JPH02201340A - Zoom teleconverter for camera - Google Patents

Abstract

PURPOSE:To suppress an increase in the fitting length between a fixed lens barrel and a movable lens barrel for zooming by providing a detachable holder to a camera main body which is so sized and constituted that a movable lens barrel for the teleconverter abuts on the movable lens barrel for zooming. CONSTITUTION:This teleconverter has a guide shaft 3 which is positioned in parallel to the optical axis of the movable lens barrel 2 for the teleconverter and guides and supports the movable lens barrel 2 for the teleconverter 2 along the optical axis and energizing means 6 and 7 which energize the movable lens barrel 2 for the teleconverter 2 toward the movable lens barrel 10 for zooming. Then one end of the guide shaft 3 is held to support the movable lens barrel 2 for the teleconverter through the guide shaft 3 and the camera main body which is so size and constituted that when the teleconverter is mounted on a camera, the movable lens barrel 2 for the teleconverter abuts on the movable lens barrel 10 for zooming is equipped with the detachable holder 5. Consequently, the fitting length between the camera-side room movable lens barrel 10 and the fixed lens barrel 1 which guides it need not be increased.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a zoom teleconverter for a camera with a zoom lens.

[Conventional technology]

Conventionally, in cameras equipped with a zoom lens, a teleconverter is often attached to the zoom lens in order to expand the zoom range. FIG. 4 shows the conventional example.
This figure shows the zoom teleconverter attached to a camera with a zoom lens. In the figure, reference numeral E indicates a camera body, and a movable zoom lens barrel B that is movable along a photographing optical axis OX is mounted within a fixed lens barrel that is fixedly installed within the camera body E. The movable zoom lens barrel B is supported by the fixed lens barrel and is movable along the photographing optical axis OX. In addition, a female thread (not shown) is cut on the front surface of the movable zoom lens barrel B, and a male thread (not shown) formed on the rear surface of the teleconverter A is attached to this female thread.
(not shown) are screwed together, the movable zoom lens barrel B and the teleconverter A are integrated, and when a zoom operation is performed, both AB are moved back and forth together along the photographing optical axis OX.

[Problem to be solved by the invention]

When a conventional teleconverter is installed, the center of gravity of the movable parts, that is, the teleconverter A and the movable zoom lens barrel B1, is lower than the center of gravity of the movable zoom lens barrel B before the teleconverter A is installed. , as a matter of course, it moves forward and also becomes heavier due to the importance of moving parts. Therefore, a problem occurs between the fixed lens barrel and the movable zoom lens barrel B.
The tilt eccentricity with respect to the photographing optical axis OX increases, in other words, the optical performance deteriorates. In addition, the tilting of the movable lens barrel B causes an increase in driving load. Therefore, in order to reduce the tilt eccentricity, it is necessary to make sure that the movable zoom lens barrel B and the fixed lens barrel are sufficiently fitted together even when the movable lens barrel B is extended the most. It was necessary to increase the fitting length between B and the fixed lens barrel, and as a result, the depth of the camera body E had to be increased. The present invention has been made to solve this problem, and its purpose is to support the teleconverter without tilting or eccentricity without increasing the length of the fitting between the fixed lens barrel and the movable zoom lens barrel. Another object of the present invention is to provide a zoom teleconverter in which the movable lens barrel of the teleconverter and the zoom movable lens barrel on the camera side are not impaired in their integral movement.

