JP2006235548A - Diaphragm element, diaphragm element unit and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diaphragm element, a diaphragm element unit and an imaging apparatus capable of forming a completely round diaphragm aperture. <P>SOLUTION: The diaphragm element is equipped with a fluid storing container transmitting light at least in a predetermined optical axis direction, having a planer transparent wall crossing in the optical axis direction and internal space along the wall and storing fluid in the internal space; an opaque magnetic fluid stored in the internal space of the fluid storing container and existing to be deviated in ring shape along the wall; a transparent non-magnetic fluid stored in the internal space of the fluid storing container together with the magnetic fluid, non-mixed with the magnetic fluid and forming a boundary in ring shape with the magnetic fluid on the wall; and a magnetic field generator for generating magnetic field to change the size of the ring of the boundary by itself or by other's help. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an aperture element that adjusts the luminous flux of light, an aperture element unit, and an imaging device that forms image of subject light to acquire image data.

  2. Description of the Related Art Conventionally, an imaging device that captures a subject has been provided with an aperture, an ND filter, and the like for adjusting the amount of subject light according to the brightness of the shooting location. For the diaphragm, a pre-perforated plate is placed so that the hole is on the optical axis to narrow the light flux, or the diaphragm is surrounded by multiple diaphragm blades, and the size of the enclosed diaphragm hole is changed. For example, there is one that controls the amount of light passing through the aperture. Among them, the diaphragm using a plurality of diaphragm blades has an advantage that the size of the diaphragm hole can be adjusted in a plurality of stages, and the degree of freedom of light amount adjustment is high.

  By the way, many apertures using a plurality of aperture blades are designed so that the shape of the aperture hole when the aperture is opened is a perfect circle, and as the aperture is reduced, the overlapping portion of the aperture blades becomes square. Therefore, when the small aperture is set, the shape of the aperture becomes a shape close to a polygon. When shooting in such a state, for example, when shooting a blurred photo such as portrait shooting, the blur is clearly reflected in the polygon and does not become a smooth blur, When shooting, the number of light beams corresponding to the number of vertices of the polygon appears. In addition, if the shape of the aperture hole at the time of small aperture is to be close to a perfect circle, a considerable number of aperture blades must be used, resulting in a complicated structure.

In this regard, Patent Document 1 discloses that the shape of the diaphragm blades is devised so that only a small number of diaphragm blades form a perfect circular aperture hole both at the time of opening and at the time of small aperture, and other openings. Sometimes, a diaphragm device that forms a shape close to a perfect circle is described.
JP 2002-99022 A

  However, even with the diaphragm device described in Patent Document 1, it is not possible to form a perfect circular diaphragm hole at all apertures, and there is a problem that the above-described problems cannot be avoided completely.

  In view of the above circumstances, an object of the present invention is to provide a diaphragm element, a diaphragm element unit, and an imaging device that can form a perfect circular diaphragm hole.

An aperture element of the present invention that achieves the above object has a planar transparent wall that intersects the optical axis direction and an internal space along the wall that transmits light at least in a predetermined optical axis direction. A fluid container for containing fluid;
An opaque magnetic fluid that is contained in the interior space of the fluid container and is annularly biased along the wall;
A transparent non-magnetic fluid that is contained in the interior space of the fluid container together with the magnetic fluid and that is immiscible with the magnetic fluid and that forms an annular boundary with the magnetic fluid on the wall;
And a magnetic field generator for generating a magnetic field for changing the size of the boundary ring by itself or other force.

  According to the aperture element of the present invention, when a magnetic field is applied by the magnetic field generator, the magnetic fluid in the fluid container is attracted by the magnetic field, and the size of the ring at the boundary between the magnetic fluid and the nonmagnetic fluid changes. . The light incident on the aperture element passes through the transparent portion inside the ring and is absorbed by the opaque portion outside the transparent portion. Therefore, according to the aperture element of the present invention, a circular aperture hole can be formed. it can.

  In the aperture element of the present invention, it is preferable that the magnetic field generator includes a plurality of concentric magnetic field generators.

  By providing a plurality of stages of magnetic field generators, the magnetic field applied to the fluid container can be adjusted to a plurality of stages concentrically, and a plurality of stages of aperture values can be realized.

