Stereo lens device and imaging apparatus

Abstract

To reduce a shift in the drive of movable groups in two optical systems in a stereo lens device.SOLUTION: A stereo lens device has two optical systems arranged in parallel. The two optical systems each have a front group L1, a reflection part PR, and rear groups L2-L4, which are arranged in order from an object side to an image side, and the reflection part bends an optical path to reduce the optical axis interval between the rear groups compared to the optical axis interval between the front groups in the two optical systems. The rear groups in the two optical systems each have movable groups FA, FB that are movable. The stereo lens device has a holding member CP that integrally holds the movable groups in the two optical systems, and an actuator ACT that drives the holding member.SELECTED DRAWING: Figure 16

Description

[Technical field]

[0001] The present invention relates to a lens device suitable for capturing an image that can be viewed stereoscopically (stereo image). [Background technology]

[0002] As a stereo lens device that enables acquisition of a stereo image by imaging, one in which two optical systems are arranged in parallel to have a parallax between them is used. Patent Document 1 discloses a stereo lens device in which two optical systems are arranged in parallel and two reflecting members are arranged in each optical system to bend the optical path. By bending the optical path, it is possible to narrow the interval between the image-side lens groups while ensuring the base length between the object-side lens groups in the two optical systems, so that the image circles of the two optical systems can be formed on a single imaging element. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-008629 A Summary of the Invention [Problem to be solved by the invention]

[0004] When an autofocus mechanism is installed in the stereo lens device as described above, for example, the image-side lens group, which is lighter than the object-side lens group, is driven as the focus lens group. However, if there is a deviation in the driving of the focus lens group in each of the two optical systems, a difference occurs in the focus state and image magnification of the subject image formed by each of the two optical systems. In addition, when an anti-vibration lens group that shifts with respect to the optical axis is arranged in each of the two optical systems to reduce image blur caused by hand shake or the like, if there is a deviation in the driving of these anti-vibration lens groups, a difference occurs in the blur state of the subject image formed by each of the two optical systems.

[0005] The present invention provides a stereo lens device that is capable of reducing the drive deviation of the lens groups (movable groups) in the two optical systems. [Means for solving the problem]

[0006] A stereo lens device according to one aspect of the present invention has two optical systems arranged in parallel. Each of the two optical systems has a front group, a reflecting section, and a rear group arranged in this order from the object side to the image side, and the optical path is bent by the reflecting section, so that the optical axis distance between the rear groups is smaller than the optical axis distance between the front groups in the two optical systems. Each of the rear groups of the two optical systems has a movable group. The stereo lens device according to one aspect of the present invention has a holding member that holds the movable groups of the two optical systems together, and an actuator that drives the holding member. An imaging device having the above-mentioned stereo lens device and an imaging element also constitutes another aspect of the present invention. Effect of the Invention

[0007] According to the present invention, it is possible to reduce drive deviations of the movable groups in the two optical systems in a stereo lens device. [Brief description of the drawings]

[0008] [Figure 1] FIG. 4 is a cross-sectional view of the optical system of the first embodiment (Numerical Example 1). [Diagram 2] 4A to 4C are longitudinal aberration diagrams of the optical system of Numerical Example 1. [Diagram 3] 4A to 4C are diagrams showing lateral aberration in the optical system of Numerical Example 1 during image stabilization. [Figure 4] FIG. 11 is a cross-sectional view of an optical system according to a second embodiment (Numerical Example 2). [Diagram 5] 6A to 6C are longitudinal aberration diagrams of the optical system of Numerical Example 2. [Figure 6] 4A to 4C are diagrams showing lateral aberration in the optical system of Numerical Example 2 during image stabilization. [Figure 7] FIG. 11 is a cross-sectional view of an optical system according to a third embodiment (Numerical Example 3). [Figure 8] 11A to 11C are longitudinal aberration diagrams of the optical system of Numerical Example 3. [Figure 9] FIG. 11 is a cross-sectional view of an optical system according to a fourth embodiment (Numerical Example 4). [Figure 10]11A to 11C are longitudinal aberration diagrams of the optical system of Numerical Example 4. [Figure 11] 4A to 4C are diagrams showing lateral aberration in the optical system of Numerical Example 4 during image stabilization. [Figure 12] FIG. 13 is a cross-sectional view of an optical system according to a fifth embodiment (Numerical Example 5). [Figure 13] 11A to 11C are longitudinal aberration diagrams of the optical system of Numerical Example 5. [Figure 14] 13A to 13C are diagrams showing lateral aberration in the optical system of Numerical Example 5 during image stabilization. [Figure 15] FIG. 2 is a plan view of a stereo optical system using two optical systems according to the first embodiment. [Figure 16] FIG. 13 is a diagram showing a configuration in which focus lens groups of two optical systems are integrally held. [Figure 17] FIG. 13 is a diagram showing another configuration in which the focus lens groups of the two optical systems are integrally held. [Figure 18] FIG. 1 is a diagram showing an imaging device using the optical systems according to Examples 1 to 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0010] The stereo lens device (hereinafter simply referred to as the lens device) of the embodiment has two optical systems arranged in parallel to obtain an image that can be viewed stereoscopically, and is used in various imaging devices such as digital still cameras, video cameras, broadcast cameras, and surveillance cameras.

[0011] 15 shows the two optical systems in the lens device of Example 1 as viewed from the Z direction. In this figure, the direction from the object side on the left side to the image side on the right side is the X direction, and the direction in which the two optical systems are arranged in parallel is the Y direction. The direction perpendicular to the X and Y directions (vertically upward from the paper surface of the figure) is the Z direction.

[0012] Each of the two optical systems has a front group, an aperture stop (hereinafter simply referred to as stop) SP, a reflecting section PR, and a rear group, arranged in this order from the object side to the image side. The two optical systems form image circles ICA and ICB on the imaging plane (IP) of one (single) image sensor by folding the light (optical path) incident from the front group twice at the reflecting section PR and passing it through the rear group. The base length Din, which is the distance between the vertices of the lens surfaces closest to the object in the two optical systems, in other words the distance between the optical axes of the front groups (optical axis distance), is set to around 60 mm, which corresponds to the distance between the left and right eyes of a human being. In addition, the distance Dout, which is the distance between the vertices of the lens surfaces closest to the image in the two optical systems (optical axis distance of the rear groups), is shorter than the base length.

[0013] FA and FB denote focus lens groups as movable groups provided in the rear groups of the two optical systems, respectively, and IA and IB denote vibration-proof lens groups as other movable groups provided in the rear groups. The focus lens groups FA and FB perform focusing by moving in the optical axis direction. The vibration-proof lens groups IA and IB perform optical vibration reduction, which reduces (corrects) image blur by moving (shifting) relative to the optical axis of the rear group in response to lens shake such as camera shake. Note that the movable group or lens group is a group of one or more lenses that move together during focusing or optical vibration reduction, and is further a group of one or more lenses that are adjacent to the moving lens group. The lens group may include an aperture stop.

