JP5355270B2 - Imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact imaging apparatus capable of taking a diagonal image and a circumferential image, by obtaining a super-wide photographing angle of view, using a general-purpose image forming optical system. <P>SOLUTION: A camera has the image forming optical system M as a variable power optical system and an imaging device, and an afocal optical system AT, that changes the photographic angle of viewing to a wide angle is attachably/detachably arranged on an object side of a photographic optical system. The afocal optical system has an objective optical system L, having a positive refractive power as a whole on the object side, and a correction lens group H, having positive refractive power closer to the photographic optical system than to the objective optical system. If the maximum exiting angle of a light beam exiting from the afocal optical system is defined as &theta;, the lengths of a short side and a long side of an effective imaging area of the imaging device are defined as VL and HL, the focal length of the image forming optical system at a wide angle end is defined as fw, and the focal length of the image forming optical system at a telephoto end is defined as being ft, the parameters satisfy the relations: 0&lt;fw&times;¾tan&theta;¾&le;0.5&times;VL and 0&lt;0.5&times;(VL<SP>2</SP>+HL<SP>2</SP>)<SP>1/2</SP>&le;ft&times;¾tan&theta;¾. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an imaging apparatus.

  There is an increasing demand for an imaging device capable of obtaining a diagonal image and a circumferential image by obtaining a super wide angle of view with a small configuration. For this reason, Patent Document 1 proposes a fish-eye optical system that is small and excellent in optical performance, and Patent Document 2 is an imaging optical system as a variable-magnification optical system with a wide-angle end state angle of view of 80 ° or more. A wide converter to be installed is proposed.

JP 2007-94371 A JP 2006-276220 A

  However, since Patent Document 1 is an interchangeable lens for a single-lens reflex camera, it cannot cope with a small-sized imaging device such as a compact digital camera. Further, Patent Document 2 cannot cope with a general-purpose imaging optical system because the angle of view of the imaging optical system has to be wider in order to obtain a circumferential image.

  It is an exemplary object of the present invention to provide an imaging apparatus capable of capturing a diagonal image and a circumferential image by using a general-purpose imaging optical system to obtain a small and super wide-angle imaging field angle. .

An imaging apparatus according to one aspect of the present invention includes an imaging optical system as a variable magnification optical system and an imaging element that photoelectrically converts a subject image formed by the imaging optical system. An imaging apparatus configured to be detachable from an imaging optical system that changes a shooting angle of view to a wide angle. The imaging optical system includes an objective optical system having positive refractive power as a whole on the object side, and the objective A correction lens group that has a positive refractive power closer to that of the imaging optical system than that of the optical system and collimates axial rays, and forms an image twice with the imaging optical system. Θ is the maximum emission angle of light emitted from the system, VL and HL are the lengths of the short and long sides of the effective imaging area of the image sensor, fw is the focal length of the wide-angle end of the imaging optical system, and the imaging optics When the focal length at the telephoto end of the system is ft, 0 <fw · | tan θ | ≦ 0.5 · V ^{, 0 <0.5 · (VL 2} + HL 2) 1/2 ≦ ft · | and satisfies a | tan .theta.

  The present invention can provide an imaging apparatus capable of capturing a diagonal image and a circumferential image by using a general-purpose imaging optical system to obtain a small and ultra-wide angle of field of view.

It is each optical path diagram of the imaging device (optical device) to which the afocal optical system and the imaging optical system of the present embodiment are connected. FIG. 2 is an optical path diagram of the imaging apparatus according to Numerical Example 1. FIG. 3 is an aberration diagram of the circumferential image state 1 in FIG. 2. FIG. 3 is an aberration diagram of the circumferential image state 2 in FIG. 2. FIG. 3 is an aberration diagram of the diagonal image state of FIG. 2. FIG. 6 is an optical path diagram at the wide-angle end, the middle, and the telephoto end of the image forming optical system according to Numerical Example 1. 6 is an aberration diagram at the wide-angle end of the image forming optical system according to Numerical Example 1. FIG. FIG. 4 is an aberration diagram at an intermediate focal position of the imaging optical system according to Numerical Example 1. FIG. 3 is an aberration diagram at the telephoto end of the image forming optical system according to Numerical Example 1. 6 is an optical path diagram of an imaging apparatus according to Numerical Example 2. FIG. FIG. 11 is an aberration diagram of the circumferential image state 1 in FIG. 10. FIG. 11 is an aberration diagram of the circumferential image state 2 in FIG. 10. FIG. 11 is an aberration diagram of the diagonal image state in FIG. 10. FIG. 6 is an optical path diagram at the wide-angle end, the middle, and the telephoto end of the image forming optical system according to Numerical Example 2. 10 is an aberration diagram at the wide-angle end of the image forming optical system according to Numerical Example 2. FIG. FIG. 6 is an aberration diagram at an intermediate focal position of the imaging optical system according to Numerical Example 2. 10 is an aberration diagram at the telephoto end of the image forming optical system according to Numerical Example 2. FIG.