Further, the aperture element unit of the present invention that achieves the above object has a planar transparent wall that intersects the optical axis direction and an internal space along the wall that transmits light at least in a predetermined optical axis direction. A fluid container for containing fluid in the internal space;
An opaque magnetic fluid that is contained in the interior space of the fluid container and is annularly biased along the wall;
A transparent non-magnetic fluid that is contained in the interior space of the fluid container together with the magnetic fluid and that is immiscible with the magnetic fluid and that forms an annular boundary with the magnetic fluid on the wall;
A magnetic field generator that generates a magnetic field that changes the size of the boundary ring by itself or other force;
And a control unit that controls the magnetic field generated by the magnetic field generator and changes the size of the boundary ring.

  According to the aperture element unit of the present invention, as in the aperture element of the present invention, a circular aperture hole can be formed and the luminous flux of light can be adjusted with high accuracy.

  It should be noted that the diaphragm element unit according to the present invention is only shown in its basic form here, but this is merely to avoid duplication, and the diaphragm element unit according to the present invention has only the above basic form. Instead, various forms corresponding to each form of the aperture element described above are included.

The image pickup apparatus of the present invention that achieves the above object includes a planar transparent wall that intersects the optical axis direction and an internal space along the wall that transmits light at least in a predetermined optical axis direction. A fluid container for containing a fluid in the space;
An opaque magnetic fluid that is contained in the interior space of the fluid container and is annularly biased along the wall;
A transparent non-magnetic fluid that is contained in the interior space of the fluid container together with the magnetic fluid and that is immiscible with the magnetic fluid and that forms an annular boundary with the magnetic fluid on the wall;
A magnetic field generator that generates a magnetic field that changes the size of the boundary ring by itself or other force;
A control unit that controls the magnetic field generated by the magnetic field generator to change the size of the boundary ring; and
And an imaging device for generating an image signal representing the subject light by imaging the subject light passing through the fluid container on the surface.

  The image pickup device referred to in the present invention refers to a CCD, a CMOS sensor, or the like provided with a plurality of light receiving elements that receive light and generate a light reception signal.

  According to the imaging apparatus of the present invention, it is possible to adjust the light beam with a circular diaphragm hole, and it is possible to obtain a captured image that suppresses light glare or realizes smooth blurring.

  It should be noted that the imaging apparatus according to the present invention is only shown in its basic form here, but this is merely for avoiding duplication, and the imaging apparatus according to the present invention is not limited to the above basic form. Various forms corresponding to the respective forms of the aperture element described above are included.

  According to the present invention, it is possible to provide a diaphragm element, a diaphragm element unit, and an imaging apparatus capable of forming a perfect circular diaphragm hole.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is an external perspective view of a digital camera to which an embodiment of the present invention is applied as seen from diagonally above the front.

  As shown in FIG. 1, the digital camera 100 is provided with a photographing lens 101 and a diaphragm ring 105 for adjusting a diaphragm value of a diaphragm built in the photographing lens 101 by rotating the photographing lens 101 at the center of the front surface. . Further, an optical viewfinder objective window 102 and an auxiliary light emitting unit 103 are provided on the upper front of the digital camera 100. Further, a slide-type power switch 104 and a release switch 150 are provided on the upper surface of the digital camera 100.

  FIG. 2 is a schematic configuration diagram of the digital camera 100 shown in FIG.

  As shown in FIG. 2, the breakdown of the digital camera 100 is divided into a photographing optical system 110 and a signal processing unit 120. In addition to these, the digital camera 100 includes an image display unit 130 for displaying captured images, an external recording medium 140 for recording captured image signals, and various processes for capturing digital cameras. A zoom switch 170, a shooting mode switch 160, a release switch 150, and an aperture changeover switch 180 for switching the aperture value of the aperture 113 are provided.

  First, the configuration of the photographing optical system 110 will be described with reference to FIG.

  In the digital camera 100, when subject light is incident from the left in FIG. 2, passes through a zoom lens 115 and a focus lens 114, passes through a diaphragm 113 for adjusting the amount of the subject light, and then the shutter 112 is open. Then, an image is formed on the CCD 111 arranged in the subsequent stage. Originally, a plurality of lenses are provided in the photographing optical system, and at least one of the plurality of lenses is largely involved in the focus adjustment, and the relative position of each lens is involved in the focal length. A lens related to a change in focal length is schematically shown as a zoom lens 115, and a lens related to focus adjustment is schematically shown as a focus lens 114.

