JP2007025350A - Lens barrel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely prevent erroneous attachment by making a lens holding frame on an intermediate adapter side interfere with a cover member on a lens barrel side when an intermediate adapter is to be attached to a lens barrel non-adaptable to the intermediate adapter. <P>SOLUTION: The aperture shape of the cover member on the imaging surface side of an interchangeable lens is made almost rectangular shape whose diagonal length is longer than the diameter of the projection part of the intermediate adapter and whose long side length or short side length is shorter than the diameter of the projection part of the intermediate adapter. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an interchangeable lens barrel of a camera system having an intermediate adapter that is mounted between a lens barrel and a camera body and has an optical system that protrudes closer to the subject with respect to a lens barrel mounting reference plane. In particular, the present invention is suitable for a digital camera, a video camera, a film camera, etc., in which lenses can be exchanged.

  As an accessory for interchangeable-lens camera systems such as single-lens reflex cameras, an interchangeable lens that can be used for close-up photography by extending the back focus of the interchangeable lens by interposing it between the camera body and the interchangeable lens. An intermediate adapter having a function of enlarging the image magnification of a lens is known. The former is called a close-up ring or an extension tube, and the latter is called a teleconverter or an extender. This teleconverter has an optical system for realizing the above-described functions. As shown in FIG. 2, the optical system and the lens holding frame for holding the optical system with respect to the interchangeable lens mounting reference surface of the teleconverter are as follows. Some of them have a diameter of φA and protrude by C on the interchangeable lens side.

  On the other hand, as an interchangeable lens of the above-described camera system, an interchangeable lens compatible with a teleconverter has a long back focus so that it can be attached in consideration of the shape of the above-described protrusion, and the cover member at the rear end is opened. The caliber is larger. Many lenses that are not compatible with teleconverters have a short back focus, and because the required opening diameter of the cover member at the rear end is small, it is impossible to install them. Even in this case, the cover member and the teleconverter-side lens holding frame are in contact with each other first, so that the optical system is not directly touched, and there is no possibility of scratches or damage.

Patent Document 1 discloses a camera system, a camera body, an interchangeable lens, and an intermediate adapter that limit the mounting of an interchangeable lens having a common back mount but a back focus of a certain level or less. In this camera system, a flange portion is provided inside the mount of a conventional camera body or intermediate adapter, and a fixed projection provided on an interchangeable lens with a short back focus is in contact with the flange portion, thereby restricting the mounting of the interchangeable lens. To be.
Japanese Patent No. 3210586, FIG.

  However, in recent years, in a camera system having a 35 mm film and an image sensor of the same size as that, the zoom lens has become more high-spec, and while maintaining a wide angle of view equivalent to, for example, 28 mm on the short focal length side, There are those having an angle of view equivalent to 300 mm and relatively bright ones having an open F value of, for example, about F4 even at a focal length equivalent to 100 mm. In the case of such an interchangeable lens, since the opening diameter of the cover member described above becomes large, in the case of a simple circular shape considering the light beam effective diameter, the protruding portion of the teleconverter passes through the opening diameter of the cover member, There is a possibility that the tip of the teleconverter-side lens holding frame directly interferes with the optical system on the interchangeable lens side. In this case, since it is impossible to attach the teleconverter in practice, it is easy for the user to determine whether the teleconverter can be attached before the installation. In the case where the lens group on the side largely moves back and forth, the teleconverter may be mountable when the lens group closest to the imaging surface is closest to the subject side. If you perform an inadvertent zooming operation in such a state, the tip of the teleconverter-side lens holding frame may directly interfere with the optical system on the interchangeable lens side, which may cause scratches or damage. Therefore, it is necessary to limit the wearing.

  Further, in the camera system proposed in Patent Document 1, it is possible to restrict the mounting of an interchangeable lens whose back focus is less than or equal to a certain value and the preceding intermediate adapter, but there is also a limitation on the camera body. Therefore, combinations of interchangeable lenses and camera bodies that can be used are limited, which is not preferable.

  Therefore, an exemplary object of the present invention is to mount a lens barrel in which the lens group closest to the imaging surface advances and retracts in the optical axis direction by zooming or focusing operation, and between the lens barrel and the camera body, In a camera system having a teleconverter having an optical system that protrudes closer to the subject with respect to the lens barrel mounting reference surface, while maintaining compatibility with the camera body, for a lens not compatible with the teleconverter An object of the present invention is to provide a lens barrel that reliably prevents the teleconverter from being mounted.