  In this embodiment, an afocal optical system is detachably disposed on the object side of an imaging optical system that is originally provided in a digital compact camera (imaging apparatus or optical apparatus) and functions as a photographing optical system by itself. A photographic optical system including an optical system and an afocal optical system is configured. The imaging optical system M is a variable magnification optical system having a relatively long entrance pupil position in which the lens unit closest to the object moves during zooming. Thus, the present embodiment realizes a photographing optical system that forms a subject image by forming an image twice as a whole. The afocal optical system is a fish-eye optical system or an attachment optical system (imaging optical system) that changes the shooting angle of view to a wide angle so that it becomes a near-fish-eye optical system with a field angle of about 120 degrees. With a photographic optical system that forms images twice, a super wide-angle photographic field angle can be obtained without increasing the lens outer shape. The imaging device incorporates an imaging element that photoelectrically converts a subject image formed by the imaging optical system.

  Further, the imaging apparatus can switch between circumferential image shooting and diagonal image shooting by satisfying the following conditional expressions 2 and 4. Note that the effective imaging area of the imaging device is rectangular with respect to the image circle image of the imaging optical system. For this reason, the circumferential image becomes a rectangular photograph circumscribing or slightly larger than the image circle image, and the diagonal image is a rectangular photograph inscribed in or slightly smaller than the image circle image.

  FIG. 1A is an optical path diagram of an afocal optical system AT of a digital camera (imaging device) in which the afocal optical system AT is mounted on the object side of the imaging optical system M, and FIG. 2 is an optical path diagram of an optical system M. FIG. In FIG. 1B, IP is an image plane of the imaging optical system M.

  In FIG. 1A, a light beam having a maximum incident angle incident on the afocal optical system AT without vignetting becomes a boundary of a circumferential image, and the incident light beam is emitted through the afocal optical system AT. The angle formed with the optical axis is θ.

  FIG. 1B shows an angle formed with the optical axis when the imaging optical system M is composed of two groups of the negative lens group MB1 and the positive lens group MB2 from the object side and obtains a zooming action by changing the distance between them. This shows a state in which a light beam incident at θ forms an image at an image height of a distance Y from the center of the imaging screen on the imaging plane IP.

  In the digital camera (imaging device), the attachment optical device that houses the afocal optical system AT is mounted on the object side of the converter attachment that houses the imaging optical system M in a replaceable manner (for example, by screws). The converter attachment is an adapter ring attached to the digital camera, and is an intermediate member for fixing the attachment optical device to the digital camera. In addition, since the image becomes an inverted image at the time of image formation twice, an electric mechanism for making the image upright is incorporated in the electronic display device on the camera side.

  The afocal optical system AT includes an objective optical system L, a field lens group F, and a correction lens group H in order from the object side, as shown in FIG. The objective optical system L as a whole has a positive refractive power. Although not essential, the field lens group F is disposed in the vicinity of the imaging position of the objective optical system L, has a positive refractive power, deflects off-axis rays, and guides them to the imaging optical system M. The correction lens group H exits from the afocal optical system AT with the axial ray collimated and has a positive refractive power. The correction lens group H is closer to the imaging optical system M than the objective optical system L.

  If the imaging optical system M has a small distortion characteristic within ± 5%, the incident light beam forms an image with the focal length of the imaging optical system M set to FL and the incident angle of light to the imaging optical system M set to θ. If the distance from the center of the imaging surface (optical axis position on the imaging surface) emitted to the surface is Y, the following equation is established.