[0014] 1, 4, 7, 9, and 12 respectively show a cross section of one of the two optical systems included in the lens devices of Examples 1, 2, 3, 4, and 5 (Numerical Examples 1 to 5). The left side of each figure is the object side, and the right side is the image side. The configuration of the other optical system is the same as that of the first optical system, except that the direction of reflection of light at the reflecting portion PR is different. In each cross section, the reflecting portion PR is shown expanded in the optical axis direction of the optical system.

[0015] In addition, while Examples 1, 2, 4, and 5 have focus lens groups FA and FB and vibration-proof lens groups IA and IB, Example 3 does not have a vibration-proof lens group. As an embodiment of the present invention, it is sufficient to have at least one of a focus lens group and a vibration-proof lens group. Furthermore, the rear group may have a lens group other than the focus lens group and the vibration-proof lens group as a movable group that can be moved.

[0016] In each cross-sectional view, L1 is a front group, and L2 to L5 are lens groups constituting the rear group. FP provided in the rear group indicates a field stop that determines off-axis light rays. IP is an image plane. An imaging surface of an imaging element (photoelectric conversion element) such as a CCD sensor or CMOS sensor is disposed on the image plane IP. When the lens device is used in a silver halide film camera, the film surface of the silver halide film is disposed on the image plane IP.

[0017] Although not shown, optical blocks such as an optical filter, a face plate, a low-pass filter, and an infrared cut filter may be disposed between the image plane IP and the optical system. The reflecting portion PR is composed of a single optical member such as a prism having two reflecting surfaces (a first reflecting surface and a second reflecting surface). However, the reflecting portion may be composed of two reflecting members (mirrors) each having a reflecting surface. The first reflecting surface and the second reflecting surface each bend the optical path by 45°.

[0018] In each embodiment (numerical example), a typical image sensor is used, with the short side of the imaging surface being 24 mm long and the long side being 36 mm long. If two optical systems without a reflecting portion are arranged in parallel and a baseline length of about 60 mm is set, the image circles of the two optical systems cannot be contained within the imaging surface with a long side length of 36 mm. For this reason, the optical system in each embodiment is designed to accommodate the image circles ICA and ICB of the two optical systems within the imaging surface of a single image sensor by arranging two reflecting surfaces to bend the optical path, as shown in FIG. 15.

[0019] Since the length of the long side of the imaging surface is 36 mm, the length of the long side direction of the area forming the image circle of one optical system on the imaging surface is half that, 18 mm. In this embodiment, the image circle is 16.00 mm, and a 2 mm interval is set between the image circles of the two optical systems. The image circle is an area inside which an optical image is formed to obtain a viewable image. Outside the image circle, there is an area that is not suitable for imaging to obtain a viewable image due to insufficient light or deterioration of the optical performance of the optical system. Even outside the image circle, there is an area with a non-zero light amount, and taking into consideration the positional deviation of the image circle due to manufacturing errors, a 2 mm interval is set between the image circles of the two optical systems. In this case, the optical axis interval Dout between the front groups of the two optical systems is 18.0 mm.

[0020] In the optical system of Numerical Example 1, the optical axis spacing Din between the front groups is set to 60.00 mm, the first reflecting surface is located 7.75 mm from the entrance surface of the reflecting portion PR, and the second reflecting surface is located 21.00 mm from that position.

[0021] In the optical system of Numerical Example 2, the optical axis spacing Din between the front groups is set to 62.50 mm, the first reflecting surface is located 7.50 mm from the entrance surface of the reflecting portion PR, and the second reflecting surface is located 22.25 mm from that position.

[0022] In the optical system of Numerical Example 3, the optical axis spacing Din between the front groups is set to 54.00 mm, the first reflecting surface is located 9.25 mm from the entrance surface of the reflecting portion PR, and the second reflecting surface is located 18.00 mm from that position.

[0023] In the optical system of Numerical Example 4, the optical axis spacing Din between the front groups is set to 59.50 mm, the first reflecting surface is located 8.75 mm from the entrance surface of the reflecting portion PR, and the second reflecting surface is located 20.75 mm from that position.

[0024] In the optical system of Numerical Example 5, the optical axis spacing Din between the front groups is set to 62.50 mm, the first reflecting surface is located 7.25 mm from the entrance surface of the reflecting portion PR, and the second reflecting surface is located 22.25 mm from that position.

[0025] The optical axial distance between the front groups and the position of the reflecting surfaces can be set to suit specifications such as the size of the image sensor, the baseline length and peripheral light amount of the optical system, the size of the image circle, and even the distance between the two image circles.

[0026] The optical system in each numerical example is a telephoto lens of the central projection type. However, it may be a fisheye lens as disclosed in Patent Document 1. In the case of a fisheye lens, the projection type can be set to the equiangular projection type, the equisolid angle projection type, the orthogonal projection type, etc.

[0027] As explained above, when the image circles of two optical systems are formed on a single image sensor, if there is a drive misalignment (a drive timing or drive position misalignment) between the focus lens group and the movable group, which are the vibration-proof lens group, of the two optical systems, two good images for stereoscopic viewing cannot be obtained. If there is a drive misalignment in the focus lens group, a difference in image magnification occurs between the two optical systems, and the observer cannot fuse the images during stereoscopic viewing or the resolution of the observed image decreases. It is possible to correct the difference in image magnification by image processing, but this increases the burden and time of image processing.

[0028] For this reason, the lens device of each embodiment is provided with a holding member that holds the movable groups of the two optical systems together, and the holding member is driven by an actuator, thereby reducing the driving misalignment of the movable groups of the two optical systems.

[0029] As shown in Fig. 15, the rear groups of the two optical systems are disposed adjacent to each other immediately before the image sensor (IP). By disposing the movable groups of the two optical systems adjacent to each other, it becomes easy to hold the focus lens groups FA and FB together by a holding member CP as shown in Fig. 16, for example. By driving this holding member CP in the optical axis direction by an actuator ACT, it is possible to reduce (eliminate) the drive deviation of the focus lens groups FA and FB during focusing. Furthermore, instead of providing an actuator for each of the focus lens groups FA and FB, it is sufficient to provide only one actuator ACT, which makes it possible to reduce the size of the lens device and its power consumption.

[0030] As shown in FIG. 17, when the focus lens groups FA and FB of the two optical systems are held by separate barrel members, a holding member CP may be provided to integrally connect these barrel members, that is, to integrally hold the focus lens groups FA and FB. In this case, the barrel members that hold the focus lens groups FA and FB are used as holding member bodies, and the holding member that holds the focus lens groups FA and FB integrally is configured by the holding member CP as a connecting part that connects these holding member bodies. Then, by driving the holding member CP as a connecting part with an actuator ACT, it is possible to reduce (eliminate) the drive deviation of the focus lens groups FA and FB. Note that, as shown by the dashed line in the figure, instead of directly driving the holding member CP with the actuator ACT, one of the barrel members that are integrally connected with the holding member CP may be driven with the actuator ACT. Both the configurations shown in FIG. 16 and FIG. 17 correspond to a configuration in which the holding member that holds the movable group integrally is driven by an actuator. The configurations in FIG. 16 and FIG. 17 can also be applied to the vibration-proof lens groups IA and IB.

