JP2017026984A - Imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus having a function to extend the focus distance of an exchange lens capable of reducing the size of an imaging system.SOLUTION: The imaging apparatus capable of mounting an exchange lens, which includes: an image pick-up device; and an optical system that changes the focus distance of the exchange lens. Defining a distance from the lens face apex at the closest to the object in the optical system to the image pick-up device as L; and defining a distance from the lens face apex closest to image of a lens having a refractive power included in the optical system to the image pick-up device as Skc, 0.1<Skc/L<0.7 is satisfied.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an imaging apparatus, and more particularly to an imaging apparatus that can be fitted with an interchangeable lens and has a function of displacing the focal length of the interchangeable lens.

  Conventionally, various methods have been proposed in which an optical system is disposed between a photographic optical system (main lens system) and an image pickup element to displace the focal length of the photographic optical system. For example, Patent Document 1 proposes an imaging apparatus that has an optical system for displacing the focal length in the imaging apparatus and makes the focal length of the imaging optical system longer. Patent Document 2 proposes an attachment that extends the focal length of an interchangeable lens by inserting an optical system between an interchangeable lens that is a photographing optical system and an imaging device.

JP 2000-19613 A JP-A-11-258499

  In recent years, imaging devices such as TV cameras, movie cameras, photographic cameras, video cameras, and the like have been desired to have both high pixels and high sensitivity, and imaging devices having large-size imaging elements are required. . On the other hand, there is a demand for users to use existing interchangeable lens assets. For this reason, for example, there is a strong need to use a 2/3 inch format interchangeable lens for an image pickup apparatus of a super 35 mm format having a larger image pickup device. In this case, it is necessary to arrange an optical system that makes the focal length of the interchangeable lens longer to be between the interchangeable lens and the imaging device, and to enlarge the image circle of the interchangeable lens.

  In Patent Document 1, an example of an image pickup apparatus in which a photographing optical system (main lens system) is provided integrally with an image pickup apparatus main body is presented, and it is not configured to be able to attach an interchangeable lens. In Patent Document 2, since an external attachment is inserted between the interchangeable lens and the imaging device, the distance from the interchangeable lens to the imaging device becomes long, and the size of the photographing system increases.

  It is an object of the present invention to provide an imaging apparatus that has a function of changing the focal length of an interchangeable lens and has achieved a reduction in size and weight of an imaging system.

In order to achieve the above object, an imaging apparatus according to the present invention is an imaging apparatus in which an interchangeable lens can be mounted, and includes an imaging element and an optical system that changes a focal length of the interchangeable lens. When the distance from the most object-side lens surface vertex to the image sensor is L, and the distance from the most image-side lens surface vertex of the lens having refractive power included in the optical system to the image sensor is Skc,
0.1 <Scc / L <0.7
It is characterized by satisfying.

  According to the present invention, it is possible to obtain an imaging apparatus having a function of changing the focal length of an interchangeable lens, and having a small and lightweight imaging system and good optical performance.

Basic configuration diagram of Embodiment 1 Cross section of interchangeable lens at wide-angle end, focusing on infinity Longitudinal aberration diagram of the interchangeable lens at the wide-angle end and focusing on infinity Sectional view of the lens with an interchangeable lens attached to the image pickup apparatus of Embodiment 1 Longitudinal aberration diagram when the interchangeable lens is mounted on the image pickup apparatus of Example 1 and the interchangeable lens is in wide-angle end and focused at infinity Lens cross-sectional view in a state where an interchangeable lens is attached to the imaging apparatus of Embodiment 2 Longitudinal aberration diagram when the interchangeable lens is mounted on the imaging apparatus of Example 2 and the interchangeable lens is in wide-angle end and focused at infinity Basic configuration diagram of Embodiment 2 Lens cross-sectional view in a state where an interchangeable lens is attached to the image pickup apparatus of Embodiment 3 Longitudinal aberration diagram when the interchangeable lens is mounted on the imaging apparatus of Example 3 and the interchangeable lens is in wide-angle end and focused at infinity Lens sectional view of the imaging device of Example 4 with an interchangeable lens mounted Longitudinal aberration diagram when the interchangeable lens is mounted on the image pickup apparatus of Example 4 and the interchangeable lens is in wide-angle end and focused at infinity Cross-sectional view of a lens with an interchangeable lens attached to the image pickup apparatus of Embodiment 5 Longitudinal aberration diagram when the interchangeable lens is mounted on the image pickup apparatus of Example 5 and the interchangeable lens is in wide-angle end and focused at infinity Cross-sectional view of a lens with an interchangeable lens attached to the image pickup apparatus of Embodiment 6 Longitudinal aberration diagram when the interchangeable lens is mounted on the image pickup apparatus of Example 6 and the interchangeable lens is in wide-angle end and focused at infinity Longitudinal aberration diagram when the interchangeable lens is mounted on the image pickup apparatus of Example 6, the optical system in the image pickup apparatus is zoomed to the long focal length side, and the interchangeable lens is at the wide-angle end and focused at infinity. Optical path diagram of the optical system in the imaging apparatus when the interchangeable lens is mounted on the imaging apparatus of Embodiment 1 and the interchangeable lens is in the wide-angle end and focused at infinity

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows a basic configuration diagram of Embodiment 1 of the present invention. The imaging apparatus 101 of the present invention has a mount 104 on which an optical system 102, an imaging element 103, and an interchangeable lens can be attached. The optical system 102 forms an image on the image sensor 103 with respect to an object point on the image side of the surface closest to the object side of the optical system 102. The object point is an imaging point of the interchangeable lens when the interchangeable lens is mounted on the mount 104 and the image side of the interchangeable lens is air. In other words, the optical system 102 forms an image of the imaging point of the interchangeable lens (the object point of the optical system 102) on the image sensor 103. In addition, the optical system 102 changes the focal length of the interchangeable lens to enlarge or reduce the image circle of the interchangeable lens.

