JP5154766B2 - Optical path switching device and camera incorporating the same - Google Patents

Description

The present invention relates to an optical path opening / closing device capable of opening / closing an optical path and a camera incorporating the optical path opening / closing device .

  A shutter and a diaphragm incorporated in an optical device such as a camera have a function of opening and closing or narrowing a part of an optical path of these optical devices. For this reason, the light-shielding blade constituting the main part is required not only to have a light-shielding property but also to have a low surface frictional resistance and be difficult to be charged in order to realize a smooth opening / closing operation. This is because it is common to use a plurality of light shielding blades superimposed on each other. In addition, in order to prevent light leakage from between the light shielding blades that overlap each other, it is also important that the light reflectance of the surface of the light shielding blade is low, and high flatness of the surface of the light shielding blade is also required. This flatness, that is, the flatness of the light shielding blades is also important for preventing breakage due to the collision of the light shielding blades during the opening and closing operation.

  In order to satisfy such a requirement, conventionally, a light shielding blade having various materials and various treatments has been proposed. For example, Patent Document 1 discloses a light shielding blade in which layers made of a thermosetting resin containing carbon black, a lubricant, and a matting agent are bonded to both surfaces of a film mainly composed of a thermoplastic resin. In addition, aluminum is used as the base material of the light shielding blade, an anodized film is formed on the surface, black organic dye is impregnated into the fine pores of the anodized film, and black coating is further applied thereon. Has also been proposed.

  As described above, since it is necessary to provide the light-shielding blade with characteristics such as light-shielding property, slidability, non-reflective property, and non-charging property, surface treatment such as painting is usually applied to the surface of the substrate. Is done. More specifically, a coating film is formed on the film substrate constituting the main part of the light-shielding blade by a spray method or a dipping method, and drying and baking are performed to fix the coating layer on the surface of the film substrate. A light shielding blade having a predetermined shape is cut out by a press or the like. In addition, when forming a coating film, adding an inorganic or organic filler in the paint for the purpose of improving slidability and non-chargeability is also known.

JP-A-9-274218

  When the coating layer is formed on the surface of the film substrate by the spray method when manufacturing the light shielding blade, the coating efficiency is poor, and when the filler content is increased, the viscosity of the coating is increased and the handling of the coating itself is caused by the sedimentation of the filler. There is a problem that decreases. Furthermore, since the adhesion strength of the filler to the coating material is low, the filler may fall off from the cured coating film, which may adversely affect the optical device. In particular, in a digital camera using an image sensor, the adhesion of dust to the surface of the image sensor causes a reduction in image quality as it is. For this reason, peeling off of the filler from the light shielding blades has a high possibility of adversely affecting the image sensor, which is a very important problem in the digital camera. However, if the filler content is reduced in order to avoid such problems, the slidability of the light-shielding blade is also reduced, and a high-hardness coating film cannot be formed.

  Further, when the coating layer is formed by the dipping method, there is a similar problem. Since the filler contained in the coating settles under its own weight, it is very difficult to form a coating film having a uniform thickness and composition. In particular, when it is necessary to form a thick coating film, there is a high possibility that the coating film on the edge portion of the light shielding blade becomes abnormally thick due to the fluidity of the coating material. In addition, dust or the like may be mixed in the coating film itself, or pinholes may be generated, and a highly reliable light shielding blade cannot be obtained.

  In addition, the above-described conventional coating method uses a large amount of an organic solvent in combination, and is not preferable as a working environment in terms of harmfulness and safety.

  On the other hand, in the case of a light shielding blade in which a black organic dye is impregnated into an anodized film formed on the surface of a substrate, it is difficult to deeply penetrate the black organic dye into the anodized film. As a result, if the light reflectance on the surface of the light shielding blade is to be reduced, the film thickness of the anodized film must be greatly increased, and the film thickness can be kept uniform to ensure dimensional accuracy. It becomes extremely difficult.

The present invention has been made in order to solve the above-described conventional problems related to an optical path opening and closing device incorporating a light shielding blade. That is, it is an object to provide a surface stable quality optical channel opening and closing device shielding blade is incorporated in and such an optical path switching device is incorporated in particular low light reflectivity camera .