[0031] The front groups of the two optical systems are far apart to ensure the baseline length, and if they were to be held by a single large holding member, the lens device would become large. In addition, the weight of the driven part, including the holding member and the two front groups, would increase, which would increase the power consumption of the actuator.

[0032] In response to this, in each embodiment, the movable groups provided in the two adjacent rear groups are held together by a holding member and the holding member is driven by an actuator, thereby reducing the drive misalignment of the two movable groups while also reducing power consumption.

[0033] As described above, it is preferable that the reflecting portion PR is formed by a single optical member having two reflecting surfaces. If the two reflecting surfaces are provided on separate members, the positional deviation of the image circle on the imaging surface will increase due to an assembly error during the manufacture of the lens device. As a result, problems such as a part of the image circle protruding from the imaging surface or image circles interfering with each other will occur. To prevent this, it becomes necessary to set the size of the image circle small, which reduces the number of pixels in the image obtained by imaging, thereby degrading the image quality.

[0034] Furthermore, when two reflecting surfaces are formed on one optical member, it is preferable to place the aperture stop SP on the object side of the reflecting portion PR. As shown in Fig. 15, the rear groups of the two optical systems, which are closer to the image side than the reflecting portion PR, are placed close to each other. For this reason, if the aperture stop SP is placed on the image side of the reflecting portion PR, it becomes difficult to place the aperture stops SP of the two optical systems without interfering with each other.

[0035] In addition, it is preferable to arrange a lens group with positive refractive power (positive lens group) closest to the object in the rear group. In order to prevent interference between the rear groups arranged close to each other, it is necessary to reduce the diameter of the lenses constituting the rear group. However, in the optical systems of the embodiments, a reflecting portion PR is arranged to bend the optical path twice, and the optical path length from the aperture SP to the rear group via the reflecting portion PR becomes long, so the lens diameter of the rear group tends to become large. For this reason, it is preferable to arrange a positive lens group closest to the object in the rear group to converge the off-axis light beam, thereby reducing the outer diameter of the lenses in the rear group.

[0036] When the focal length of the positive lens unit closest to the object in the rear group is fp and the distance on the optical axis from the aperture stop SP to the lens surface of the positive lens unit closest to the object is d, it is preferable to satisfy the condition shown in the following equation (1).

[0037] 0.20≦fp / d≦1.20 (1) The condition of formula (1) is a condition for achieving high optical performance while reducing the lens diameter of the rear group. If fp / d falls below the lower limit of formula (1), the power of the positive lens group becomes too strong, and off-axis aberrations such as astigmatism and curvature of field increase. In addition, the positive lens group also strongly converges the axial light beam, which undesirably increases the spherical aberration. If fp / d exceeds the upper limit of formula (1), it becomes difficult to reduce the lens diameter of the rear group, and interference occurs between the rear groups, which is undesirable.

[0038] It is more preferable that the numerical range of formula (1) is as follows:

[0039] 0.30≦fp / d≦1.00 (1a) It is more preferable that the numerical range of formula (1) is as follows:

[0040] 0.40≦fp / d≦0.90 (1b) In addition, it is preferable that the movable group that performs focusing or optical vibration reduction is disposed closer to the image side than the positive lens group disposed closest to the object side in the rear group. By making the lens group at the position where the light beam is converged by the positive lens group the movable group, it is possible to reduce the size and weight of the movable group. As a result, it is possible to reduce the size of the lens device and reduce power consumption.

[0041] In addition, the focus lens group as the movable group is preferably a lens group with negative refractive power (movable negative lens group). In the rear group, the focus lens group as the movable negative lens group is arranged closer to the image side than the positive lens group having the strongest power closest to the object side, so that the focus sensitivity, which is the ratio of the movement amount of the image plane to the movement amount of the focus lens group, can be increased. This makes it possible to reduce the movement amount of the focus lens group required for focusing, and as a result, it becomes possible to shorten the length of the rear group in the optical axis direction and reduce the lens diameter.

[0042] Furthermore, when the focal length of the focus lens group as the movable negative lens group is denoted by fs and the focal length of the entire optical system is denoted by f, it is preferable to satisfy the condition of the following formula (2).

[0043] -0.45≦fs / f≦-0.15 (2) The condition of formula (2) is the condition for the refractive power of the focus lens group to be appropriate for the optical performance and compactness of the optical system. If fs / f falls below the lower limit of formula (2), the refractive power of the focus lens group becomes too small, and the amount of movement required for focusing becomes large. As a result, the diameter of the lenses after the focus lens group increases, causing interference between the rear groups, which is undesirable. If fs / f exceeds the upper limit of formula (2), the refractive power of the focus lens group becomes too strong, and the optical performance deteriorates significantly during focusing, which is also undesirable.

[0044] It is more preferable that the numerical range of the formula (2) is as follows:

[0045] -0.40≦fs / f≦-0.16 (2a) It is more preferable that the numerical range of the formula (2) is as follows:

[0046] -0.35≦fs / f≦-0.18 (2b) In addition, it is preferable that the vibration-proof lens group as the movable group is a lens group with positive refractive power (movable positive lens group). When optical vibration is prevented by a lens group that is far away from the aperture stop SP in the image plane direction, it is necessary to strengthen the refractive power of the lens group in order to miniaturize the mechanism that drives it. However, when the vibration-proof lens group has negative refractive power, strengthening the refractive power causes too much positive distortion, narrowing the angle of view for obtaining a good image. For this reason, it is preferable that the vibration-proof lens group has positive refractive power.

[0047] When the focal length of the vibration-reduction lens group serving as the movable positive lens group is denoted by fi, it is preferable that the condition of the following formula (3) be satisfied.

[0048] 0.20≦fi / f≦0.65 (3) The condition of formula (3) is a condition for the refractive power of the vibration-proof lens group to be appropriate for the optical performance and compactness of the optical system. If fi / f is below the lower limit of formula (3), the refractive power of the vibration-proof lens group becomes too strong, which increases decentering chromatic aberration and decentering coma aberration during optical vibration reduction, which is not preferable. If fi / f is above the upper limit of formula (3), the refractive power of the vibration-proof lens group becomes too weak, which increases the amount of drive of the vibration-proof lens group for optical vibration reduction, which increases the size of the mechanism for driving the vibration-proof lens, which is not preferable.

[0049] It is more preferable that the numerical range of the formula (3) is as follows:

[0050] 0.25≦fi / f≦0.60 (3a) It is more preferable that the numerical range of the formula (3) is as follows:

[0051] 0.30≦fi / f≦0.55 (3b) Furthermore, when the lateral magnification of the image stabilization lens group when focused at infinity is denoted by βis, it is preferable that the condition of the following expression (4) be satisfied.

