetermined upper limit threshold, it is possible to improve the imaging characteristics.

When the focal length of the second lens group 302 is f2, conditional expression 1.0 <f2 / fw <1.8 (conditional expression 5)
Is preferably satisfied. The lens system 300 can be reduced in size by satisfying the upper limit of conditional expression 5, that is, by making the refractive power of the second lens group 302 higher than a predetermined lower limit threshold. By satisfying the lower limit of Conditional Expression 5, that is, by making the refractive power of the second lens group 302 not higher than a predetermined upper limit threshold, it is possible to improve imaging characteristics.

The second lens group 302 may include at least three convex lenses. It is preferable that the Abbe number v of all convex lenses included in the second lens group 302 is greater than 50. By setting all Abbe numbers of the convex lenses of the second lens group 302 to 50 or more, chromatic aberration can be suppressed while increasing the refractive power of the second lens group 302. Thereby, the lens system 300 can be reduced in size while improving the imaging characteristics.

When the refractive index of the positive lens of the first lens group 301 is n4 and the Abbe number is v4, two conditional expressions n4> 1.9 (conditional expression 6)
v4 <35 (Condition 7)
Is preferably satisfied. When the positive lens included in the first lens group 301 satisfies the conditional expressions 6 and 7, the thickness of the first lens group 301 in the optical axis direction can be reduced. This contributes to shortening the overall length of the lens system 300.

The fourth lens group 304 and the fifth lens group 305 may be composed of a single lens or a cemented lens. At least one of the fourth lens group 304 and the fifth lens group 305 may have a focus function. At least one of the fourth lens group 304 and the fifth lens group 305 may have an anti-vibration function.

In order to realize the focus function or to realize the image stabilization function in the lens system, it is necessary to drive one of the lens groups. In the lens system 300, the lens driving mechanism can be simplified by using a single lens or a cemented lens as the lens group responsible for the focus function or the image stabilization function. In addition, the lens driving element can be reduced in weight. As a result, the entire lens system 300 is reduced in size.

Among the three lenses having negative refractive power included in the first lens group 301, at least one of the two lenses on the object side is preferably an aspheric lens. The lens on the object side has a large difference in height between the axial ray and the peripheral ray. In the lens system 300, at least one of the two lenses on the object side is aspherical, so that distortion and field curvature can be effectively corrected.

The second lens group 302 preferably includes at least one single lens that is an aspheric lens having a positive refractive power. It is desirable that the most object side lens included in the second lens group 302 is a single aspherical lens having positive refractive power. In order to increase the positive refractive power of the second lens group 302, it is necessary to increase the refractive power of the positive lens constituting the second lens group 302. The total length of the lens system 300 can be shortened by increasing the positive refractive power of the lens on the object side of the second lens group 302. In addition, aberration can be effectively corrected by using an aspherical surface for a lens having strong power.

FIG. 3 shows the lens configuration of the lens system 300 in the first embodiment, together with the image sensor 221. FIG. 3 shows the positions of the first lens group 301, the second lens group 302, the third lens group 303, the fourth lens group 304, and the fifth lens group 305 at the wide-angle end, the intermediate field angle, and the telephoto end, respectively. . Note that STO indicates an aperture. In the first example, the fourth lens group 304 has negative refractive power. That is, the lens system 300 includes five groups of negative positive negative negative positive.

Here, the meaning of symbols and the like used in the description of the embodiment of the lens system 300 will be described. A plurality of surfaces of the lens system 300 are identified by a surface number i. The first surface of the lens as viewed from the object side is the first surface, and thereafter the surface numbers are counted up in the order in which the light passes through the surface. “Di” indicates an interval on the optical axis between the i-th surface and the (i + 1) -th surface.

“F” indicates the focal length. “Fno” indicates an F number. “Ω” indicates a half angle of view. “R” indicates a radius of curvature. In the radius of curvature, “INF” indicates a plane. “N” represents a refractive index. v represents the Abbe number. The refractive index n and the Abbe number v are values at the d-line (λ = 587.6 nm).

Table 1 shows lens data of lenses included in the lens system 300 in the first example. In Table 1, Di is shown in association with the surface number i.

