JP6727795B2 - Imaging device and imaging system having the same - Google Patents

Description

The present invention relates to an image pickup apparatus and an image pickup system having the same, and is suitable for obtaining an image with a wide field of view such as omnidirectional shooting and panoramic shooting.

Conventionally, super wide-field optics such as omnidirectional optics, panoramic imaging optics, and fisheye optics have been used in various fields such as surveillance, remote control, video conferencing, medical endoscopes, and scientific surveying. ing. In such a field, it is required to have a wide imaging field of view (wide angle of view) and at the same time have high optical performance. As an optical system having a wide angle of view and high optical performance, an optical system including a front group having a negative refracting power, an aperture stop, and a rear group having a positive refracting power in order from the object side to the image side is known (Patent Document 1). 1).

As a method for obtaining a captured image with an ultra-wide field of view, there is known a technique for joining a plurality of images from a captured image obtained by a plurality of optical systems by a method such as pattern matching. At that time, if the entrance pupil positions of the optical systems forming the image pickup apparatus are different, parallax occurs between the picked-up images, and a shift occurs when joining the images. There is known an imaging device configured to reduce parallax between captured images between the optical systems of such an imaging device (Patent Documents 2 and 3).

Generally, when a plurality of optical systems are arranged on one plane, the image pickup device becomes large. Therefore, in order to reduce the parallax between captured images and reduce the size of the entire image pickup apparatus, the refractive power arrangement of the optical system and the lens configuration are appropriately set, and each optical system is appropriately arranged. Will be required.

As an omnidirectional imaging optical system, an optical system with an imaging angle of view of 180° or more in which, in order from the object side to the image side, a front group having negative refracting power, a reflecting surface bending the optical axis by 90 degrees, and a rear group having positive refracting power are arranged. An imaging device using two systems is known (Patent Document 4). Patent Document 4 discloses a small-sized image pickup apparatus in which two optical systems are combined so that the object side directions thereof are opposite to each other.

JP, 2004-145256, A JP 2004-184862A JP-A-2002-314867 JP, 2013-25255, A

In Patent Document 1, a cemented lens having a positive refractive power is arranged closest to the image side. When the image height is Y, the focal length of the entire system is f, and the half angle of view is ω, a central projection method with Y=f×tan(ω) as the ideal image height is used to obtain a good optical angle with a wide angle of view. Has gained performance. In the image pickup apparatus of Patent Document 2, a plurality of image pickup sections having an optical system (lens front lens) and an image pickup element are radially arranged. Then, the refracting power of the lenses forming the optical system is set so that the position of the entrance pupil of each optical system is behind the image sensor. The imaging device arranges a plurality of optical systems concentrically around the entrance pupil position to reduce the deviation of the entrance pupil position between the optical systems.

As a result, the parallax between the picked-up images by the respective optical systems is reduced, and when the picked-up image with a wide field of view is obtained by the image combination, the shift of the joint is reduced. However, when the entrance pupil is arranged behind the image sensor, the angle of view of each optical system becomes small, and a large number of optical systems are required to obtain a wide-field imaged image, which increases the size of the entire apparatus.

In Patent Document 3, a plurality of optical systems are provided, and each optical system is provided with a wide air gap near the entrance pupil of the optical system. The plurality of optical systems are arranged such that the entrance pupils of the respective optical systems are coincident with or close to each other and the optical paths of the respective optical systems partially intersect. In this case, the position of the entrance pupil can be arranged in front of the optical system, the angle of view of the optical system can be easily widened, and a wide-field picked-up image can be obtained with a small number of optical systems. However, Patent Document 3 does not show a specific lens configuration of an optical system in which the entrance pupil positions are made to coincide with or close to each other at a wide angle of view and have a wide air gap.

Patent Document 4 discloses a wide-angle lens used in a spherical imaging device. In Patent Document 4, a reflecting member is arranged near the entrance pupil of a wide-angle lens having an imaging field angle of 180° or more. By disposing the two wide-angle lenses with the reflecting member facing each other so that the object side directions are opposite to each other, the parallax between the captured images is reduced and the overall size of the imaging device is reduced.

By the way, in an optical system having an image pickup angle of view of 180° or more, a subject can be projected onto a finite area of an image pickup surface by a special projection method. Due to this feature, it is possible to capture an ultra-wide-field image that cannot be theoretically captured by an image capturing apparatus that captures images using a general central projection (perspective projection) method. However, an optical system based on a special projection method such as a fisheye optical system for capturing an ultra-wide field image inevitably distorts the shape of the subject image in the image obtained as a result of the capturing. In particular, a large amount of shape distortion occurs in the peripheral portion of the image. Therefore, when synthesizing a plurality of images, the deviation of each captured image becomes large.

It is an object of the present invention to provide an image pickup apparatus in which the entire system is small and has a wide angle of view, and it is easy to obtain a high-quality image over the entire screen, and an image pickup system including the image pickup apparatus .

In addition, in the present invention, in an image pickup apparatus including a plurality of optical systems, the displacement of the entrance pupil position when each optical system is arranged is small, and the parallax of the respective picked-up images when the picked-up images obtained by the respective optical systems are joined together. It is an object of the present invention to provide an imaging device in which a good image can be easily obtained with a small number of pixels.