  Here, consider a case where an external attachment that changes the focal length of the interchangeable lens is mounted between the interchangeable lens and the imaging device, and the image circle of the interchangeable lens is enlarged or reduced. In general, in an imaging apparatus, an optical filter insertion / removal mechanism such as an ND filter, a low-pass filter, or an IR cut filter is disposed in front of the imaging device. For this reason, the external attachment needs to ensure a long back focus in order to secure a space in which the optical filter and the like are arranged. Further, in order to shorten the total length of the attachment while ensuring a long back focus, it is necessary to dispose the lens of the external attachment in the vicinity of the final surface of the interchangeable lens.

  On the other hand, in the first embodiment, an optical system for changing the focal length is built in the imaging apparatus, and a space in which an optical filter or the like is arranged is secured on the object side of the optical system. As a result, the optical system can shorten the back focus, and the lens constituting the optical system can be arranged on the imaging element side as compared with the external attachment. By placing the optical system close to the imaging device, the on-axis marginal ray and the off-axis principal ray can be separated, and correction of off-axis aberrations becomes easy, so that the imaging system achieves good optical performance. be able to.

  As a further effect of shortening the back focus, the distance from the final surface of the interchangeable lens is increased in order to secure a space in which the optical filter can be disposed. As shown in FIG. 18, the lens can be arranged at a location where the on-axis light beam and the off-axis light beam are small, the lens outer diameter can be reduced, and the imaging system can be reduced in size and weight.

  Further, as a further effect, the lens can be arranged at a location where the axial marginal ray is relatively low, and it becomes easy to strengthen the refractive power of the lens constituting the optical system, so that the correction of Petzval sum is advantageous, It is possible to correct field curvature at the periphery of the screen.

  When the image circle is enlarged or reduced using an external attachment, the external attachment is attached between the mount of the imaging device and the mount of the interchangeable lens. For this reason, the rigidity of the entire imaging system becomes a problem, and there is an influence on performance due to the deviation of the optical axes of the imaging element, the external attachment, and the interchangeable lens due to the influence of manufacturing errors.

  Since the imaging apparatus of the present invention has an optical system for enlarging or reducing the image circle in the imaging apparatus, the overall imaging system has higher rigidity and less influence of manufacturing errors compared to an external attachment.

The imaging apparatus of the present invention is an imaging apparatus having a mount on which an interchangeable lens can be mounted and an imaging element, and the imaging apparatus incorporates an optical system that changes the focal length of the interchangeable lens. When the distance from the vertex of the lens surface closest to the object side of the optical system to the imaging device is L, and the distance from the vertex of the lens surface closest to the image side to the imaging device among the lenses having the refractive power of the optical system is Skc, The following conditional expression (1) is satisfied.
0.1 <Scc / L <0.7 (1)

  Conditional expression (1) is the ratio of the distance L from the vertex of the lens surface closest to the object side to the image sensor in the lens having the refractive power of the optical system and the distance Skc from the vertex of the lens surface closest to the image side of the optical system to the image sensor. Is stipulated. Note that L includes the glass block of the optical filter, and Skc does not include the glass block of the optical filter. By satisfying conditional expression (1), the back focus of the optical system is appropriately set for the entire length of the optical system, thereby achieving both compactness and light weight of the photographing system and good optical performance. . If the upper limit of conditional expression (1) is not satisfied, Skc will be too long, and the refractive power of each lens will be reduced to increase Skc, making it difficult to reduce the size and weight. Alternatively, L becomes too short, the refractive power of each lens becomes too strong, and it becomes difficult to achieve good optical performance. If the lower limit of conditional expression (1) is not satisfied, Skc will be too short, and the refractive power of each lens will be increased in order to shorten Skc, making it difficult to achieve good optical performance. Alternatively, L becomes too long, making it difficult to reduce the size and weight.

More preferably, conditional expression (1) is preferably set as follows.
0.16 <Skc / L <0.4 (1a)

Furthermore, in the present invention, it is preferable that the following conditional expression (2) is satisfied when the diagonal length of the image sensor is IC.
2.0 <L / IC <4.0 (2)

  Conditional expression (2) defines the conditions for achieving both optical performance and small size by defining the ratio of the diagonal length of the image sensor and the distance from the optical system that changes the image size to the image sensor. If the upper limit of conditional expression (2) is not satisfied, the distance from the optical system to the image sensor becomes too short with respect to the diagonal length of the image sensor, making it difficult to obtain good optical performance. If the lower limit of conditional expression (2) is not satisfied, the diagonal length of the image sensor becomes too long with respect to the distance from the optical system to the image sensor, making it difficult to achieve miniaturization.

