JPH04361213A - Converter device and camera system formed by using this device - Google Patents

Abstract

PURPOSE:To obtain a depth of field having good balance and to obtain good images in a wide range of object distances by limiting the distance measurement operation of a distance measuring means by a distance measurement limiting member at the time of changing the focal length of the entire system. CONSTITUTION:This camera system is so constituted that a member 1a exists in the aperture of a photodetecting system 22 to prevent the incidence of the reflected luminous flux from a subject from entering the photodetecting system 22 when the converter device 1 is mounted on a camera body 4. The photodetector 9 of the photodetecting system 22 is prevented from receiving any light quantity at all when a release button is pushed at the time of photographing. The information on the distance measurement obtd. by the photodetector 9 is made into the infinite information in which the light quantity corresponds to zero in this way. Further, the focusing lens of the photographic lens system 5 is moved on the optical axis by a driving means so as to be focused to the infnite object. The good images are obtd. at the object distances of a wide range when the converter device 1 is mounted on the camera body in this way.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to still video cameras and
Regarding a converter device suitable for a photographic camera for 5mm film and a camera system using the same, in particular, when the converter device is attached to the camera body and the focal length of the entire system is changed, the converter device is installed independently of the photographic lens system. So-called non-TTL
The present invention relates to a converter device and a camera system using the converter device, which limits the distance measuring operation of the distance measuring means of the conventional method, so that good images can be obtained over a wide range of object distances.

0002

2. Description of the Related Art Conventionally, various converter devices have been proposed that are attached to the front or rear of a photographic lens system to change the focal length of the entire system while maintaining a constant focal position.

[0003] Among these, various camera systems have been proposed in which a converter device is attached to a part of the non-TTL camera body in which a distance measuring means is provided independently of the photographic lens system, and the focal length of the entire system is changed. ing. In this case, in order to perform proper distance measuring operation, it is necessary to correct the optical configuration of the distance measuring means (distance measuring optical system) in accordance with the change in the focal length of the photographing lens system.

Conventionally, this correction was carried out by installing a correction lens system in front of the distance measuring means (distance measuring optical system) that corresponds to the change in focal length to correct the distance measurement information obtained by the distance measuring means. was.

[0005]

[Problem to be Solved by the Invention] A method for correcting distance measurement information obtained by attaching a converter device to a photographing lens system and also attaching a correction lens system in front of a distance measuring means is (a) a photographing lens system. It is necessary to mount the converter device and correction lens system so that the optical axes of the converter device and the correction lens system are precisely aligned with the optical axes of the optical system, finder system, and distance measuring means, but this is generally very difficult. In many cases, eccentricity errors occur and optical performance deteriorates. (b) Due to parallax when it comes to close-range objects (approximately several tens of centimeters), objects other than the target object are brought into focus, making it impossible to obtain a good image. (c) Since a correction lens system is provided as part of the converter device, the entire camera system becomes complicated and large. There were problems such as.

In the present invention, a converter device is attached to a camera body having a non-TTL distance measuring means, and when changing the focal length of the entire system, the distance measuring operation of the distance measuring means is restricted by a distance measuring limiting member. The object of the present invention is to provide a converter device that can obtain a well-balanced depth of field and obtain good images over a wide range of object distances, and a camera system using the converter device.

[0007]

[Means for Solving the Problems] The converter device of the present invention is a converter device that is attached to a part of a photographing lens system of a camera body and changes the focal length of the entire system. It is characterized by having a distance measurement limiting member that limits the distance measurement operation of the non-TTL distance measurement means provided on the camera body when the camera body is mounted.

[0008] In addition, as a camera system, when a converter device is attached to a camera body equipped with a distance measuring means independent of the photographic lens system and the focal length of the entire system is changed, the converter device It has a distance measurement restriction member that limits the distance measurement operation of the distance measurement means when worn, and the distance measurement means performs focusing based on the distance measurement information restricted by the distance measurement restriction member. It is a feature.

[0009] The distance measurement limiting member is characterized in that it provides constant distance information to the distance measurement means.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic front view of a converter device of the present invention, and FIG. 2 is a cross-sectional view of a main part of a camera system in which the converter device of the present invention is mounted in front of a photographic lens system of a camera body.
FIG. 3 is a schematic front view of the camera body according to the present invention, and FIG. 4 is a schematic side view of FIG. 3.

In this embodiment, a still video camera (SV camera) is used as an example of a camera body, and a converter device is attached to the camera body.

In the figure, 1 is a converter device. The converter device 1 includes a wide converter lens 2 that is attached to the front of the photographic lens system 5 of the camera body 4 and changes the focal length of the entire system in a short direction, and a converter device 1 that is attached to the front of the finder system 11 of the camera body 4 that changes the focal length of the entire system in a short direction. It is integrally constructed with a finder correction lens 3 that corrects optical characteristics. Furthermore, when the converter device 1 is attached to the camera body 4,
The members 1a and 1b around the wide converter lens 2 block light from both the apertures (windows) of the light projecting system 21 and the light receiving system 22 of the distance measuring means provided in the camera body 4, thereby restricting the distance measuring operation of the distance measuring means. That's what I do. That is, in this embodiment, member 1a
, 1b has a function as a distance measurement limiting member. Reference numeral 6 denotes an image sensor such as a CCD, which converts a subject image formed on its surface by the photographic lens system 5 into an electrical signal.