[0052] 0.060≦βis≦0.600 (4) The condition of formula (4) is a condition related to the vibration reduction sensitivity of the vibration reduction lens group. If βis falls below the lower limit of formula (4), the vibration reduction sensitivity becomes too large, making it difficult to control the position of the vibration reduction lens group during optical vibration reduction, which is undesirable. If βis exceeds the upper limit of formula (4), the vibration reduction sensitivity becomes too small, increasing the amount of movement of the vibration reduction lens group during optical vibration reduction, and the mechanism for driving the vibration reduction lens group becomes large, which is undesirable.

[0053] It is more preferable that the numerical range of the formula (4) is as follows:

[0054] 0.080≦βis≦0.500 (4a) It is more preferable that the numerical range of the formula (4) is as follows:

[0055] 0.100≦βis≦0.400 (4b) In addition, the rear group preferably has a positive lens group, a focus lens group as a movable negative lens group, and an anti-vibration lens group as a movable positive lens group, which are arranged in this order from the object side to the image side.As described above, by arranging the focus lens group as a movable negative lens group on the image side of the positive lens group, the movement amount of the focus lens group during focusing can be reduced.In addition, since the movable negative lens group has the effect of diverging off-axis light beams, the anti-vibration lens group as the subsequent movable positive lens group can converge the off-axis light beams again, thereby making it possible to reduce the lens diameter of the rear group.

[0056] Furthermore, it is preferable to arrange a lens group with negative refractive power (negative lens group) closest to the image side in the rear group. By arranging the negative lens group closest to the image side, it is possible to configure the optical system as a telephoto type, and the overall length of the optical system can be shortened. Furthermore, by arranging negative lens groups on the object side and image side of the vibration-proof lens group as the movable positive lens group, it is possible to reduce decentering aberrations that occur during optical vibration prevention, and improve the image quality of the image obtained by imaging.

[0057] When the focal length of the negative lens unit closest to the image side in the rear group is taken as fr, it is preferable that the condition of the following expression (5) be satisfied.

[0058] -1.20≦fr / f≦-0.40 (5) The condition of formula (5) is a condition for achieving high image quality and compactness. If fr / f is below the lower limit of formula (5), the refractive power of the negative lens group closest to the image side in the rear group becomes too weak, reducing the effect of shortening the total length as described above, and the lens device becomes large, which is undesirable. If fr / f is above the upper limit of formula (5), the refractive power of the negative lens group closest to the image side in the rear group becomes too strong, which increases off-axis aberrations such as astigmatism and curvature of field, which is undesirable.

[0059] It is more preferable that the numerical range of the formula (5) is as follows:

[0060] -1.05≦fr / f≦-0.50 (5a) It is more preferable that the numerical range of the formula (5) is as follows:

[0061] -0.90≦fr / f≦-0.60 (5b) Furthermore, when the lateral magnification of the negative lens unit closest to the image side in the rear group when focused at infinity is denoted by βr, it is preferable that the following condition (6) be satisfied.

[0062] 1.000≦βr≦1.800 (6) The condition of formula (6) is a condition related to the vibration reduction sensitivity and optical performance of the vibration reduction lens group. If βr is below the lower limit of formula (6), the vibration reduction sensitivity of the vibration reduction lens group becomes too small, the amount of movement of the vibration reduction lens group during optical vibration reduction becomes large, and the mechanism for driving the vibration reduction lens group becomes large, which is not preferable. If βr is above the upper limit of formula (6), the vibration reduction sensitivity of the vibration reduction lens group becomes too large, which makes it difficult to control the position of the lens group during vibration reduction, which is not preferable.

[0063] It is more preferable to set the numerical range of the formula (6) as follows:

[0064] 1.050≦βr≦1.650 (6a) It is more preferable that the numerical range of the formula (6) is as follows:

[0065] 1.100≦βr≦1.550 (6b) In each embodiment, the front group has a configuration similar to an afocal system in order to reduce the size of the reflector PR and the rear group. As shown in FIG. 15, the reflector PR is disposed closer to the image side than the aperture stop SP, and its size is determined by the on-axis light beam. In order to reduce the size of the reflector PR, it is necessary to converge the on-axis light beam, and it is preferable to give the front group a strong positive refractive power. However, in this case, the incidence angle of the off-axis light beam to the aperture stop surface becomes acute, so the lens diameter of the rear group on the image side of the long reflector PR becomes large, and interference between the rear groups becomes a problem.

[0066] For this reason, in each embodiment, the first lens group L1 as the front group is composed of a sub-lens group (positive sub-lens group) L1A with positive refractive power and a sub-lens group (negative sub-lens group) L1B with negative refractive power, which are arranged in order from the object side to the image side. The largest air gap in the front group is provided between the positive and negative sub-lens groups L1A and L1B. With this configuration, an almost afocal system is realized by the composite focal length of the positive and negative sub-lens groups L1A and L1B. The positive sub-lens group L1A, which has a strong positive refractive power, converges the on-axis light beam to make the reflecting portion PR smaller, and the negative sub-lens group L1B, which has a strong negative refractive power, reduces the angle of incidence of the off-axis light beam with respect to the aperture surface, making it possible to reduce the lens diameter of the rear group.

[0067] When the focal length of the front group is taken as ff, it is preferable to satisfy the following condition (7):

[0068] 1.50≦|ff / f| (7) The condition of the formula (7) is a condition regarding the miniaturization of the reflecting portion PR and the lens diameter of the rear group. If ff / f is below the lower limit of the formula (7), the lens diameter of the rear group becomes large, which is not preferable.

[0069] It is more preferable to set the numerical range of the formula (7) as follows:

[0070] 2.00≦|ff / f| (7a) It is more preferable that the numerical range of the formula (7) is as follows:

[0071] 2.40≦|ff / f| (7b) Furthermore, when the focal length of the positive sub-lens group L1A is f1A, it is preferable to satisfy the condition of the following formula (8).

[0072] 0.55≦f1A / f≦1.30 (8) Formula (8) is a condition for miniaturizing the reflecting portion PR. If f1A / f falls below the lower limit of formula (8), the refractive power of the positive sub-lens group L1A becomes too strong, which increases spherical aberration and coma aberration, degrading the optical performance of the optical system, which is not preferable. If f1A / f exceeds the upper limit of formula (8), it becomes difficult to miniaturize the reflecting portion PR, which is not preferable.

[0073] It is more preferable to set the numerical range of the formula (8) as follows:

[0074] 0.58≦f1A / f≦1.20 (8a) It is more preferable that the numerical range of the formula (8) is as follows:

[0075] 0.60≦f1A / f≦1.10 (8b) It is preferable that the base length (distance between the optical axes of the front group) Din and the optical axis distance Dout of the rear group of the two optical systems satisfy the condition of the following expression (9).