A first aspect of the present invention is an optical path opening and closing device that is arranged so as to cross an optical path and that can open and close the optical path, and includes two or more light shielding blades that can open and close the optical path , The light shielding blade includes a first light reflection reducing layer formed by a colored anodic oxide film that is colored by subjecting an anodic oxide film formed on the surface of a metal base material to electrolytic color development, and the colored anodic oxide film The second light reflection reducing layer of black or a dark color close to black formed by a metal or an oxide thereof excessively deposited in the fine pores of the colored anodic oxide film and subjected to sealing treatment comprising the door, during the opening and closing operation of the optical path by the plurality of shutter blades, surfaces on each of the second reflection reduction layer of the plurality of shutter blades are formed side is a Rukoto that Sessu sliding in overlap with each other Features A.

In the present invention, when the light shielding blade is driven to open and close the optical path, the metal deposited in the void portion of the first light reflection reducing layer by the colored anodic oxide film formed on the surface of the light shielding blade overlapping each other or the oxidation thereof Part of the second light reflection reducing layer of black or dark color due to the object is in sliding contact with each other.

Second embodiment of the present invention, there is provided a camera for forming an image on the imaging medium using a lens, a first aspect of the present invention which is arranged so as to cross the optical path between the lens and the imaging medium The optical path opening / closing device according to the embodiment is incorporated.

Also in the present invention, when the light path opening / closing device drives the light shielding blade to open and close the light path, the metal deposited on the void portion of the first light reflection reducing layer formed on the surface of the light shielding blade overlapping with each other or the oxide thereof A part of the second light reflection reducing layer of black or dark color close to black comes into sliding contact with each other.

In the optical path opening / closing device according to the first aspect of the present invention, which is arranged so as to cross the optical path, the first light reflection reduction by the colored anodic oxide film formed on the surface of the metal substrate is provided. Two or more light-shielding blades having a layer and a black or near dark light reflection reducing layer formed by depositing a metal or its oxide in the fine pores of the colored anodic oxide film are incorporated. Yes. For this reason, when the light shielding blades are driven, it is possible to suppress the generation of static electricity due to the friction of the light shielding blades that overlap each other, and minute dust in the air adheres to the light shielding blades or adheres to the imaging medium. Or the like can be reduced. In addition, since the colored anodic oxide film that is harder than the base material and excellent in wear resistance covers the base material, when the light shielding blades are driven, the colored anodic oxide film may be peeled off due to the friction of the light shielding blades that overlap each other. Can be prevented in advance.

The camera of the second embodiment of the present invention for forming an image on the imaging medium by using a lens, according to a first embodiment of the present invention which is arranged so as to cross the optical path between the lens and the imaging medium An optical path opening and closing device is incorporated. For this reason, when the light shielding blades are driven, it is possible to suppress the generation of static electricity due to the friction of the light shielding blades that overlap each other, and minute dust in the air adheres to the light shielding blades or adheres to the imaging medium. Or the like can be reduced. In addition, since the colored anodic oxide film that is harder than the base material and excellent in wear resistance covers the base material, when the light shielding blades are driven, the colored anodic oxide film may be peeled off due to the friction of the light shielding blades that overlap each other. Can be prevented in advance. These advantages are particularly effective in the case of a digital camera using a CCD or the like that dislikes adhesion of dust as an imaging medium.

  An embodiment in which an optical path opening and closing device according to the present invention is applied to a focal plane shutter of a digital single-lens reflex camera will be described in detail with reference to FIGS. However, the present invention is not limited to such an embodiment, and any change or modification included in the concept of the present invention described in the claims can be made. Therefore, other modifications belonging to the spirit of the present invention are possible. Of course, it can also be applied to technology.

  The concept of a digital single lens reflex camera (hereinafter simply abbreviated as “camera”) in this embodiment is schematically shown in FIG. 1, the front shape of the focal plane shutter unit is shown in FIG. The structure is shown in FIG. That is, a photographing lens 13 incorporating a diaphragm device 12 for adjusting the amount of passing light is disposed on the front surface of the main body 11 of the camera 10, and the photographing lens 13 passes through the rear surface of the main body 11. An image pickup device 14 such as a CCD through which the light is guided is disposed. Further, a low-pass filter 15 that transmits a low-frequency component of light incident on the image sensor 14 is disposed immediately before the image sensor 14. Further, a focal plane shutter unit (hereinafter simply referred to as a shutter unit) 16 for opening and closing an optical path from the photographing lens 13 to the image sensor 14 is disposed immediately before the low-pass filter 15.

