JPH0254222A - Accessory for camera - Google Patents

Abstract

PURPOSE:To excellently correct the parallax of a finder at the time of close-up photographing by mounting a close-up lens and an accessory provided with a half mirror surface, total-reflecting mirror surface, and prescribed fitting means to a front lens barrel section by utilizing a positioning means. CONSTITUTION:The title camera is provided with a close-up lens 101, half mirror surface 4a which reflects a part of the luminous flux passed through a close-up lens 101 to the side section of a photographing lens 7, total-reflecting mirror surface 5a which guides the luminous flux reflected by the mirror surface 4a to an optical element 17 provided in the vicinity of the photographing lens 7, and a removable mounting means 3a which is mounted to a part of the lens barrel 6 of the photographing lens. Therefore, a luminous flux is separated into transmissive light and reflected light by means of a half mirror 4 after passing through the close-up lens 101 when an accessory 1 is fitted and the transmissive light is guided to film through the 1st lens group 7 of the photographing lens and the reflected light is guided to the objective lens 7 of a finder system through a total-reflecting mirror 5. Consequently, close-up photographing can be made to a further closer object and, simultaneously, the parallax of the finder produced at the time of close-up photographing can be corrected excellently.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a removable camera accessory that is attached in front of a photographic lens, and in particular, the finder system is attached to a part of the photographic lens barrel separate from the photographic optical path. The present invention relates to a camera accessory which is attached in front of the photographing lens to correct the variation of the finder during close-up photography in a camera having a range finder provided in parallel with the photographing optical path.

(Prior art) Cameras with a rangefinder, which has a viewfinder system installed in a part of the camera body independent of the photographing optical path, have been widely used because it is relatively easy to make the entire camera smaller and lighter. .

However, this camera has a problem in that parallax occurs in the viewfinder field of view as the shooting distance changes because the photographing lens and the objective lens of the finder system are provided separately.

For this reason, conventionally in many cameras of this type, marks for correcting parallax are provided within the field of view of the finder to correct parallax that occurs when the photographing distance changes. FIG. 5 is a schematic diagram of the viewfinder field of view of a camera with a conventional rangefinder. In the figure, a field frame 60 is used to check the composition of a subject that is 2 m or more away, for example, within the viewfinder field of view 62, and a mark 61 is newly provided to check the composition of a subject that is 2 m or less away. Parallax is corrected.

However, with this method, a mark is always displayed in the viewfinder field of view, making it very difficult to see the viewfinder image.Also, with this method, the relative relationship between the background or scenery and the target subject is still observed using the viewfinder system. There was a problem that it was different from the original.

Furthermore, in a so-called zoom camera in which the photographing lens is a zoom lens, parallax changes as the viewfinder magnification changes. In particular, the subject distance at which a parallax correction mark should be used during close-up photography differs depending on the zoom position of the photographic lens. For this reason, when a photographer uses a zoom camera to take a picture, there is a problem in that it is very difficult for the photographer to know the exact shooting range due to the finder system.

(Problems to be Solved by the Invention) The present invention provides a camera having a range finder, in particular, a real-image finder type objective lens that is housed in a part of the lens barrel of the photographic lens in parallel with the photographic lens. A removable attachment to the photographic lens barrel that can effectively correct finder parallax during close-up photography over the entire zoom range by using the close-up lens and half-mirror surface for zoom cameras with similar configurations. The purpose of the present invention is to provide a camera accessory with a means for use.

(Means for solving the problem) A camera accessory that is detachably attached to the front of a photographic lens, and the accessory includes a close-up lens and a part of the light flux that has passed through the close-up lens. A half-mirror surface that reflects the light to the side of the lens, a total reflection mirror surface that guides the reflected light flux from the half-mirror surface to an optical element arranged near the photographic lens, and a part of the lens barrel of the photographic lens. and a removable attachment means for attaching the device to the device.

In particular, in the accessory according to the present invention, the half mirror surface and the total reflection mirror surface are arranged in parallel, and the mounting means includes a positioning member that is positioned and mounted on the lens barrel of the photographic lens. It is characterized by

(Example) Fig. 1 is a central vertical cross-sectional view of the first embodiment when the accessory according to the present invention is attached to a zoom camera, and Fig. 2 is a central vertical sectional view of the first embodiment.
FIG. 3 is a perspective view showing the accessory of the present invention shown in the figure and the mount portion of the zoom camera.

In the figure, 1 is a camera accessory, and 12 is a zoom camera to which the accessory 1 is detachably attached. Reference numeral 3 denotes an outer cylinder of the accessory 1, and three mounting parts 3a are provided at a phase interval of 120 degrees on the circumference of the end thereof to be positioned and mounted to the bayonet type zoom camera 2.

101 is a lens for close-up photography and has positive refractive power,
It is supported by a close-up lens frame 102 and held within the outer cylinder 3 of the accessory 1. This shortens the close-up shooting distance.