  The afocal optical system AT is an optical system (imaging optical system) that emits a substantially parallel light beam after forming a subject image, and the maximum emission angle of the light beam emitted therefrom is θ. In addition, it is assumed that the imaging apparatus has an imaging element in which the lengths of the short side and the long side of the effective imaging area are VL and HL. Further, the focal length at the wide-angle end of the imaging optical system M is fw, and the focal length at the telephoto end is ft. At this time, if the following equation is satisfied, a circumferential image and a diagonal image can be obtained by the imaging device.

  Formula 2 is a condition for photographing a circumferential image on the wide-angle side. When the short side of the effective imaging area circumscribes the image circle image of the photographing optical system, the left side and the right side are equal.

  In addition, the right side is actually 0 or more.

  Formula 4 is a condition for capturing a diagonal image on the telephoto side. When the diagonal side of the effective imaging area of the image sensor is inscribed in the image circle image of the imaging optical system, the left side and the right side are equal.

  Moreover, the left side is actually 0 or more.

  The imaging apparatus has a switch (not shown) that switches between a mode for capturing a circumferential image and a mode for capturing a diagonal image. In this case, the zoom position for shooting the circumferential image and the zoom position for shooting the diagonal image may be stored in advance, and these may be selected by an operation member (not shown) at the time of shooting. The image pickup apparatus is originally provided with a scaling unit that performs zooming of the subject image by changing the distance between the lens groups of the imaging optical system M. In the image zooming area of the zooming means, there is a zooming area for photographing a circumferential image on the wide angle side, and a zooming area for photographing a diagonal image is provided on the telephoto side.

  Preferably, the objective optical system L includes a front lens group having negative refractive power, which is composed of two negative lenses each having a strong concave surface on the image side in order from the object side. To reduce the occurrence of astigmatism. The objective optical system L is a rear lens having a positive refractive power composed of a cemented lens having a positive refractive power and a convex lens, the whole of which a positive lens negative lens is cemented in order from the object side with an air gap therebetween. Have a group.

  The field lens group F includes a positive lens having a convex shape on the object side in order from the object side and a negative lens having a concave shape on the object side with an air gap in between. After the incident light is deflected by the positive lens, the negative lens on the image side corrects the spherical aberration. As a result, the light emitted from the field lens group becomes near-parallel light, and it is possible to prevent peripheral vignetting of an image that is re-imaged through the relay lens group.

  The correction lens group H preferably has a doublet in which a positive lens and a negative lens are combined in order to suppress the occurrence of chromatic aberration.

  Numerical Example 1 is an example in which the afocal optical system AT is mounted on a two-group moving imaging optical system M. Numerical Example 2 is an example in which the afocal optical system AT of this example is mounted on a four-group moving imaging optical system M. Table 1 shows the values of the variables constituting the mathematical formulas 2 and 4 in the respective attachment optical systems of the numerical examples 1 and 2.

  In each numerical example, Ri is the i-th lens thickness and air interval in order from the object side, and Ni and νi are the refractive index and Abbe number of the glass of the i-th lens arranged in order from the object side. The aspheric coefficients K, A, B, C, and D give the aspheric shape by the following formula. Where X is the amount of displacement in the direction from the lens apex optical axis, H is the distance from the optical axis, and R is the radius of curvature.