  An erecting prism (a pentaprism in the illustrated example) 17 and an eyepiece 18 are disposed on the upper portion of the main body 11. A focusing plate 19 is disposed directly below the erecting prism 17, and a reflecting mirror 20 that is disposed between the photographing lens 13 and the shutter unit 16 and guides the light that has passed through the photographing lens 13 to the focusing plate 19 is provided below the erecting prism 17. It is arranged. The reflecting mirror 20 is inclined with respect to the optical axis of the photographic lens 13. In this state, light passing through the photographic lens 13 is guided to the focusing screen 19 and does not reach the imaging element 14 side. However, when the shutter unit 16 is opened and closed, it is flipped up so as to be close to the focusing screen 19, and the light from the photographing lens 13 is guided to the image sensor 14 side through the shutter unit 16.

  In the present embodiment, an exposure sensor 21 that detects the amount of light that reaches a predetermined area of the focusing screen 19 is incorporated in the vicinity of the light emitting end face of the erecting prism 17. The exposure sensor 21 can control the exposure amount with respect to the image sensor 14 based on the detected light amount, and the opening degree of one of the aperture device 12 and the shutter unit 16 is automatically adjusted.

  Accordingly, when the photographer operates the photographing lens 13 while looking into the eyepiece lens 18 to form an image of the subject on the focusing screen 19, and operates a shutter release button (not shown), the reflecting mirror 20 first jumps to the focusing screen 19 side. . Next, a front curtain 22 (to be described later) of the shutter unit 16 moves from the light shielding position to the exposure position to open the optical path, and light from the photographing lens 13 enters the image sensor 14. A predetermined time after the front curtain 22 starts to move to the exposure position, a rear curtain 23 (to be described later) moves from the exposure position to the light shielding position to close the optical path, and the reflecting mirror 20 returns to the state shown in FIG. The operation is complete.

  The shutter unit 16 in the present embodiment is a so-called vertical running type. In the present embodiment, in FIG. 1, a plurality of light shielding blades 24, 25, 26, 27, and 28 that overlap each other as the front curtain 22 and the rear curtain 23 that run in the vertical direction (5 and 4 in the illustrated example, respectively). 29, 30, 31, 32 are used. Between the frame-shaped cover plate 34 and the frame-shaped shutter base plate 35 assembled in parallel with each other via a plurality of spacers 33, a frame-shaped partition plate 36 that partitions the front curtain 22 and the rear curtain 23 is provided. It is assembled in an inclined state. The front curtain 22 is disposed between the cover plate 34 and the partition plate 36, and the rear curtain 23 is disposed between the partition plate 36 and the shutter base plate 35. A front-curtain support arm 37 and a front-curtain drive arm 38 are respectively pinned to one end side (left side in FIG. 1) in the longitudinal direction of the light shielding blades 24 to 28 constituting the front curtain 22. Similarly, the rear curtain support arm 39 and the rear curtain drive arm 40 are also pinned to one end in the longitudinal direction of the light shielding blades 29 to 32 constituting the rear curtain 23. The front curtain drive arm 38 and the rear curtain drive arm 40 are slidably engaged with arcuate guide grooves 41 and 42 formed in the cover plate 34 and the shutter base plate 35, respectively. Further, these base end portions are connected to driving sources (not shown) for opening and closing the front curtain 22 and the rear curtain 23, respectively.

  The specific configuration of the shutter unit 16 itself is well known in Japanese Patent Laid-Open Nos. 10-186448, 2002-229097, 2003-280065, and the like.

  FIG. 4 shows a state where one of the light shielding blades 24 to 32 in the present embodiment is created (hereinafter, these are represented as 43 for convenience). The light shielding blade 43 is formed by forming an anodized film on the surface of a base material and forming a light reflection reducing layer on the anodized film. For this reason, it is preferable to employ aluminum, magnesium, titanium, or an alloy thereof capable of forming an anodized film as the base material of the light shielding blade 43. The substrate itself does not necessarily have low reflection, but it is not preferable that the reflectance fluctuates greatly depending on the wavelength of light or that the reflectance varies greatly. Furthermore, as a recent trend of digital cameras, priority is given to less generation of dust or the like by the operation of the shutter unit, rather than low reflectance of the light shielding blades. From this point of view, aluminum and its alloys are considered to be optimal in consideration of material costs and workability.