More preferably, conditional expression (2) is preferably set as follows.
2.5 <L / IC <3.5 (2a)

Furthermore, in the present invention, it is preferable that the following conditional expression (3) is satisfied when the air-converted flange back of the interchangeable lens attached to the imaging device is Skm.
0.1 <Scc / Skm <0.7 (3)

  Conditional expression (3) defines the condition of the distance from the apex of the lens surface having the refractive power closest to the image side of the optical system that changes the focal length of the interchangeable lens and the air-converted flange back of the interchangeable lens to the image sensor. . Satisfying conditional expression (3) achieves both compactness and light weight of the photographing system and good optical performance. If the upper limit of conditional expression (3) is not satisfied, Skc becomes too large, making it difficult to reduce the size and weight and correct off-axis aberrations. Or, the Skm becomes too small, and the lens surface closest to the image side of the interchangeable lens and the surface closest to the object side of the optical system built in the imaging apparatus are not good. If the lower limit of conditional expression (3) is not satisfied, Skc becomes too small and the refractive power of each lens becomes strong, making it difficult to achieve good optical performance.

More preferably, conditional expression (3) is preferably set as follows.
0.15 <Skm / Skc <0.6 (3a)

Furthermore, in the present invention, when the largest air interval of the optical system in the imaging apparatus is La, and the distance from the most object side lens surface vertex to the most image side refractive lens surface vertex is Lc, It is preferable that the following conditional expression (4) is satisfied.
0.1 <La / Lc <0.7 (4)

  Conditional expression (4) defines the ratio of the largest air gap in the optical system to the total thickness of the optical system. In addition, the largest air space | interval of an optical system makes the glass block of optical filters the air conversion, and the glass block of the filters arrange | positioned behind an optical system is not included in the total thickness of an optical system. By optimizing the total thickness of the optical system and the air gap, both optical performance and light weight are achieved. If the upper limit of conditional expression (4) is not satisfied, the air spacing becomes too large with respect to the total thickness of the optical system, and it becomes difficult to correct aberrations because the number of glasses that can be used is reduced to make the optical system the same total thickness. It is difficult to achieve high optical properties. If the lower limit of the conditional expression (4) is not satisfied, the air interval becomes too short with respect to the total thickness of the optical system, the number of glasses necessary for aberration correction increases, and it becomes difficult to achieve weight reduction.

More preferably, conditional expression (4) is preferably set as follows.
0.3 <La / Lc <0.6 (4a)

Further, in the present invention, the optical system in the imaging apparatus has a front group having a negative refractive power on the object side and a rear group having a positive refractive power on the image side, with the largest air gap. When the focal length is f and the focal length of the front group is f1, it is preferable that the following conditional expression (5) is satisfied.
0.05 <| f1 / f | <1.5 (5)

  Conditional expression (5) defines the ratio of the focal length f of the optical system in the imaging apparatus to the focal length of the front group f1 on the object side from the largest air gap. As a result, the distance between the optical system 102 and the image sensor 103 can be made appropriate. If the upper limit of conditional expression (5) is not satisfied, the refractive power of the front group becomes weaker than the refractive power of the optical system, so that the largest air space of the optical system becomes too large, and the total length of the optical system is shortened. It becomes difficult. If the lower limit of conditional expression (5) is not satisfied, the refractive power of the front group becomes too strong with respect to the refractive power of the optical system, and the number of glasses necessary for aberration correction increases, making it difficult to reduce the weight of the optical system. .

More preferably, conditional expression (5) is set as follows.
0.1 <| f1 / f | <1.1 (5a)

Further, in the present invention, it is preferable that the following conditional expression (6) is satisfied, where Nna is an average refractive index of a lens having a negative refractive power of the optical system in the imaging apparatus: 1.8 <Nn (6)

More preferably, conditional expression (6) is preferably set as follows.
1.85 <Nn (6a)

  By satisfying conditional expression (6), the use of a material having a high refractive index for a negative lens having a strong refractive power makes the curvature of the negative lens loose and facilitates correction of spherical aberration. As a further effect, correction of Petzval sum is advantageous, and correction of curvature of field at the periphery of the screen is possible. If the lower limit of the conditional expression (6) is not satisfied, the refractive index of the negative lens becomes too small, it becomes difficult to correct the Petzval sum, and it becomes difficult to achieve high optical performance.

Furthermore, in the present invention, the most object side lens in the image pickup apparatus is a negative lens, and the following conditional expression (7) is satisfied when the radius of curvature of the object side and the image side of the negative lens is r1 and r2, respectively. It is preferable to do.
0.01 <| r2 / r1 | <0.9 (7)

Conditional expression (7) defines the relationship of the radius of curvature of the negative lens closest to the object side of the optical system.
The spherical aberration is corrected by increasing the refractive power of the image-side surface relative to the refractive power of the object-side surface at the position where the axial marginal ray is highest.

More preferably, conditional expression (7) is set as follows.
0.05 <| r2 / r1 | <0.75 (7a)

Further, in the present invention, the distance from the paraxial object point position of the optical system in the image pickup apparatus to the image side surface vertex of the strongest negative lens (single lens or negative cemented lens) in the optical system is Lo. It is preferable that the following conditional expression (8) is satisfied.
−0.4 <Lo / L <0.4 (8)

  Conditional expression (8) defines the relationship between the paraxial object point position of the optical system and the image side vertex position of the strongest negative lens in the optical system. This makes it possible to reduce the effective diameter of a negative lens having a strong refractive power in the optical system, thereby achieving Petzval sum correction and device miniaturization.