In Table 1, a surface numbered with * is a surface having an aspherical shape. Table 2 shows the surface number of the surface having the aspheric shape and the aspheric parameter. In Table 2, “κ” represents a conic constant (conic constant). “A”, “B”, “C”, and “D” are fourth-order, sixth-order, eighth-order, and tenth-order aspheric coefficients, respectively. In the aspheric coefficient, “Ei” represents an exponential expression with 10 as the base. That is, “ ^Ei ” represents “10 ⁻ⁱ ”. For example, “6.04845E-06” represents “6.04845 × 10 ⁻⁶ ”.

When “x” is the distance in the optical axis direction from the apex of the lens surface, “y” is the height in the direction perpendicular to the optical axis, and “c” is the paraxial curvature at the apex of the lens, the aspherical shape is It is defined by the following formula.
x = cy ² / (1+ (1- (1 + κ) c ² y ² ) ^1/2 ) + Ay ⁴ + By ⁶ + Cy ⁸ + Dy ¹⁰
“X” is also called a sag amount. “Y” is also called image height. The paraxial curvature is the reciprocal of the radius of curvature.

Table 3 shows the focal length, F number, and half angle of view of the lens system 300 at each of the wide angle end, the intermediate angle of view, and the telephoto end.

At the time of zooming between the wide-angle end and the telephoto end in the lens system 300, the surface distance D8 between the first lens group 301 and the second lens group 302, and between the second lens group 302 and the third lens group 303. The surface distance D15, the surface distance D21 between the third lens group 303 and the fourth lens group 304, the surface distance D29 between the fourth lens group 304 and the fifth lens group 305, and the fifth lens group 305. And the imaging element 221 can change the surface distance D31. Table 4 shows the surface spacing at each of the wide-angle end, the intermediate field angle, and the telephoto end.

Table 5 shows focal lengths of the first lens group 301, the second lens group 302, the third lens group 303, the fourth lens group 304, and the fifth lens group 305.

FIG. 4 shows that the first lens group 301, the second lens group 302, the third lens group 303, the fourth lens group 304, and the fifth lens group 305 move during zooming of the lens system 300 from the wide-angle end to the telephoto end. A locus is schematically shown. The arrow indicates that the lens system 300 moves upon zooming. As shown in FIGS. 3 and 4, the distance from the first lens group 301 to the image sensor 221 is constant during zooming.

The first lens group 301 has four lenses of a negative lens L1, a negative lens L2, a negative lens L3, and a positive lens L4 from the object side. The negative lens L1 is an aspheric lens. Of the lenses constituting the first lens group 301, two lenses disposed on the object side are preferably concave lenses, and at least one concave lens is preferably an aspheric lens. More preferably, a concave lens is disposed on the object side. Thereby, since the off-axis light beam on the wide-angle side where the incident angle becomes particularly large can be bent gently, the imaging characteristics with respect to the peripheral light beam can be enhanced. Also, on the object side, the peripheral rays are separated from other rays. By disposing an aspheric lens on the object side, aberrations such as distortion and curvature of field can be favorably corrected. Further, since the negative power of the first lens group 301 is shared by the three negative lenses L1 to L3, the negative power of the first lens group 301 can be increased while suppressing aberrations. Further, the overall length of the lens system 300 can be shortened.

It is desirable that the refractive power and the Abbe number of the positive lens L4 of the first lens group 301 satisfy n> 1.9 and v <35. The Abbe numbers of the negative lenses L1 to L3 in the first lens group 301 are all preferably v> 60. In particular, in the first lens group 301, the Abbe numbers of the negative lens L2 and the negative lens L3 are v> 70. It is desirable that at least one Abbe number among the three negative lenses L1 to L3 constituting the first lens group 301 is v> 70. By setting the Abbe number of at least one negative lens included in the first lens group 301, which is a negative lens, to v> 70, it is possible to satisfactorily correct lateral chromatic aberration particularly on the wide angle side.

The second lens group 302 includes negative and positive cemented lenses L5 and L6 and positive single lenses L7 and L8 from the object side. It is desirable that at least one of the lenses constituting the second lens group 302 is a cemented lens. The Abbe number of the lens L6 constituting the cemented lens is preferably v> 65.