In the present embodiment, the belt-shaped sheet material 44 as shown in FIG. 4 serving as a base material is pressed while leaving a part of the contour shape of the previous light shielding blade 43. Next, the pressed sheet material 44 is subjected to an anodic oxidation treatment and an electrolytic coloring treatment and an electrolytic coloring treatment described below to form first and second light reflection reducing layers. Thereafter, the surplus portion 45 is mechanically trimmed to finish the light shielding blade 43.

As in the present embodiment, it is preferable to finish the main contour shape of the light shielding blade 43 before performing the anodizing process, the electrolytic coloring process, and the electrolytic coloring process. If the contour shape of the light blocking blade 43 by pressing after performing anodic oxidation treatment and an electrolytic coloring treatment and electrolytic coloring treatment on the surface of the sheet material 44, a state in which the base material itself is exposed to the shear plane, this part of the light May cause diffuse reflection. In this embodiment, since the base material is finally exposed at the portion where the surplus portion 45 is trimmed, it is preferable to set the trimming portion at a position where the light from the photographing lens 13 does not reach. . As a result, it is possible to eliminate the need to form an anodic oxide film again on the shearing surface and form the light reflection reducing layer there again. By performing such electrolytic treatment, it is possible to completely eliminate the problems caused by the conventional spraying method and dipping method.

  There are two methods for forming the light reflection reducing layer on the anodized film formed on the surface of the base material: electrolytic coloring treatment and electrolytic coloring treatment.

  The electrolytic coloring method generally deposits metal in the fine pores of an anodized film such as alumite by AC electrolysis of an anodized film in an electrolyte containing a metal salt as a main component, thereby reducing the light reflection reducing layer. Is a technology to form In the electrolytic coloring method, a dark light reflection reducing layer close to black can be formed by selecting electrolytic conditions. In this case, nickel (Ni) salt, copper salt, tin (Sn) salt, cobalt salt, lead salt, manganese salt, gold salt, silver salt, molybdenum salt, selenium salt or the like can be used as the metal salt. However, in view of the hue of the obtained light reflection reducing layer, those containing Sn salt and / or Ni salt as the main component are preferable. As the form of the metal salt, inorganic acid salts such as sulfates, and organic acid salts such as acetates and oxyacid salts can be used. Furthermore, the light reflection reducing layer can be colored almost black by setting the electrolytic treatment time sufficiently long. Moreover, since the light reflection reducing layer excessively precipitated in the fine pores in the anodized film using Sn salt has lubricity, it can be said that this is also preferable as a characteristic of the light shielding blade.

  Usually, after forming a light reflection reducing layer in the anodized film by electrolytic coloring treatment, the anodized film is sealed by immersion in a nickel acetate-based sealant solution or by a hydration reaction by hot water or steam treatment. It is preferable to perform the treatment to prevent the corrosion deterioration of the substrate.

  The concept of the present invention includes a tertiary electrolytic coloring treatment in which a secondary anodic oxide film is formed over the primary anodic oxide film, and a metal is deposited in the micropores in the secondary anodic oxide film.

  On the other hand, the electrolytic coloring treatment is to color the anodic oxide film itself by electrolyzing the anodic oxide film using an organic acid electrolytic solution. For example, when the main component of the substrate is aluminum, it contains oxalic acid. An anodized film can be formed as a light reflection reducing layer using electrolysis. However, in the present invention, what is called an alloy coloring process in which a specific additive component in the metal composition constituting the base material is selectively deposited during the anodizing process to develop a color is also included in the concept of the electrolytic coloring process. Defined as For example, when the base material is aluminum containing a large amount of silicon (Si), by subjecting it to an electrolytic treatment with sulfuric acid, Si fine particles are deposited as an anodic oxide film, which can be used as a light reflection reducing layer.

The above-described electrolytic coloring treatment and electrolytic coloring treatment are combined, and metal is deposited by electrolytic coloring treatment in the micropores of the anodized film as the light reflection reducing layer formed by the electrolytic coloring treatment, and this is subjected to the second light reflection. It formed as a reducing layer.

  The light reflectance of the light shielding blade 43 used in the camera 10 in this embodiment is sufficient if it is about 5% in the visible region. The thickness of the anodic oxide film having the light reflection reducing layer having such light reflectance is sufficient. Is about 5 μm.