More preferably, conditional expression (8) is set as follows.
-0.2 <Lo / L <0.4 (8a)

  The optical system according to the present invention includes three or more and seven or less lenses, and the lenses include a positive lens and a negative lens.

  Hereinafter, a specific configuration of the imaging apparatus of the present invention will be described based on the characteristics of the optical system of Numerical Example 1 corresponding to Example 1. FIG.

  FIG. 2 is a lens cross-sectional view of the interchangeable lens as an example that is mounted on the imaging device of each embodiment of the present invention when focused at infinity at the wide angle end. FIG. 3 is a longitudinal aberration diagram when the interchangeable lens is focused at infinity at the wide-angle end. The value of the focal length is a value when a numerical example described later is expressed in mm. The same applies to the following numerical examples.

  In FIG. 2, a first lens unit (focus lens unit) U1 having a positive refractive power for focusing is provided in order from the object side to the image side. Further, the zoom lens has a second lens unit (variator) U2 having a negative refractive power for zooming which moves toward the image side upon zooming from the wide angle end to the telephoto end. Furthermore, it has a third lens unit (compensator) U3 having a positive refractive power that moves non-linearly on the optical axis in conjunction with the movement of the second lens unit U2 and corrects image plane fluctuations accompanying zooming. ing. Further, it has a fourth lens group (relay lens group) U4 having a positive refractive power that has a fixed image forming action upon zooming. The second lens unit U2 and the third lens unit U3 constitute a zooming system. SP is an aperture stop, which is disposed on the object side of the fourth lens unit U4. P is a color separation optical system or an optical filter, and is shown as a glass block. I is an imaging surface, which corresponds to the imaging surface of the solid-state imaging device.

  In the longitudinal aberration diagram, the straight line and the alternate long and short dash line in the spherical aberration are the e line and the g line, respectively. The dotted line and solid line in astigmatism are the meridional image surface and the sagittal image surface, respectively, and the alternate long and short dash line in the lateral chromatic aberration is the g line. ω is a half angle of view, and Fno is an F number. In the longitudinal aberration diagram, spherical aberration is drawn on a scale of 0.5 mm, astigmatism is 0.5 mm, distortion is 10%, and lateral chromatic aberration is drawn on a scale of 0.1 mm.

  FIG. 4 is a lens cross-sectional view in a state where an interchangeable lens is mounted on the imaging apparatus of the present embodiment. In FIG. 4, ML is an interchangeable lens, CV is an optical system built in the image sensor, and F is an optical filter such as an ND filter, a low-pass filter, or an IR cut filter. I is an image pickup surface, which corresponds to the image pickup surface of the solid-state image sensor. FIG. 5 is a longitudinal aberration diagram when the interchangeable lens is in focus at infinity at the wide angle end in a state where the interchangeable lens is attached to the imaging apparatus of the present embodiment. The optical system of the present example is disposed at a position 12 mm from the 55th surface, which is the surface closest to the image side of the interchangeable lens, to the image side.

  Next, the optical system in the present embodiment will be described. The optical system includes, in order from the object side to the image side, a negative meniscus lens concave on the image side, a cemented lens of a biconcave negative lens G2 and a positive meniscus lens G3 convex on the object side, a biconvex positive lens G4, and both It consists of a cemented lens with a concave negative lens G5 and a biconvex positive lens G6. In the imaging apparatus of the present embodiment, an optical filter F is disposed between the interchangeable lens and the optical system. In this embodiment, the front group is G1, and the rear group is G2 to G6. By attaching an interchangeable lens to the imaging apparatus of the present embodiment, the image circle of the interchangeable lens is enlarged by 1.8 times. Further, the imaging apparatus of the present embodiment has an imaging element having a diagonal length of 19.8 mm.

  Table 1 shows values corresponding to the conditional expressions of this example. The present embodiment satisfies the conditional expressions (1) to (8), has a function of extending the focal length of the interchangeable lens, and achieves a reduction in size and weight of the photographing system.

  FIG. 8 shows a basic configuration diagram of Embodiment 2 of the present invention. The imaging apparatus 101 of the present invention has a mount 104 on which an optical system 102, an imaging element 103, and an interchangeable lens can be attached. The optical system 102 forms an image on the image sensor 103 with respect to an object point on the image side of the surface closest to the object side of the optical system 102. In addition, the optical system 102 extends the focal length of the interchangeable lens and enlarges the image circle of the interchangeable lens. Further, a space for arranging the optical filter 105 in the optical system 102 is secured. Therefore, by disposing negative lenses with the largest air gap compared to Example 1, the refractive power of each negative lens can be reduced, and aberration correction is facilitated.

  FIG. 6 is a lens cross-sectional view in a state where an interchangeable lens is attached to the imaging apparatus of the present embodiment. In FIG. 7, ML is an interchangeable lens, CV is an optical system built in the image sensor, and F is an optical filter such as an ND filter, a low-pass filter, or an IR cut filter. I is an image pickup surface, which corresponds to the image pickup surface of the solid-state image sensor. FIG. 7 is a longitudinal aberration diagram when the interchangeable lens is in focus at infinity at the wide-angle end in a state where the interchangeable lens is attached to the imaging apparatus of the present embodiment. The optical system of the present example is disposed at a position 12 mm from the 55th surface, which is the surface closest to the image side of the interchangeable lens, to the image side.