  The zoom lens 115, the focus lens 114, the diaphragm 113, and the shutter 112 are driven and moved by the zoom motor 115a, the focus motor 114a, the diaphragm controller 113a, and the shutter motor 112a, respectively. Instructions for operating the zoom motor 115a, the focus motor 114a, the aperture controller 113a, and the shutter motor 112a are transmitted directly from the digital signal processing unit 120b in the signal processing unit 120 or through the motor driver 120c.

  The zoom lens 115 is moved in the direction along the optical axis by the zoom motor 115a. When the zoom lens 115 is moved to a position corresponding to a signal from the signal processing unit 120, the focal length is changed and the photographing magnification is determined.

  The focus lens 114 is a lens for realizing a TTLAF (Through The Lens Auto Focus) function. With this TTLAF function, the contrast of the image signal obtained by the CCD 111 is detected by the AF / AE calculation unit 126 of the signal processing unit 120 while moving the focus lens in the direction along the optical axis, and the peak of the contrast is obtained. The focus lens 114 is adjusted to the focus position with the lens position to be focused as the focus position. By this TTLAF function, it is possible to automatically focus on an object with a peak contrast and perform shooting.

  The throttle 113 is configured by accommodating a transparent nonmagnetic fluid and an opaque magnetic fluid in a container. When the photographer rotates the aperture ring 105 in FIG. 1, an aperture value corresponding to the movement position of the aperture ring 105 is set by the aperture switch 180 in FIG. 2. The aperture value information is transmitted to the system controller 121, and further transmitted from the system controller 121 to the aperture controller 113a. The diaphragm controller 113a applies a magnetic field to the magnetic fluid stored in the container of the diaphragm 113 according to the diaphragm value transmitted from the system controller 121, and moves the boundary position between the non-magnetic fluid and the magnetic fluid. The diaphragm 113 and the diaphragm controller 113a will be described in detail later.

  The subject light that has passed through the zoom lens 115, the focus lens 114, the stop 113, and the shutter 112 is imaged on the CCD 111, and the CCD 111 generates an image signal representing the subject image. The CCD 111 corresponds to an example of an image pickup device according to the present invention.

  The imaging optical system 110 is configured as described above.

  Next, the configuration of the signal processing unit 120 will be described.

  The subject image formed on the CCD 111 is read as an image signal to the analog processing (A / D) unit 120a, and the analog signal is converted into a digital signal by the analog processing unit (A / D) 120a. 120b. A system controller 121 is provided in the digital signal processing unit 120b, and signal processing in the digital signal processing unit 120b is performed in accordance with a program showing an operation procedure in the system controller 121. Data exchange between the system controller 121 and the image signal processing unit 122, the image display control unit 123, the image compression unit 124, the media controller 125, the AF / AE calculation unit 126, the key controller 127, and the buffer memory 128 is performed. The internal memory 129 serves as a buffer when data is transferred via the bus 1200 and data is transferred via the bus 1200. Data serving as variables is written to the internal memory 129 as needed according to the progress of the processing process of each unit, and the system controller 121, the image signal processing unit 122, the image display control unit 123, the image compression unit 124, and the media controller 125 are written. The AF / AE calculation unit 126, the key controller 127, and the angle calculation unit 129 perform appropriate processing by referring to the data. That is, an instruction from the system controller 121 is transmitted to each of the above units via the bus 1200, and a processing process of each unit is started. Then, the data in the internal memory 129 is rewritten in accordance with the progress of the process, and is further referred to on the system controller 121 side to manage the operation of each unit described above. In other words, the power is turned on, and the process of each unit is started according to the procedure of the program in the system controller 121. For example, when the mode switch 170, the shooting mode switch 160, the release switch 150, and the aperture switch 180 are operated, information indicating that the operation has been performed is transmitted to the system controller 121 via the key controller 127, and according to the operation. The processing is performed according to the procedure of the program in the system controller 121.

  When a release operation is performed, the image data read from the CCD 111 is converted from an analog signal to a digital signal by an analog processing (A / D) unit 120a, and the digitized image data is stored in the digital signal processing unit 120b. Are once stored in the buffer memory 128 of the memory. The RGB signal of the digitized image data is converted into a YC signal by the image signal processing unit 122, and further compression called JPEG compression is performed by the image compression unit 124 so that the image signal becomes an image file and the media controller 125 is set. To the external recording medium 140. The image data recorded as the image file is reproduced on the image display unit 130 through the image display control unit 123. In this process, the AF / AE calculation unit 126 detects the contrast for each subject distance from the RGB signals for focus adjustment. Based on the detection result, focus adjustment is performed by the focus lens 114. The AF / AE calculation unit 126 extracts a luminance signal from the RGB signals, and detects the field luminance therefrom.