  When impregnating an anodized film with an organic dye like a conventional light-shielding blade, it is necessary to set the thickness of the anodized film to 15 μm or more in order to obtain a light reflectance of 5%. However, when a black coating film is further formed, the thickness of the anodized film can be about 5 μm or more, but the thickness of the coating film needs to be about 5 μm or more. In the case of a light shielding blade in which only a coating film is formed on the surface of a substrate without forming an anodized film, the thickness of the coating film needs to be 10 μm or more. In the present invention, an anodic oxide film having a thickness of about 5 μm may be formed on the surface of the substrate, and the cost required for the surface treatment of the substrate can be reduced as compared with the conventional one.

  Next, various characteristics of the light shielding blade 43 according to the present invention are shown in Table 1 below as Examples 1 to 4 together with Comparative Examples 1 and 2 for comparison. The film thickness (unit: μm) of the anodized film was measured using a film thickness meter for the anodized film. The surface properties of the light-shielding blade 43 are measured by using a surface roughness meter to measure the centerline average roughness Ra (unit: μm), and the surface static friction coefficient is measured using a surface measuring machine (manufactured by Shinto Kagaku Co., Ltd.). It was measured. In addition, the wear resistance was measured by using a No. 2000 wrapping tape with an abrasion tester (manufactured by Suga Test Instruments Co., Ltd.) and reciprocating 400 times in a state where a load of 300 g was applied to the surface of the light shielding blade 43. Judgment was made by measuring weight loss. Further, the light-shielding blades 43 obtained in Examples 1 to 4 and Comparative Examples 1 and 2 are incorporated as the front curtain 11 and the rear curtain 12 of the shutter unit 10 shown in FIGS. The durability test and the presence or absence of peeling of the members constituting the surface were also examined.

Example 1
An aluminum sheet (A2024) having a thickness of 70 μm serving as a base material was prepared, and this was subjected to pressing as shown in FIG. 4 to obtain a sheet material 44 to which the light shielding blades 43 were connected via the surplus portion 45. Next, the sheet material 44 was degreased, immersed in a sulfuric acid aqueous solution and energized, and an anodized film was formed on the surface. Further, this anodized sheet material 44 was subjected to electrolytic coloring treatment in an aqueous sulfuric acid solution containing nickel sulfate, and nickel was deposited in the fine pores of the anodized film to form a light reflection reducing layer. Thereafter, this was immersed in a solution containing a nickel acetate-based sealing agent to seal the anodic oxide film.

(Example 2)
After forming the same anodic oxide film as in Example 1 and performing a degreasing treatment, electrolytic coloring treatment of the sheet material 44 is performed in a sulfuric acid aqueous solution containing stannous sulfate, and tin is formed in the fine pores of the anodic oxide film. A light reflection reducing layer was formed by deposition. Then, this was immersed in the solution containing a nickel acetate type sealing agent, and the sealing process of the anodic oxide film was performed.

(Example 3)
An aluminum sheet (A2024) having a thickness of 70 μm serving as a base material was prepared, and this was subjected to pressing as shown in FIG. 4 to obtain a sheet material 44 to which the light shielding blades 43 were connected via the surplus portion 45. Next, the sheet material 44 was degreased and then energized in an aqueous oxalic acid solution to form a colored anodic oxide film colored blackish, that is, a light reflection reducing layer, by electrolytic coloring treatment. Thereafter, the sheet material 44 was immersed in a solution containing a nickel acetate-based sealing agent to seal the anodic oxide film as the light reflection reducing layer.

Example 4
In Example 3, electrolytic coloring treatment was further performed in a sulfuric acid aqueous solution containing nickel sulfate on the sheet material 44 on which an electrolytic coloring treatment was performed to form a coloring anodic oxidation coating. To form a second light reflection reducing layer. Then, this was immersed in the solution containing a nickel acetate type sealing agent, and the sealing process of the anodic oxide film was performed.

(Comparative Example 1)
A so-called black alumite film was formed by impregnating the anodized film formed on the surface of the sheet material 44 by the same anodizing treatment as in Example 1 with a black dye.