An image pickup apparatus of the present invention is an image pickup apparatus having an optical system and an image pickup element that receives an image formed by the optical system,
The optical system includes a first lens group having negative refracting power arranged on the object side and a positive refracting power arranged on the image side, with the largest interval among the intervals on the optical axis of adjacent lenses as a boundary. Consisting of the second lens group of
The distance between the first lens group and the second lens group is L, the focal length of the first lens group is f1, the focal length of the second lens group is f2, the focal length of the optical system is f, and the imaging device is Let IH be half the length of the diagonal line of X, and X be the distance on the optical axis from the front principal point position of the first lens group to the object-side lens surface of the most object-side lens of the second lens group. When
−0.60<f1/L<−0.10
3.20<L/f<5.50
1.2<f2/IH<2.6
3.50<X/f<5.50
It is characterized by satisfying the following conditional expression.
Another imaging device of the present invention is an imaging device having an optical system and an imaging element that receives an image formed by the optical system,
The optical system includes a first lens group having negative refracting power arranged on the object side and a positive refracting power arranged on the image side, with the largest interval among the intervals on the optical axis of adjacent lenses as a boundary. Consisting of the second lens group of
The second lens group includes a front lens group having a positive refractive power that is immovable during focusing, a focus lens group that moves during focusing, and a rear lens group that does not move during focusing, which are sequentially arranged from the object side to the image side.
The distance between the first lens group and the second lens group is L, the focal length of the first lens group is f1, the focal length of the second lens group is f2, the focal length of the optical system is f, and the imaging device is When IH is half the length of the diagonal of
−0.60<f1/L<−0.10
3.20<L/f<5.50
1.2<f2/IH<2.6
It is characterized by satisfying the following conditional expression.
Another imaging device of the present invention is an imaging device having an imaging element that receives an image formed by the optical system,
The optical system includes a first lens group having negative refracting power arranged on the object side and a positive refracting power arranged on the image side, with the largest interval among the intervals on the optical axis of adjacent lenses as a boundary. Consisting of the second lens group of
The first lens group is composed of one negative lens,
The distance between the first lens group and the second lens group is L, the focal length of the first lens group is f1, the focal length of the second lens group is f2, the focal length of the optical system is f, and the imaging device is When IH is half the length of the diagonal of
−0.60<f1/L<−0.10
3.20<L/f<5.50
1.2<f2/IH<2.6
It is characterized by satisfying the following conditional expression.

An image pickup system of the present invention has a plurality of image pickup devices, and an optical system included in the plurality of image pickup devices is provided at a point on the optical axis between the first lens group and the second lens group of each optical system. It is characterized in that the optical axes of the respective optical systems are arranged so as to intersect each other.

INDUSTRIAL APPLICABILITY The present invention can provide an image pickup apparatus and an image pickup system including the same, in which an entire system is small and has a wide angle of view, and it is easy to obtain a high-quality image over the entire screen.

In addition, in the present invention, in an image pickup apparatus including a plurality of optical systems, the displacement of the entrance pupil position when each optical system is arranged is small, and the parallax of the respective picked-up images when the picked-up images obtained by the respective optical systems are joined together. It is possible to obtain an image pickup device in which a good image can be easily obtained with a small number of pixels.

Lens cross-sectional view of Example 1 upon focusing on an object at infinity (A), (b) Aberration diagrams of Example 1 when focused on an object at infinity and at an object distance of 1.0 m. Lens cross-sectional view of Example 2 upon focusing on an object at infinity (A), (b) Aberration diagrams of Example 2 when focusing on an object at infinity and at an object distance of 1.0 m. Lens cross-sectional view of Example 3 upon focusing on an object at infinity (A), (b) Aberration diagrams of Example 3 for focusing on an object at infinity and focusing on an object distance of 1.0 m. Lens cross-sectional view of Example 4 upon focusing on an object at infinity (A), (b) Aberration diagrams of Example 4 when focusing on an object at infinity and at an object distance of 1.0 m. Schematic diagram of main parts in the horizontal direction of the image pickup apparatus of the present invention Schematic diagram of a main part of an image pickup apparatus of the present invention in a vertical direction

Examples of the optical system used in the image pickup apparatus of the present invention will be described below. FIG. 1 is a lens cross-sectional view of the optical system of Example 1 when focusing on an object at infinity. FIG. 2A is an aberration diagram of the first embodiment upon focusing on an infinitely distant object. FIG. 2B is an aberration diagram of Example 1 when the object distance is 1.0 m. Here, the object distance is the distance from the image plane when the numerical data described later is expressed in mm. This is the same hereafter.

FIG. 3 is a lens sectional view of the optical system of Example 2 when an object at infinity is in focus. FIG. 4A is an aberration diagram of Example 2 when an object at infinity is in focus. FIG. 4B is an aberration diagram of Example 2 when the object distance is 1.0 m. FIG. 5 is a lens cross-sectional view of Example 3 when focused on an object at infinity. FIG. 6A is an aberration diagram of Example 3 when an object at infinity is in focus. FIG. 6B is an aberration diagram of Example 3 when the object distance is 1.0 m.

FIG. 7 is a lens cross-sectional view of Example 4 when focused on an object at infinity. FIG. 8A is an aberration diagram of Example 4 when an object at infinity is in focus. FIG. 8B is an aberration diagram of Example 4 when the object distance is 1.0 m. FIG. 9 is an example of a horizontal arrangement diagram of a plurality of optical systems that make up the image pickup apparatus of the present invention. FIG. 10 is an example of a vertical layout diagram of a plurality of optical systems that constitute the image pickup apparatus of the present invention.

In the lens cross-sectional views of FIGS. 1, 3, 5, and 7, the left side is the object side and the right side is the image side. L0 is an optical system. L1 represents the first lens group, and L2 represents the second lens group. FL is a focus group. SP is an aperture stop and IP is an image plane. When the optical system is used in a video camera, a digital still camera or the like, the image plane corresponds to the image pickup surface of an image pickup element (photoelectric conversion element) such as a CCD sensor or a CMOS sensor.