[Means for Solving the Problems and Effects] (Structure) In order to achieve the above object, the present invention was structured as follows. That is, the zoom teleconverter of the present invention is a zoom teleconverter that is attached to a camera and expands the zoom range in cooperation with a movable zoom lens barrel built into the camera.
A movable teleconverter movable lens barrel with a built-in teleconverter photographing optical system is located parallel to the optical axis of the teleconverter movable lens barrel, and the teleconverter movable lens barrel is positioned parallel to the optical axis of the teleconverter movable lens barrel. a guide shaft that guides and supports the teleconverter movable lens barrel along the zoom lens barrel; biasing means that biases the teleconverter movable lens barrel toward the zoom movable lens barrel; and holding one end of the guide shaft;
When the teleconverter movable lens barrel is supported via the guide shaft and mounted on a camera, the optical axis of the teleconverter movable lens barrel and the photographing optical axis of the camera coincide with each other. The camera body is provided with a removable holder whose dimensions are configured so as to come into contact with a movable lens barrel or a movable zoom lens barrel. According to an embodiment of the present invention, the biasing means is located at a substantially axially symmetrical position with respect to the optical axis, preferably with respect to a first biasing spring provided at an outer station of the guide shaft. It is preferable that the second spring is provided at a position away from the optical axis and the distance between the first spring and the second spring. Furthermore, it is preferable that the second biasing spring has a weaker spring force than the first biasing spring. (Function) According to the above configuration, the present zoom teleconverter is connected to the camera.
When the teleconverter movable lens barrel is mounted, the movable teleconverter lens barrel is urged into contact with the zoom movable lens barrel of the camera by the biasing means. Therefore, when the zoom teleconverter is operated, it can be moved together with the movable zoom lens barrel, and when the camera is in a normal shooting position, the weight of the zoom teleconverter hardly acts on the movable zoom lens barrel of the camera. Furthermore, by dividing the biasing means into two parts, even when the camera is pointed downward with the zoom teleconverter attached, it is able to withstand the moment caused by the weight of the movable teleconverter barrel. A moment generated by the second biasing spring acts in a direction that cancels out. Therefore, a spring with a weak spring force can be used as the second biasing spring. Note that it is preferable to design so that the sum of both moments becomes 0 (zero). Furthermore, when the camera is pointed upward in the attached state, both of the above moments act in directions that place a burden on the driving force that drives the movable zoom lens barrel, so the biasing force of the second biasing spring is weaker. is preferred.

