JPS62194242A - Interchangeable lens barrel - Google Patents

Abstract

PURPOSE:To obtain a interchangeable lens barrel of a simple constitution which can be mounted on an autofocus conversion lens freely by providing the lens barrel with a stop mechanism, a stop-down transmission mechanism and no focusing mechanism. CONSTITUTION:The interchangeable lens barrel 1 consists of the 1st optical system L1 and the 2nd optical system L2, which are so constituted as to focus a subject at or beyond infinite distance when only the interchangeable lens barrel 1 is mounted on a camera body; and the lens barrels is mounted on the camera body 3 across the autofocus conversion lens 2. An automatic stop- down mechanism consists of a stop preset ring 8, a coupling lever 9, a preset cam 10, a driving ring 12, a stop blade 15, a stop-down lever 16. The stop-down lever 16 is driven by being coupled with a stop driving lever 43 of the camera body 3 through the stop coupling lever 27 of the conversion lens 2.

Description

Detailed Description of the Invention (Technical Field of the Invention) The present invention is capable of being attached to an autofocus conversion lens having a mechanism for adjusting focus by moving at least a part of the conversion optical system according to the output of an autofocus detection device. This is about interchangeable lenses.

(Background of the Invention) Conventionally, there has been a convergence optical system that changes the photographing magnification of a photographic lens, and an automatic system that adjusts the focus by moving at least a part of the conversion optical system according to the output of an automatic focus detection device. Focal convergence lenses have been proposed. When this autofocus converter lens is attached to a camera body equipped with an autofocus detection device, focus adjustment is performed by the conversion optical system. Therefore, the inventor proposes an optimal structure for an interchangeable lens barrel that can be freely attached to this autofocus conversion lens.

(Objective of the Invention) An object of the present invention is to provide an interchangeable lens barrel that can be freely attached to an autofocus conversion lens and has a simple configuration.

(Summary of the Invention) The interchangeable lens barrel of the present invention is attachable to an autofocus conversion lens that adjusts the focus of a convergence optical system according to the output of an autofocus detection device, and includes an aperture mechanism that drives aperture blades. The technology has an aperture transmission mechanism that operates the aperture mechanism according to aperture information from the camera body, and does not have a focusing mechanism that drives the optical system in the optical axis direction to focus on the subject. This is the main point.

(Example) FIG. 1 shows an example of the present invention. The interchangeable lens barrel 1 is
It is attached to a camera body 3 via an autofocus conversion lens 2. This interchangeable lens barrel 1 has a first optical system Ll and a second optical system L2. The autofocus conversion lens 2 has a convergence optical system L3 that changes the magnification of the interchangeable lens barrel 1. The camera body 3 includes the first optical system Ll and the second optical system L2.
The in-focus state of the light beam l entering through the converging optical system L3 is detected by an automatic focus detection device 46 (known pupil-splitting automatic focus detection device) disposed at the bottom of the camera body, and a non-focus state is detected. When in focus, the conversion optical system L3 of the autofocus conversion lens 2 is driven to lead to the in-focus state. Each configuration will be explained in detail below.

[Configuration of interchangeable lens barrel 1] The interchangeable lens barrel 1 includes a first optical system Ll and a second optical system L.
These optical systems are configured so that when the interchangeable lens barrel 1 is attached to the camera body, the subject is focused at infinity or beyond infinity (i.e., it is focused near infinity). The optical system LL of this interchangeable lens barrel 1 is
Since L2 is attached to the camera body 3 via the autofocus conversion lens 2, it is
As disclosed in Publication No. 8, an automatic focus detection device 46
In order to prevent vignetting from occurring in the detected light flux l, the following relationship must be satisfied.
o, the composite F value of the interchangeable lens barrel 1 and the conversion lens 2 is F e-, the magnification of the conversion lens 2 is k
Then, from Fe≦Fd and Fe=k−Fa, Fd≧k′F.

becomes.

The interchangeable lens barrel 1 includes the aforementioned optical systems LL and L2, a mount portion 4 that can be attached to a mount portion 21 of the conversion lens 2 or a mount portion (not shown) of the camera body 3, and this mount portion 4 is fixed. It consists of a fixed lens barrel 5 and a known automatic aperture mechanism. A first optical system Ll and a second optical system are fixed to this fixed lens barrel 5, and a barrel member 17 for the first optical system Ll is integrally incorporated therein. In this embodiment, the fixed lens barrel 5 and the barrel member 17 are separate members, but it is obvious that they can be constructed as an integrated member. When assembling the first optical system Ll and the second optical system L2 into the fixed lens barrel 5, it may be determined whether or not to integrally mold the barrel member depending on ease of assembly, workability, or required accuracy.