When the optical system is used in a silver salt film camera, the image plane corresponds to the film plane. The image taken on the film may be read into the image processing apparatus and image combination processing may be performed. The arrow relating to the focus indicates the moving direction during focusing.

In the spherical aberration diagram, Fno is an F number. Further, d is a d-line (wavelength 587.6 nm) and g is a g-line (wavelength 435.8 nm). In the astigmatism diagram, M is the meridional image plane at the d-line, and S is the sagittal image plane at the d-line. The distortion diagram shows the d-line. The lateral chromatic aberration diagram shows the g-line with respect to the d-line. ω is a half angle of view (degree).

The optical system according to the present invention (hereinafter also referred to as the “optical system of the present invention”) employs an equidistant projection method as a projection method. Here, the equidistant projection method means that when the focal length of the optical system is f, the image pickup angle of view is θ (radian), and the size of the image is y,
y=f·θ
Is a projection method. Therefore, the distortion diagram shows the deviation from the ideal image height in the equidistant projection method.

The image pickup apparatus of the present invention obtains one image having a super wide field of view such as a panoramic image or an omnidirectional image by combining images from a plurality of picked-up images obtained by a plurality of optical systems. It is known that images are stitched together by pattern matching or the like in image synthesis. However, if the entrance pupil positions of the optical systems are different, parallax occurs and a shift occurs at the stitched positions. In order to reduce the parallax, it is necessary to bring the positions of the entrance pupils close to each other between a plurality of optical systems to perform imaging. As a method thereof, Patent Document 4 proposes a method in which two imaging optical systems having an ultra-high field angle of 180° or more are arranged such that the lens surfaces on the object side are in opposite directions.

However, in an optical system with an image pickup angle of view of 180° or more, the image distortion due to the projection method becomes large around the screen, and it becomes difficult to combine the images. Further, in Patent Document 4, a reflecting member is used in the optical system to bring the entrance pupil closer, but in an optical system having an imaging angle of view of 180°, the position of the entrance pupil is too close to the object side, and the parallax shift becomes large. Further, in order to achieve high optical performance, it is necessary to dispose many negative lenses particularly on the object side of the image pickup optical system, which tends to increase the size of the optical system.

Next, the image pickup apparatus of the present invention will be described. The image pickup apparatus of the present invention has a plurality of optical systems. The plurality of optical systems are arranged such that the optical axes of the optical systems intersect each other at a point on the optical axis between the first lens group and the second lens group of each optical system.

Specifically, in the image pickup apparatus of the present invention, in order to obtain a horizontal image pickup angle of 360°, as shown in FIG. 9, three optical systems L0 are arranged at equal angular intervals in the horizontal direction. Each optical system L0 has an image pickup angle of view of 120° or more in the horizontal direction of the image pickup surface, a wide air gap is provided near the incident position of the optical system L0, and three optical systems L0 are located at the positions of the air gaps. Are arranged so that the optical axes intersect with each other with the optical axis shifted by 120° in the horizontal direction.

As a result, the entrance pupil can be brought closer, and a captured image with less parallax can be obtained. By using the three optical systems L0, the imaging angle of view of each optical system L0 also becomes small, the image distortion due to the projection method in the peripheral portion of the screen can be reduced, and the image distortion at the time of image combination can be reduced. ..

However, by using three optical systems, it becomes difficult to reduce the size of the entire system by using a reflecting member as in Reference 4, and the size of the entire image pickup apparatus increases. In particular, if the size of the image pickup device is increased to improve image quality, the size of the entire image pickup device tends to increase. In order to reduce the size of the entire image pickup apparatus, it is necessary to optimally arrange the refracting power of each optical system L0 and appropriately arrange so that the entrance pupil position of each optical system L0 approaches. Therefore, the optical system L0 of the present invention is constructed as follows.

In the optical system L0 of the present invention, the largest distance among the distances between the adjacent lenses on the optical axis serves as a boundary.
It is composed of a first lens group having a negative refractive power arranged on the object side and a second lens group having a positive refractive power arranged on the image side . The lens distance between the first lens group and the second lens group is L, the focal length of the first lens group L1 is f1, and the focal length of the optical system is f. At this time,
−0.60<f1/L<−0.10 (1)
3.20<L/f<5.50 (2)
Satisfies the conditional expression

Next, the technical meanings of the above conditional expressions will be described. FIG. 9 is an explanatory diagram when each member interferes when a plurality of optical systems L0 of the present invention are arranged so that the optical axes of the plurality of optical systems L0 intersect on a plane.

In the region A in FIG. 9, the off-axis light beam La that passes through the first lens unit L1a having a negative refractive power and enters the second lens unit L2a having a positive refractive power is the second lens unit L2b of the other optical system L0. It shows a region that may interfere with the lens and the lens barrel. Further, in FIG. 9, a region B shows a region where the light flux Lc incident on the first lens unit L1c may interfere with the imaging surface IPb. In particular, when the image pickup device is made large for high image quality, interference easily occurs. Conditional expressions (1) and (2) are expressions for reducing the interference at this time and achieving high performance by downsizing the entire system.

If the negative refractive power of the first lens unit L1 is strong (the absolute value of the negative refractive power is large), it becomes easier to bring the off-axis light flux after passing through the first lens unit L1 closer to the optical axis, and It becomes easy to reduce the interference between the external light flux and the second lens unit L2 of the other optical system. Further, it is possible to reduce the interference by widening the air space between the lens groups, but the optical system L0 becomes large. Therefore, in order to reduce the interference while reducing the size of the optical system L0, it is necessary to appropriately arrange the negative refractive power of the first lens unit L1 with respect to the air gap.