The third lens group 303 includes a stop STO, a single lens L10, and negative and positive cemented lenses L11 and L12. The fourth lens group 304 includes negative and positive cemented lenses L13 and L14, positive and negative cemented lenses L15 and L16, and a single lens L17. Both the third lens group 303 and the fourth lens group 304 preferably include at least one or more cemented lenses. By using at least one of the lenses included in the third lens group 303 and the fourth lens group 304 as a cemented lens, axial chromatic aberration can be favorably corrected.

The fifth lens group 305 is a single lens. The fifth lens group 305 may be a cemented lens. The fifth lens group 305 functions as a focus lens. By using the fifth lens group 305 having the focus function as a single lens or a cemented lens, it is possible to reduce the weight load on the drive mechanism of the fifth lens group 305. In addition, the holding frame that holds the fifth lens group 305 can be reduced in size.

3 and 4, when zooming from the wide-angle end to the telephoto end, the second lens group 302 moves in one direction from the image plane side to the object side. In zooming of the lens system 300, the first lens group 301 and the second lens group 302 are responsible for the main zooming component, and the third lens group 303, the fourth lens group 304, and the fifth lens group 305 are sub-magnifying components. Take on. The fifth lens group 305 is also responsible for correcting image plane fluctuations accompanying zooming.

The third lens group 303 moves from the image plane side to the object side during zooming from the wide angle end to the telephoto end. At this time, the third lens group 303 moves so as to be spaced from the second lens group 302. At the time of zooming from the wide angle end to the telephoto end, the fourth lens group 304 moves from the image plane side to the object side. At this time, the fourth lens group 304 moves so that the distance from the third lens group 303 approaches. At the time of zooming from the wide-angle end to the telephoto end, the fifth lens group 305 moves toward the image sensor 221 along a convex movement locus. The movement of the lens group in a convex movement locus toward the image sensor 221 means, for example, that the horizontal axis is the angle of view or the focal length, the vertical axis is the amount of displacement of the lens group in the optical axis direction, and the direction toward the image sensor 221 is This means that when the movement locus of the lens group is drawn as the positive direction of the vertical axis, the movement locus of the lens group becomes convex. The distance between the fifth lens group 305 and the fourth lens group 304 increases from the wide angle end until a predetermined angle of view is reached. The distance between the fifth lens group 305 and the fourth lens group 304 can be narrowed until reaching the telephoto end from a predetermined angle of view.

FIG. 5 shows spherical aberration, astigmatism and distortion at the wide angle end. FIG. 6 shows spherical aberration, astigmatism and distortion at an intermediate angle of view. FIG. 7 shows spherical aberration, astigmatism and distortion at the telephoto end.

In the spherical aberration diagrams shown in FIGS. 5 to 7, the solid line indicates the value of the d-line (587.56 nm), and the broken line indicates the value of the g-line (435.84 nm). In the astigmatism diagrams shown in FIGS. 5 to 7, the solid line indicates the value of the sagittal image plane of the d line, and the broken line indicates the value of the meridional image plane of the d line. The distortion diagrams shown in FIGS. 5 to 7 show values for the d-line. From the respective aberration diagrams, it can be seen that the lens system 300 is excellent in various aberrations and has excellent imaging performance.

FIG. 8 shows a spherical aberration diagram of the lens system 300 for light of three wavelengths. The thick line indicates the value of c-line (656.28 nm), the solid line indicates the value of d-line (587.56 nm), and the broken line indicates the value of g-line (435.84 nm). At each of the wide-angle end, the intermediate angle of view, and the telephoto end, the spherical aberration is within a range of 0.1 mm or less for each wavelength of light. Thereby, it can be seen that the axial chromatic aberration is corrected well.