A housing barrel 6 for improving the appearance of the interchangeable lens barrel 1 is fixed to the fixed barrel 5, and can be integrally molded with the lens barrel 5. This housing lens barrel 6 includes
Attachment screws for attaching accessories such as filters are formed at the tip. Inside the fixed lens barrel 5,
A decorative ring 7 is attached. An aperture preset ring 8 is provided on the outer periphery of the fixed lens barrel 5, and a connecting lever 9 for connecting the aperture preset ring 8 and an aperture preset cam 10 is provided on the aperture preset ring 8. The aperture unit main body 14 includes known aperture blades ff.
115, a drive ring 12, and a narrowing lever 16 connected to the drive ring. The aperture preset ring 8, the connection lever 9, the preset cam 10, the drive ring 12, the aperture blades 15, and the aperture lever 16 constitute a known automatic aperture mechanism. This aperture lever 16 is connected to the aperture drive lever 43 of the camera body 3 via the aperture connecting lever 27 of the conversion lens 2.
It is connected and driven. The aperture lever 16 and the drive ring 12 are each loaded with a spring (not shown), and are constantly biased to the minimum aperture value.

[Ti configuration of conversion lens 2] The conversion lens 2 is provided with a mount part 21 to which the interchangeable lens barrel 1 is attached and a mount part 26 to which the camera body 3 is attached, respectively, at the front and rear, and the housing member 22 and the main body 23 are connected to each other. are integrally formed. The conversion optical system L3 is fixed to a barrel member 24 having a helicoid screw 24a screwed into a helicoid screw 23a formed on the main body 23. A bottle 28 is implanted in the barrel member 24, and the bottle 28 is configured to fit into and slide in a circumferentially elongated hole 23b of the main body 23. A segment gear 25 is fitted around this main body 23 so that it can rotate, and a lever 29 fixed to this segment gear 25 is connected to a bin 28. This segment gear 25 is a drive device (48) for the camera body 3.
~50) is transmitted via the binion 31, and when the segment gear 25 is rotated by this driving force, the barrel member 24 is rotated via the bin 28, and the conversion optical system L3 is extended in the optical axis direction to focus. Adjustments are made. The conversion lens 2 is rotatably provided with an aperture connection lever 27, which protrudes toward the mount 26 and connects to the aperture drive lever 4 of the camera body 3.
It is configured to be connected to 3.

[Configuration of camera body 3] The light beam β that has passed through the interchangeable lens barrel 1 and the conversion lens 2 passes through the semi-transparent part 44a of the reflection mirror 44, is reflected by the sub-mirror 45, and is guided to the focus detection device 46. . The focus adjustment state is detected by the focus detection device 46, and the detection signal drives the motor 48, which is transmitted to the coupling 50 via the gear 49 of the motor 48, and the rotation of the coupling 50 is transmitted to the pinion 31. The conversion optical system L3 is moved in the optical axis direction and guided to the in-focus position.

Since it is configured as above, focus &! Even if the interchangeable lens barrel 1 has no function, it becomes possible to perform autofocus photography by combining it with an autofocus conversion lens 2 and attaching it to a camera body 3 having an autofocus detection device. Furthermore, the interchangeable lens barrel l used in the system that combines the autofocus conversion lens 2 and the camera 3 has the first optical system Ll and the second optical system L2 inside the lens barrel so that focusing operation is not necessary. Since it can be fixed, a helicoid mechanism or a cam mechanism as a focusing mechanism can be omitted, and a focusing ring can be omitted, the structure can be simplified, ease of assembly and workability can be improved, and costs can be reduced. Furthermore, even if this interchangeable lens barrel 1 is attached directly to the camera body 3, if the aperture is stopped down, the depth of field will allow for the closest shadow to be captured.

In the embodiment, the aperture presetting mechanism is provided in the interchangeable lens barrel 1, but the aperture presetting mechanism may be omitted and the aperture can be preset within the camera body 3. Also, this interchangeable lens barrel 1 includes an integrated circuit (ROM, CPU) in which lens information (for example, information on the aperture f-number, focal length, optical system performance, etc.) is stored.
etc.), and the integrated circuit may be configured so that it can be connected to the automatic focus detection device, exposure control device, etc. of the camera body 3 via the conversion lens 2. Although this is a focusing lens, a similar configuration can also be used for a zoom lens barrel, in which case only a zooming mechanism is added. Further, in the embodiment, the automatic focus detection device 46 and the drive device (48 to 50) are provided within the camera body, but they may also be provided within the conversion lens 2.

(Effects of the Invention) As described above, according to the present invention, since the focusing mechanism is not provided in the interchangeable lens barrel, it is possible to have a simple structure, which is compact, easy to assemble, and inexpensive. Furthermore, by reducing the number of movable members, an interchangeable lens barrel with good optical performance can be obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of an interchangeable lens barrel 1, a conversion lens 2, and a camera body 3 of the present invention. (Explanation of symbols of main parts) 1...Interchangeable lens barrel, 3...Camera body 2...
・Conversion lens

Claims (1)

[Claims] Can be freely attached to an autofocus conversion lens that has a conversion optical system that changes the photographing magnification of the photographic lens and has a mechanism that adjusts the focus by moving at least a part of the conversion optical system according to the output of the automatic focus detection device. This interchangeable lens has an aperture mechanism that drives the aperture blades, and an aperture transmission mechanism that operates the aperture mechanism according to aperture information from the camera body, and moves the optical system along the optical axis to focus on the subject. An interchangeable lens barrel characterized by not having a focusing mechanism that drives in the direction.