JPS5898712A - Automatic focus adjusting adaptor for interchangeable lens system camera - Google Patents

Abstract

PURPOSE:To quickly complete a focal adjustment, by limiting a moving range of a moving lens of a conversion lens optical system by receiving an intrinsic signal from an interchangeable lens installed to a lens mount provided on an adaptor body. CONSTITUTION:Light L from an object to be photographed passed through a photographic lens 4 and a conversion lens 11, a part of which is reflected to a focusing screen 13 by a rocking mirror 12, and a part of the other is reflected by a submirror 14, an image is formed on the photodetecting surface of a photoelectric transducer 15, this output is sent to a focus detecting circuit 19, and this focus detecting signal reaches a focal adjustment controlling circuit 21 through a connector 20. By a signal outputted from this circuit 21, a driving motor 22 is controlled as to its operations of forward and backward rotations, and start and stop, and a moving lens barrel 10 is rotated. Also, this rotation moves the barrel 10 in the optical axis direction in accordance with lead of a screw 9, therefore, the conversion lens 11 also rotates and moves in the optical axis direction, and the focal adjustment is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic focusing adapter provided between an interchangeable lens and a camera body.

Conventionally, in an interchangeable lens camera, such as an eye reflex camera, a focus detection device is provided in a relay adapter installed between the interchangeable lens barrel and the camera body, and the output of the focus detection device is An automatic focus adjustment adapter has been proposed in which the negative front group lens of the conversion lens in the relay adapter is configured to be movable, thereby enabling automatic focus adjustment for existing interchangeable lenses and camera bodies.

Conversion lens installed inside the relay adapter (
(including those with equal magnification), there are those that consist of a negative front lens group and a positive rear group lens, and those that consist only of an optical system with negative power that combines positive and negative lenses. However, in any case, the movable range of the movable lens of the conversion lens optical system (hereinafter simply referred to as "movable lens") for focus adjustment and the corresponding focusability 1 The subject distance changes depending on the focal length t of the attached interchangeable lens. If you change the focus, you can focus from infinity (oo) to a close distance where you can shoot.The longer the focal length of the interchangeable lens used, the greater the amount of movement of the moving lens that is necessary to focus, allowing you to take pictures. The shorter the close distance, the greater the distance. Therefore, in order to be able to use such an automatic focusing adapter for various interchangeable lenses with different focal lengths, the movable range of the movable lens must be adjusted in advance for the various interchangeable lenses. The maximum value of the movable lid, that is, the amount of movement of the movable lens determined by the focal length and near distance of the interchangeable lens, ν, must be set.

However, providing the movable lens of the conversion lens optical system with such a large amount of movement for focus adjustment causes the following disadvantages. In other words, if the movable range of the movable lens is determined to accommodate, for example, a long focal length interchangeable lens as described above, when using a standard lens or a wide-angle lens with a shorter focal length, The range is so large that objects located closer than the closest distance that the interchangeable lens itself can take are also focused. However, in reality, there is a risk that various aberrations will increase and exceed the limit that can be used as a photograph, resulting in a failed photograph.

Furthermore, when scanning with a movable lens for focusing, the shorter the focal length of the attached interchangeable lens, the more unnecessary movement range may be moved and scanned, resulting in wasted time for focus adjustment. It takes a lot of effort and wastes energy. The same thing can be said when attaching interchangeable lenses with the same focal length but different close-up distances.

The present invention solves the above-mentioned drawbacks by appropriately regulating the range of the movable lens of the conversion lens optical system depending on the interchangeable lens used.
Do not exceed the convenient shooting distance limit of the interchangeable lenses installed (and also quickly complete the focal point A).
The purpose of the present invention is to provide an automatic focusing adapter that can perform automatic focusing.

In order to achieve the object 1 mentioned in item 1-1, the present invention provides that at least a part of the conversion lens optical system in the relay adapter installed between the interchangeable lens and the camera body is equipped with a focus detection device. The output of the automatic focus adjustment adapter, which enables focus adjustment by hyperactivity, is installed, and the conversion lens is adjusted according to the unique signal of the interchangeable lens mounted on the lens mount provided on the adapter body. The provision of a movable and range regulating device that limits the 0T moving range of the optical system is granted amnesty.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.

Figure 1 is a cross-sectional view of the first embodiment of the present invention installed between the camera body and the interchangeable lens, showing the automatic focus adjustment adapter (
Hereinafter, it will be simply referred to as "adapter". ) A photographic lens 4 is provided in an interchangeable lens 5 mounted on a lens mount 2 of a main body 1 so as to be movable along an optical axis 6# by rotation of a distance adjustment ring 5. On the other hand, the other end of the adapter body 1 is attached to the lens mount (
(not shown) A removable mounting cap 8 is formed. Light from a subject (not shown) passes through a photographic lens 4 and is applied to a conversion lens 1 with 1 ikCa applied to a movable lens barrel 10 screwed together with an adapter body 1 by a screw 9.
1, a part of it is reflected by the swinging mirror 12# in the camera body 7 towards the focusing plate 13, and the other part is reflected by the sub mirror 14 and is transmitted to the photoelectric conversion element 15.
leading to. Focus plate 15 and this light 1! Since the conversion element 15 is placed at a position conjugate with the film plane F, the image to be formed on the film plane is focused on the focusing plate 15 and the light receiving surface of the photoelectric conversion element 15 (the image is formed on the focusing plate 13). The statue of
The object is observed through a finder optical system consisting of a lens 16, a pentaprism 17, and an eyepiece 18. On the other hand, the output of the photoelectric conversion element due to the optical image that is V-shaped on the photoelectric conversion element 15 is sent to the focus detection circuit 191. The focus detection signal generated by the focus detection device including the photoelectric conversion element 15 and the focus detection circuit 19 is transmitted through the connector 20 provided on the attachment part 8 of the adapter main body 1.
This leads to a focus adjustment control circuit 21 provided inside the adapter main body 1. This focus adjustment control circuit 21 outputs a signal that controls the rotation of the drive motor 220, and the drive motor 22 performs normal rotation, reverse rotation, starting, and floating operations according to the signal.
The movable lens barrel 10 is rotated via a gear 24 with a wide tooth width that meshes with a gear 23. This moving lens barrel 10
The rotation of the lens barrel 10 moves according to the lead of the screw 9.
is moved in the optical axis direction, so the Funversion lens 1
Focus adjustment is performed by moving the lens 1 in the optical axis direction while rotating.