(Numerical example 1)
Image sensor dimensions Long side (HL): 5.71 x Short side (VL): 4.28 mm
f = 0.95 to 2.23 Fno = 3.28 to 5.80
(F = 5.94 to 14.04 Fno = 3.28 to 5.59 2ω = 62.0 ° to 28.5 on the 17th to 27th surfaces)
R 1 = 7.066 D 1 = 0.80 N 1 = 1.77250 ν 1 = 49.6
R 2 = 2.806 D 2 = 1.80
R 3 = 12.997 D 3 = 0.60 N 2 = 1.69680 ν 2 = 55.5
R 4 = 2.122 D 4 = 4.28
R 5 = -5.902 D 5 = 1.50 N 3 = 1.48749 ν 3 = 70.2
R 6 = -1.313 D 6 = 0.50 N 4 = 1.84666 ν 4 = 23.9
R 7 = -2.125 D 7 = 0.15
R 8 = 22.407 D 8 = 1.40 N 5 = 1.48749 ν 5 = 70.2
R 9 = -5.431 D 9 = 6.25
R10 = 6.089 D10 = 2.50 N6 = 1.60311 ν6 = 60.6
R11 = −5.489 D11 = 0.50 N 7 = 1.84666 ν 7 = 23.9
R12 = -32.918 D12 = 9.81
R13 = 10.223 D13 = 0.80 N 8 = 1.84666 ν 8 = 23.9
R14 = 8.095 D14 = 0.25
R15 = 13.810 D15 = 1.80 N 9 = 1.77250 ν 9 = 49.6
R16 = -11.457 D16 = variable
* R17 = 89.080 D17 = 1.00 N10 = 1.85300 ν10 = 41.0
* R18 = 3.651 D18 = 1.15
R19 = 6.879 D19 = 1.50 N11 = 2.00330 ν11 = 28.3
R20 = 22.911 D20 = variable
* R21 = 3.146 D21 = 2.30 N12 = 1.48749 ν12 = 70.2
R22 = -11.076 D22 = 0.20
R23 = 16.212 D23 = 0.90 N13 = 1.82114 ν13 = 24.1
* R24 = 5.301 D24 = 0.70
R25 = Aperture D25 = Variable
R26 = ∞ D26 = 1.70 N14 = 1.51633 ν14 = 64.1
R27 = ∞
Focal length 0.95 1.35 2.23
(Focal length of 17-27 surfaces 5.94 8.45 14.04)
Variable interval -----------------------------------------
D16 2.00 4.07 3.65
D20 9.14 5.21 1.49
D25 6.65 8.51 12.65
Aspheric coefficient
17th page: K = 0.00000e + 000 A = 0.000000 + 000 B = -4.60564e-004
C = 2.14338e-005 D = 1.63593e-007 E = -1.78694e-008
18th side: K = -1.33788e + 000 A = 0.000000e + 000 B = 9.90444e-004
C = 3.01472e-005 D = 1.78011e-006 E = -1.14335e-007
21st surface: K = 6.76779e-002 A = 0.00000e + 000 B = -1.95399e-003
C = -1.47877e-004 D = -1.22905e-005 E = -3.07398e-006
Twenty-fourth surface: K = 1.39106e-001 A = 0.00000e + 000 B = 5.46066e-003
C = 9.85838e-004 D = -4.10843e-005 E = 1.79299e-005
FIG. 2 is an optical path diagram of an imaging apparatus in which the afocal optical system AT represented by the first to sixteenth surfaces is mounted on the object side of the imaging optical system M represented by the seventeenth to twenty-seventh surfaces in the numerical example 1. It is. In FIG. 2, a circumferential image state 1 is a state in which the imaging optical system M is in the wide-angle end state and a circumferential image is formed on the image sensor surface. The circumferential image state 2 is a state in which the variable magnification state of the imaging optical system M is set to an intermediate position such that the short side length of the imaging element and the diameter of the circumferential image are substantially equal. The diagonal image state is a state in which imaging is performed with the diagonal length of the image sensor and the diameter of the circumferential image being substantially equal. FIG. 3 is an aberration diagram in the circumferential image state 1, FIG. 4 is an aberration diagram in the circumferential image state 2, and FIG. 5 is an aberration diagram in the diagonal image state, and has good optical characteristics.

  As shown in FIG. 2, the afocal optical system AT includes an objective optical system L, a field lens group F, and a correction lens group H in order from the object side. The objective optical system L includes a front lens unit B1 having a negative refractive power and a rear lens unit B2 having a positive refractive power, and has a positive refractive power as a whole. The field lens group F is disposed near the imaging position of the objective optical system L and has a positive refractive power. The correction lens group H has a positive refractive power and has a function of focusing an aerial image formed by the objective optical system L on the position of the imaging plane IP of the imaging optical system M. SP is an iris diaphragm, FIL is a filter such as an infrared cut or low pass, and IP is an image plane.

  The imaging optical system M is a variable magnification optical system, and the imaging apparatus has a variable magnification unit that performs variable magnification of a subject image. FIG. 6 shows optical path diagrams of the focal length regions at the wide-angle end, the middle, and the telephoto end of the imaging optical system M, and FIGS. 7, 8, and 9 show aberration diagrams in the respective variable magnification regions. As shown in these drawings, the imaging optical system M can perform general photographing with good image quality by itself and has sufficiently small distortion.