  In order to achieve the above object, the lens barrel of the present invention has a lens barrel in which the lens group closest to the imaging surface advances and retreats in the optical axis direction by zooming or focusing operation, and between the lens barrel and the camera body. And an intermediate adapter having an optical system that protrudes closer to the subject with respect to the lens barrel mounting reference plane, and the opening shape of the imaging surface side cover member of the lens barrel is substantially The rectangular shape has a diagonal length longer than the diameter of the protruding portion of the intermediate adapter, and the length of the long side or the short side of the substantially rectangular shape is shorter than the diameter of the protruding portion. And

  The substantially rectangular shape is optimized for the maximum image sensor size of the camera body to which the camera body is attached, and also serves as a shield for harmful light incident on the image sensor.

  Further objects and other features of the present invention will be made clear by the preferred embodiments described below with reference to the accompanying drawings.

  According to the present invention, the lens group closest to the imaging surface is mounted between the lens barrel and the camera body by zooming or focusing operation, and the lens barrel is attached between the lens barrel and the camera body. In the camera system having an intermediate adapter having an optical system protruding toward the subject with respect to the surface, the opening shape of the imaging surface side cover member of the lens barrel is a substantially rectangular shape, and the diagonal length thereof is The length of the long side or the short side of the substantially rectangular shape is shorter than the diameter of the protrusion, and is longer than the diameter of the protrusion of the intermediate adapter. When attaching the intermediate adapter to the lens barrel, the lens holding frame on the intermediate adapter side and the cover member on the lens barrel side interfere with each other. It is possible to provide a lens capable barrel.

  In addition, the substantially rectangular shape is optimized for the maximum image pickup device size of the camera body to be attached, and also serves as a shield for harmful light incident on the image pickup device. Since it is a rectangular shape that is a general shape of an image sensor, and by taking into consideration the size of the image sensor, unnecessary long and short side rays can be cut, so it is generally called ghost or flare. In addition, it is possible to provide a lens barrel that can suppress a phenomenon that adversely affects an image.

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

  FIG. 1 is a cross-sectional view of an interchangeable lens for a single-lens reflex camera, which is an optical apparatus according to a first embodiment of the present invention, in a long focal length state (hereinafter referred to as a TELE state). FIG. 2 is an external view of an intermediate adapter which is an accessory attached between the interchangeable lens of FIG. 1 and the camera body. FIG. 3 is a right side view of the interchangeable lens of FIG. 1 and shows the opening shape of the rear end portion. FIG. 4 is a cross-sectional view of the interchangeable lens of FIG. 1 when the zoom operation is performed to bring it into a short focal length state (hereinafter referred to as WIDE state).

  First, the configuration of the lens barrel will be described with reference to FIGS. 1, 3, and 4.

  This lens barrel is a zoom lens having a focal length range of 24 mm to 105 mm. By rotating the zoom operation ring 1, the cam ring 2 is rotated at a fixed position with respect to the guide cylinder 3 (parts constituting the fixed portion). The focal length changes. L1 to L7 represent lens groups, and each group is fixed to the same lens barrel and moves as shown below.

  One group of L1 is held by the first group barrel 4, and the first group barrel 4 is integrated with the filter frame 5 by screws (not shown). The filter frame 5 is fixed to the rectilinear cylinder 6 with screws (not shown), and is linearly fixed integrally to the rectilinear cylinder 6 in a rectilinear groove provided in the guide cylinder 3 and a cam groove provided in the cam ring 2. As the cam follower 7 enters, the focal length changes from the WIDE state to the TELE state as the cam ring 2 rotates, and changes forward in the optical axis direction. The first lens barrel 4 and the filter frame 5 can be adjusted in position before being fixed with screws.

  The second group L2 is held by the second group barrel 8, and a cam follower portion (not shown) and a key interlocking portion (not shown) are formed on the outer periphery of the second group barrel 8. 9, the cam 9 a on the inner periphery and a focus key (not shown) in the focus unit 10 are fitted and slid. When the focus key rotates as an output of the focus unit 10, the cam 9 a and the cam follower are It moves in the optical axis direction while rotating from the relationship. This lens barrel is an inner focus lens, and has a configuration in which the amount of extension of the second group L2 for focus adjustment differs depending on the focal length. That is, the above configuration is realized by changing the use position of the focus cam 9a according to the focal length. The focus cam ring 9 is integrated with the focus cam ring 9 in an interlocking groove in the optical axis direction of the cam ring 2 and a correction cam provided in the guide tube 3 in order to correct the position of the second group L2. As the cam follower slides, it rotates with the cam ring 2 and moves forward and backward in the direction of the optical axis, so that L2 can be moved to a position that does not shift the focus position even if the use position of the focus cam 9a is changed depending on the focal length. It is configured.