  Next, the optical system in the present embodiment will be described. The optical system includes, in order from the object side to the image side, a negative meniscus lens G1 convex to the object side, a cemented lens of a biconvex positive lens G2 and a biconcave negative lens G3, and a biconvex positive lens G4. Yes. In this example, the front group is G1, and the rear group is G2 to G4. By attaching the interchangeable lens to the image pickup apparatus of the present embodiment, the image circle of the interchangeable lens is enlarged by 1.5 times. Further, the imaging apparatus of the present embodiment has an imaging element having a diagonal length of 16.5 mm.

  Table 1 shows values corresponding to the conditional expressions of this example. The present embodiment satisfies the conditional expressions (1) to (8), has a function of extending the focal length of the interchangeable lens, and achieves a reduction in size and weight of the photographing system.

  The basic configuration of the third embodiment is the same as that of the first embodiment, and a space for arranging the optical filter is secured between the interchangeable lens and the optical system.

  FIG. 9 is a lens cross-sectional view in a state where an interchangeable lens is attached to the imaging apparatus of the present embodiment. In FIG. 10, ML is an interchangeable lens, CV is an optical system built in the image sensor, and F is an optical filter such as an ND filter, a low-pass filter, or an IR cut filter. I is an image pickup surface, which corresponds to the image pickup surface of the solid-state image sensor. FIG. 10 is a longitudinal aberration diagram when the interchangeable lens is mounted on the imaging apparatus of the present embodiment and the interchangeable lens is focused at infinity at the wide angle end. The optical system of the present example is disposed at a position of 16.78 mm from the 55th surface which is the most image side surface of the interchangeable lens to the image side.

  Next, the optical system in the present embodiment will be described. The optical system includes, in order from the object side to the image side, a biconcave negative lens G1, a convex positive meniscus lens G2 on the image side, and a biconvex positive lens G3. An optical filter is disposed between the interchangeable lens and G1. doing. In this embodiment, the front group is G1 to G2, and the rear group is G3. By attaching the interchangeable lens to the image pickup apparatus of the present embodiment, the image circle of the interchangeable lens is enlarged by 1.35 times. Further, the image pickup apparatus of the present embodiment has an image pickup element having a diagonal length of 14.9 mm.

  Table 1 shows values corresponding to the conditional expressions of this example. The present embodiment satisfies the conditional expressions (1) to (6) and (7), has a function of extending the focal length of the interchangeable lens, and achieves a reduction in size and weight of the photographing system. Yes.

  The basic configuration of the fourth embodiment is the same as that of the first embodiment, and a space for arranging the optical filter is secured between the interchangeable lens and the optical system.

  FIG. 11 is a lens cross-sectional view in a state where an interchangeable lens is attached to the imaging apparatus of the present embodiment. In FIG. 11, ML is an interchangeable lens, CV is an optical system built in the image sensor, and F is an optical filter such as an ND filter, a low-pass filter, or an IR cut filter. I is an image pickup surface, which corresponds to the image pickup surface of the solid-state image sensor. FIG. 12 is a longitudinal aberration diagram when the interchangeable lens is in focus at infinity at the wide-angle end in a state where the interchangeable lens is attached to the imaging apparatus of the present embodiment. The optical system of the present example is disposed at a position of 16.91 mm on the image side from the 55th surface which is the surface closest to the image side of the interchangeable lens.

  Next, the optical system in the present embodiment will be described. The optical system includes, in order from the object side to the image side, a biconcave negative lens G1, a cemented lens of a negative meniscus lens G2 concave to the image side and a biconvex positive lens G3, and a biconvex positive lens G4 to the object side. It is composed of a cemented lens with a concave negative meniscus lens G5 and a positive meniscus lens convex on the image side. The optical filter is disposed in the optical filter between the interchangeable lens and G1. In this embodiment, the front group is G1 to G3, and the rear group is G4 to G6. By attaching the interchangeable lens to the image pickup apparatus of the present embodiment, the image circle of the interchangeable lens is enlarged by 2.0 times. Further, the imaging apparatus of the present embodiment has an imaging element having a diagonal length of 22.0 mm.

  Table 1 shows values corresponding to the conditional expressions of this example. The present embodiment satisfies the conditional expressions (1) to (8), has a function of extending the focal length of the interchangeable lens, and achieves a reduction in size and weight of the photographing system.

  The basic configuration of the fifth embodiment is the same as that of the second embodiment, and a space for arranging the optical filter is secured in the optical system.

  FIG. 13 is a lens cross-sectional view in a state where an interchangeable lens is attached to the imaging apparatus of the present embodiment. In FIG. 13, ML is an interchangeable lens, CV is an optical system built in the image sensor, and F is an optical filter such as an ND filter, a low-pass filter, or an IR cut filter. I is an image pickup surface, which corresponds to the image pickup surface of the solid-state image sensor. FIG. 14 is a longitudinal aberration diagram when the interchangeable lens is in focus at infinity at the wide angle end in a state where the interchangeable lens is attached to the imaging apparatus of the present embodiment. The optical system of the present example is disposed at a position of 12.78 mm from the 55th surface which is the surface closest to the image side of the interchangeable lens to the image side.