If the upper limit of conditional expression (1) is exceeded and the negative refractive power of the first lens unit L1 becomes too strong, interference will be reduced, but a large amount of field curvature will occur, making it difficult to maintain high optical performance. Becomes If the number of lenses of the first lens unit L1 is increased in order to achieve high optical performance, the effective diameter of the front lens becomes large and interference easily occurs. When the negative refracting power of the first lens unit L1 becomes weaker than the lower limit of conditional expression (1) (when the absolute value of the negative refracting power becomes small), the light ray passing through the first lens unit L1 is deviated from the optical axis. Since they are separated, interference with the second lens group of another optical system is likely to occur.

Preferably, the numerical range of conditional expression (1) is set as follows.
-0.55<f1/L<-0.15 (1a)
More preferably, the numerical range of conditional expression (1a) is set as follows.
-0.50<f1/L<-0.20... (1b)

Conditional expression (2) is for downsizing the optical system L0. When the maximum air gap becomes longer than the upper limit value of the conditional expression (2), when the plurality of optical systems L0 are arranged, the interference between the optical systems L0 becomes small but the optical system L0 becomes large. When the maximum air gap becomes shorter than the lower limit value of the conditional expression (2), interference is likely to occur between the optical systems L0 when the plurality of optical systems L0 are arranged.

Preferably, the numerical range of conditional expression (2) is set as follows.
3.25<L/f<5.00 ··· (2a)
With the above configuration, it is possible to obtain an optical system in which the entire system is small, has a wide angle of view, high performance, and a plurality of optical systems can be easily arranged to intersect each other near the entrance pupil position.

In the optical system of the present invention, it is more preferable to satisfy at least one of the following conditional expressions. The distance on the optical axis from the front principal point position of the first lens unit L1 to the object-side lens surface of the most object-side lens of the second lens unit L2 is X.

Let T be the distance from the most object-side lens surface of the optical system L0 to the entrance pupil position of the optical system L0. Let P be the point at which the optical axis intersects the perpendicular line drawn from the effective diameter position of the light beam on the lens surface closest to the image side of the first lens unit L1 to the optical axis. The distance on the optical axis from the point P to the lens surface of the first lens unit L1 closest to the object side is DL1 (see FIG. 1 above).

At this time, it is preferable to satisfy at least one of the following conditional expressions.
3.50<X/f<5.50 (3)
0.50<T/DL1<2.50 (4)
Next, the technical meanings of the above conditional expressions will be described.

Conditional expression (3) is for reducing the size of the entire system while reducing the interference between the respective optics when arranging the plurality of optical systems. If the lower limit of conditional expression (3) is exceeded, the effective diameter of the first lens unit L1 can be reduced, but the air gap becomes too short, and interference between the respective optics is likely to occur. If the air gap becomes longer than the upper limit of the conditional expression (3), the effective diameter of the first lens unit L1 becomes too large, and the optical system becomes large.

Preferably, the numerical range of conditional expression (3) is set as follows.
3.75<X/f<5.25 (3a)
More preferably, the numerical range of conditional expression (3a) is set as follows.
4.00<X/f<5.00 (3b)

Conditional expression (4) relates to the position of the entrance pupil of the optical system L0 and is intended to reduce the size of the image pickup apparatus when applied to the image pickup apparatus. When the value goes below the lower limit of the conditional expression (4), the entrance pupil position is located too far in front of the first lens unit L1, so that a large parallax occurs between the plurality of optical systems L0, which causes a problem in image combination. When the upper limit of conditional expression (4) is exceeded, the parallax between the optical systems L0 decreases, but the effective diameter of the front lens of the optical system L0 increases. Alternatively, the angle of view of each optical system L0 becomes small, the number of optical systems L0 required for the image pickup apparatus increases, and the overall size increases. Preferably, the numerical range of conditional expression (4) is set as follows.

0.65<T/DL1<2.00 (4a)
More preferably, the numerical range of conditional expression (4a) is set as follows.
0.80<T/DL1<1.50 (4b)

In each of the embodiments, the second lens unit L2 is a front lens unit (front lens unit) that is arranged in order from the object side to the image side and has a positive refractive power that does not move during focusing, a focus lens unit that moves during focusing, and a rear lens unit that does not move during focusing. (Rear group).

As described above, in each embodiment, focusing is performed by a part of the lenses forming the second lens unit L2. This is because when focusing is performed by a lens on the object side of the entrance pupil, the position of the entrance pupil varies greatly depending on the object distance, and when a wide-field image is combined, the image shift increases.

In the present invention, it is preferable that the first lens unit L1 having a negative refractive power be composed of one negative lens. When a positive lens is arranged in the first lens group L1, the effective diameter of the first lens group L1 becomes large, and interference with the second lens group of another optical system is likely to occur. The first lens unit L1 may be composed of two negative lenses, which facilitates aberration correction when a wide angle of view is achieved.

The image pickup apparatus of the present invention includes an optical system L0 and an image pickup element that receives an image formed by the optical system L0. IH is half the length of the diagonal line of the image sensor. The focal length of the second lens unit L2 is f2.

At this time, it is preferable to satisfy at least one of the following conditional expressions.
-1.40<f1/IH<-0.40 (5)
1.2<f2/IH<2.6 (6)

Next, the technical meanings of the above conditional expressions will be described.
The conditional expression (5) is to obtain high optical performance while reducing the interference of each element and achieving miniaturization of the entire system, together with the conditional expression (1) described above.

If the negative refractive power of the first lens unit L1 becomes too strong beyond the upper limit of the conditional expression (5), the optical performance deteriorates as described above. If the lower limit of conditional expression (5) is exceeded and the negative refractive power of the first lens unit L1 becomes too weak, interference easily occurs.