  As shown in FIGS. 1B and 2, the imaging optical system M has a two-group configuration including a negative lens group MB1 and a positive lens group MB2 in order from the object side. The imaging optical system M has a variable magnification structure that does not cause focal point movement even during variable magnification by changing the relative distance between the negative lens group MB1 and the positive lens group MB2 and changing the position from the imaging plane IP. .

Further, the image pickup apparatus originally includes a focus adjustment unit (focus function) that adjusts the focus by moving the lens group of the imaging optical system M in the optical axis direction. The afocal optical system can be focused even if the object distance changes from infinity to the closest position near the lens surface position closest to the object side of the afocal optical system by using the focus adjusting means. Since the afocal optical system does not require a dedicated focus mechanism (lens group moving mechanism), the image pickup apparatus can be reduced in size. In FIG. 2, the focus adjusting means is indicated by Focus, and the focusing action is performed by moving the lens group MB1 in the optical axis direction.
(Numerical example 2)
Image sensor dimensions Long side (HL): 7.52 x short side (VL): 5.64 mm
f = 0.80-3.75 Fno = 2.88-4.90
(F = 7.62 to 35.53 Fno = 2.88 to 4.90 2ω = 63.3 ° to 15.1 ° on the 18th to 36th surfaces)
R 1 = 15.439 D 1 = 1.20 N 1 = 1.77250 ν 1 = 49.6
R 2 = 8.892 D 2 = 3.93
R 3 = 45.734 D 3 = 1.20 N 2 = 1.69680 ν 2 = 55.5
R 4 = 6.469 D 4 = 16.78
R 5 = -42.355 D 5 = 4.17 N 3 = 1.48749 ν 3 = 70.2
R 6 = -6.265 D 6 = 0.80 N 4 = 1.84666 ν 4 = 23.9
R 7 = -9.462 D 7 = 0.20
R 8 = 49.361 D 8 = 2.50 N 5 = 1.48749 ν 5 = 70.2
R 9 = -19.515 D 9 = 26.66
R10 = 21.284 D10 = 5.50 N 6 = 1.60311 ν 6 = 60.6
R11 = -70.473 D11 = 1.93
R12 = -18.401 D12 = 1.40 N 7 = 1.77250 ν 7 = 49.6
R13 = -35.756 D13 = 70.04
R14 = 46.332 D14 = 1.50 N8 = 1.84666 ν8 = 23.9
R15 = 42.173 D15 = 1.01
R16 = 132.191 D16 = 3.00 N9 = 1.69680 ν9 = 55.5
R17 = -64.052 D17 = variable
R18 = 25.758 D18 = 0.97 N10 = 1.84666 ν10 = 23.9
R19 = 18.488 D19 = 3.45 N11 = 1.69680 ν11 = 55.5
R20 = 206.825 D20 = variable
R21 = 28.479 D21 = 0.70 N12 = 1.88300 ν12 = 40.8
R22 = 6.693 D22 = 3.41
R23 = -21.529 D23 = 0.65 N13 = 1.69680 ν13 = 55.5
R24 = 20.660 D24 = 0.65
R25 = 14.781 D25 = 1.94 N14 = 1.84666 ν14 = 23.9
R26 = -990.152 D26 = variable
R27 = Aperture D27 = 0.86
* R28 = 7.941 D28 = 2.48 N15 = 1.58313 ν15 = 59.4
* R29 = -24.952 D29 = 0.22
R30 = 5.513 D30 = 1.72 N16 = 1.48749 ν16 = 70.2
R31 = 10.653 D31 = 0.86 N17 = 1.84666 ν17 = 23.9
R32 = 4.204 D32 = Variable
R33 = 10.934 D33 = 2.15 N18 = 1.58313 ν18 = 59.4
R34 = 53.668 D34 = variable
R35 = ∞ D35 = 2.15 N19 = 1.51633 ν19 = 64.1
R36 = ∞
Focal length 0.80 2.11 3.75
(Focal distance of 18-36 surfaces 7.62 19.99 35.53)
Variable interval ------------------------------------
D17 22.14 10.83 5.00
D20 0.43 13.78 17.54
D26 14.03 5.43 2.01
D32 7.75 12.08 20.61
D34 2.15 3.19 1.35
Aspheric coefficient
28th surface: K = -2.51604e-001 A = 0.000000 + 000 B = -9.78818e-005
C = 2.38159e-006 D = 2.80967e-007 E = 0.000000 + 000
Side 29: K = 9.03719e + 000 A = 0.00000e + 000 B = 2.77596e-004
C = 4.38159e-006 D = 3.26865e-007 E = 0.00000e + 000
FIG. 10 is an optical path diagram of an imaging apparatus in which the afocal optical system AT represented by the first to 17th surfaces is mounted on the object side of the imaging optical system M represented by the 18th to 36th surfaces in Numerical Example 2. It is. The configuration of the afocal optical system AT is the same as that of Numerical Example 1. The signs such as SP and the state such as the circumferential image state 1 are the same as in FIG. FIG. 11 is an aberration diagram of the circumferential image state 1, FIG. 12 is an aberration diagram of the circumferential image state 2, and FIG. 13 is an aberration diagram of the diagonal image state, and has good optical characteristics.