  On the other hand, an epoxy-based paint in which 10% by weight of PTFE powder having an average particle size of 0.5 μm was dispersed was prepared, and the viscosity was adjusted with a thinner, which was then used as a sheet material 44 on which a black alumite film was formed. It was made to adhere to the surface by the spray method. Thereafter, it was baked for 20 minutes in a baking furnace at 180 ° C. to form a coating film having a thickness of about 5.8 μm on the surface of the black alumite film of the sheet material 44.

(Comparative Example 2)
After degreasing the pressed sheet material 44 as in Example 1, this was energized in a sulfuric acid aqueous solution for about three times as long as in Example 1 to form an anodized film having a thickness of about 15 μm. Further, this anodized film was impregnated with a black dye to form a so-called black alumite film.

  As is clear from Table 1, the surface roughness of Examples 1 to 4 and Comparative Example 2 is the surface roughness of the anodized film itself, so that it is more accurate than the surface roughness of the coating film in Comparative Example 1 It has become a numerical value. Moreover, the coating sample which employ | adopted the spray method of the comparative example 1 was easy to wear, and it has confirmed that a part of coating film disappeared and weight loss was large. It was also confirmed that scratch marks due to friction were formed on the surface. Regarding Comparative Example 2, it is necessary to set the film thickness of the anodized film to be thicker than those of Examples 1 to 4 in order to reduce the light reflectance of the surface. As a result, fading of the surface color was observed. In the samples of Examples 1 to 4, no defects as in Comparative Examples 1 and 2 occurred.

  Furthermore, using a spectrophotometer manufactured by Hitachi, Ltd., the light reflectance of the light shielding blade obtained in Example 1 and Comparative Example 1 was measured in the range from visible light to near infrared (350 to 800 nm), The result is shown in FIG. In Comparative Example 1 indicated by the broken line, the light reflectance starts to increase suddenly in the red to near-infrared region, whereas in Example 1 indicated by the solid line, it is substantially constant over the entire visible region. It was confirmed that the light reflectance was maintained.

It is a system conceptual diagram showing the schematic structure of one Embodiment which applied the optical path switching device by this invention to the focal plane shutter unit of a digital single-lens reflex camera. It is a front view of the shutter unit in the embodiment shown in FIG. FIG. 3 is a cross-sectional view taken along the line III-III of the shutter unit shown in FIG. 2. It is a top view showing the state in the middle of manufacture of the light-shielding blade | wing which comprises some shutter units shown in FIG. It is a graph showing the relationship between the wavelength of light and the light reflectance in the samples of Example 1 and Comparative Example 1.

Explanation of symbols

10 cameras (digital single-lens reflex cameras)
DESCRIPTION OF SYMBOLS 11 Main body 12 Aperture apparatus 13 Shooting lens 14 Image sensor 15 Low-pass filter 16 Shutter unit (focal plane shutter unit)
17 Upright prism (penta prism)
DESCRIPTION OF SYMBOLS 18 Eyepiece 19 Focusing plate 20 Reflector 21 Exposure sensor 22 Front curtain 23 Rear curtain 24-32 Shading blade 33 Spacer 34 Cover plate 35 Shutter base plate 36 Partition plate 37 Front curtain support arm 38 Front curtain drive arm 39 Rear curtain support arm 40 Rear curtain drive arm 41, 42 Guide groove 43 Shading blade 44 Sheet material 45 Surplus part

Claims (2)

An optical path opening and closing device arranged to cross the optical path and capable of opening and closing the optical path,
Two or more light shielding blades that can open and close the optical path are incorporated, and the plurality of light shielding blades are:
A first light reflection reducing layer formed by a colored anodic oxide film colored by applying an electrolytic color treatment to the anodized film formed on the surface of the metal substrate;
The colored anodic oxide film is subjected to electrolytic coloring treatment to form a black or nearly dark second black formed by a metal or oxide thereof excessively precipitated in the fine pores of the colored anodic oxide film and subjected to sealing treatment. Light reflection reducing layer
The comprising, during the opening and closing operation of the optical path by the plurality of shutter blades, characterized Rukoto that Sessu the surfaces on each of the plurality of the second side of the reflection-reducing layer is formed of a light-shielding blade is overlapped with each other sliding An optical path opening and closing device. The optical path opening and closing device according to claim 1 , which is a camera that forms an image on an imaging medium using a lens, and is arranged so as to cross an optical path between the lens and the imaging medium. A camera characterized by that.

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