JPH02120834A - Single-lens reflex camera - Google Patents

Abstract

PURPOSE:To readily confirm a telescopic effect through a finder by inserting an auxiliary lens into the luminous flux of an objective lens when an optical system is switched to a finder observing state, moving at least one lens of the other lenses along an optical axis with the auxiliary lens fixed and variably magnifying the finder. CONSTITUTION:In the case of normal photographing, a rotary mirror 2 retreats outside the optical path, and the auxiliary lens 11 is inserted into the optical axis. An image of the objective lens 1a has positive power, is reduced by the auxiliary lens 1a with a reducing effect, is formed near a field lens 4, turns into a positive image through mirrors 5 and 7 and positive lenses 61a and 62a, and is further formed in the position of a visual field frame 8. In the case of dummy telescopic photographing, positive lenses 61b and 62b move to the side of the mirror 5 by changing their space although the focal length of the objective lens is the same as the normal photographing. Consequently, the finder can be variably magnified with finder diopter maintained at a fixed level. Thus, a photographer can confirm a telescopic effect with his eyes when observing an object through the finder.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a single-lens reflex camera, and more specifically, to a single-lens reflex camera in which an auxiliary lens is inserted into the light beam of an objective lens during viewfinder observation to change the magnification of the finder image. Regarding reflex cameras.

[Conventional technology] As a conventional single-lens reflex camera of this type,
The one described in Japanese Patent No. 29143 is known. In this system, an auxiliary positive lens is inserted during viewfinder observation, and the subject is observed through a pentaprism. According to this proposal, the size of the screen on the focus board can be reduced, making it possible to downsize the pentaprism, which in turn makes the entire finder device smaller and lighter.
Cost reduction can be achieved.

In addition, a camera that can switch the shooting screen between full size and half size and shoot #ffi shadows was released in 1986-5.
It is disclosed in Japanese Patent No. 7577. This means that if you switch from full size to half size and print on photographic paper of the same size, the same effect as an enlarged print can be obtained.

Furthermore, US Pat. No. 3,490,844 discloses a so-called pseudo-format camera. This is because the photographic lens does not change the magnification, but instead records the enlarged screen size in a code on a part of the film, and prints are sometimes enlarged based on the code to create a pseudo-telephoto effect. It is something to do.

[Problem that the invention seeks to solve] However,
The above conventional example had the following problems.

(1) Regarding Utility Model Publication No. 53-29143, since a small pentaprism is used in the finder optical path, the cost is high and there are limits to miniaturization and weight reduction.

■Regarding Japanese Patent Publication No. 60-57577, when switching from full size to half size, the configuration is simple, just masking both ends of the viewfinder field of view, but the screen printed on photographic paper of the same size is The disadvantage is that while the image is enlarged and printed, the viewfinder field of view is smaller than the full size image and difficult to see.

- Regarding U.S. Patent No. 3,490,844, if you try to make it an eye reflex camera, the focal length of the photographic lens will not change, so you will not be able to see the telephoto effect in the viewfinder.
To confirm this, I had to use masking to make the viewfinder field of view smaller and harder to see. or,
In order to overcome this drawback, a complicated finder transformation optical system is required, but it is also expensive and lacks compactness, making it impractical.

[Means for Solving the Problems] The present invention solves the drawbacks of the above-mentioned conventional example. In a single-lens reflex camera in which the light flux of the objective lens is guided to both the IR shadow screen viewfinder, the optical system is improved. When switching to the viewfinder observation state, an auxiliary lens is inserted into the light beam of the objective lens, and by moving at least one of the other lenses along the optical axis while keeping the auxiliary lens fixed, the viewfinder magnification can be changed. Since this is done, the telephoto effect can be easily confirmed through the finder even in a pseudo-format camera, for example.