  The imaging optical system M is a variable magnification optical system, and the imaging apparatus has a variable magnification unit that performs variable magnification of a subject image. FIG. 14 shows optical path diagrams of the focal length regions at the wide-angle end, the middle, and the telephoto end of the imaging optical system M, and FIGS. 15, 16, and 17 show aberration diagrams in the respective variable magnification regions. As shown in these drawings, the imaging optical system M can perform general photographing with good image quality by itself and has sufficiently small distortion.

  As shown in FIG. 14, the imaging optical system M has a four-group configuration including a positive lens group MB1, a negative lens group MB2, a positive lens group MB3, and a positive lens group MB4 in order from the object side. The imaging optical system M performs a zooming operation by changing the distance between the lens groups, and at the same time, moves the lens groups so that the position of the imaging plane IP does not change. In addition, the imaging optical system M includes a focus adjusting unit Focus as in the first numerical embodiment, and performs a focusing action by moving the lens group MB4 in the optical axis direction.

  The value of θ is an angle with respect to the optical axis of the light beam emitted from the afocal optical system when the light beam incident at the maximum angle of view at the intermediate position in the variable magnification region of each numerical example.

  The imaging device can be applied to imaging a subject.

AT afocal optical system L objective optical system B1 front lens group B2 rear lens group F field lens group H correction lens group M imaging optical system

Claims (4)

An imaging optical system that functions as a variable magnification optical system and an imaging device that photoelectrically converts a subject image formed by the imaging optical system, and that changes an imaging angle of view to a wide angle on the object side of the imaging optical system An imaging device configured to be detachable from an optical system,
The imaging optical system includes an objective optical system having a positive refractive power as a whole on the object side, and an axial light beam having a positive refractive power disposed closer to the photographing optical system than the objective optical system. A correction lens group for collimating
The imaging optical system forms an image twice with the photographing optical system,
The maximum emission angle of the light beam emitted from the imaging optical system is θ, the lengths of the short and long sides of the effective imaging area of the image sensor are VL and HL, and the focal length of the wide angle end of the imaging optical system is fw. When the focal length of the telephoto end of the photographing optical system is ft,
0 <fw · | tan θ | ≦ 0.5 · VL,
0 <0.5 · (VL ² + HL ² ) ^1/2 ≦ ft · | tan θ |
An imaging device characterized by satisfying the above.   The imaging apparatus according to claim 1, wherein the imaging optical system further includes a field lens group having a positive refractive power between the objective optical system and the correction lens group.   The field lens group includes a positive lens having a convex shape on the object side and a negative lens having a concave shape on the object side with an air gap in order from the object side. Imaging device. An imaging optical system that includes an imaging optical system and an afocal optical system that is detachably disposed on the object side of the imaging optical system and changes the imaging angle of view to a wide angle;
An image sensor that photoelectrically converts the subject image;
A zooming unit that zooms the subject image by changing an interval between lens groups of the imaging optical system;
Have
The afocal optical system includes an objective optical system having a positive refractive power as a whole on the object side, and a correction lens group having a positive refractive power closer to the imaging optical system than the objective optical system. ,
The maximum emission angle of light emitted from the afocal optical system is θ, the lengths of the short and long sides of the effective imaging area of the image sensor are VL and HL, and the focal length of the wide-angle end of the imaging optical system is fw, where ft is the focal length of the telephoto end of the imaging optical system,
0 <fw · | tan θ | ≦ 0.5 · VL,
0 <0.5 · (VL ² + HL ² ) ^1/2 ≦ ft · | tan θ |
An imaging device characterized by satisfying the above.