JP2509711B2 - Single-lens reflex camera - Google Patents

Description

The present invention relates to a compact single-lens reflex camera using a large screen size photosensitive material such as an instant film.

[Conventional technology]

A mono-sheet type instant film is known in which the shooting result can be viewed immediately after shooting. Such an instant film has a screen size much larger than that of a so-called 35 mm film (for example, Fuji Instant Color Film FI-10 provided by the applicant of the present invention.
(Product name) has an area ratio of about 8 times, and it is known that the photographing lens of a camera using such a large screen size photosensitive material has a long focal length. For example, 35
The focal length of the lens of a compact camera using a millimeter film is generally around 38 mm, but the corresponding focal length is around 110 mm. For this reason, the optical path length becomes long and the camera becomes large, so that it is not easy to handle and it is not necessary to carry.

As a camera that has improved these drawbacks, Polaroid
SX-70 (trade name) is known. The SX-70 is a folding single-lens reflex camera that guides the subject light incident from the shooting lens through a plurality of mirrors to the eyepiece lens, and covers the exposure opening of the film pack immediately after the shutter release operation. The large mirror, which had been used, bounces up, and the subject light is guided to the photosensitive material through this mirror for exposure.

[Problems to be Solved by the Invention]

However, as is apparent from the above-mentioned configuration, the large-sized mirror in the first half requires a large area for completely covering the exposure opening of the pack, which is large and heavy. Therefore,
In order to drive such a mirror instantaneously, a strong driving mechanism is required, and there are drawbacks that vibration and noise during the mirror operation become extremely large. further,
In order to fold it compactly, a so-called off-axis optical system is adopted in which the subject light is reflected twice by the large mirror and guided to the eyepiece. Therefore, this finder
Despite being a single-lens reflex viewfinder that allows you to directly observe the subject to be shot through the shooting lens,
Distortion is likely to appear in the finder image, and the subject cannot be observed accurately.

[Object of the Invention]

The present invention has been made to solve the above-described problems, and is compact while using a large screen size film, and has less vibration and noise at the time of shooting, and allows the subject to be accurately observed. An object of the present invention is to provide a single-lens reflex camera equipped with a viewfinder.

[Means for solving the problem]

In order to achieve the above object, the single-lens reflex camera of the present invention includes a switching mirror that is movable between a shooting position inserted in the shooting light beam behind the shooting lens and a finder observation position retracted from the shooting light beam, A fixed mirror for reflecting the photographing light flux reflected by the switching mirror on the film surface, a switching lens fixed to the back surface of the switching mirror and inserted in the photographing optical path when the switching mirror is at the finder observation position, And a real image type finder optical system formed by inserting the switching lens into the photographing optical path. Further, by forming the switching lens as a part of a conversion lens system that shortens the focal length of the taking lens, it is possible to secure a swing space for the switching mirror without impairing compactness.

[Action]

According to the above configuration, the switching mirror is in the finder observation position in the normal state, but when the shutter is released, the switching mirror is moved to the observation position. As a result, the subject light that has passed through the taking lens is reflected by the switching mirror, and then guided to the film surface through the fixed mirror to expose the film. After the exposure is completed, the optical system switching mirror is returned to the finder observation position, and the switching lens is inserted into the photographing light beam to form the real image type finder optical system.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

〔Example〕

The single-lens reflex camera 1, which is an embodiment of the present invention,
A monosheet type instant film 2 is used. This mono sheet type instant film 2
The unit includes a photosensitive sheet having a photosensitive layer and an image receiving layer, a developing solution pod containing a developing solution, and the like, and can be handled as a single sheet from the beginning to the end.

In FIG. 2, a taking lens 3 having a standard angle of view (an angle of view equivalent to a standard lens of a so-called 35 mm camera)
A diaphragm 4 is provided behind, and behind the diaphragm 4,
A finder optical system is provided. This viewfinder optical system is composed of a concave lens 6 and a convex lens 7 for reducing the focal length of the taking lens 3, a condenser lens 9, a relay lens 10, an eyepiece lens 11 and two fixed mirrors 12, 13. It is a real image finder.

The concave lens 6 is fixed to the back surface of an optical system switching mirror 15 that switches between a finder optical system and a photographing optical system. The optical system switching mirror 15 is rotatably mounted about a shaft 16 and is normally at the position of the solid line regulated by a stopper 18 as shown in FIG. 1, but a shutter (not shown) is provided. Is a so-called quick-return type mirror that is rotated immediately after the release and moves to the position of the broken line regulated by the stopper 19 and returns to the original position of the solid line at the next moment after the exposure is completed.

When the optical system switching mirror 15 is at the position indicated by the broken line, a so-called Z-type optical axis photographing optical system is formed between the optical system switching mirror 15 and the large fixed mirror 20. As mentioned above, Instant Film 2 has 35
Since it has a larger screen size than a millimeter film, the focal length of the taking lens 3, which is a standard lens for forming an image on it, is about 2 to 3 times as long as that of a camera using a 35 mm film. Focus (eg about 105 mils),
The optical path length is also 2-3 times as long. The Z optical axis optical system is
A long optical path length due to the taking lens 3 having a long focal length can be formed compactly. And a large fixed mirror
The light reflected by 20 is imaged on the photosensitive surface of the instant film 2. Reference numeral 22 denotes a light shielding plate that prevents the reflected light from the optical system switching mirror 15 from directly entering the instant film 2.