  The digital camera 100 is basically configured as described above.

  Hereinafter, the adjustment of the diaphragm 113 by the diaphragm controller 113a will be described in detail.

  FIG. 3 is a schematic configuration diagram of the diaphragm 113.

  Part (A) of FIG. 3 shows a view of the diaphragm 113 as viewed from above the optical axis, and part (B) of FIG. 3 shows a state when the diaphragm 113 is cut along a plane perpendicular to the optical axis. A cross-sectional view is shown.

  First, the diaphragm 113 will be described.

  The diaphragm 113 is formed by accommodating a magnetic fluid 210 to which a colored dye is added and a transparent nonmagnetic fluid 220 in a transparent fluid container 300.

  The diaphragm 113 includes a transparent fluid container 300, transparent coils 500 a, 500 b, and 500 c that generate a magnetic field upon application of an electric current, and a magnetic fluid that is contained in the fluid container 300 and to which a colored dye is added. 210 and a transparent non-magnetic fluid 220.

The fluid container 300 has a circular thin plate shape, and the magnetic fluid 210 and the nonmagnetic fluid 220 are stored in the thin plate shape. In this embodiment, a fluid container 300 made of a light-transmitting plastic (for example, ZEONOR: a plastic made of a bicyclic aliphatic monomer manufactured by ZEON Corporation) is applied, and the fluid container is used. The inner surface of the thin plate-shaped side surface of 300 is covered with a hydrophilic film having hydrophilicity (for example, a SiO ₂ film prepared from perhydropolysilazane). And a hydrophobic membrane having hydrophobic properties (for example, Cytop: a fluorine-based polymer manufactured by Asahi Glass Co., Ltd.). The fluid container 300 corresponds to an example of the fluid container referred to in the present invention.

  The fluid container 300 as described above contains a magnetic fluid 210 and a non-magnetic fluid 220 that are immiscible with each other. In recent years, it has been reported that a liquid magnetic substance can be synthesized by using an ionic liquid (Chemistry Letters, page 1590, issued in 2004). In this embodiment, such an ionic liquid is used. Water-based magnetic fluid 210 (for example, ionic liquid such as imidazolium ferrate chloride: refractive index: 1.50), and non-magnetic fluid 220 is an oil-based fluid (for example, a hydrocarbon-based compound, more preferably Hydrocarbon aromatic compounds such as mesitylene: refractive index 1.498, orthoxylene: refractive index 1.503, etc.). The magnetic fluid 210 corresponds to an example of the magnetic fluid according to the present invention, and the nonmagnetic fluid 220 corresponds to an example of the nonmagnetic fluid according to the present invention.

  The magnetic fluid 210 repels the hydrophobic film applied to the inner surface of the fluid container 300 on the side surface of the thin plate shape, and the non-magnetic fluid 220 is hydrophilic applied to the inner surface of the central portion of the upper and lower surfaces of the thin plate shape. Repels the sex film. As a result, as shown in Part (B) of FIG. 3, the magnetic fluid 210 is present in an annular shape biased toward the side surface of the thin plate shape, and the nonmagnetic fluid 220 is present in the ring.

  The coils 500a, 500b, and 500c have mutually different shaft diameters, and are arranged with their axes aligned on the rear side of the fluid container 300 (the object light emission side). The diaphragm controller 113a can adjust the application position of the magnetic field to the fluid container 300 in a plurality of stages (in this example, three stages) by applying current individually to the coils 500a, 500b, and 500c. it can. The coils 500a, 500b, and 500c are examples of a magnetic field generator according to the present invention, and the aperture controller 113a corresponds to an example of a control unit according to the present invention.

  The throttle 113 having the above configuration is provided with a reserve tank 400 in which the magnetic fluid 210 and the nonmagnetic fluid 220 are accommodated. The reserve tank 400 is connected to the fluid container 300 of the throttle 113, and the magnetic fluid 210 and the non-magnetic fluid 220 freely enter and leave the fluid container 300.

  The aperture value of the aperture 113 is adjusted by the following procedure.