[Example] An example of the present invention will be described below with reference to the drawings. 1 and 2 are plan views of the single-lens reflex camera of the present invention viewed from above, with FIG. 1 showing the arrangement of the optical system during photographing, and FIG. 2 showing the arrangement of the optical system during viewfinder observation. Further, FIG. 3 is a side view of paper A in FIG. 1. In these figures, C
is the camera body, l is the objective lens, and 2 is a rotating mirror that can freely rotate around the glaze 2a.The rotating mirror 2 emitted the objective lens 1 when it was tilted at 45 degrees with respect to the optical axis as shown in Fig. 3. The light beam is bent by 90" and guided to a film 3 arranged parallel to the optical axis (parallel to the plane of the paper in this case). Reference numeral 4 denotes a field lens provided outside the rotation locus of the rotating mirror 2, and 5 .7 is a mirror tilted at 45 degrees with respect to the optical axis of the objective lens 1. 61.62 is an erecting lens composed of two groups, and the erecting lens 61.62 is similar to the mirror 5.7.
It is held by a cam or the like and is movable in the direction of the optical axis. Here, when the erecting lenses 61 and 62 move toward the mirror 5 side, the imaging magnification increases, and the viewfinder image is enlarged while keeping the field of view constant. 8 is a field frame, 9 is a field lens, and 10 is an eyepiece lens. 1
Reference numeral 1 denotes an auxiliary lens which is retracted out of the optical path during photographing as shown in FIG. 1, and in this embodiment, a reduction auxiliary lens having positive power is used as the auxiliary lens 11.

When observing through the finder shown in FIG. 2, the auxiliary lens 11 is inserted into the optical path instead of the rotating mirror 2 being retracted out of the optical path (rotated approximately 45° counterclockwise from the state shown in FIG. 3). There is. In the figure, reference numerals 61a and 62a indicate royal lenses in normal shooting mode. Furthermore, 6
1b and 62b indicate the royal lenses when switched to pseudo-telephoto mode, which will be explained in detail later.

Photographing in the pseudo-telephoto mode described above will be described below.

FIG. 4 is a perspective view of a trimming signal recording section of a pseudo-format camera related to the present invention.

In the figure, O is the optical axis after the light beam emitted from the objective lens 1 is bent at a substantially right angle by the rotating mirror 2, and the film 3 is disposed on the extension line of the optical axis. Numerals 20 and 21 are light emitting diodes that imprint a trimming signal, which will be described later, between the perforation controllers of the film 3. SWt and SWl are switches that control the light emitting states of the light emitting diodes 20 and 21, respectively. If you take a picture in the standard state now, SWl will turn on, the light emitting diode 20 will light up, and the dot image will be 1
A predetermined position 2 between the perforations of only one film 3
When this negative film is placed on an enlarger after development, the enlarger detects this dot image, recognizes that the image was taken in the standard state of a pseudo-format camera, and crops the entire screen. Stretch without stretching. Next, when photographing is performed in a pseudo-telephoto state, both SWt and SWl are turned on, light-emitting diodes 20 and 21 are turned on, and two dot images are imprinted on predetermined positions between the perforations of the film 3. After development, the enlarger detects these two dot images, recognizes that the image was taken in the telephoto state of a pseudo-format camera, performs the specified trimming, and enlarges the image at a higher magnification than the standard state. In this way, when photographing in a pseudo-telephoto state, a print with a larger magnification than that taken in a standard state is obtained, and the intended purpose is achieved.

Also, when the present invention is applied to a camera that switches the screen between full size and half size, the image will be enlarged to the same print size according to the screen size of the image without using a trimming signal. The image is enlarged to a greater extent, resulting in a telephoto effect.

Next, the operation of the first embodiment having the above configuration will be explained. First, to explain the photographing condition with reference to FIGS. 1 and 3, the light beam exiting the objective lens 1 is 45° to the optical axis.
It is bent by 90 degrees by the tilted rotating mirror 2 and guided to the film 3, and the photographic screen is exposed. At this time, the image is reversed by the rotating mirror 2 and the film 3 is exposed in a so-called back-printing state, but this is a problem because the subsequent printing process can produce a regular print. There isn't.