The numerical range of conditional expression (5) is preferably set as follows.
−1.38<f1/IH<−0.50 (5a)
More preferably, the numerical range of conditional expression (5) is set as follows.
−1.35<f1/IH<−0.60 (5b)

Conditional expression (6) is for obtaining high optical performance while achieving downsizing of the entire system. If the lower limit of conditional expression (6) is exceeded and the positive refractive power of the second lens group becomes too strong, spherical aberration and coma will increase, making it difficult to obtain high optical performance. If the upper limit of conditional expression (6) is exceeded and the positive refractive power of the second lens unit L2 becomes too weak, the total lens length becomes long and the image pickup apparatus becomes large.

Preferably, the numerical range of conditional expression (6) is set as follows.
1.25<f2/IH<2.50 (6a)
More preferably, the numerical range of conditional expression (6a) is set as follows. 1.30<f2/IH<2.35 (6b)
In addition, the numerical range of conditional expression (6) may be set as follows.
1.2<f2/IH<2.50 (6c)

As described above, according to the present invention, in the image pickup apparatus including a plurality of optical systems, the deviation of the entrance pupil position of each optical system L0 is small, and it is possible to obtain a small size, high performance, and a wide angle of view. ..

Next, the lens configuration of each lens group of each example will be described. Hereinafter, it is assumed that the lens configurations of the respective lens groups are sequentially arranged from the object side to the image side.

[Example 1]
The first embodiment is an optical system having an imaging field angle of 153.4° and an F number of 4.0. The first lens unit L1 includes a meniscus negative lens having a convex surface directed toward the object side and a meniscus negative lens having a convex surface directed toward the object side. Both lens surfaces of the negative lens closest to the object side are aspherical. The aspherical surface favorably corrects off-axis aberrations such as field curvature and distortion. The second lens unit L2 has a biconvex positive lens that does not move during focusing and an aperture stop SP.

A focus group FL that moves during focusing is provided behind (on the image side). The focus group FL has a cemented lens in which a biconvex positive lens and a meniscus negative lens are cemented, a biconvex positive lens, and a biconcave negative lens and a meniscus positive lens are cemented. Further, it is composed of a cemented lens in which a biconvex positive lens and a biconcave negative lens are cemented.

Behind it is a cemented lens in which a biconvex positive lens that does not move during focusing and a biconcave negative lens are cemented, and a biconvex positive lens. The object-side lens surface of the most image-side positive lens of the second lens unit L2 has an aspherical shape. This aspherical surface favorably corrects off-axis aberrations such as field curvature.

[Example 2]
The second embodiment is an optical system having an image pickup angle of view of 150.2° and an F number of 2.9. The first lens unit L1 includes a meniscus negative lens having a convex surface directed toward the object side. Both surfaces of the meniscus negative lens are aspherical. The aspherical surface favorably corrects off-axis aberrations such as field curvature and distortion. The second lens unit L2 includes a biconvex positive lens that does not move during focusing, and an aperture stop SP.

A focus group FL that moves during focusing is provided behind it. The focus group FL has a cemented lens in which a biconvex positive lens and a meniscus negative lens are cemented, a biconvex positive lens, and a biconcave negative lens and a meniscus positive lens are cemented. Further, it has a cemented lens in which a biconvex positive lens and a biconcave negative lens are cemented.

A meniscus-shaped negative lens having a convex surface facing the object that does not move during focusing and a biconvex positive lens are provided behind it. The image side lens surface of the meniscus negative lens and the image side lens surface of the biconvex positive lens are aspherical. The aspherical surface favorably corrects off-axis aberrations such as field curvature.

[Example 3]
The third embodiment is an optical system having an imaging angle of view of 148.6° and an F number of 4.0. The first lens unit L1 includes a meniscus negative lens having a convex surface facing the object side and a biconcave negative lens. The object-side lens surface of the meniscus negative lens and the object-side lens surface of the biconcave negative lens are aspherical. These aspherical surfaces favorably correct off-axis aberrations such as field curvature and distortion. The second lens unit L2 includes a biconvex positive lens that does not move during focusing, and an aperture stop SP.

A focus group FL that moves during focusing is provided behind it. The focus group FL includes a cemented lens in which a biconvex positive lens and a meniscus negative lens are cemented, a biconvex positive lens, a lens in which a biconcave negative lens and a meniscus positive lens are cemented, and a biconvex lens. It has a positive lens and a biconcave negative lens. Behind it, there is a cemented lens in which a positive biconvex lens that does not move during focusing and a negative meniscus lens are cemented, and a positive lens. Both lens surfaces of this positive lens are aspherical. This aspherical surface favorably corrects off-axis aberrations such as field curvature.

[Example 4]
The fourth embodiment is an optical system having an imaging field angle of 145.0° and an F number of 2.91. The first lens unit L1 includes a meniscus negative lens having a convex surface facing the object side, and a negative lens having a concave lens surface on the object side. Both surfaces of the meniscus negative lens are aspherical. The aspherical surface favorably corrects off-axis aberrations such as field curvature and distortion. The second lens unit L2 has a positive lens and an aperture stop SP that are immobile during focusing and have a convex lens surface on the image side.

A focus group FL that moves during focusing is provided behind it. The focus group FL has a cemented lens in which a biconvex positive lens and a meniscus negative lens are cemented, a biconvex positive lens, and a biconcave negative lens and a meniscus positive lens are cemented. There is. Further, it has a cemented lens in which a biconvex positive lens and a biconcave negative lens are cemented.

A biconvex positive lens that does not move during focusing is provided behind it. Both lens surfaces of the positive lens have an aspherical shape. This aspherical surface favorably corrects off-axis aberrations such as field curvature.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist thereof. Note that in the description of FIG. 9, an image pickup device in which three optical systems L0 are arranged is described as an image pickup device that obtains a wide-field image of 360° in the horizontal direction. You may comprise from the optical system L0 of a stand.