  When the photographer rotates the aperture ring 105 in FIG. 1, an aperture value corresponding to the moving position of the aperture ring 105 is set in the aperture switch 180 in FIG. 2. The aperture value information is transmitted to the aperture controller 113a via the system controller 121.

  For example, if the aperture value of the first step among all three steps is set by the aperture switch 180, the aperture controller 113a applies reverse currents to the outer coil 500a and the central coil 500b, respectively.

  FIG. 4 is a diagram illustrating the relationship between the applied current and the generated magnetic field.

  In part (B) of FIG. 3, when currents in opposite directions are applied to the outer coil 500a and the central coil 500b, as shown in part (A) of FIG. A reverse magnetic field is generated. As a result, in the portion where the magnetic field generated in the outer coil 500a and the magnetic field generated in the central coil 500b overlap, the magnetic fields in the opposite directions cancel each other, as shown in part (B) of FIG. Only the magnetic field surrounding the outer coil 500a remains.

  When a magnetic field as shown in part (B) of FIG. 4 is applied to the fluid container 300, the magnetic fluid 210 is attracted to the magnetic field surrounding the outer coil 500a, and the boundary between the magnetic fluid 210 and the nonmagnetic fluid 220 is It moves to the position of the outer coil 500a while maintaining the annular shape (see Part (A) of FIG. 3). When light enters the aperture 113, the light passes through the nonmagnetic fluid 220 and is absorbed by the magnetic fluid 210, so that the light beam becomes an annular size at the boundary between the nonmagnetic fluid 220 and the magnetic fluid 210. It is adjusted together. Thus, the annular size of the boundary between the non-magnetic fluid 220 and the magnetic fluid 210 is changed according to the aperture value designated by the photographer, and the aperture value of the aperture 113 is adjusted.

  Also, assuming that the aperture value of the second step among all three steps is set by the aperture switch 180, reverse currents are applied to the center coil 500b and the inner coil 500c by the aperture controller 113a. . As a result, only the magnetic field surrounding the central coil 500a remains and is applied to the fluid container 300.

  FIG. 5 is a diagram illustrating a boundary between the magnetic fluid 210 and the non-magnetic fluid 220 when the second-stage aperture value is set.

  When a reverse current is applied to the central coil 500b and the inner coil 500c, a magnetic field surrounding the central coil 500a is applied to the fluid container 300, and the boundary between the magnetic fluid 210 and the nonmagnetic fluid 220 is annular. Is moved to the position of the central coil 500b. At this time, the annular shape at the boundary between the nonmagnetic fluid 220 and the magnetic fluid 210 is smaller than the annular shape at the boundary shown in Part (A) of FIG. In this state, a larger amount of light is attenuated by the diaphragm 113 than in the state shown in part (A) of FIG.

  Thus, according to the diaphragm 113 of the present embodiment, a circular diaphragm can be realized with a simple configuration.

  Here, in the above, examples of the magnetic liquid and the non-magnetic liquid are shown as examples of the magnetic fluid and the non-magnetic fluid according to the present invention, but the magnetic fluid and the non-magnetic fluid according to the present invention are sols. It may be.

In the above description, a coil that generates a magnetic field by receiving an electric current is shown as an example of the magnetic field generator according to the present invention. However, the magnetic field generator according to the present invention is a permanent generator that generates a magnetic field by itself. It may be a magnet. In this case, the movement of the magnetic fluid is realized by the movement of the permanent magnet itself. Subsequently, various modes that can be adopted in each component constituting the present invention will be described.

  The magnetic fluid used in the present invention may be any type, but is preferably an ionic liquid. The ionic liquid means an ionic compound composed of a cationic compound and an anionic compound and is a liquid. An ionic liquid is a volatile compound corresponding to a vapor pressure, whereas an ionic liquid is expected to be used as a solvent for a functional material as a non-volatile liquid having no vapor pressure. As the ionic liquid used in the present invention, any ionic liquid may be used. Preferably, examples of the cationic compound include imidazolium salt compounds, pyridinium salt compounds, ammonium salt compounds, and phosphonium salt compounds. Specific examples include 1-ethyl-3-methylimidazolium, 1-n-butyl-3-methylimidazolium, 1-ethyl-3-ethylimidazolium, and the like. Preferably, it is an imidazolium salt compound. More preferred are 1-ethyl-3-methylimidazolium salt compounds and 1-n-butyl-3-methylimidazolium salt compounds. The anionic compound preferably contains an element that exhibits magnetism, and examples of the element that exhibits magnetism include iron, cobalt, and nickel. Particularly preferred is iron.

