JP2007171303A - Lens barrel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens barrel capable of effectively preventing occurrence of ghosts and flare even when the lens barrel is installed in a camera having an imaging means of different dimensions. <P>SOLUTION: In the lens barrel 1 having a filter supporting means 3 which can be inserted/extracted into/from an optical path while supporting a filter, the filter supporting means 3 supports the filter 4 and at the same time, can support a light shielding member 5 having an aperture smaller than the aperture of the filter 4 and capable of shielding a part of light passing through the optical path. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lens barrel.

  Conventionally, as a single-lens reflex camera, for example, a film camera using a 35 mm film or a digital camera provided with an image sensor is known. Since an image pickup device is usually smaller than a 35 mm film, a digital camera is characterized in that a subject image is formed with a screen size smaller than that of a film camera. Therefore, when a lens used in a digital camera requires a small image circle and a lens having the same focal length as a lens used in a film camera (hereinafter referred to as a “film camera lens”) is designed, There is an advantage that the tube can be reduced in size and weight. For this reason, a lens with a small image circle has been proposed as a lens dedicated to a digital camera (hereinafter referred to as “digital camera lens”).

In addition, these lenses usually have a high possibility of causing ghosts and flares when light that is not necessary for image formation, that is, unnecessary light fluxes enter the outside of the image circle, so that unnecessary light fluxes are cut as much as possible. The flare prevention mechanism is provided (for example, refer to Patent Document 1).
JP-A-6-201966

  Here, the digital camera lens and the film camera lens have the same mount for mounting on the camera body, and the film camera lens has a larger image circle than the digital camera lens as described above. It is also possible to shoot with the camera attached to the main body. However, in such a case, the screen size of the digital camera is small, and the subject image is formed only by the light that has passed through the central part of the film camera lens, so the light outside the central part becomes unnecessary light, causing ghosts and flares. There is a problem of causing it.

  Accordingly, the present invention has been made in view of the above problems, and provides a lens barrel capable of satisfactorily preventing ghosts and flares even when mounted on cameras having different sizes of imaging means, that is, screen sizes. For the purpose.

In order to solve the above problems, the present invention
A lens barrel having a filter support means that supports the filter and can be inserted into and removed from the optical path,
A lens barrel characterized in that the filter support means supports a light shielding member that supports the filter and has an opening smaller than the opening of the filter and shields a part of a light beam passing through the optical path. I will provide a.

The lens barrel of the present invention is
The opening of the light shielding member corresponds to the size of the imaging unit of the imaging device to which the lens barrel is attached, and it is desirable to shield light reaching outside the imaging unit among light passing through the optical path. .

The lens barrel of the present invention is
The lens barrel preferably has a single-focus optical system whose focal length does not change.

The lens barrel of the present invention is
The filter support means is preferably disposed on the image side of any lens held in the lens barrel.

  According to the present invention, it is possible to provide a lens barrel that can satisfactorily prevent ghosts and flares even when mounted on cameras having different sizes of imaging means.

Hereinafter, a lens barrel according to an embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a diagram showing a configuration of a lens barrel according to an embodiment of the present invention.
As shown in FIG. 1, a lens barrel 1 according to this embodiment is a lens for a 35 mm film camera that holds a lens whose position in the optical axis direction is fixed, that is, a single focus lens (not shown) that does not operate zooming. The lens barrel body 2, the plug-in type filter holder 3, the screw-in type filter 4 that can be attached to and detached from the plug-in type filter holder 3, and the flare-cut mask 5.

  As shown in FIG. 1 and FIG. 3 to be described later, the present lens barrel 2 can insert and remove the plug-in type filter holder 3 into the optical path closer to the image side than the lens 6 held in the barrel main body 2. An insertion slot 7 is formed for insertion. In addition, a mount portion 8 is provided at the rear end of the barrel main body 2 so as to be detachably attached to the mount of the 35 mm film camera main body. The structure of the mount unit 8 is known and can be attached to the mount of the main body of a digital camera (hereinafter referred to as “DX format camera”) having an image sensor of 23.7 mm × 15.6 mm. .

FIG. 2A and FIG. 2B are a front view and a partial cross-sectional view showing the configuration of the plug-in type filter holder in the present embodiment, respectively.
As shown in FIG. 2, the plug-in filter holder 3 has a holder body 10 that is a substantially tongue-shaped member, and has a circular opening (not shown) that is larger than an opening 11 of a flare-cut mask 5 described later. A screw groove 12 for screwing the screw-in type filter 4 is formed on the inner periphery thereof.

  In addition, a knob portion 13 for fixing the holder main body 10 to the barrel main body 2 is provided at the top of the plug-in type filter holder main body 10. A leaf spring 14 for urging the flare cut mask 5 downward is fixed to the holder body 10 by a leaf spring retainer 15, and in the vicinity of the arms 14 a and 14 b of the leaf spring 14 in the holder body 10. Recesses 10a and 10b are respectively formed in the. Furthermore, a lower end portion of the holder body 10 has a cutout portion 10c for a projection 5c of the mask 5 described later, and a fringe portion for locking the lower end portion of the flare cut mask 5 on both sides thereof. 16a and 16b are formed.