[0076] 0.05≦Dout / Din≦0.50 (9) The condition of formula (9) is a condition regarding the stereoscopic effect and discomfort felt when viewing a stereoscopic image obtained by imaging. If Dout / Din falls below the lower limit of formula (9), the baseline length becomes extremely longer than the distance between the human eyes, and the parallax of the images obtained through the two optical systems becomes too large, which is likely to cause fatigue to the viewer, and is therefore undesirable. If Dout / Din exceeds the upper limit of formula (9), the parallax of the images becomes too small, which is undesirable because no stereoscopic effect can be obtained.

[0077] It is more preferable to set the numerical range of the formula (9) as follows:

[0078] 0.10≦Dout / Din≦0.45 (9a) It is more preferable that the numerical range of the formula (9) is as follows:

[0079] 0.15≦Dout / Din≦0.40 (9b) Next, the configuration of each group in the optical system will be described. In the following description, the lens groups and lenses that make up each group are assumed to be arranged from the object side to the image side unless otherwise specified.

[0080] The first lens group L1 as the front group in each embodiment has a nearly afocal refractive power arrangement. In the first lens group L1 in the first embodiment, the positive sub-lens group L1A is composed of a biconvex lens, and the negative sub-lens group L1B is composed of a biconvex lens and a biconcave lens. In the first lens group L1 in the second, third, and fourth embodiments, the positive sub-lens group L1A is composed of a biconvex lens, and the negative sub-lens group L1B is composed of a cemented lens in which a biconvex lens and a biconcave lens are cemented together. In the first lens group L1 in the fifth embodiment, the positive sub-lens group L1A is composed of a positive meniscus lens with a convex surface facing the object side, and the negative sub-lens group L1B is composed of a cemented lens in which a biconvex lens and a biconcave lens are cemented together.

[0081] In each embodiment, a stop SP is disposed on the image side of the first lens unit L1, a reflecting portion PR is disposed on the image side of the stop SP, and a rear group is disposed further on the image side of the reflecting portion PR.

[0082] In the first, second and fourth embodiments, the rear group is composed of the second lens group L2 with positive refractive power, the third lens group L3 with negative refractive power, the fourth lens group L4 with positive refractive power and the fifth lens group L5 with negative refractive power. In the third embodiment, the rear group is composed of the second lens group L2 with positive refractive power, the third lens group L3 with negative refractive power and the fourth lens group L4 with positive refractive power. In the fifth embodiment, the rear group is composed of the second lens group L2 with positive refractive power, the third lens group L3 with negative refractive power and the fourth lens group L4 with positive refractive power.

[0083] In Examples 1, 2 and 4, the third lens group L3 is a focus lens group and the fourth lens group L4 is an anti-vibration lens group. In Example 3, the third lens group L3 is a focus lens group and no anti-vibration lens group is provided. In Example 5, the second lens group L2 is a focus lens group and the third lens group L3 is an anti-vibration lens group.

[0084] In Examples 1 and 4, the second lens group L2 is composed of a positive meniscus lens with a convex surface facing the image side, and a cemented lens in which a biconvex lens and a negative meniscus lens with a convex surface facing the image side are cemented together. In Example 2, the second lens group L2 is composed of a positive meniscus lens with a convex surface facing the image side, and a cemented lens in which a biconvex lens and a biconcave lens are cemented together. In Example 3, the second lens group L2 is composed of a biconvex lens, and a cemented lens in which a biconvex lens and a negative meniscus lens with a convex surface facing the image side are cemented together. In Example 5, the second lens group L2 is composed of a cemented lens in which a biconvex lens and a negative meniscus lens with a convex surface facing the image side are cemented together.

[0085] In Examples 1, 2, and 4, the third lens group L3 is composed of a cemented lens in which a positive meniscus lens having a convex surface facing the image side and a biconcave lens are cemented together. In Example 3, the third lens group L3 is composed of a cemented lens in which a biconvex lens and a biconcave lens are cemented together. In Example 5, the third lens group L3 is composed of a positive meniscus lens having a convex surface facing the image side and a cemented lens in which a biconcave lens is cemented together.

[0086] In the first embodiment, the fourth lens group L4 is composed of a cemented lens in which a negative meniscus lens with a convex surface facing the object side and a positive meniscus lens with a convex surface facing the object side are cemented together, and a positive meniscus lens with a convex surface facing the object side. In the second and fourth embodiments, the fourth lens group L4 is composed of a cemented lens in which a negative meniscus lens with a convex surface facing the object side and a positive meniscus lens with a convex surface facing the object side are cemented together. In the first embodiment, the vibration reduction sensitivity is set higher than in the second and fourth embodiments, and the fourth lens group L4 has two positive lenses, thereby reducing decentering aberrations during optical vibration reduction. In the third embodiment, the fourth lens group L4 is composed of a cemented lens in which a biconvex lens and a biconcave lens are cemented together, and a positive meniscus lens with a convex surface facing the object side. In the fifth embodiment, the fourth lens group L4 is composed of a cemented lens in which a negative meniscus lens with a convex surface facing the object side and a biconvex lens are cemented together, a biconcave lens, and a biconvex lens.

[0087] The fifth lens group L5 is composed of a biconcave lens and a positive meniscus lens with a convex surface facing the object side in Examples 1 and 4. In Example 2, the fifth lens group L5 is composed of a negative meniscus lens with a convex surface facing the object side and a positive meniscus lens with a convex surface facing the object side.

[0088] Numerical data for Numerical Examples 1 to 5 are shown below. In each numerical example, surface number i indicates the order of the surface when counted from the object side. r is the radius of curvature (mm) of the i-th surface from the object side, d is the lens thickness or air gap (mm) between the i-th and (i+1)-th surfaces, and nd is the refractive index at the d-line of the optical material between the i-th and (i+1) surfaces. νdi is the Abbe number based on the d-line of the optical material between the i-th and (i+1) surfaces. The Abbe number νd is expressed as νd=(Nd-1) / (NF-NC), where Nd, NF, and NC are the refractive indices at the d-line (587.6 nm), F-line (486.1 nm), and C-line (656.3 nm) of the Fraunhofer lines.

[0089] BF stands for back focus (mm). "Back focus" is the distance on the optical axis from the final surface of a zoom lens (the lens surface closest to the image) to the paraxial image plane expressed in air equivalent length. "Total lens length" is the distance on the optical axis from the foreground surface of a zoom lens (the lens surface closest to the object) to the final surface plus the back focus.

[0090] The relationship between the above-mentioned conditions (conditional expressions (1) to (9)) and numerical examples is summarized in Table 1. Numerical Examples 1 to 4 satisfy all of the conditional expressions (1) to (9). Numerical Example 5 satisfies all of the conditions (1) and (4) to (9) except for the conditional expressions (2) and (3).