  Next, the optical system in the present embodiment will be described. The optical system includes, in order from the object side to the image side, a negative meniscus lens G1 convex toward the object side, a cemented lens of a biconcave negative lens G2 and a biconvex positive lens G3, and a biconvex positive lens G4 and a biconcave lens. The lens is composed of a cemented lens with a negative lens G5 and a biconvex positive lens, and an optical filter is disposed between G1 and G2. In this embodiment, the front group is G1, and the rear group is G2 to G6. By attaching the interchangeable lens to the image pickup apparatus of the present embodiment, the image circle of the interchangeable lens is enlarged by 2.0 times. Further, the imaging apparatus of the present embodiment has an imaging element having a diagonal length of 22.0 mm.

  Table 1 shows values corresponding to the conditional expressions of this example. The present embodiment satisfies the conditional expressions (1) to (8), has a function of extending the focal length of the interchangeable lens, and achieves a reduction in size and weight of the photographing system.

  The basic configuration of the sixth embodiment is the same as that of the first embodiment, and a space for arranging the optical filter is secured between the interchangeable lens and G1.

  FIG. 15 is a lens cross-sectional view in a state where an interchangeable lens is attached to the imaging apparatus of the present embodiment. In FIG. 15, ML is an interchangeable lens, CV is an optical system built in the image sensor, and F is an optical filter such as an ND filter, a low-pass filter, or an IR cut filter. I is an image pickup surface, which corresponds to the image pickup surface of the solid-state image sensor. FIG. 16 is a longitudinal aberration diagram when the interchangeable lens is mounted on the image pickup apparatus of the present embodiment and the interchangeable lens is focused at infinity at the wide-angle end, and the optical system is in the reference state. FIG. 17 shows the state in which the interchangeable lens is mounted on the image pickup apparatus of the present embodiment, and when the interchangeable lens is focused at infinity at the wide angle end, the optical system moves the zoom range of the interchangeable lens to the long focal length side. FIG. 6 is a longitudinal aberration diagram when shifting by a factor of 1.2. The optical system of the present example is disposed at a position of 14.59 mm on the image side from the 55th surface which is the most image side surface of the interchangeable lens.

  Next, the optical system in the present embodiment will be described. The optical system includes, in order from the object side to the image side, a biconcave lens G1, a cemented lens of a biconcave negative lens G2 and a biconvex positive lens G3, a biconvex positive lens G4, an object side concave negative meniscus lens G5, It is composed of a cemented lens of an image-side convex negative meniscus lens G6 and a biconvex positive lens G7. The optical filter is disposed between the interchangeable lens and G1. In this embodiment, the front group is G1 to G3, and the rear group is G4 to G7. By attaching the interchangeable lens to the image pickup apparatus of the present embodiment, the image circle of the interchangeable lens is enlarged by 2.5 times. Further, the imaging apparatus of the present embodiment has an imaging element having a diagonal length of 27.5 mm. Further, in this embodiment, the zoom range of the interchangeable lens is shifted 1.2 times to the long focal length side by moving the front group and the rear group on the optical axis. By shifting the focal length of the interchangeable lens to the long focal length side, it is possible to obtain a more powerful image depending on the subject.

  Table 1 shows values corresponding to the conditional expressions of this example. The present embodiment satisfies the conditional expressions (1) to (8), has a function of extending the focal length of the interchangeable lens, and achieves a reduction in size and weight of the photographing system.

  Numerical examples corresponding to the embodiments of the present invention will be shown below. In each numerical example, i indicates the order of the surfaces from the object side, ri is the radius of curvature of the i-th surface from the object side, di is the i-th and i + 1-th interval from the object side, ndi , Νdi are the refractive index and Abbe number of the i-th optical member. BF is an air equivalent back focus. The last three surfaces are glass blocks such as filters.

The aspherical shape is the X axis in the optical axis direction, the H axis in the direction perpendicular to the optical axis, the light traveling direction is positive, R is the paraxial radius of curvature, k is the cone constant, and A4, A6, A8, and A10 are non- The spherical coefficient is expressed by the following equation. “E-Z” means “× 10 ^−Z ”.