【Example】

An embodiment of the teleconverter according to the present invention will be specifically described below with reference to FIGS. 1 to 3. FIG. 1 is an exploded perspective view of the teleconverter, and in the figure,
1 indicates a fixed lens barrel of a teleconverter;
has an opening 1a on its front wall 1b through which the movable lens barrel 2 of the teleconverter can go in and out, and a guide shaft 3 on the back side of this front wall tb for guiding the movable lens barrel 2 along the photographing optical axis. and a rotation stopper shaft 4 for regulating the rotation of the movable lens barrel 2 are respectively fitted into holes (not shown). or,
The rear surface facing the front wall lb is open. Further, the rear surface has a mounting part (not shown) formed with a female thread for threading the teleconverter holder 5. The movable lens barrel 2 is provided with a teleconverter lens group 9 having a lens disposed in the front opening. Further, the outer wall includes a guide bearing member 2a having a guide bearing through hole 2a' into which the guide shaft 3 is fitted, a first overhang member having a notch 2b into which the rotation stopper shaft 4 is fitted, and an upper part. The attachment provided on the left side wall surface and to which the tension spring 6 (second biasing spring) is attached is provided with a second extension member having a portion 2C. Furthermore, as shown in FIG. 2, on the back side of the movable lens barrel 2, there is a pressing protrusion 2d that comes into contact with the front surface of the zoom lens barrel 10 of the camera body (not shown) and moves simultaneously with the zoom movement. The movable lens barrel 2 comes into contact with the front surface of the zoom lens barrel 10 only when the lens barrel 2 receives an inadvertent pressing force from the outside.
This prevents large deformation of the guide shaft 3 and movable lens barrel 2.
A security protrusion 2e is provided to prevent the holder from being broken. Note that this pressing projection 2d is provided close to the guide bearing member 2a. As described above, the guide shaft 3 has a small diameter portion at one end that is fixed and fits into a hole when mounted on the back of the lens barrel 1, a large diameter portion that passes through the guide bearing through hole 2a', and a small diameter portion of the other end that fits into the hole for mounting on the back of the lens barrel 1. Front wall 5
The mounting hole formed in a is adapted to fit into the hole 5b. Around the guide shaft 3, there is a compression spring 7 (interposed between the back surface of the fixed lens barrel l and the front wall of the guide bearing member 2a) that biases the movable lens barrel 2 inward (towards the camera body). A first biasing spring) is provided to bring the pressing protrusion 2d into contact with the front surface of the zoom lens barrel 10. Similarly, the small diameter portion at one end of the rotation stopper shaft 4 is fitted into the hole for mounting the fixed lens barrel I on the back, and the large diameter portion is fitted into the hole as described above.
It fits into the notch 2b, and the small diameter part of the other end is connected to the front wall 5a of the holder 5.
The mounting formed in is fitted into the hole 5c. As described above, the tension spring 6 is movable by hooking the bent portion at one end to the portion 2c for attaching the second overhang member, and hooking the bent portion at the other end to the member 5d for attachment to the left side wall of the holder 5. The lens barrel 2 is urged inward. The front wall 5a of the holder 5 is formed with an opening 5e through which the zoom lens barrel 10 can be inserted and removed, and a hole 5f for mounting the fixed lens barrel I. The bottom of the holder 5 is provided with a bearing hole 5m (a member 5g for attaching the lower arm 8) for rotatably attaching the lower arm 8 via the shaft member 5Q, and the upper part of the holder 5 is provided with a A of the main body
It is provided with an opening 5h for a P-purpose light receiving section and a photometry section, and a finder opening 51 for attaching a finder lens 12 whose magnification is equivalent to the teleconverter of the photographic lens on the front of the camera finder. A bearing hole (not shown) into which a shaft that rotatably supports the upper arm l i is fitted is also provided. The upper arm 11 is provided with a downwardly bent portion 11a provided on the inner wall thereof with a locking member 11b that engages with a locking member provided on the eyepiece portion of the camera body, and a t display portion disposed on the top surface of the camera body. It is provided with an opening lid through which the converter can be viewed visually, and a switch operation convex member lie for inputting a converter installation signal to the camera side. A large shaft-fitting hole 11c is provided on the side surface of the upper arm 11. The lower arm 8 has a female threaded part 8a in the center for attaching a tripod.
Furthermore, the tripod mount provided at the bottom of the camera body is screwed into the concave part 8b recessed from the bottom of the arm, and the camera mount of the tripod for attaching the teleconverter is screwed into the female screw. A female screw hole 8c is formed through which an equivalent screw member 13 can pass. The lower arm 8 is rotatably connected to the holder 5 by a fork-shaped rotating hinge 8d that fits into a pair of grooves formed in the member 5g. The arm is attached in such a manner that the clockwise rotation angle of the lower arm 8 with respect to the holder 5 is regulated in cooperation with the rotational direction regulating protrusion 5 of the member 5g. This prevents unnecessary force from being applied to the zoom lens barrel 10 when removing the teleconverter from the camera direction, and also prevents folding of the teleconverter by rotating the lower arm 8 counterclockwise. It is possible. To attach the teleconverter with the above configuration to the camera,
The lower arm 8 is brought into contact with the bottom surface of the camera and screwed with the screw member 13, and the upper arm II is rotated clockwise to engage the locking member 11b with the locking member provided on the eyepiece portion of the camera. Complete the installation. At this time, the switch for attaching the teleconverter (not shown) disposed on the camera body is operated by the switch operation convex member 11e, and the movement range of the zoom lens barrel 10 is restricted. If the zoom lens barrel 10 is not located in a zoom range suitable for use with the teleconverter, move the zoom lens barrel 10 to the wide end of the zoom range (
Teleconverter - Move to the shortest focus position of the zoom range suitable for use. Note that this movement, for example,
The switch may be configured to not move when the switch is activated, such as during a release operation, a zooming operation, or when a barrier is opened. When the zoom lens barrel 10 moves to the wide end of the teleconverter zoom range, the front surface of the zoom lens barrel 10 and the protrusion 2d of the movable lens barrel 2 come into contact with each other due to the biasing force of the biasing spring 6.7. Thereafter, by the zooming operation, the zoom lens barrel 10 and the movable lens barrel 2 are simultaneously moved back and forth along the photographing optical axis by the urging spring force. FIG. 2 shows a state in which the teleconverter is attached and the camera is directed downward. The moment due to the weight of the movable lens barrel 2: (FaXf2t) and the moment due to the tension spring 6: (pbtxcs) are in opposite directions with respect to the guide shaft 3, so the starting position of the tension spring 6 is set so that this difference becomes approximately 0. When the force is selected, the frictional force generated on the 3 parts of the guide shaft is approximately O
becomes. Therefore, the necessary biasing force Fc of the compression spring 7 at the starting position can be reduced. In addition, when installing the tension spring 6, the distance Q between the part 2c and the guide shaft 3 can be made longer by locating both members symmetrically with respect to the optical axis, and the starting position biasing force Fb of the tension spring 6 can be increased. It is possible to make it smaller. In this way, if the starting position biasing force of each biasing spring 6.7 can be reduced, as shown in FIG. 3, when the teleconverter is moved to the telephoto end with the camera facing upward,
In other words, each spring 6.7 is in a state where the driving force required as the zoom lens barrel driving force when the teleconverter is attached is maximum.
The biasing force of the movable lens barrel 2 due to its own weight: (FaXI2t) and the moment + (F'b, , the frictional force generated on the guide shaft 3 can also be reduced. Therefore, the maximum driving force of the zoom lens barrel 10 can be small, and can be made smaller than the driving torque of the zoom lens barrel drive motor on the camera side.