FIG. 9 shows the lens configuration of the lens system 900 in the second embodiment together with the image sensor 221. The lens system 900 includes a first lens group 901, a second lens group 902, a third lens group 903, a fourth lens group 904, and a fifth lens group 905. The first lens group 901, the second lens group 902, the third lens group 903, the fourth lens group 904, and the fifth lens group 905 are respectively the first lens group 301, the second lens group 302, and the like in the lens system 300. This corresponds to the third lens group 303, the fourth lens group 304, and the fifth lens group 305. In the description of the lens system 900, only the differences from the lens system 300 among the characteristics of the lens system 900 will be described, and the same characteristics may be omitted. Further, symbols and the like used in the description of the lens system 900 have the same meanings as symbols and the like described in relation to the lens system 300 unless otherwise specified.

In the second embodiment, the fourth lens group 904 has positive refractive power. That is, the lens system 900 includes five groups of negative positive negative positive positive.

FIG. 9 shows the positions of the first lens group 901, the second lens group 902, the third lens group 903, the fourth lens group 904, and the fifth lens group 905 at the wide-angle end, the intermediate field angle, and the telephoto end, respectively. It is shown.

Table 6 shows lens data of lenses included in the lens system 900.

In Table 6, surfaces with * in the surface number are surfaces having an aspherical shape. Table 7 shows surfaces having an aspheric shape in the lens system 900 and aspheric parameters. “A”, “B”, “C”, “D”, and “E” are fourth-order, sixth-order, eighth-order, tenth-order, and twelfth-order aspheric coefficients, respectively.

When “x” is the distance in the optical axis direction from the apex of the lens surface, “y” is the height in the direction perpendicular to the optical axis, and “c” is the paraxial curvature at the apex of the lens, the aspherical shape is It is defined by the following formula.
x = cy ² / (1+ (1- (1 + κ) c ² y ² ) ^1/2 ) + Ay ⁴ + By ⁶ + Cy ⁸ + Dy ¹⁰ + Ey ¹²

Table 8 shows the focal length, F-number, and half angle of view of the lens system 900 at the wide angle end, the intermediate field angle, and the telephoto end, respectively.

Upon zooming between the wide-angle end and the telephoto end in the lens system 900, the surface distance D8 between the first lens group 901 and the second lens group 902, and between the second lens group 902 and the third lens group 903. The surface distance D15, the surface distance D21 between the third lens group 903 and the fourth lens group 904, the surface distance D29 between the third lens group 903 and the fourth lens group 904, and the fifth lens group 905. The surface distance D31 between the imaging element 221 can change. Table 9 shows the focal length and the surface interval at the wide angle end, the intermediate field angle, and the telephoto end, respectively.

Table 10 shows focal lengths of the first lens group 901, the second lens group 902, the third lens group 903, the fourth lens group 904, and the fifth lens group 905.

FIG. 10 shows that the first lens group 901, the second lens group 902, the third lens group 903, the fourth lens group 904, and the fifth lens group 905 move during zooming of the lens system 900 from the wide-angle end to the telephoto end. A locus is schematically shown. The arrow indicates that the lens system 900 moves upon zooming. As shown in FIGS. 9 and 10, the distance from the first lens group 901 to the image sensor 221 is constant at the time of zooming.

The first lens group 901 has four lenses, a negative lens L1, a negative lens L2, a negative lens L3, and a positive lens L4, from the object side. In the second embodiment, Li is a symbol for indicating that the lens is the i-th optical element from the object side. The same symbol as the symbol Li assigned to the lens in the first embodiment does not mean that it is the same lens.

By configuring the first lens group 901 to include the four lenses of the negative lens L1, the negative lens L2, the negative lens L3, and the positive lens L4, off-axis rays on the wide-angle side where the incident angle is particularly large can be moderated. Can be bent. Therefore, it is possible to satisfactorily correct off-axis aberrations such as distortion, coma, and field curvature. In addition, the spherical aberration on the telephoto side can be corrected well. Further, since the negative power of the first lens group 901 is shared by the three negative lenses L1 to L3, the negative power of the first lens group 901 can be increased while suppressing aberrations. Further, the overall length of the lens system 900 can be shortened.

The negative lens L1 is an aspheric lens. Of the lenses constituting the first lens group 901, two lenses disposed on the object side are preferably concave lenses, and at least one concave lens is preferably an aspherical lens. More preferably, a concave lens is disposed on the object side. Thereby, since the off-axis light beam on the wide-angle side where the incident angle becomes particularly large can be bent gently, the imaging characteristics with respect to the peripheral light beam can be enhanced. Also, on the object side, the peripheral rays are separated from other rays. By disposing an aspheric lens on the object side, aberrations such as distortion and curvature of field can be favorably corrected.