  The third group of L3 is held by the third group barrel 11, and a sub-aperture unit 12 is fixed to the front side (subject side) of the third group barrel 11. The fourth group of L4 is held by a fourth group lens barrel 13, and a diaphragm unit 14 for determining the aperture diameter of the lens barrel is fixed to the front side, and three connecting portions are equally divided on the rear side (image surface side). The seventh group lens barrel 15 is fixed to the tip thereof with a screw (not shown). Further, the third group barrel 11 is fixed to the front end face of the fourth group barrel 13, and three cam followers are integrally fixed to the outer peripheral surface equally. The cam follower slides in a cam groove provided in the cam ring 2 and a straight advance groove provided in the guide tube 3, and the three groups L3, L4, and L7 are integrated with the rotation of the cam ring. Moving.

  L5 is a shift group, which is held by a lens barrel constituting the image stabilization unit 16, and is held so as to be freely movable (shiftable) on the vertical plane of the optical axis by the driving means inside the image stabilization unit 16. . A sixth group lens barrel 16a is fixed to the rear side (image plane side) of the fixed portion in the image stabilization unit 16 by three screws (not shown). Three cam followers are fixed to the outer periphery of the vibration isolation unit 16 and slide into the cam groove of the cam ring 2 and the straight groove of the guide tube 3, respectively. The two groups L5 and L6 are cam rings in the optical axis direction. It moves integrally with the rotation. In addition, since it is well-known about the internal structure and detailed control of the image stabilization unit 16, detailed description in this embodiment is abbreviate | omitted.

  The seventh group of L7 is held by the seventh group lens barrel 15, and is fixed to the rear end of the connecting portion of the third group lens barrel 11 as described above.

  In the lens barrel having the above optical system configuration, the cam ring 2 is rotated together by an interlocking key (not shown) when the photographer rotates the zoom operation ring 1, and moves forward and backward in the optical axis direction. The cam ring 2 is bayonet-coupled with the guide tube 3 and rotates at a fixed position with respect to the guide tube. The guide tube 3 is a fixed portion of the lens barrel, and is fixed integrally with a fixed joint tube 17, an outer ring 18, and a mount 19 for mounting on the camera. Reference numeral 20 denotes a back cover that prevents internal reflection in the lens barrel and also serves as a cover member that protects components in the lens barrel such as the mounting substrate 21 described later from being directly touched. As shown in FIG. 3, the shape of the central opening is a circular shape of φB as shown by the broken line in the drawing when the effective beam diameter is originally considered. The shape of the element is a rectangle having a long side: a short side of 4: 3 or 3: 2, etc., and thus has a rectangular shape having a diagonal length B, a short side length E, and a long side length F. Further, this rectangular shape is configured to shield harmful light caused by internal reflection of light rays in the lens barrel so as not to reach the image sensor. Reference numeral 22 denotes a sealing rubber, which is configured so that the mount 19 can come into contact with the camera when the lens barrel is attached to the camera and can exhibit waterproof and drip-proof performance near the mount. Reference numeral 23 denotes a contact block that performs communication with the camera side, and is connected to a mounting board 21 on which a CPU that controls the lens barrel is mounted by an FPC (not shown).

  Reference numeral 10 denotes a focus unit composed of a so-called ultrasonic motor, which is fixed to the guide tube 3. A fixed cylinder 24 is fixed in the vicinity of the tip of the fixed portion of the focus unit 10, and two vibration gyros (not shown) as vibration detection means are surrounded by a space between the fixed cylinder 24 and the focus unit 10. Is retained. Such an arrangement eliminates the influence of disturbances such as noise. The vibrating gyroscope is connected to the mounting substrate 21 by an FPC (not shown). A focus ring 25 is disposed between the front end surfaces of the fixed cylinder 24 and the fixed joint cylinder 17, and a rear end portion of the focus ring 25 is fitted to a connecting portion in the focus unit 10, and rotates the focus ring 25. By doing so, the focus key is rotated to move the second group L2 forward and backward in the optical axis direction so that manual focusing can be performed. The inner periphery of the focus ring 25 has an all-around groove 25a, and rollers (not shown) provided at three locations on the periphery thereof are fitted and slid to be regulated in the optical axis direction. The three rollers are fixed to the fixed cylinder 24 by screws (not shown).

  Reference numerals 26 and 27 denote operation rubbers which respectively enter the grooves of the focus ring 25 and the zoom ring 1 to improve the operation ring. Reference numeral 28 denotes a sheet on which a distance scale is printed, which is fixed on a rotary ring to which a focus key is fixed, and can be confirmed by a photographer through a window disposed on the fixed joint tube 17.

  Next, the teleconverter as the intermediate adapter in FIG. 2 will be described.