On the other hand, one end of interchangeable lens 3? If the interchangeable lens 3 is attached to the lens mount 2r of the adapter body 1, the limit switch will be activated. The signal hinge 25 is configured to push a slide rod 27 supporting the limit switch 26 at one end against the bias of a tension spring 2 to set the position of the limit switch 26.

The length of the signal bin 25, that is, the limit switch 2
6q> position is determined by the focal length of each interchangeable lens and the occurrence of lens aberration during close-range focusing when combined with the conversion lens 11. When the movable lens barrel 10 begins to retreat toward the film plane from a predetermined position corresponding to an object at infinity (place 1Iiii in the figure) and reaches the usable close-up position limit determined by each interchangeable lens, the movable lens barrel 10 The limit switch 26 is turned off by the rear end surface 10' of the cylinder 10.

In response to this signal from the limit switch 26, the focus adjustment control circuit 21 reverses or stops the motor 22. Therefore, in the end, the amount of movement of the movable lens barrel 10 in the direction of the camera body, that is, the movable range of the movable lens 11 of the conversion lens optical system is regulated by the signal pin 25 of the interchangeable lens.

□ FIG. 2 shows a second embodiment of the present invention, in which a fixed lens 111 is added to the conversion lens optical system. The contact end surface of the interchangeable lens 5 connected to the lens mount 2 of the adapter body 1 has a terminal 31 for transmitting an electrical signal such as a resistance value corresponding to the closest shooting distance of 14It, and a terminal 31 for transmitting an electrical signal such as a resistance value corresponding to the focal length Terminals 32 for transmitting the information as electrical signals are provided, and these electrical signals can be transmitted via connectors 31' and 32' of the adapter body 1. Additionally, a brush 35 provided on the movable lens barrel 10 of the adapter body 1, a sliding resistor 34 provided on the adapter body 1, and a position signal of the movable lens 11 of the reconversion lens optical system are generated. is configured to do so. These three signals are sent to the focus adjustment control circuit 21 and calculated. From the focal length signal of the interchangeable lens and the position signal of the movable lens 11, the focus adjustment control circuit 21 calculates the shooting distance at that time.
40 rotations are appropriately controlled to limit the close range when using the adapter. Note that since the amount of movement of the movable lens is determined by the closest shooting distance and the focal length of the interchangeable lens, a variable range signal is emitted from the terminal 32 and transmitted from the resistance device of the brush 55 and the sliding resistor 64. The position signal of the moving lens emitted may be compared by the focus adjustment control circuit 21 and the motor 22 may be controlled. In this case, the terminal 31 and connector 31' can be omitted.

As described above, according to the present invention, the movable range of the movable lens of the conversion lens optical system is appropriately regulated according to the interchangeable lens used, and at least the closest distance limits WN, t, which can be photographed by the interchangeable lens are regulated. Since the conversion lens is not scanned and focused, there is no risk of unknowingly taking a picture of poor quality, and there is no need to drive and scan unnecessary areas, so the time required for focusing is reduced. can be shortened, and waste of time and power can be avoided. Furthermore, when a convergence lens with a large magnification is used, the various aberrations existing in the interchangeable lens become worse in proportion to the magnification of the conversion lens, but according to the present invention, the aberrations of each interchangeable lens are It is also possible to limit and regulate the shooting distance range depending on the situation.

Note that the camera to which the present invention can be applied is not limited to a -eye reflex camera, but may also be an interchangeable lens video camera.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the invention, and FIG. 2 is a sectional view showing another embodiment of the invention. 1...Adapter body 2...Lens mount 5.4.5...Interchangeable lens 7...Camera body 11.11'...・Conversion lens optical system 15.19...Focus detection device 25...Signal pin 51.52...Signal terminal 26-28.311, S2', 55.34.21...・
...Movement range regulating device applicant Takao Watanabe, agent of Nippon Kogaku Kogyo Co., Ltd.

Claims (2)

[Claims] (1) moving at least a part of the conversion lens optical system provided within the adapter body that relays the interchangeable lens and the camera body in accordance with the output of the focus detection device;
In an automatic focusing adapter that enables focus adjustment for a plurality of interchangeable lenses with different focal lengths, a lens mounting point provided on the main body of the adapter receives a unique signal from the attached interchangeable lens. An automatic focus adjustment adapter for an interchangeable lens type camera, characterized in that it is provided with a movable range limiting device that limits the movable range of the movable lens of the conversion lens optical system. (2) In the adapter according to claim 1, the movable range limiting device is a limit switch (E) that is displaced by a mechanical signal @t on the interchangeable lens side, or an electrical signal 31 on the interchangeable lens side. An automatic focus adjustment adapter for an interchangeable lens type camera, characterized in that it includes a focus adjustment control circuit Q]) for comparing an electrical signal 35.32 representing the position of the moving lens 11 with an electric signal 35.