Further, although the description has been given in which the optical axis is displaced by 120° between the respective optical systems L0, it can be arbitrarily changed depending on the angle of view of the optical system L0. Further, although the description has been given of arranging the three optical systems L0 in the horizontal direction, they may be arranged at an angle in the vertical direction from the horizontal plane. Further, although the description has been made regarding the horizontal photographing, as shown in FIG. 10, the horizontal optical system L0H and the vertical optical system L0V are combined with each other to perform the omnidirectional photographing. May be. In FIG. 10, one optical system L0H and one optical system L0V are arranged in the horizontal and vertical directions respectively, but a plurality of optical systems may be arranged.

Hereinafter, specific numerical data of Examples 1 to 4 of the optical system used in the image pickup apparatus will be shown. In each numerical data, i indicates the order of counting from the object side, ri is the radius of curvature of the i-th optical surface (i-th surface), and di is on the axis between the i-th surface and the (i+1)th surface. Indicates the interval. Further, ndi and νdi are the refractive index and Abbe number of the material of the i-th optical member with respect to the d-line, respectively. The aspherical shape is the X axis in the optical axis direction, the H axis in the direction perpendicular to the optical axis, the traveling direction of light is positive, R is the paraxial radius of curvature, K is the conical constant, and A4, A6, A8, A10, and A12 are respectively When the aspherical coefficient is

It is expressed by the formula. * Means a surface having an aspherical shape. "E-x" means ^{10 -x.} BF is an air-equivalent back focus. Table 1 shows the relationship between the above-mentioned conditional expressions and numerical data.

[Numerical data 1]
Unit mm
Surface data Surface number rd nd νd Effective diameter
1* 56.827 1.00 1.76385 48.5 36.21
2* 10.986 7.23 23.20
3 48.773 1.00 1.59522 67.7 22.95
4 16.173 43.67 20.57
5 19.737 2.23 1.59270 35.3 14.26
6 -1244.811 1.95 14.14
7 (Aperture) ∞ (Variable) 13.67
8 12.050 4.40 1.49 700 81.5 13.76
9 -19.732 0.63 1.77250 49.6 13.43
10 -129.912 1.03 13.18
11 34.242 2.20 1.49700 81.5 12.57
12 -32.118 0.15 12.20
13* -198.495 0.63 1.85400 40.4 11.72
14 7.307 2.59 1.49 700 81.5 10.63
15 20.297 0.15 10.66
16 10.861 5.11 1.49700 81.5 10.96
17 -7.398 0.80 1.83481 42.7 10.72
18* 69.169 (variable) 11.48
19 20.723 4.99 1.59270 35.3 12.06
20 -7.719 0.80 1.88300 40.8 12.04
21 24.947 6.35 13.61
22* 2067.479 6.60 1.55332 71.7 21.84
23 -15.258 5.00 23.22
Image plane ∞

Aspherical data First surface
K = 0.00000e+000 A 4=-6.08061e-006 A 6=-1.24220e-008 A 8= 7.93535e-011 A10=-1.65251e-013 A12= 1.34148e-016

Second side
K =-3.21565e-001 A 4= 3.10757e-007 A 6= 8.75689e-008 A 8=-1.50560e-010 A10=-1.58901e-012

Surface 13
K = 0.00000e+000 A 4=-4.30555e-005 A 6= 4.20230e-007 A 8=-8.01783e-010 A10= 3.00523e-011

Surface 18
K = 0.00000e+000 A 4=-4.63316e-005 A 6=-1.40423e-006 A 8=-4.66678e-009 A10=-5.89483e-010

22nd surface
K = 0.00000e+000 A 4= 1.23627e-006 A 6=-1.17636e-007 A 8=-4.26294e-010 A10= 2.66390e-012

Various data

Focal length 10.20
F number 4.00
Half angle of view (degree) 76.7
Image height 13.66
Total lens length 100.00
BF 5.00

Focused at infinity Focused at 1 m
d 7 0.61 0.50
d18 0.89 1.00

Entrance pupil position 11.96
Exit pupil position -50.90
Front principal point position 20.30
Rear principal point position -5.20

Lens group Data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 -11.02 9.23 2.86 -4.61
2 5 29.67 42.10 2.43 -52.14

Single lens Data lens Start surface Focal length
1 1 -18.00
2 3 -41.12
3 5 32.80
4 8 15.78
5 9 -30.19
6 11 33.72
7 13 -8.24
8 14 21.55
9 16 9.76
10 17 -7.97
11 19 10.15
12 20 -6.60
13 22 27.41

[Numerical data 2]
Unit mm
48.97129
Surface data Surface number rd nd νd Effective diameter
1* 146.603 2.00 1.85400 40.4 40.01
2* 13.121 48.97 26.33
3 62.618 1.66 1.64769 33.8 14.23
4 -75.210 1.00 14.56
5 (Aperture) ∞ 1.15 15.22
6 14.285 (Variable) 1.49 700 81.5 17.21
7 -39.420 0.80 1.83481 42.7 17.00
8 -187.242 4.49 16.87
9 25.504 3.42 1.49 700 81.5 15.52
10 -25.487 0.15 15.13
11* -55.997 0.80 1.85400 40.4 14.62
12 9.463 3.26 1.49 700 81.5 13.81
13 27.372 0.15 14.19
14 12.573 5.01 1.59522 67.7 15.84
15 -31.626 0.80 1.90366 31.3 15.60
16 16.185 (Variable) 15.29
17 49.639 1.20 1.58313 59.4 17.34
18* 29.802 2.80 18.15
19 34.145 4.43 1.55332 71.7 24.17
20* -54.944 5.00 24.68
Image plane ∞