As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

<Interchangeable lens>
Unit mm

Surface data surface number rd nd vd Effective diameter
1 * 17634.271 4.70 1.69680 55.5 183.19
2 109.899 46.92 152.38
3 -201.325 4.50 1.69680 55.5 151.93
4 1829.577 0.15 155.00
5 283.523 12.64 1.80518 25.4 158.03
6 2167.464 5.15 157.76
7 -2805.896 18.49 1.48749 70.2 157.47
8 -196.467 0.20 157.29
9 -1000.469 4.40 1.80518 25.4 149.49
10 603.998 16.55 1.48749 70.2 146.78
11 -307.782 32.56 146.03
12 315.156 17.48 1.48749 70.2 155.94
13 -596.320 0.15 156.09
14 191.137 4.40 1.80518 25.4 155.18
15 118.065 0.39 149.21
16 119.291 35.44 1.48749 70.2 149.24
17 -534.941 0.15 148.58
18 * 200.940 12.13 1.62041 60.3 141.59
19 826.607 (variable) 140.30
20 129.425 1.50 1.88300 40.8 52.29
21 64.705 6.90 48.69
22 -200.592 1.50 1.72916 54.7 47.84
23 41.776 10.46 1.84666 23.8 43.43
24 -106.134 1.50 1.72916 54.7 42.53
25 86.715 6.25 41.00
26 -81.264 1.50 1.88300 40.8 40.91
27 227.627 (variable) 41.93
28 600.754 6.75 1.62041 60.3 51.99
29 -114.148 0.15 52.85
30 117.668 11.71 1.48749 70.2 53.85
31 -75.558 0.09 53.66
32 -76.874 1.60 1.80518 25.4 53.57
33 -134.820 0.15 53.89
34 86.226 1.60 1.80518 25.4 52.65
35 48.805 10.30 1.48749 70.2 50.88
36 2324.271 0.15 50.18
37 94.553 6.65 1.62041 60.3 49.18
38 -6865.358 (variable) 47.86
39 (Aperture) ∞ 3.42 29.98
40 -46.195 1.50 1.77250 49.6 29.29
41 36.572 7.11 1.78472 25.7 28.98
42 -43.549 1.50 1.77250 49.6 28.89
43 69.864 5.93 28.57
44 -41.024 19.74 1.77250 49.6 28.98
45 -41.228 8.40 37.08
46 -195.562 4.78 1.62041 60.3 37.58
47 -59.391 0.20 37.84
48 277.984 1.80 1.88300 40.8 36.81
49 37.998 7.73 1.48749 70.2 35.68
50 -82.491 0.20 35.71
51 81.354 8.17 1.48749 70.2 34.96
52 -31.106 1.80 1.83400 37.2 34.70
53 -201.103 0.20 35.02
54 180.091 6.65 1.48749 70.2 34.93
55 -40.373 5.00 34.74
56 ∞ 33.00 1.60859 46.4 40.00
57 ∞ 13.20 1.51633 64.2 40.00
58 ∞ 12.00 40.00
Image plane ∞

Aspheric data 1st surface
K = 1.68492e + 004 A 4 = 2.64785e-008 A 6 = -1.47610e-012 A 8 = 8.96960e-017 A10 = -3.30657e-021

18th page
K = -1.44619e-001 A 4 = -7.46282e-009 A 6 = -2.04300e-013 A 8 = 1.70939e-017 A10 = -3.75331e-021

Various data

Focal length 6.70
F number 1.50
Angle of view 39.38
Statue height 5.50
Total lens length 606.22
BF 12.00

d19 3.93
d27 173.49
d38 1.30

Entrance pupil position 107.96
Exit pupil position 328.64
Front principal point position 114.80
Rear principal point position 5.30

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 120.59 216.39 131.11 72.76
2 20 -30.00 29.61 13.82 -6.54
3 28 50.00 39.16 11.50 -15.21
4 39 40.05 130.33 45.82 10.33

<Numerical Example 1>
Unit mm

Surface data surface number rd nd vd Effective diameter
56 ∞ 2.00 1.51633 64.1 40.00
57 ∞ 9.00 40.00
58 309.413 1.10 1.95375 32.3 23.34
59 38.956 12.68 22.57
60 -142.088 0.80 1.88300 40.8 22.33
61 19.287 5.08 1.84666 23.8 22.64
62 465.162 2.00 22.78
63 30.476 5.07 1.51633 64.1 23.67
64 -59.957 0.80 1.88300 40.8 23.44
65 146.710 9.70 23.34
66 47.934 3.26 1.58913 61.1 24.01
67 -317.061 13.55 23.78
Image plane ∞

Various data

Focal length 12.06
F number 2.70
Angle of view 39.38
Statue height 9.90
BF 13.55

Entrance pupil position 107.96
Exit pupil position -1570.06
Front principal point position 119.92
Rear principal point position 1.49

<Numerical Example 2>
Unit mm

Surface data surface number rd nd vd Effective diameter
56 233.327 1.10 1.83400 37.2 28.73
57 90.976 9.91 28.13
58 ∞ 2.00 1.51633 64.1 40.00
59 ∞ 13.10 40.00
60 344.328 3.40 1.80809 22.8 19.54
61 -46.989 0.80 1.88300 40.8 19.02
62 24.027 6.02 18.30
63 20.307 4.30 1.60342 38.0 20.89
64 622.815 11.39 20.54
Image plane ∞
Various data

Focal length 10.05
F number 2.25
Angle of view 39.38
Statue height 8.25
BF 11.39

Entrance pupil position 107.96
Exit pupil position -406.45
Front principal point position 117.76
Rear principal point position 1.34

<Numerical Example 3>
Unit mm

Surface data surface number rd nd vd Effective diameter
56 ∞ 2.00 1.51633 64.1 40.00
57 ∞ 8.68 40.00
58 -67.258 1.10 1.95375 32.3 14.94
59 46.031 3.87 14.96
60 -25.872 2.34 1.80809 22.8 15.65
61 -23.076 9.18 16.60
62 33.125 5.27 1.63980 34.5 19.49
63 -135.639 16.34 19.14
Image plane ∞

Various data

Focal length 9.04
F number 2.02
Angle of view 39.38
Statue height 7.42
BF 16.34

Entrance pupil position 107.96
Exit pupil position 142.48
Front principal point position 117.65
Rear principal point position 7.29