[0091] 2, 5, 8, 10, and 13 show longitudinal aberration (spherical aberration, astigmatism, distortion, and chromatic aberration) of the optical systems of Numerical Examples 1 to 5 when focused at infinity. FIG. 3, 6, 11, and 14 show transverse aberration of the optical systems of Numerical Examples 1, 2, 4, and 5 at 0.5° vibration reduction. In the spherical aberration diagrams, Fno indicates the F-number, the solid line indicates the spherical aberration for the d-line (wavelength 587.6 nm), and the dashed line indicates the spherical aberration for the g-line (wavelength 435.8 nm). In the astigmatism diagrams, the solid line S indicates the sagittal image plane, and the dashed line M indicates the meridional image plane. The distortion aberration is shown for the d-line. The chromatic aberration diagrams show the chromatic aberration of magnification for the g-line. ω is the half angle of view (°). Any of the lens surfaces may be aspheric. [Numerical example 1] Unit: mm Surface Data Surface number rd nd νd Effective diameter 1 51.287 2.71 1.76385 48.5 18.75 2 -278.413 11.77 18.48 3 28.406 3.34 1.43875 94.7 14.15 4 -41.071 0.20 13.40 5 -40.184 1.20 1.78590 44.2 13.25 6 24.397 6.84 12.63 7(Aperture) ∞ 2.00 12.53 8 ∞ 36.00 1.77250 49.6 12.50 9∞2.00 12.18 10 -28.886 1.82 2.00100 29.1 12.16 11 -20.478 0.20 12.47 12 18.794 4.39 1.49700 81.5 11.98 13 -15.730 1.00 1.67270 32.1 11.65 14 -60.435 2.11 11.57 15 -73.822 2.41 2.00100 29.1 11.13 16 -11.541 1.00 1.88300 40.8 11.09 17 16.372 3.52 10.77 18 22.190 1.00 1.80810 22.8 12.38 19 14.160 2.76 1.77250 49.6 12.35 20 121.562 0.20 12.35 21 23.551 1.81 1.77250 49.6 12.42 22 35.190 6.14 12.13 23 -46.840 1.00 1.72916 54.7 11.74 24 18.038 2.60 11.90 25 19.649 3.16 1.69895 30.1 13.90 26 233.329 3.85 14.00 27∞ 11.45 14.49 Image plane ∞ Various data Focal length 75.00 F-number 4.00 Half angle of view (°) 6.09 Image height 8.00 Lens length 116.50 BF 11.45 Entrance pupil position 38.42 38.42 Exit pupil position -55.05 -55.05 Front principal point position 28.83 28.83 Back principal point position -63.55 -63.55 Group Data Group Starting surface Ending surface Focal length Lens length Front principal point position Rear principal point position L1 1 6 657.01 19.22 -287.64 -211.08 L2 10 14 23.41 7.42 1.87 -2.75 L3 15 17 -17.22 3.41 1.39 -0.31 L4 18 22 25.40 5.77 -0.27 -3.51 L5 23 27 -53.20 10.62 -4.10 -13.64 Single lens data Lens starting surface focal length 1 1 56.90 2 3 38.84 3 5 -19.16 4 8 0.00 5 10 63.40 6 12 17.99 7 13 -31.90 8 15 13.41 9 16 -7.54 10 18 -51.28 11 19 20.52 12 21 86.33 13 23 -17.74 14 25 30.51 [Numerical example 2] Unit: mm Surface Data Surface number rd nd νd Effective diameter 1 73.385 2.78 1.91650 31.6 18.75 2 -240.253 2.95 18.50 3 26.794 3.77 1.65160 58.5 17.10 4 -87.993 1.20 1.89800 34.0 16.20 5 22.993 15.23 15.16 6(Aperture) ∞ 2.00 14.15 7 ∞ 36.75 1.77250 49.6 14.01 8∞2.00 12.50 9 -66.445 1.93 1.80810 22.8 12.38 10 -27.429 0.20 12.45 11 27.212 3.84 1.63860 63.4 11.96 12 -17.943 1.00 1.71736 29.5 11.13 13 165.058 2.15 10.90 14 -222.742 2.33 1.90058 29.7 10.66 15 -12.336 1.00 1.84750 43.0 10.61 16 19.985 5.88 10.40 17 19.463 1.00 1.90110 27.1 12.50 18 12.695 3.41 1.72916 54.7 12.27 19 106.379 7.37 12.15 20 426.471 1.00 1.77250 49.6 12.03 21 13.209 1.87 11.98 22 14.817 3.34 1.71300 53.9 14.03 23 57.502 2.05 14.00 24∞ 11.45 14.25 Image plane ∞ Various data Focal length 75.00 F-number 4.00 Half angle of view (°) 6.09 Image height 8.00 Lens length 116.50 BF 11.45 Entrance pupil position 33.09 Exit pupil position -44.58 Front principal point position 7.71 Back principal point position -63.55 Group Data Group Starting surface Ending surface Focal length Lens length Front principal point position Rear principal point position 1 1 5 223.06 10.70 -39.84 -39.73 3 9 13 29.86 6.97 0.84 -3.27 4 14 16 -23.62 3.33 1.64 -0.11 5 17 19 37.25 4.41 -0.91 -3.34 6 20 23 -58.03 8.25 -1.98 -8.52 Single lens data Lens starting surface focal length 1 1 61.60 2 3 31.94 3 4 -20.20 4 7 0.00 5 9 56.56 6 11 17.51 7 12 -22.51 8 14 14.42 9 15 -8.87 10 17 -43.57 11 18 19.47 12 20 -17.66 13 22 27.11 [Numerical example 3] Unit: mm Surface Data Surface number rd nd νd Effective diameter 1 54.198 2.55 1.90110 27.1 18.90 2 -1873.002 9.22 18.62 3 22.472 