Aspherical data First surface
K = 0.00000e+000 A 4=-7.60231e-007 A 6=-6.46800e-011 A 8=-1.31881e-012 A10=-2.98640e-015 A12= 5.70337e-018

Second side
K =-6.66969e-001 A 4= 2.87712e-005 A 6= 1.92622e-008 A 8= 7.22750e-010 A10=-1.52479e-012

Surface 11
K = 0.00000e+000 A 4=-1.03698e-004 A 6=-1.18830e-007 A 8= 1.21543e-009 A10=-1.73718e-012

Surface 18
K = 0.00000e+000 A 4=-6.42176e-005 A 6= 9.50059e-007 A 8=-8.47415e-009 A10= 5.57358e-011

Surface 20
K = 0.00000e+000 A 4= 5.09890e-005 A 6=-6.22674e-007 A 8= 4.60423e-009 A10=-1.43761e-011

Various data

Focal length 10.42
F number 2.90
Half angle of view (degree) 75.1
Image height 13.66
Total lens length 95.00
BF 5.00

Focused at infinity Focused at 1 m
d 6 1.15 1.00
d16 3.10 3.25

Entrance pupil position 13.93
Exit pupil position -27.48
Front principal point position 21.01
Rear principal point position -5.42

Lens group Data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 -16.99 2.00 1.19 0.11
2 3 23.31 39.03 -4.51 -32.61

Single lens Data lens Start surface Focal length
1 1 -16.99
2 3 53.01
3 6 21.75
4 7 -59.96
5 9 26.23
6 11 -9.43
7 12 27.44
8 14 15.78
9 15 -11.75
10 17 -130.81
11 19 38.74

[Numerical data 3]
Unit mm

Surface data Surface number rd nd νd Effective diameter
1* 80.699 1.00 1.76385 48.5 36.04
2 12.800 8.97 23.32
3* -66.337 1.00 1.55332 71.7 22.92
4 42.030 35.38 21.34
5 59.409 1.37 1.59270 35.3 11.66
6 -83.109 0.20 11.71
7 (Aperture) ∞ (Variable) 11.72
8 12.188 3.71 1.49 700 81.5 12.60
9 -34.884 0.63 1.77250 49.6 12.48
10 -862.364 5.94 12.47
11 12.217 3.92 1.49 700 81.5 12.20
12 -17.786 0.29 11.70
13* -17.398 0.63 1.85400 40.4 11.47
14 8.453 3.20 1.43875 94.9 11.14
15 113.748 0.15 11.70
16 14.334 5.18 1.43875 94.9 12.77
17 -10.325 0.15 12.95
18 -11.301 0.80 1.88300 40.8 12.64
19 19.486 (Variable) 13.99
20 48.556 6.54 1.59270 35.3 15.76
21 -10.079 0.80 1.88300 40.8 16.92
22 -22.396 0.15 20.31
23* -139.147 4.18 1.55332 71.7 24.26
24* -38.692 5.25 25.43
Image plane ∞

Aspherical data First surface
K = 0.00000e+000 A 4= 1.75953e-006 A 6= 3.84174e-009 A 8= 1.58863e-012 A10=-2.19310e-015

Third side
K = 0.00000e+000 A 4=-4.18429e-006 A 6= 3.20166e-008 A 8=-4.61206e-010 A10= 9.80443e-013

Surface 13
K = 0.00000e+000 A 4=-1.31951e-004 A 6= 1.29614e-006 A 8=-2.36908e-008 A10= 2.33009e-010

Surface 23
K = 0.00000e+000 A 4= 1.15661e-004 A 6=-9.91467e-008 A 8=-2.46412e-009 A10= 9.02614e-013

Surface 24
K = 0.00000e+000 A 4= 8.28006e-005 A 6=-3.23909e-009 A 8=-2.95562e-009 A10=-2.01462e-012

Various data

Focal length 10.53
F number 4.00
Half angle of view (degree) 74.3
Image height 13.66
Total lens length 92.00
BF 5.25

Focused at infinity Focused at 1 m
d 7 1.22 0.99
d19 1.34 1.57

Entrance pupil position 12.65
Exit pupil position -27.05
Front principal point position 19.75
Rear principal point position -5.27

Lens group Data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 -12.28 10.97 3.13 -5.92
2 5 20.89 40.39 -8.34 -33.54

Single lens Data lens Start surface Focal length
1 1 -20.04
2 3 -46.35
3 5 58.66
4 8 18.66
5 9 -47.08
6 11 15.23
7 13 -6.59
8 14 20.62
9 16 14.62
10 18 -8.00
11 20 14.69
12 21 -21.41
13 23 95.45

[Numerical data 4]
Unit mm

Surface data Surface number rd nd νd Effective diameter
1* 99.465 1.50 1.76385 48.5 42.02
2* 13.117 11.03 27.11
3 -110.200 1.50 1.49700 81.5 26.93
4 ∞ 39.00 26.34
5 -110.923 1.79 1.64769 33.8 14.37
6 -51.350 0.20 15.17
7 (Aperture) ∞ (Variable) 15.71
8 16.600 7.52 1.59522 67.7 18.16
9 -23.656 0.63 1.77250 49.6 17.81
10 -112.302 2.41 17.77
11 14.736 6.67 1.49 700 81.5 16.91
12 -24.609 0.15 15.41
13* -30.690 0.63 1.85400 40.4 15.07
14 10.204 3.49 1.49 700 81.5 13.94
15 76.050 0.15 14.08
16 23.984 5.80 1.49 700 81.5 14.34
17 -10.946 0.80 1.83481 42.7 14.30
18 21.653 (variable) 15.70
19* 52.178 7.27 1.55332 71.7 21.32
20* -25.551 5.34 23.90
Image plane ∞