Reference numeral 4 denotes a half mirror, which is fixedly supported within the outer cylinder 3 of the accessory 1 so as to be inclined at 45 degrees with respect to the optical axis of a photographing lens, which will be described later. 5 is a total reflection mirror;
It is fixedly supported in the outer cylinder 3 of the accessory 1 substantially parallel to the half mirror 4 so as to be inclined at 45 degrees with respect to the optical axis of the photographic lens. 4a is a reflective surface of the half mirror 4, which is located on the subject side. 5a is a reflective surface of the total reflection mirror 5, which is located on the camera side.

Reference numeral 6 denotes a lens barrel, and three mounting portions 6a and rotation stop portions 6b for mounting the accessory 1 are provided at three locations on the circumference of the front end at a phase interval of 120 degrees. 7 is the Luns group,
A second lens group 8 includes a second front lens group 8a and a second rear lens group 8b. 9 is a third lens group, and these 1st, 2nd, . The third lens group constitutes a zoom lens as a photographic lens. 10 is a first lens frame that holds the first lens group 7. A second front lens frame 11 holds a second front lens group 8a. A second rear lens frame 12 holds the second rear lens group 8b. A third lens frame 13 holds the third lens group 9. Reference numeral 14 denotes a shutter blade that also serves as an aperture, which is held on a shutter base plate 15 and driven by a chargeless electromagnetic shutter drive mechanism 16. a second front lens frame 11 and a second rear lens frame 12;
The shutter base plate 15 is positioned so that the centers of the optical axes coincide, and is fixed together with screws, etc., and the lens barrel 6
Fixedly supported inside.

Reference numeral 17 denotes an objective lens, which is held in the first lens frame 10 together with the first lens group 7. Reference numeral 18 denotes an intermediate lens, which is held on the shutter base plate 15 and housed within the lens barrel 6.

Reference numeral 19 denotes a Porro prism for erecting a normal image, and a finder image formed by an objective lens 17 and an intermediate lens 18 is formed in a part of the prism.

(Although in the same figure, the Porro prism 19 is shown as an expanded block diagram with two reflective surfaces for simplicity, it actually consists of an optical block with four reflective surfaces.) 20 is an eyepiece. This lens is used to observe a finder image formed within the Porro prism 19.

In this embodiment, an objective lens 17, an intermediate lens 18, a Porro prism 19, and an eyepiece 20 constitute a real-image finder system.

The Porro prism 19 and the eyepiece 20 are supported by a finder block 21, which is fixed to a camera body 22.

The support bar 23 is fixed to the second front lens frame 11 and holds the first lens frame 10 slidably in the optical axis direction. Support bar 2
4 is fixed to the second front lens frame 12 and holds the third lens frame 13 slidably in the optical axis direction. 25 is a motor;
The lens barrel 6 is moved in the optical axis direction. 26 is a motor pinion gear, and 27 is an internal gear that meshes with the motor pinion gear, and is rotatably fitted to the inner diameter 6C of the lens barrel 6. 28 is a male threaded shaft, which integrally has a gear portion 28a that meshes with the internal gear 27 and a trapezoidal threaded portion 28b. Further, a trapezoidal thread 28b of the male threaded shaft 28 is screwed into a female thread 22a provided on the camera body 22.

Reference numeral 29 denotes a holding plate, which presses the internal gear 27 and the gear 28a of the male threaded shaft 28 against the lens barrel 6. Further, the push plate 29 has a hole 29 corresponding to the small diameter portion 28c of the male screw shaft 28.
a, which rotatably holds the male threaded shaft 28 and is fixed to the lens barrel 6.

Reference numeral 30 denotes a reflecting mirror, which is held by a light shielding plate 35 and guides a portion of the light flux from the photographing lens to the AF block 34. 31 is a field lens, 32 is a secondary lens, and 33 is a light receiving means with two light receiving element arrays 33a and 33b.
have.

The AF device according to this embodiment uses a so-called phase detection method, in which two object images are formed on the light-receiving element rows from the light beams from the subject that have passed through different pupils of the photographic lens. The focus of the photographic lens is detected by determining the relative positional relationship between two object images.

The AF block 34 holds a field lens 31, a secondary lens 32, and a light receiving means, and is fixed to the camera body 22. Further, the light shielding plate 35 is connected to the camera body 2 (not shown).
It is rotatably supported on the second axis, and is retracted from the photographing optical path during film exposure. 36 is a back cover that is opened when putting in and taking out the cartridge. 37 is a pressure plate held on the back cover 36. 38 is an outer casing cover.

Next, the zoom operation of the zoom camera and the attachment operation of accessories in this embodiment will be explained.

When the zoom switch (not shown) is turned on, the motor 25 is energized, the onion gear 26 rotates, and then the internal gear 2
7 rotates. A rotational force is applied to the male threaded shaft 28 by the internal gear 27, and the male threaded shaft 28, which is held by a presser plate 29 fixed to the lens barrel 6, moves in the axial direction with respect to the main body 22 to which it is screwed.

Therefore, when the motor rotates in the normal direction, the lens barrel 6 holding the second lens group 8 moves forward in the optical axis direction with respect to the camera, and when the motor rotates in the reverse direction, it moves backward. At the same time, a cam (not shown) interlocking with the internal gear 27 moves the first lens frame 10 holding the lens group 7 and the third lens frame 13 holding the third lens group 9 onto the support bar 23 and the support bar 24, respectively. The distance between the lenses relative to the second lens group 8 changes. The photographic lens is zoomed by such an operation.