  A dye can be added to the magnetic fluid of the present invention as necessary. Any dye may be used, and examples thereof include azo dyes, anthraquinone dyes, perylene dyes, merocyanine dyes, azomethine dyes, phthaloperylene dyes, indigo dyes, azulene dyes, dioxazine dyes, and polythiophene dyes. .

  In the above embodiment, the colored ferrofluid was synthesized according to the method described in the literature (Chemistry Letters, page 1590, 2004).

It is the external appearance perspective view which looked at the digital camera with which one Embodiment of this invention was applied from front diagonally upward. It is a schematic block diagram of the digital camera 100 shown in FIG. 3 is a schematic configuration diagram of a diaphragm 113. FIG. It is a figure explaining the relationship between an applied electric current and the magnetic field to generate | occur | produce. It is a figure which shows the boundary of the magnetic fluid 210 and the nonmagnetic fluid 220 when the aperture value of the 2nd step is set.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Digital camera 150 Release button 101 Shooting lens 102 Optical viewfinder objective window 103 Auxiliary light emission part 104 Power switch 105 Aperture ring 110 Shooting optical system 111 CCD
112 shutter 112a shutter motor 113 aperture 113a aperture controller 114 focus lens 114a focus motor 115 zoom lens 115a zoom motor 120 signal processing unit 120a analog processing (A / D) unit 120b digital signal processing unit 120c motor driver 121 system controller 122 image signal Processing unit 123 Image display control unit 124 Image compression unit 125 Media controller 126 AF / AE calculation unit 127 Key controller 128 Buffer memory 129 Internal memory 1200 Bus 130 Image display unit 140 External recording medium 150 Release switch 160 Shooting mode switch 170 Zoom switch 180 Aperture changeover switch 210 Magnetic fluid 220 Non-magnetic fluid 300 Fluid container 50 a, 500b, 500c coil

Claims (4)

A fluid container for containing fluid in the internal space, having a planar transparent wall intersecting the optical axis direction and an internal space along the wall, which transmits light at least in a predetermined optical axis direction;
An opaque magnetic fluid which is accommodated in the interior space of the fluid container and which is present in an annularly-balanced manner along the wall;
A transparent non-magnetic fluid which is contained in the interior space of the fluid container together with the magnetic fluid and which is immiscible with the magnetic fluid and forms an annular boundary with the magnetic fluid on the wall;
A diaphragm element comprising: a magnetic field generator for generating a magnetic field for changing the size of the boundary ring by itself or other force.   The aperture element according to claim 1, wherein the magnetic field generator includes a plurality of concentric magnetic field generators. A fluid container for containing fluid in the internal space, having a planar transparent wall intersecting the optical axis direction and an internal space along the wall, which transmits light at least in a predetermined optical axis direction;
An opaque magnetic fluid which is accommodated in the interior space of the fluid container and which is present in an annularly-balanced manner along the wall;
A transparent non-magnetic fluid which is contained in the interior space of the fluid container together with the magnetic fluid and which is immiscible with the magnetic fluid and forms an annular boundary with the magnetic fluid on the wall;
A magnetic field generator for generating a magnetic field that changes the size of the ring of the boundary by itself or other force;
A diaphragm unit comprising: a control unit that controls a magnetic field generated by the magnetic field generator to change a size of the boundary ring. A fluid container for containing fluid in the internal space, having a planar transparent wall intersecting the optical axis direction and an internal space along the wall, which transmits light at least in a predetermined optical axis direction;
An opaque magnetic fluid which is accommodated in the interior space of the fluid container and which is present in an annularly-balanced manner along the wall;
A transparent non-magnetic fluid which is contained in the interior space of the fluid container together with the magnetic fluid and which is immiscible with the magnetic fluid and forms an annular boundary with the magnetic fluid on the wall;
A magnetic field generator for generating a magnetic field that changes the size of the ring of the boundary by itself or other force;
A control unit for controlling the magnetic field generated by the magnetic field generator to change the size of the boundary ring;
An image pickup apparatus comprising: an image pickup device configured to form an image signal representing the subject light by imaging the subject light passing through the fluid container on the surface.

Images