Aspherical data First surface
K = 0.00000e+000 A 4= 5.75320e-006 A 6=-3.40441e-008 A 8= 6.28497e-011 A10=-5.58284e-014 A12= 1.85945e-017

Second side
K =-8.71392e-001 A 4= 4.82803e-005 A 6= 1.28409e-007 A 8= 7.43289e-011 A10= 3.96598e-013

Surface 13
K = 0.00000e+000 A 4=-8.36386e-005 A 6= 1.86174e-007 A 8= 1.73103e-009 A10=-1.49476e-011

Side 19
K = 0.00000e+000 A 4= 6.29148e-005 A 6=-1.02073e-006 A 8= 1.09313e-008 A10=-5.41860e-011

Surface 20
K = 0.00000e+000 A 4= 8.16195e-005 A 6=-1.96244e-006 A 8= 1.98991e-008 A10=-7.40920e-011

Various data

Focal length 10.80
F number 2.91
Half angle of view (degree) 75.1
Image height 13.66
Total lens length 99.91
BF 5.34

Focused at infinity Focused at 1 m
d 7 0.75 0.50
d18 3.29 3.55

Entrance pupil position 14.86
Exit pupil position -29.28
Front principal point position 22.29
Rear principal point position -5.46

Lens group Data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 -17.50 14.03 1.85 -10.57
2 5 24.07 41.55 -3.99 -33.60

Single lens Data lens Start surface Focal length
1 1 -19.93
2 3 -221.68
3 5 145.89
4 8 17.62
5 9 -38.92
6 11 19.65
7 13 -8.90
8 14 23.30
9 16 16.00
10 17 -8.61
11 19 32.07

L0 optical system L1 first lens group L2 second lens group FL focus group

Claims (10)

An imaging device having an optical system and an imaging element for receiving an image formed by the optical system,
The optical system includes a first lens group having negative refracting power arranged on the object side and a positive refracting power arranged on the image side, with the largest interval among the intervals on the optical axis of adjacent lenses as a boundary. Consisting of the second lens group of
The distance between the first lens group and the second lens group is L, the focal length of the first lens group is f1, the focal length of the second lens group is f2, the focal length of the optical system is f, and the imaging device is Let IH be half of the diagonal length of the first lens group, and X be the distance on the optical axis from the front principal point position of the first lens group to the object side lens surface of the most object side lens of the second lens group. When
−0.60<f1/L<−0.10
3.20<L/f<5.50
1.2<f2/IH<2.6
3.50<X/f<5.50
An image pickup apparatus which satisfies the following conditional expression. The distance on the optical axis from the most object side lens surface of the optical system to the entrance pupil position of the optical system is T, and the optical axis from the effective diameter position of the light beam on the most image side lens surface of the first lens group When the point at which the optical axis intersects the perpendicular line drawn below is defined as point P, and the distance on the optical axis from the point P to the lens surface closest to the object side of the first lens group is DL1,
0.50<T/DL1<2.50
The imaging device according to claim 1, wherein the following conditional expression is satisfied. The second lens group includes a front lens group having a positive refracting power that is stationary during focusing, a focus lens group that moves during focusing, and a rear lens group that does not move during focusing, which are sequentially arranged from the object side to the image side. The imaging device according to claim 1 or 2 . An imaging device having an optical system and an imaging element for receiving an image formed by the optical system,
The optical system includes a first lens group having negative refracting power arranged on the object side and a positive refracting power arranged on the image side, with the largest interval among the intervals on the optical axis of adjacent lenses as a boundary. Consisting of the second lens group of
The second lens group includes a front lens group having a positive refractive power that is immovable during focusing, a focus lens group that moves during focusing, and a rear lens group that does not move during focusing, which are sequentially arranged from the object side to the image side.
The distance between the first lens group and the second lens group is L, the focal length of the first lens group is f1, the focal length of the second lens group is f2, the focal length of the optical system is f, and the imaging device is When IH is half the length of the diagonal of
−0.60<f1/L<−0.10
3.20<L/f<5.50
1.2<f2/IH<2.6
An image pickup apparatus characterized by satisfying the following conditional expression. The image pickup apparatus according to claim 1, wherein the first lens group is composed of one negative lens. An imaging device having an optical system and an imaging element for receiving an image formed by the optical system,
The optical system includes a first lens group having negative refracting power arranged on the object side and a positive refracting power arranged on the image side, with the largest interval among the intervals on the optical axis of adjacent lenses as a boundary. Consisting of the second lens group of
The first lens group is composed of one negative lens,
The distance between the first lens group and the second lens group is L, the focal length of the first lens group is f1, the focal length of the second lens group is f2, the focal length of the optical system is f, and the imaging device is When IH is half the length of the diagonal of
−0.60<f1/L<−0.10
3.20<L/f<5.50
1.2<f2/IH<2.6
An image pickup apparatus which satisfies the following conditional expression. The image pickup apparatus according to claim 1, wherein the first lens group is composed of two negative lenses. -1.40<f1/IH<-0.40
Imaging device according to any one of claims 1 to 7, characterized by satisfying the conditional expression. 1.2<f2/IH<2.50
The imaging apparatus according to any one of claims 1 to 8, characterized in that to satisfy the condition. A plurality of image pickup devices according to any one of claims 1 to 9 are provided, and an optical system included in the plurality of image pickup devices has an optical system between the first lens group and the second lens group of each optical system. An imaging system, wherein the optical axes of the optical systems are arranged so as to intersect with each other at one point on the optical axis.