A plurality of the instant films 2 are stored in an instant film pack (hereinafter referred to as film pack) 23 in a stacked state, and are pressed by a spring from the back surface. When the photographing is completed, it is pushed out by a well-known claw member, and its tip is extended by the developing rollers 27, 28 (second
(See the figure), they are transferred while being pressurized and discharged to the outside. With the lapse of time, development by the developing solution developed by the developing rollers 27, 28 progresses, and when a predetermined time elapses, the subject image is reproduced on the instant film 2.

The operation of the camera 1 configured as above will be described. When the shooting lens 3 is aimed at the subject, the light from the subject is captured by the shooting lens.
3, Pass through the diaphragm 4 and enter the concave lens 6 of the converter 8. Here, the optical system switching mirror 15 is brought into contact with the stopper 18 to perform precise position regulation, so that the converter 8 is accurately configured. The subject image once formed by the converter 8 is condensed by the condenser lens 9 and fixed mirror 12
Is reflected by the fixed mirror 13 again via the relay lens 10 and guided to the eyepiece lens 11. This finder optical system is an erecting real image type single-lens reflex finder, as shown in the optical path of FIG. 2, and an object image can be observed extremely clearly. In addition, a well-known autofocus device (not shown) is used to focus on a subject with the taking lens 3 directed.

After confirming the viewfinder image and selecting the subject and composition, the shutter is released at a desired timing. Photometry is performed by a well-known automatic exposure control device (not shown),
The aperture 4 is set to an appropriate aperture diameter and focus lock is performed. At the same time, the shutter is once closed, and then the optical system switching mirror 15 is rotated from the solid line position to the broken line position. At the position of the broken line, the tip of the optical system switching mirror 15 contacts the stopper 19 and the optical system switching mirror 15 is accurately positioned, and a Z-type optical axis photographing optical system is configured. At the next moment, the shutter is opened and the subject light is reflected by the optical system switching mirror 15 and guided to the large fixed mirror 20, where it is roughly reflected and focused on the photosensitive surface of the instant film 2.

When the exposure time determined by the automatic exposure mechanism elapses and the exposure of the instant film 2 is completed, the shutter is closed, and immediately thereafter, the optical system switching mirror 15 is rotated to return to the original solid line position. Immediately after this, the shutter returns to the open state again, and when the optical system switching mirror 15 is rotated to the broken line position, the finder image that has been darkened can be viewed again. At the same time, the exposed instant film 2 is transferred to the camera 1 by the developing rollers 27 and 28.
The new instant film 2 is discharged to the outside and is set in the exposure opening of the film pack 23 by the spring bias in the film pack 23, preparation for the next shooting such as shutter charging is made, and one shooting sequence is completed. .

As described above, since a part of the converter 8 is fixed to the optical system switching mirror 15, it is possible to secure a swing space for the optical system switching mirror 15 in the finder optical system, so that the camera 1 can be made compact. In addition to contributing, the positioning of the optical system switching mirror 15 can be accurately performed by a simple stopper mechanism, so that switching between the finder optical path and the photographing optical path can be reliably performed. Also,
Although the camera 1 is a single-lens reflex system, the viewfinder eyepiece can be placed at the end of the camera body by the configuration of the viewfinder optical system and the shooting optical system, so that the viewfinder can be easily seen and the camera can be easily held. I was able to improve.

〔The invention's effect〕

As described above, according to the single-lens reflex camera of the present invention, the photographing optical system includes the switching mirror and the fixed mirror, so-called Z.
Since the optical system of the mold optical axis is configured, a long optical path length can be achieved compactly even if a film having a large screen size is used and a taking lens having a long focal length is mounted. Further, since a part of the conversion lens is fixed to the switching mirror, a swinging space for rotating the switching mirror can be secured without enlarging the camera size, which can contribute to downsizing of the camera. . Further, since the switching mirror is provided behind the taking lens, the switching mirror can be made smaller, so that vibration and noise at the time of shooting can be reduced. Further, since the real image type finder optical system is adopted, it is possible to provide a single-lens reflex camera which has a compact structure and can obtain an accurate finder image.

[Brief description of drawings]

 FIG. 1 is a plan sectional view of an embodiment of the present invention. FIG. 2 is a side sectional view of the embodiment shown in FIG. 1 …… Camera 2 …… Instant film 3 …… Shooting lens 6 …… Concave lens 8 …… Converter 11 …… Eyepiece 12,13 …… Fixed mirror 15 …… Optical system switching mirror 18.19 …… Stopper 20 …… Large fixed mirror.

Claims (2)

(57) [Claims] 1. A switching mirror that is movable between a shooting position inserted into the shooting light flux behind the shooting lens and a finder observation position retracted from the shooting light flux, and a shooting light flux reflected by the switching mirror. A fixed mirror for reflecting the light on a surface, a switching lens fixed to the back surface of the switching mirror and inserted in the shooting optical path when the switching mirror is in the finder observation position, and this switching lens being inserted in the shooting optical path. A single-lens reflex camera having a real-image viewfinder optical system formed by the. 2. The single-lens reflex camera according to claim 1, wherein the switching lens is part of a conversion lens system that shortens the focal length of the taking lens.