On the other hand, in the finder system, the finder magnification is changed by moving the intermediate lens 18 together with the lens barrel 6 and the objective lens 17 together with the first lens frame 10 in the optical axis direction as the photographing lens zooms.

FIG. 3 shows the mirror rfJ6 moved forward in FIG. Second. This shows the state when zooming toward the telephoto side by changing the distance between the third lens group.

Next, a method of attaching the accessory 1 according to the present invention to the lens barrel 6 of the zoom camera 2 will be explained.

The outer cylinder 3 of the accessory 1 and the lens barrel 6 of the zoom camera 2 each have three mounting parts 3a on the mount parts.

6a are provided at a phase interval of 120 degrees. For this reason,
First, the indicator 6d provided on the mirror %916 and the accessory 1 in the position where the mounting parts do not overlap each other, that is, the mirror 916 in Fig. 2.
and the indicator 3b provided on the outer cylinder 3 of the accessory 1, rotate the outer ti 43 of the accessory 1 clockwise relative to the zoom camera 2, and the mounting part 3a of the accessory 1 comes into contact with the stopper 6b. Rotate it approximately 60 degrees. In the mounted state positioned in this way, the half mirror 4 in the outer cylinder 3 on the accessory 1 side is located just in front of the lens group 7 of the zoom camera 2, as shown in FIG. is located just in front of the objective lens 17 of the finder system. Therefore, the light beam that was incident on the photographic lens when the accessory 1 was not attached passes through the close-up lens 101 when the accessory 1 is attached, and is then divided by the half mirror 4 into two beams: transmitted light and reflected light. Of these, the transmitted light is guided to the film through the lens group 7 of the photographic lens, and the reflected light is guided to the objective lens 7 of the finder system via the total reflection mirror 5.

This allows for shorter close-up shots and effectively compensates for finder variation that occurs during close-up shots.

In addition, in this embodiment, the half mirror in accessory 1
The total reflection mirror may be constructed by combining two prism bodies 51 and 52 having a half mirror surface 50 and a prism body 54 having a total reflection surface 53 as shown in FIG. 4, for example.

(Effects of the Invention) According to the present invention, for a camera in which a finder type objective lens is disposed in a part of the lens barrel of the photographing lens, the front lens barrel includes a close-up lens, a half mirror surface, and a full mirror surface. By configuring an accessory that has a reflective mirror surface and a predetermined attachment means to be attached using a positioning means, it is possible to take closer shots and eliminate the drawbacks of conventional cameras with rangefinders. According to the present invention, it is possible to provide a camera accessory that can satisfactorily correct the variax of the viewfinder.

Furthermore, according to the present invention, when attaching the accessory to the camera, it can be easily and reliably attached to and detached from the lens barrel of the camera by using attachment means such as a bayonet. Attach accessories to the camera only when you need to be careful about balax.
Other features include being able to take pictures without wearing it.

Additionally, in the case of close-up photography, the depth of field is generally shallow, and strobe photography is often used. In this case, when trying to take pictures with a strobe on the built-in camera, there was a tendency for overexposure to occur even when the aperture was set to the minimum aperture due to the size of the GNo. On the other hand, according to the present invention, since the close-up lens (positive refractive power) and the half mirror are integrated, the half mirror can be adjusted to match the positive refractive power of the close-up lens (accordingly, to match the shooting distance). It has the advantage of being able to control the transmittance of - and having the same optical effect as when an ND filter is attached, making it easy to take photographs with proper exposure.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a central sectional view of the first embodiment when the present invention is applied to a zoom camera, and FIG. 2 is a perspective view showing the accessories shown in FIG. 1 and a mount for the zoom camera. FIG. 3 is a schematic view of the photographing lens shown in FIG. 1 when zoomed, FIG. 4 is a schematic view of the second embodiment of the present invention, and FIG. 5 is an explanatory view of the field of view of a conventional finder. In the figure, 1 is an accessory, 12 is a zoom camera, 3 is an outer tube, 4 is a half mirror, 15 is a total reflection mirror, 6 is a lens barrel, 2
2 is a camera body, 3a is a mounting portion, 51 is a spigot ring, 101 is a close-up lens, and 102 is a close-up lens frame. figure

Claims (2)

[Claims] (1) A camera accessory that is detachably attached to the front of the photographic lens, and the accessory includes a close-up lens and a half mirror that reflects part of the light beam that has passed through the close-up lens to the side of the photographic lens. a total reflection mirror surface for guiding the reflected light flux from the half mirror surface to an optical element disposed near the photographic lens; and a removable mounting means that is mounted on a part of the lens barrel of the photographic lens. A camera accessory characterized by having: (2) The half mirror surface and the total reflection mirror surface are arranged in parallel, and the mounting means includes a positioning member that is positioned and mounted on the lens barrel of the photographic lens. Camera accessories described in item 1.