It is desirable that the refractive power and Abbe number of the positive lens L4 of the first lens group 901 satisfy n> 1.9 and v <35. The Abbe numbers of the negative lenses L1 to L3 in the first lens group 901 are all preferably v> 60. In particular, in the first lens group 901, the Abbe numbers of the negative lens L2 and the negative lens L3 are v> 70. It is desirable that at least one Abbe number among the three negative lenses L1 to L3 constituting the first lens group 901 is v> 70. By setting the Abbe number of at least one negative lens included in the first lens group 901, which is a negative lens, to v> 70, it is possible to satisfactorily correct lateral chromatic aberration particularly on the wide angle side.

The second lens group 902 includes a positive single lens L5, negative positive cemented lenses L6 and L7, and a positive single lens L8 from the object side. It is desirable that at least one lens among the lenses constituting the second lens group 902 be a cemented lens. It is preferable that the Abbe number v of all convex lenses included in the second lens group 902 is greater than 50. By setting the Abbe numbers of the convex lenses of the second lens group 902 to 50 or more, chromatic aberration can be suppressed while increasing the refractive power of the second lens group 902. Thereby, the lens system 900 can be reduced in size while improving the imaging characteristics.

The third lens group 903 includes a stop STO, a negative lens L10, and negative positive cemented lenses L11 and L12. The fourth lens group 904 includes a positive single lens L13, negative and positive cemented lenses L14 and L15, and negative and positive cemented lenses L16 and L17. It is desirable that both the third lens group 903 and the fourth lens group 904 include at least one cemented lens. By using at least one of the lenses included in the third lens group 903 and the fourth lens group 904 as a cemented lens, axial chromatic aberration can be favorably corrected.

The fifth lens group 905 is a single lens. The fifth lens group 905 may be a cemented lens. The fifth lens group 905 functions as a focus lens. By using the fifth lens group 905 having a focus function as a single lens or a cemented lens, it is possible to reduce the weight load on the drive mechanism of the fifth lens group 905. In addition, the holding frame that holds the fifth lens group 905 can be reduced in size.

9 and 10, when zooming from the wide-angle end to the telephoto end, the second lens group 902 moves in one direction from the image plane side to the object side. In zooming of the lens system 900, the first lens group 901 and the second lens group 902 are responsible for the main zooming component, and the third lens group 903, the fourth lens group 904, and the fifth lens group 905 are the sub-magnifying components. Take on. The fifth lens group 905 is also responsible for correcting image plane variation accompanying zooming.

The third lens group 903 moves from the image plane side to the object side during zooming from the wide angle end to the telephoto end. At this time, the third lens group 903 moves so as to be spaced from the second lens group 902. At the time of zooming from the wide angle end to the telephoto end, the fourth lens group 904 moves from the image plane side to the object side. At this time, the fourth lens group 904 moves so that the distance from the third lens group 903 approaches. At the time of zooming from the wide-angle end to the telephoto end, the fifth lens group 905 moves along a convex movement locus toward the image sensor 221. The distance between the fifth lens group 905 and the fourth lens group 904 increases from the wide angle end until a predetermined angle of view is reached. The interval between the fifth lens group 905 and the fourth lens group 904 can be narrowed until reaching the telephoto end from a predetermined angle of view.

FIG. 11 shows spherical aberration, astigmatism and distortion at the wide angle end. FIG. 12 shows spherical aberration, astigmatism and distortion at an intermediate angle of view. FIG. 13 shows spherical aberration, astigmatism and distortion at the telephoto end.

In the spherical aberration diagrams shown in FIG. 11 to FIG. 13, the solid line shows the value of d-line (587.56 nm), and the broken line shows the value of g-line (435.84 nm). In the astigmatism diagrams shown in FIGS. 11 to 13, the solid line indicates the value of the sagittal image plane of the d line, and the broken line indicates the value of the meridional image plane of the d line. The distortion diagrams shown in FIGS. 11 to 13 show values for the d-line. From each aberration diagram, it can be seen that the lens system 900 has excellent imaging performance with various aberrations corrected well.