<Numerical Example 4>
Unit mm

Surface data surface number rd nd vd Effective diameter
56 ∞ 2.00 1.51633 64.1 40.00
57 ∞ 8.68 40.00
58 -172.556 1.10 1.95375 32.3 14.85
59 29.383 6.96 14.72
60 2523.374 0.80 1.88300 40.8 17.11
61 23.171 5.92 1.84666 23.8 17.63
62 -259.103 14.96 18.52
63 75.461 8.10 1.51633 64.1 24.24
64 -25.006 0.80 1.88300 40.8 24.70
65 -40.483 6.25 25.32
66 -128.662 4.30 1.58913 61.1 25.36
67 -39.243 9.99 25.57
Image plane ∞

Various data

Focal length 13.40
F number 3.00
Angle of view 39.38
Statue height 11.00
BF 9.99

Entrance pupil position 107.96
Exit pupil position 122.26
Front principal point position 122.96
Rear principal point position -3.41

<Numerical example 5>
Unit mm

Surface data surface number rd nd vd Effective diameter
56 103.966 1.10 1.83481 42.7 22.47
57 38.745 9.82 21.51
58 ∞ 2.00 1.51633 64.1 40.00
59 ∞ 13.75 40.00
60 -38.030 0.80 1.83481 42.7 18.19
61 28.793 5.58 1.84666 23.8 19.05
62 -79.869 4.23 19.84
63 47.828 7.49 1.51633 64.1 21.19
64 -21.172 0.80 1.80610 40.9 21.15
65 43.007 1.00 22.03
66 42.532 7.50 1.51823 58.9 23.01
67 -25.936 13.40 23.91
Various data

Focal length 13.40
F number 3.00
Angle of view 39.38
Statue height 11.00
BF 24.93

Entrance pupil position 107.96
Exit pupil position -1086.11
Front principal point position 121.19
Rear principal point position 11.53

<Numerical Example 6>
Unit mm

Surface data surface number rd nd vd Effective diameter
56 ∞ 2.00 1.51633 64.1 40.00
57 ∞ (variable) 40.00
58 -490.221 1.00 2.00100 29.1 14.93
59 32.280 6.03 14.77
60 -89.318 1.10 1.88300 40.8 16.27
61 19.399 9.79 1.80809 22.8 17.15
62 -128.644 (variable) 19.42
63 53.707 11.49 1.48749 70.2 31.00
64 -28.196 0.15 31.35
65 -28.051 1.20 1.84666 23.8 31.26
66 -48.295 0.15 32.27
67 -437.939 1.20 1.95375 32.3 32.24
68 45.346 10.41 1.75520 27.5 32.38
69 -50.328 (variable) 32.96
Image plane ∞

Various data zoom ratio 1.20

Focal length 16.75 20.10
F number 3.75 4.49
Angle of view 39.38 34.38
Image height 13.75 13.75
BF 14.24 4.00

d57 10.63 11.42
d62 24.00 33.46
d69 14.24 4.00

Entrance pupil position 107.96 107.96
Exit pupil position 135.96 110.39
Front principal point position 127.01 131.85
Rear principal point position -2.51 -16.10

101 Imaging Device 102 Optical System 103 Imaging Device

Claims (13)

An imaging apparatus to which an interchangeable lens can be attached, comprising an image sensor and an optical system that changes a focal length of the interchangeable lens, and a distance from the most object-side lens surface vertex of the optical system to the image sensor L, where Skc is the distance from the most image-side lens surface vertex of the lens having refractive power included in the optical system to the image sensor,
0.1 <Scc / L <0.7
An imaging apparatus characterized by satisfying When the diagonal length of the image sensor is IC,
2.0 <L / IC <4.0
The imaging apparatus according to claim 1, wherein: When the air-converted flange back of the interchangeable lens attached to the imaging device is Skm,
0.1 <Skc / Skm <0.7
The imaging apparatus according to claim 1, wherein: When the largest air space of the optical system is La, and the distance from the most object side lens surface vertex of the optical system to the most image side lens surface vertex is Lc,
0.1 <La / Lc <0.7
The imaging device according to any one of claims 1 to 3, wherein: The optical system has a front group having a negative refractive power on the object side and a rear group having a positive refractive power on the image side with the largest air gap, and the focal length of the optical system is f, When the focal length of the group is f1,
0.05 <| f1 / f | <1.5
5. The imaging device according to claim 1, wherein: When the average refractive index of the lens having negative refractive power included in the optical system is Nn, 1.8 <Nn
The imaging device according to any one of claims 1 to 5, wherein: The most object side lens of the optical system is a lens having negative refractive power, and when the radius of curvature of the object side and the image side of the negative lens is r1 and r2, respectively.
0.01 <| r2 / r1 | <0.9
The imaging apparatus according to any one of claims 1 to 6, wherein:   The imaging apparatus according to claim 7, wherein the lens closest to the object side of the optical system is a single lens or a cemented lens. When the distance from the paraxial object point position of the optical system to the image side surface vertex of the lens having the strongest negative refractive power in the optical system is Lo,
-0.4 <Lo / L <0.4
The imaging apparatus according to claim 1, wherein:   The imaging apparatus according to claim 9, wherein the lens having the strongest negative refractive power in the optical system from the paraxial object point position of the optical system is a single lens or a cemented lens.   The image pickup apparatus according to claim 1, wherein the optical system includes three or more and seven or less lenses, and the lenses include a positive lens and a negative lens.   The image pickup apparatus according to claim 1, wherein an optical filter is arranged at a largest air gap in the optical system.   The imaging apparatus according to claim 1, wherein an optical filter is disposed on the object side of the optical system.

Images