3.60 1.55032 75.5 15.13 4 -37.590 1.20 1.68134 31.9 14.39 5 13.897 7.13 13.02 6(Aperture) ∞ 2.00 13.26 7 ∞ 36.42 1.87070 40.7 13.34 8∞2.00 14.19 9 59.207 2.76 1.88300 40.8 14.30 10 -30.665 0.20 14.16 11 32.684 4.02 1.52841 76.5 13.28 12 -19.600 1.00 1.90315 29.8 12.65 13 -121.948 2.00 12.50 14 91.820 3.60 1.86300 41.5 11.92 15 -12.509 1.00 1.81600 46.6 11.54 16 11.332 4.23 10.69 17 27.186 3.70 1.61650 31.0 12.50 18 -21.416 1.00 1.88300 40.8 12.72 19 38.021 0.21 13.19 20 14.888 2.99 1.74100 52.7 14.22 21 30.439 2.05 14.00 22∞11.45 14.19 Image plane ∞ Various data Focal length 55.00 F-number: 2.91 Half angle of view (°) 8.28 Image height 8.00 Lens length 104.33 BF 11.45 Entrance pupil position 32.28 Exit pupil position -38.82 Front principal point position 27.11 Back principal point position -43.55 Group Data Group Starting surface Ending surface Focal length Lens length Front principal point position Rear principal point position L1 1 5 -7316.62 16.57 3021.71 2129.43 L2 9 13 20.39 7.98 0.51 -4.24 L3 14 16 -17.51 ​​4.60 3.00 0.44 L4 17 22 68.87 9.95 -3.83 -10.12 Single lens data Lens starting surface focal length 1 1 58.49 2 3 26.11 3 4 -14.75 4 7 0.00 5 9 23.21 6 11 23.82 7 12 -25.98 8 14 12.96 9 15 -7.15 10 17 20.01 11 18 -15.39 12 20 36.35 [Numerical example 4] Unit: mm Surface Data Surface number rd nd νd Effective diameter 1 75.189 3.55 1.49710 81.6 25.00 2 -153.242 26.99 24.78 3 35.375 3.82 1.53256 46.0 17.62 4 -45.357 1.20 1.89190 37.1 16.97 5 52.000 3.10 16.44 6(Aperture) ∞ 2.00 16.22 7 ∞ 37.77 1.77250 49.6 16.04 8∞2.00 14.11 9 -33.456 1.85 1.80518 25.4 14.00 10 -23.789 0.20 14.21 11 21.250 4.58 1.52054 69.7 13.60 12 -17.658 1.00 1.67270 32.2 12.69 13 -79.466 2.00 12.15 14 -71.262 2.18 1.91650 31.6 10.95 15 -13.496 1.00 1.78650 50.0 10.66 16 17.100 6.37 10.32 17 21.874 1.00 1.90315 29.8 12.50 18 13.050 3.36 1.75591 51.2 12.32 19 100.961 13.42 12.25 20 -78.564 1.00 1.61881 63.9 12.68 21 13.168 0.78 12.93 22 14.178 3.85 1.69680 56.5 13.94 23 90.207 2.04 14.00 24∞ 11.46 14.27 Image plane ∞ Various data Focal length 100.00 F-number 4.00 Half angle of view (°) 4.57 Image height 8.00 Lens length 136.50 BF 11.46 Entrance pupil position 54.42 Exit pupil position -47.21 Front principal point position -16.05 Back principal point position -88.54 Zoom lens group data Group Starting surface Ending surface Focal length Lens length Front principal point position Rear principal point position L1 1 5 246.98 35.56 -80.92 -84.33 L2 9 13 28.26 7.62 1.94 -2.87 L3 14 16 -20.07 3.18 1.34 -0.33 L4 17 19 42.81 4.36 -1.04 -3.41 L5 20 23 -85.00 7.67 -1.09 -6.79 Single lens data Lens starting surface focal length 1 1 101.99 2 3 37.94 3 4 -27.01 4 7 0.00 5 9 94.24 6 11 19.30 7 12 -33.97 8 14 17.84 9 15 -9.45 10 17 -37.86 11 18 19.51 12 20 -18.15 13 22 23.65 [Numerical example 5] Unit: mm Surface Data Surface number rd nd νd Effective diameter 1 42.896 2.64 2.00069 25.5 18.75 2 470.471 3.49 18.37 3 25.280 3.44 1.43875 94.7 16.41 4 -406.305 1.20 1.85478 24.8 15.42 5 20.893 16.54 14.47 6(Aperture) ∞ 2.00 13.49 7 ∞ 36.43 1.77250 49.6 13.36 8∞4.77 12.03 9 48.836 4.13 1.87070 40.7 11.70 10 -12.410 1.00 1.90366 31.3 11.77 11 -64.359 2.00 11.88 12 -124.918 2.01 1.96300 24.1 11.73 13 -18.591 1.00 1.80400 46.6 11.74 14 22.654 2.00 11.61 15 15.873 1.00 1.85478 24.8 12.50 16 12.543 3.86 1.59522 67.7 12.22 17 -58.222 8.41 12.09 18 -15.020 1.00 1.91082 35.3 10.23 19 25.969 2.63 10.77 20 27.330 3.45 1.76385 48.5 13.47 21 -40.251 2.04 13.94 22∞ 11.46 14.33 Image plane ∞ Various data Focal length 75.00 F-number 4.00 Half angle of view (°) 6.09 Image height 8.00 Lens length 116.50 BF 11.46 Entrance pupil position 39.07 Exit pupil position -49.36 Front principal point position 21.58 Back principal point position -63.54 Zoom lens group data Group Starting surface Ending surface Focal length Lens length Front principal point position Rear principal point position L1 1 5 255.70 10.77 -60.85 -55.31 L2 9 11 34.90 5.13 1.14 -1.65 L3 12 14 -28.70 3.01 1.35 -0.21 L4 15 22 56.70 22.39 -11.43 -28.79 Single lens data Lens starting surface focal length 1 1 47.02 2 3 54.38 3 4 -23.22 4 7 0.00 5 9 11.73 6 10 -17.17 7 12 22.47 8 13 -12.56 9 15 -81.20 10 16 17.70 11 18 -10.33 12 20 21.79 [Table 1] JPEG2024045863000002.jpg71161