FIG. 14 is a spherical aberration diagram for the three-wavelength light of the lens system 900. The thick line indicates the value of c-line (656.28 nm), the solid line indicates the value of d-line (587.56 nm), and the broken line indicates the value of g-line (435.84 nm). At each of the wide-angle end, the intermediate field angle, and the telephoto end, the spherical aberration is within a sufficiently small range for each wavelength of light. It can be seen that the longitudinal chromatic aberration is corrected well.

Table 11 collectively shows numerical values according to the conditional expressions of the first and second embodiments. In Table 11, the numerical values associated with Conditional Expression 1, Conditional Expression 2, and Conditional Expression 3 indicate the Abbe numbers of the negative lens L1, the negative lens L2, and the negative lens L3, respectively. The numerical value associated with conditional expression 4 indicates the value of f1 / fw. The numerical value associated with conditional expression 5 indicates the value of f2 / fw. The numerical value associated with conditional expression 6 indicates the refractive index. The numerical value associated with conditional expression 7 indicates the Abbe number.

As described above, according to the lens system 300 and the lens system 900, it is possible to provide a zoom lens that does not move the lens located closest to the object side during zooming. Thereby, it is possible to suppress the influence of a manufacturing error, a driving error, and the like regarding the lens located closest to the object side. For example, it is possible to make it difficult for focus shift, image shift, and the like to occur during zooming.

FIG. 15 is an external perspective view showing an example of the stabilizer 800. The stabilizer 800 is another example of the moving body. For example, the camera unit 813 included in the stabilizer 800 may include an imaging device having the same configuration as the imaging device 220. The camera unit 813 may include a lens device having the same configuration as the lens device 160.

The stabilizer 800 includes a camera unit 813, a gimbal 820, and a handle portion 803. The gimbal 820 supports the camera unit 813 in a rotatable manner. The gimbal 820 has a pan axis 809, a roll axis 810, and a tilt axis 811. The gimbal 820 supports the camera unit 813 so as to be rotatable about a pan axis 809, a roll axis 810, and a tilt axis 811. The gimbal 820 is an example of a support mechanism.

The camera unit 813 is an example of an imaging device. The camera unit 813 has a slot 812 for inserting a memory. The gimbal 820 is fixed to the handle portion 803 via the holder 807.

The handle portion 803 has various buttons for operating the gimbal 820 and the camera unit 813. The handle portion 803 includes a shutter button 804, a recording button 805, and an operation button 806. By pressing the shutter button 804, a still image can be recorded by the camera unit 813. When the recording button 805 is pressed, a moving image can be recorded by the camera unit 813.

The device holder 801 is fixed to the handle portion 803. The device holder 801 holds a mobile device 802 such as a smartphone. The mobile device 802 is communicably connected to the stabilizer 800 via a wireless network such as WiFi. Thereby, an image captured by the camera unit 813 can be displayed on the screen of the mobile device 802.

Also in the stabilizer 800, it can suppress that the camera unit 813 interferes with the other site | part of the stabilizer 800. FIG.

As described above, the UAV 100 and the stabilizer 800 are taken up as an example of the moving body. An imaging device having a configuration similar to that of the imaging device 220 may be attached to a moving body other than the UAV 100 and the stabilizer.

In the above, the imaging device attached to the moving body has been described. However, the imaging device having the same configuration as that of the imaging device 220 is not limited to the imaging device attached to the moving body. A configuration similar to that of the imaging device 220 can be applied to a non-lens interchangeable camera such as a so-called compact digital camera. The same configuration as the lens device 160 can be applied to an interchangeable lens of a lens interchangeable camera such as a single-lens reflex camera. The same configuration as the lens device 160 can be applied to the configurations of various lens devices for imaging.

As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

The execution order of each process such as operations, procedures, steps, and stages in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior”. The output of the previous process is not used in the subsequent process, and can be realized in an arbitrary order. Regarding the operation flow in the claims, the description, and the drawings, even if it is described using “first”, “next”, etc. for the sake of convenience, it means that it is essential to carry out in this order. is not.