  The flare-cut mask 5 is a substantially tongue-shaped plate-like member that is smaller and thinner than the holder main body 10. When the lens barrel 1 is mounted on a DX format camera, the lens in the barrel 1 is attached. In order to block out the light that travels outside the screen size of the DX format camera among the passed light, a rectangular opening 11 that is smaller than the opening of the screw-in filter 4 and corresponds to the size of the DX format image sensor is formed. Has been. The flare-cut mask 5 is provided with two L-shaped projections 5a and 5b that slightly extend toward the subject side, and a projection 5c that slightly extends downward at the lower end portion. ing.

With the above configuration, attachment and detachment of the flare cut mask 5 to the plug-in type filter holder 3 will be described.
The protrusions 5a and 5b of the mask 5 are respectively inserted into the recesses 10a and 10b of the holder body 10, and the protrusions 5a and 5b are brought into contact with the arm tip ends 14a and 14b of the leaf spring 14, respectively. As a result, the mask 5 is urged downward by the leaf spring 14. Then, the mask 5 is pushed upward by pinching the projection 5c, and the lower end portion 5c of the mask 5 is guided and locked to the fringe portions 16a, 16b of the holder body 10 (at this time, the projection 5c is fixed to the holder body 10). Guided to the notch 14c). Thereby, the mask 5 is fixed to the holder main body 10, and the attachment of the flare cut mask 5 to the plug-in type filter holder 3 is realized. Further, with this configuration, accurate positioning of the mask 5 with respect to the holder 3 in the optical axis direction and the direction perpendicular to the optical axis can be realized with good reproducibility. Note that the flare-cut mask 5 can be easily removed in the reverse order of attachment.

FIG. 3 is a cross-sectional view of a main part showing light rays traveling in the lens barrel according to the present embodiment.
When the flare-cut mask 5 is removed from the plug-in filter holder 3 and the lens barrel 1 is attached to a 35 mm film camera, the subject light forms a subject image in an area 21 corresponding to the screen size of the film on the imaging surface 20. To do. On the other hand, when the mask 5 is attached to the holder 3 and the lens barrel 1 is attached to the DX format camera, the subject light forms a subject image in the region 22 corresponding to the screen size of the image sensor on the imaging surface 20. Other unnecessary light is blocked by the mask 5.

  As described above, the lens barrel 1 according to this embodiment can be used for a 35 mm film camera by removing the flare cut mask 5 from the plug-in filter holder 3, and the DX format by attaching the mask 5 to the filter holder 3. Unnecessary light that can be used in the camera and causes flare can be appropriately cut.

  In this embodiment, the lens barrel that can be used for the 35 mm film camera and the DX format camera is shown as described above. However, the present invention is not limited to these cameras, and the size of the other imaging means is shown. If a flare-cut mask having a corresponding opening is produced, the lens barrel of the present invention can be used in various cameras and optical devices.

  In this embodiment, the flare-cut mask is attached to and detached from one plug-in type filter holder, but two holders themselves are prepared and used separately for 35 mm format cameras and DX format cameras. It can also be. In this case, since the plug-in mask can be configured by integrating the mask with the holder, the mask removal mechanism with respect to the holder described above becomes unnecessary, and simplification can be achieved.

In this embodiment, when a gelatin filter is used as the screw-in filter, a plate-like mask can be sandwiched between the filter holder and the gelatin filter, and the mask removal mechanism as described above can be used. Can be eliminated, and simplification can be achieved.
It can also be applied to a lens barrel that holds an anti-vibration lens. In this case, the opening of the flare cut mask may be sized in consideration of the moving range of the light beam during image stabilization in addition to the size of the imaging means. It can also be applied to a zoom lens. In this case, the light reaching the outside of the imaging means may be cut at the opening of the flare cut mask with the shortest focal length.

  As described above, according to the present embodiment, it is possible to realize a lens barrel that can satisfactorily prevent ghosts and flares even when mounted on cameras having different sizes of imaging means.

It is a figure which shows the structure of the lens-barrel which concerns on embodiment of this invention. (A), (b) is the front view and partial sectional view which respectively show the structure of the plug-in type filter holder in this embodiment. It is principal part sectional drawing which shows the light ray which advances the inside of the lens-barrel which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens barrel 2 Lens barrel body 3 Insertion type filter holder 4 Screw type filter 5 Flare cut mask 8 Mount part

Claims (4)

A lens barrel having a filter support means that supports the filter and can be inserted into and removed from the optical path,
A lens barrel characterized in that the filter support means supports a light shielding member that supports the filter and has an opening smaller than the opening of the filter and shields a part of a light beam passing through the optical path. .   The opening of the light shielding member corresponds to a size of an imaging unit of an imaging apparatus to which the lens barrel is attached, and shields light reaching outside the imaging unit among light passing through the optical path. The lens barrel according to claim 1.   The lens barrel according to claim 1, wherein the lens barrel includes a single-focus optical system in which a focal length does not change.   The lens barrel according to any one of claims 1 to 3, wherein the filter support means is disposed on the image side of any lens held in the lens barrel. .

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