【Effect of the invention】

As is clear from the above description, the zoom teleconverter of the present invention does not cause a load on the zoom movable lens barrel on the camera side due to the attachment of the converter. That is, the weight of the zoom teleconverter does not directly act on the movable lens barrel. Moreover, the configuration for achieving this is also simple. Therefore, there is no need to increase the fitting length between the zoom movable lens barrel on the camera side and the fixed lens barrel that guides it, which was a problem in the conventional example. Furthermore, since the teleconverter movable lens barrel is always biased against the zoom movable lens barrel by the biasing means, both mirror sides can be moved integrally. Furthermore, the zoom teleconverter of the present invention can be configured to reduce the sliding friction load generated on the guide support section that guides and supports the movable lens barrel (i.e., by dividing the biasing means and using a spring with a weak biasing force). Therefore, the burden on the driving force on the camera side is less likely to increase.

[Brief explanation of the drawing]

1 to 3 show a teleconverter for a zoom camera according to an embodiment of the present invention, FIG. 1 is an exploded perspective view of the teleconverter, and FIG. 2 shows the teleconverter attached to the camera. An explanatory diagram to explain the forces acting on the main parts of the teleconverter when the camera lens is facing downwards, and Figure 3 is an explanatory diagram to explain the forces acting on the main parts of the teleconverter when the camera lens is facing downwards. FIG. 4 is an explanatory diagram showing the state when the camera is moved to the end, and FIG. 4 is a schematic diagram showing a camera with a conventional teleconverter attached thereto. l... Fixed lens barrel, 2... Movable lens barrel for teleconverter, 2a... Guide bearing member, 2b... Notch, 2c
... Attachment is done by parts, 3... Guide shaft, 4... Rotation stop shaft, 5... Teleconverter-boulder, 6... Second biasing spring (tension spring), 7... No. 1 biasing spring (compression spring), 8... lower arm, 9... photographing lens group, 10...
Movable zoom lens barrel (zoom lens barrel), 11...upper arm,
13...Screw member. Patent applicant Minolta Camera Co., Ltd.

Claims (1)

[Claims] 1. A zoom teleconverter that is attached to a camera and expands the zoom range in cooperation with a movable zoom lens barrel (10) built into the camera, comprising: a photographing optical system (9) for the teleconverter; a movable teleconverter barrel (2) with a built-in teleconverter movable barrel (2), and a guide shaft (located parallel to the optical axis of the teleconverter movable barrel (2) that guides and supports the teleconverter movable barrel (2) along the optical axis). 3), urging means (6, 7) for urging the teleconverter movable lens barrel (2) toward the zoom movable lens barrel (10), and holding one end of the guide shaft (3); supporting the teleconverter movable lens barrel (2) via the guide shaft (3);
When attached to the camera, the dimensions are configured so that the optical axis of the movable lens barrel (2) and the photographing optical axis of the camera match and the teleconverter movable lens barrel (2) comes into contact with the zoom movable lens barrel (10). A zoom teleconverter comprising: a holder (5) that is detachable from the camera body; 2. The biasing means is provided at a position approximately axially symmetrical to a first biasing spring (7) provided on the outer periphery of the guide shaft (3) and the first biasing spring (7) with respect to the optical axis. The second biasing spring (6
) The zoom teleconverter according to claim 1, characterized in that the zoom teleconverter comprises: 3. The second biasing spring (6) is the first biasing spring (7).
Claim 2 characterized in that it has a weaker spring force.
Zoom teleconverter as described.