DESCRIPTION OF SYMBOLS 10 Mobile system 50 Controller 52 Operation part 54 Display part 100 UAV
101 UAV main body 102 interface 104 control unit 106 memory 110 gimbal 112 control unit 114, 116, 118 driver 124, 126, 128 drive unit 130 support mechanism 134, 136, 138 rotation mechanism 140 imaging unit 160 lens device 161 drive mechanism 162 control unit 163 Memory 220, 230 Imaging device 221 Imaging device 222 Control unit 223 Memory 231 Imaging device 232 Control unit 233 Memory 234 Control unit 235 Lens 300 Lens system 301 First lens group 302 Second lens group 303 Third lens group 304 Fourth lens Group 305 Fifth lens group 800 Stabilizer 801 Device holder 802 Mobile device 803 Handle 804 Shutter button 805 Record button 806 Operation button 807 Holder 809 Pan axis 810 B Lens axis 811 tilt axis 812 slot 813 camera unit 820 gimbal 900 lens system 901 first lens group 902 second lens group 903 third lens group 904 fourth lens group 905 fifth lens group

Claims (15)

1. In order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a negative refractive power, a fourth lens group, and a first lens group having a positive refractive power. A distance between the first lens group and the image pickup element is constant at the time of zooming from the wide-angle end to the telephoto end, and the distance between the first lens group and the second lens group is reduced. The distance between the second lens group and the third lens group increases, the distance between the third lens group and the fourth lens group decreases, and the fifth lens group has a convex arc toward the image sensor. A zoom lens that moves along a trajectory.
2. Conditional expression −1.8 <f1 / fw <−1.1 where f1 is the focal length of the first lens unit and fw is the focal length of the entire system at the wide angle end.
   The zoom lens according to claim 1, wherein:
3. The first lens group includes four lenses having negative, negative, negative, and positive refractive power in order from the object side, and the three lenses having the negative refractive power included in the first lens group. If the Abbe numbers are v1, v2 and v3, respectively, the conditional expression v1> 60
   v2> 60
   v3> 60
   The zoom lens according to claim 1, wherein:
4. The first lens group includes four lenses having negative, negative, negative, and positive refractive power in order from the object side, and the three lenses having the negative refractive power included in the first lens group. The zoom lens according to claim 1, wherein at least one of the two lenses on the object side is an aspheric lens.
5. The second lens group includes at least three convex lenses, and all the convex lenses included in the second lens group satisfy the conditional expression v> 50.
   Satisfied,
   Conditional expression 1.0 <f2 / fw <1.8, where f2 is the focal length of the second lens group.
   The zoom lens according to claim 1, wherein:
6. 2. The at least one of the fourth lens group and the fifth lens group includes a single lens or a cemented lens, and the at least one of the fourth lens group and the fifth lens group has a focus function. Or the zoom lens of 2.
7. The at least one of the fourth lens group and the fifth lens group is composed of a single lens or a cemented lens, and the at least one of the fourth lens group and the fifth lens group has a vibration-proof function. The zoom lens according to 1 or 2.
8. The zoom lens according to claim 1, wherein the second lens group includes at least one single lens that is an aspherical lens having a positive refractive power.
9. The first lens group includes four lenses having negative, negative, negative, and positive refractive power in order from the object side, and the refractive index of the lens having the positive refractive power of the first lens group is n4. If the Abbe number is v4, the conditional expression n4> 1.9
   v4 <35
   The zoom lens according to claim 1, wherein:
10. The zoom lens according to claim 1, wherein the fourth lens group has negative refractive power.
11. The zoom lens according to claim 1, wherein the fourth lens group has positive refractive power.
12. The zoom lens according to claim 1 or 2,
    An imaging apparatus comprising the imaging element.
13. A moving body that moves with the zoom lens according to claim 1.
14. The moving body according to claim 13, wherein the moving body is an unmanned aerial vehicle.
15. The zoom lens according to claim 1 or 2,
    A support mechanism that displaceably supports the zoom lens;
    And a handle portion attached to the support mechanism.

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