In this embodiment, the distance measuring means provided in the camera body 4 includes a light projection system 21 that emits infrared light, etc. from the camera body 4 side independently of the photographic lens system, and a light projection system 21 that receives reflected light from the subject. The light-receiving system 22 has a light receiving system 22. The light receiving system 22 detects the incident position of the reflected light beam from the subject on the light receiving element 9 surface, or the light receiving element 9 detects the amount of reflected light, thereby measuring the distance to the subject using a so-called triangular distance measuring method. We are using.

As shown in FIG. 2, the light projecting system 21 projects infrared light from a light projecting element 7 such as an LED toward the subject using a light projecting lens 8. The light-receiving system 22 condenses the reflected light flux from the object using the light-receiving lens 10 and makes it enter the light-receiving element 9.

Based on the distance measurement information obtained by the light receiving element 9, the focusing lens of the photographing lens system 5 is moved along the optical axis by a driving means (not shown), thereby achieving focus.
It is carried out. 12 is a flash device, and 13 is a release button.

In general, a wide converter lens is set so that a photographic lens system is focused on an object at infinity, and a wide range of object distances is included in the depth of field when the lens is attached to the photographic lens system.

That is, when a wide converter lens for widening the angle of view as in this embodiment is attached to a photographing lens system, the depth of field becomes deeper and the object distance that can be photographed is expanded. As a result, the distance measurement information obtained by the distance measurement means is often included in the depth of field at this time, so that the distance measurement information obtained by the distance measurement means is approximately the same as when focusing on an arbitrary subject.

Therefore, in this embodiment, when the converter device 1 is attached to the camera body 4, the member 1a is located at the opening of the light receiving system 22 to prevent the reflected light flux from the object from entering the light receiving system 22. (In this embodiment, the light receiving system 22
Since it is fine as long as the infrared light that becomes the signal does not enter the
Although the opening of No. 1 is also shielded from light by the member 1b, it is sufficient to shield at least one of the openings. ) When the release button 13 is pressed during shooting, the light receiving element 9 of the light receiving system 22
The light receiving element 9 is configured so that it cannot receive any amount of light, so that the distance measurement information obtained by the light receiving element 9 is infinite distance information corresponding to the amount of light being zero.

The focusing lens of the photographic lens system 5 is moved along the optical axis by a driving means to focus on an object at infinity. This allows good images to be obtained over a wide range of object distances when the converter device is attached.

FIGS. 5 and 6 show a second embodiment of the converter device 1 of the present invention, which shows a part of the camera body 4,
FIG. 3 is a schematic diagram of the main parts of No. 3.

In the second embodiment shown in FIG. 5, when the converter device 1 is attached to the camera body 4, the opening of the light receiving system 22 is shielded from light by a part of the member 1a of the converter device 1, and the prism provided in the converter device 1 is A distance measurement limiting member 15 made of a reflecting mirror is positioned at the opening of the light projecting system 21. As a result, the light beam from the light projecting system 21 is reflected by the prism reflector 15, and is prevented from being emitted to the outside.
The light is incident on the second light receiving lens 10 and is incident on an auxiliary light receiving element 14 provided near the light receiving element 9.

When the auxiliary light receiving element 14 receives a predetermined amount of light, it is assumed that the converter device 1 is attached to the camera body 4, and certain distance measurement information, for example, infinity information is output. . As a result, the same effect as in the first embodiment is obtained.

Embodiment 3 of FIG. 6 differs from Embodiment 2 of FIG. The difference is that the converter device 1 is assumed to be attached to the camera body 4 when a predetermined amount of light is received, and the other configurations are the same as in the second embodiment.

It should be noted that the converter device according to the present invention can be similarly applied when a teleconverter lens is used.

[0025]

According to the present invention, by setting each element of the converter device as described above, when it is attached to a camera body having a non-TTL distance measuring means, the focal length of the entire system can be changed and the distance can be measured. By providing appropriate ranging information to the ranging means using the limiting member, it is possible to achieve a converter device that can obtain good images over a wide range of object distances, and a camera system using the converter device.

[Brief explanation of drawings]

FIG. 1 is a schematic front view of a converter device of the present invention.

[Figure 2]
A sectional view of the main parts when the converter device of the present invention is attached to the camera body

FIG. 3 is a schematic front view of the camera body according to the present invention.

[Figure 4]
Side schematic view of Figure 3

FIG. 5 is a schematic diagram of a portion of Embodiment 2 when the converter device of the present invention is attached to the camera body.

FIG. 6 is a schematic diagram of a portion of Embodiment 3 when the converter device of the present invention is attached to the camera body.

[Explanation of symbols]

1 Converter device 2 Converter lens 3. Finder correction lens 4 Camera body 5 Photographic lens system 6 Imaging device 7 Light projecting element 8　Light projection lens 9 Light receiving lens 10 Photo receiving element 11 Finder system 1a, 1b, 15 Distance measurement restriction member 21　Light projection system 22 Light receiving system

Claims (3)

[Claims] Claim 1. A converter device that is attached to a part of a photographing lens system of a camera body and changes the focal length of the entire system, wherein the converter device is attached to a non-TTL type camera body when attached to the camera body. A converter device comprising a distance measurement limiting member that limits the distance measurement operation of the distance measurement means. 2. When a converter device is attached to a camera body provided with a distance measuring means independently of the photographic lens system to change the focal length of the entire system, the converter device is attached to the camera body to change the focal length of the entire system. A camera characterized in that it has a ranging limiting member that limits the ranging operation of the ranging means, and the ranging means performs focusing based on ranging information limited by the ranging limiting member. system. 3. The camera system according to claim 2, wherein the distance measurement limiting member provides constant distance information to the distance measurement means.