  A mount 28 is attached to the camera body, and is provided with bayonet claws that engage with bayonet claws provided on the camera body. A sealing rubber 29 has the same function as the sealing rubber 22 provided on the lens barrel side, and comes into contact with the camera when the teleconverter is attached to the camera, and is waterproof and drip-proof in the vicinity of the mount 28. It is configured to be able to demonstrate. Reference numeral 30 denotes a fixed cylinder, and the mount 28 is fixed with screws (not shown), and also serves as an exterior. In addition, a bayonet claw (not shown) that is the same as the bayonet claw provided on the camera body is provided on the inner side at the same time as the front end of the subject side is the reference mounting surface of the lens barrel. The bayonet claw provided on the mount 19 is engaged. Reference numeral 31 denotes a lock release lever for releasing the lock by the lock pin 32 for attaching and holding the lens barrel. Reference numeral 33 denotes an attachment index. After matching the phase with the attachment index provided on the camera body side, the bayonet claws are engaged with each other by being rotated relative to each other by a predetermined angle to be in a mounted state. Reference numeral 34 denotes a lens holding frame which holds an optical system (not shown), and protrudes from the mounting reference surface of the lens barrel by C to the lens barrel side with a diameter φA.

  Next, a description will be given of when the teleconverter is attached to the lens barrel.

  If the shape of the opening of the rear lens barrel 20 in the lens barrel is a circular shape of φB indicated by a broken line in FIG. 3 and the relationship with the lens holding frame 34φA of the teleconverter is φA <φB, the lens barrel is shown in FIG. In the WIDE state, since the lens unit L7 protrudes toward the image plane with respect to the reference surface of the mount 19, when the teleconverter is to be mounted, the protruding portion of φA passes through the opening φB, Although it is impossible to mount the lens unit L7 by interfering with the lens unit L7, the lens unit L7 may protrude toward the image plane with respect to the reference plane of the mount 19 as described above, although there is a risk of damage if the optical unit actually interferes. Therefore, in this case, it is easy to determine whether or not it can be mounted on the appearance. However, when the lens barrel is in the TELE state of FIG. 1, the lens group L7 is located at the position D on the object side with respect to the reference surface of the mount 19, and thus the protrusion amount C of the lens holding frame 34 of the teleconverter. When D> C, the protruding portion of φA passes through the opening φB, and the teleconverter can be attached to the lens barrel. In such a mounted state, when the zoom ring 1 is operated and the lens group moves from the TELE state of FIG. 1 to the WIDE state of FIG. 4, the lens unit L7 interferes with the lens holding frame 34, and is damaged or damaged. Therefore, it is necessary to prevent erroneous mounting. Therefore, in this embodiment, the shape of the opening portion of the back pig 20 is a rectangular shape having a diagonal length B, a short side length E, and a long side length F indicated by solid lines in FIG. 3, and the relationship with the lens holding frame φA is B Since> φA> F> E, even if the teleconverter is to be attached to the lens barrel, the lens holding frame and the rear cover interfere to prevent erroneous mounting and affect the internal lens group L7. There is nothing.

It is sectional drawing which shows the TELE state of the interchangeable lens for single-lens reflex cameras which is an Example of this invention. It is an external view of the intermediate adapter which is an accessory attached between an interchangeable lens and a camera body. It is a right view of the interchangeable lens of FIG. It is sectional drawing which shows the WIDE state of the interchangeable lens for single-lens reflex cameras which is an Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Zoom operation ring 2 Cam ring 3 Guide cylinder 4 1st group barrel 5 Filter frame 6 Straight advance cylinder 7 Straight advance cam follower 8 2nd group barrel 9 Focus cam ring 9a Cam 10 Focus unit 11 3rd group barrel 12 Sub-throttle unit 13 4th group Lens barrel 14 Aperture unit 15 Group 7 lens barrel 16 Anti-vibration unit 16a Group 6 lens barrel 17 Fixed joint tube 18 Exterior ring 19 Mount 20 Back cover 21 Mounting substrate 22 Sealing rubber 23 Contact block 24 Fixed tube 25 Focus ring 25a All-round groove 26 Focus ring rubber 27 Zoom ring rubber 28 Mount 29 Sealing rubber 30 Fixed cylinder 31 Lock release lever 32 Lock pin 33 Mounting index 34 Lens holding frame

Claims (2)

A lens barrel in which the lens group closest to the imaging surface advances and retracts in the optical axis direction by zooming or focusing operation,
In a camera system having an intermediate adapter that is mounted between the lens barrel and the camera body and has an optical system that protrudes closer to the subject with respect to the lens barrel mounting reference plane,
The opening shape of the imaging surface side cover member of the lens barrel is a substantially rectangular shape, and the diagonal length is longer than the diameter of the projecting portion of the intermediate adapter, and the long side or the short side of the substantially rectangular shape. A lens barrel characterized in that the length is shorter than the diameter of the protrusion.   2. The lens barrel according to claim 1, wherein the substantially rectangular shape is optimized for a maximum image sensor size of a camera body to which the lens body is attached, and also serves as a shield for harmful light incident on the image sensor. .

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