[0092] [Imaging device] 18 shows a schematic configuration of an imaging device (digital still camera) 100 equipped with a lens device 110 according to any one of the first to fifth embodiments. The imaging device 100 is composed of a camera body 130 having an imaging element 140, and a lens device 110 that is detachable from or integral with the camera body 130. The camera body 130 may be a single-lens reflex camera having a mirror that reflects light from two optical systems 120 (only one of the optical systems is shown in the figure) in the lens device 110, or a mirrorless camera that does not have a mirror. The imaging element 140 is a photoelectric conversion element that captures (photoelectrically converts) an optical image formed by the two optical systems 120.

[0093] The imaging device of this embodiment includes the lens device 110 of any one of the first to fifth embodiments, and thus has at least one of the focusing and optical image stabilization functions, and can obtain high-quality images that can be viewed stereoscopically.

[0094] The above embodiment includes the following configurations.

[0095] (Configuration 1) A stereo lens device having two optical systems arranged in parallel, each of the two optical systems has a front group, a reflecting section, and a rear group arranged in this order from the object side to the image side, and an optical axis distance between the rear groups is smaller than an optical axis distance between the front groups in the two optical systems due to bending of an optical path by the reflecting section; the rear groups of the two optical systems each have a movable group that is movable; a holding member that holds the movable groups of the two optical systems together; and an actuator for driving the holding member. (Configuration 2) 2. The stereo lens device according to configuration 1, wherein the reflecting sections of the two optical systems are each composed of a single optical member having two reflecting surfaces. (Configuration 3) each of the two optical systems has a stop on the object side of the reflecting unit; the rear group has a lens group having a positive refractive power closest to the object side, Let fp be the focal length of the lens group having positive refractive power, and d be the distance on the optical axis from the aperture stop to the lens surface of the lens group having positive refractive power that is closest to the object, 0.20≦fp / d≦1.20 3. The stereo lens device according to claim 1 or 2, which satisfies the following conditions: (Configuration 4) 4. The stereo lens device according to configuration 3, wherein the movable group is disposed closer to the image side than the lens group having positive refractive power in the rear group. (Configuration 5) 5. The stereo lens apparatus according to any one of configurations 1 to 4, wherein the movable group moves for focusing. (Configuration 6) the movable group has negative refractive power, Let fs be the focal length of the movable group and f be the focal length of the optical system. -0.45≦fs / f≦-0.15 6. The stereo lens device according to configuration 5, wherein the following conditions are satisfied: (Configuration 7) 5. The stereo lens device according to any one of configurations 1 to 4, wherein the movable group moves for optical vibration isolation. (Configuration 8) the movable group has positive refractive power, If the focal length of the movable group is fi, then 0.20≦f i / f ≦0.65 8. The stereo lens device according to claim 7, wherein the following conditions are satisfied: (Configuration 9) When the lateral magnification of the movable group when focused at infinity is βis, 0.060≦βis≦0.600 9. The stereo lens device according to configuration 7 or 8, which satisfies the following conditions: (Configuration 10) The stereo lens device according to any one of configurations 1 to 9, characterized in that the rear group has, arranged in order from the object side to the image side, a lens group with positive refractive power, a focus lens group with negative refractive power that moves for focusing as the movable group, and an image stabilization lens group with positive refractive power that moves for optical image stabilization as the movable group. (Configuration 11) 11. The lens apparatus according to any one of configurations 1 to 10, wherein the rear group has a lens group having negative refractive power closest to the image side. (Configuration 12) Let fr be the focal length of the lens unit having negative refractive power closest to the image side in the rear group. -1.20≦fr / f≦-0.40 12. The stereo lens device according to claim 11, wherein the following conditions are satisfied: (Configuration 13) When the lateral magnification of the lens unit having negative refractive power closest to the image side in the rear group in a state where the lens is focused on infinity is βr, 1.000≦βr≦1.800 13. The stereo lens device according to claim 11 or 12, wherein the following conditions are satisfied: (Configuration 14) Let the focal length of the front group be ff, 1.50≦|ff / f| 14. The stereo lens device according to any one of configurations 1 to 13, wherein the following condition is satisfied: (Configuration 15) The stereo lens device according to any one of configurations 1 to 14, characterized in that the front group has a lens group with positive refractive power and a lens group with negative refractive power arranged in that order from the object side to the image side, and the largest air gap in the front group is provided between the positive and negative lens groups. (Configuration 16) If the focal length of the lens group having positive refractive power in the front group is f1A, 0.55≦f1A / f≦1.30 16. The stereo lens device according to any one of configurations 1 to 15, wherein the following conditions are satisfied: (Configuration 17) Let Din be the optical axis distance between the front groups of the two optical systems, and Dout be the optical axis distance between the rear groups. 0.05≦Dout / Din≦0.50 17. The stereo lens device according to any one of configurations 1 to 16, wherein the following condition is satisfied: (Configuration 18) A stereo lens device according to any one of configurations 1 to 17, and an imaging element that captures two optical images formed by the two optical systems.

[0096] The embodiments described above are merely representative examples, and various modifications and alterations are possible for each embodiment when implementing the present invention. [Explanation of symbols]

[0097] L1 First lens group L2 Second lens group L3: Third lens group L4 4th lens group L5 Fifth lens group SP Aperture IP image plane PR reflective section FA,FB focus lens group IA,IB Anti-vibration Lenses CP holding member

Claims

1. A stereo lens device having two optical systems arranged in parallel, each of the two optical systems has a front group, a reflecting section, and a rear group arranged in this order from the object side to the image side, and the optical path is bent by the reflecting section, so that the optical axis distance between the rear groups in the two optical systems is smaller than the optical axis distance between the front groups; the rear groups of the two optical systems each have a movable group; a holding member that holds the movable groups of the two optical systems together; an actuator that drives the holding member, A stereo lens device, wherein the front group is stationary relative to the image plane during focusing.

2. 2. The stereo lens device according to claim 1, wherein the reflecting portions of the two optical systems are each formed of a single optical member having two reflecting surfaces.

3. each of the two optical systems has a stop on the object side of the reflecting unit; the rear group has a lens group with positive refractive power closest to the object, When the focal length of the lens group having positive refractive power is fp and the distance on the optical axis from the stop to the lens surface of the lens group having positive refractive power that is closest to the object is d, 0.20≦fp / d≦1.20 2. The stereo lens device according to claim 1, wherein the following condition is satisfied:

4. 4. The stereo lens device according to claim 3, wherein the movable group is disposed closer to the image side than the lens group with positive refractive power in the rear group.

5. 2. The stereo lens device according to claim 1, wherein the movable group moves for focusing.

6. the movable group has negative refractive power, When the focal length of the movable group is fs and the focal length of the optical system is f, −0.45≦fs / f≦−0.15 6. The stereo lens device according to claim 5, wherein the following condition is satisfied:

7. 2. The stereo lens device according to claim 1, wherein the movable group moves for optical vibration reduction.

8. the movable group has positive refractive power, When the focal length of the movable group is fi, 0.20≦fi / f≦0.65 8. The stereo lens device according to claim 7, wherein the following condition is satisfied:

9. When the lateral magnification of the movable group when focused at infinity is βis, 0.060≦βis≦0.600 8. The stereo lens device according to claim 7, wherein the following condition is satisfied:

10. 2. The stereo lens device according to claim 1, wherein the rear group comprises, arranged in order from the object side to the image side, a lens group with positive refractive power, a focus lens group with negative refractive power that moves as the movable group for focusing, and an image stabilization lens group with positive refractive power that moves as the movable group for optical image stabilization.

11. 2. The lens apparatus according to claim 1, wherein the rear group has a lens group with negative refractive power closest to the image side.

12. When the focal length of the lens unit with negative refractive power closest to the image side in the rear group is fr, −1.20≦fr / f≦−0.40 12. The stereo lens device according to claim 11, wherein the following condition is satisfied:

13. When the lateral magnification of the lens unit with negative refractive power closest to the image side in the rear group in a state where the lens is focused at infinity is denoted by βr, 1.000≦βr≦1.800 12. The stereo lens device according to claim 11, wherein the following condition is satisfied:

14. When the focal length of the front group is ff, 1.50≦|ff / f| 2. The stereo lens device according to claim 1, wherein the following condition is satisfied:

15. 2. The stereo lens device according to claim 1, wherein the front group includes a lens group with positive refractive power and a lens group with negative refractive power arranged in that order from the object side to the image side, and the largest air gap in the front group is provided between the positive and negative lens groups.

16. When the focal length of the lens group having positive refractive power in the front group is f1A, 0.55≦f1A / f≦1.30 2. The stereo lens device according to claim 1, wherein the following condition is satisfied:

17. When the optical axis distance between the front groups of the two optical systems is Din and the optical axis distance between the rear groups is Dout, 0.05≦Dout / Din≦0.50 2. The stereo lens device according to claim 1, wherein the following condition is satisfied:

18. The stereo lens device according to any one of claims 1 to 17, and an image sensor for capturing two optical images formed by the two optical systems.

Images