Furthermore, to explain the viewfinder observation state with reference to Fig. 2, first of all, in the case of normal photography, the rotating mirror
is retracted out of the optical path, and the auxiliary lens 11 is inserted into the optical axis. In this way, the image of the objective lens 1a is reduced by the auxiliary lens 1a, which has positive power and has a reduction effect, and is formed near the field lens 4, and is further erected by the mirror 5.7 and the erecting lenses 61a and 62a. The image is formed at the position of the field frame 8.

Next, in the case of pseudo-telephoto shooting, the focal length of the objective lens 1 is the same as that for normal shooting, but the erecting lenses 61b and 62b move toward the mirror 5 side while changing the distance between them, as shown in FIG. By moving, it is possible to change the magnification of the finder while keeping the finder diopter constant. Therefore, the telephoto effect can be visually confirmed when observing through the viewfinder. In this embodiment, the imaging magnification of the erecting lens system in the normal photographing state is -0.5X, and in the pseudo-telephoto state it is -1.0X. In addition, when the present invention is applied to a camera that changes the entire #ffi shadow screen between full size and half size, the imaging magnification of the Royal lens system in the full size state is set to -0.7X, and when in the half size state, It may be set to -1.0X.

5 and 6 show a second embodiment of the present invention,
FIG. 5 shows the photographing state, and FIG. 6 shows the viewfinder observation state. According to this embodiment, unlike the first embodiment, the field lens 4 is also movable along the optical axis, but instead of the erecting lens 6 being configured as one group. In FIG. 6, the field lens 4a and the erecting lens 6a in the normal shooting mode move in the direction approaching the rotating mirror 5 in the pseudo telephoto mode, and the field lens 4b,
It is placed at the position of the erecting lens 6b. According to this configuration,
Since both the field lens 4 and the erecting lens 6 are moved 8 times along the optical axis when changing the magnification, the amount of movement of both can be set to be relatively small, for example when bending the finder optical path into a 2-shape shape. Also, since interference between lenses on adjacent optical paths can be prevented, there is an advantage that the finder optical system can be stored compactly inside the camera.

7 and 8 show a third embodiment of the present invention,
FIG. 7 shows a photographing state, and FIG. 8 shows a viewfinder observation state. According to this embodiment, the eyepiece 10
At least two lenses 101 that are movable in the optical axis direction
．． 102. , in Fig. 8,
The two lenses 101 and 102 are suffixed with suffix a during normal shooting and b during pseudo-telephoto shooting, but in this embodiment, both lenses 101 and 102 are composed of positive lenses, and the distance between the two lenses is changed during magnification. It's starting to shrink. That is, during normal shooting, the second lenses 101a and 102a move closer to each other along the optical axis in eight rows during pseudo-telephoto shooting, and are positioned at the lenses 101b and 102b, so that the diopter is kept constant. You can change the magnification of the viewfinder while maintaining the same value. According to this configuration, since it is necessary to move only the smallest eyepiece lens 100, there are advantages such as a small lens driving force and a small shock when moving the lens. In addition, since the eyepiece lens 100 is arranged at the outermost part of the camera body C and is very small, it is easy and most efficient to arrange a mechanism for moving the eyepiece lens 100 inside the camera body C. is good.

9 and 10 show a fourth embodiment of the present invention, with FIG. 9 showing a photographing state and FIG. 10 showing a finder observing state, respectively. According to this embodiment, when the objective lens 1 with two groups is wide (I W) and when tele (1 lens)
This is a zoom lens that moves in the optical axis direction while changing the air gap, and in the photographing state shown in FIG. 9, the auxiliary lens 11 is retracted from the optical path as in the other embodiments described above. Furthermore, in the finder observation state shown in FIG. 10, the optical path is changed by rotating the mirror 5, and the erecting lens 6 and mirror 7 are movable on the changed optical path. That is, in the standard photographing state, the light flux that has passed through the field lens 4 is guided to the eyepiece 10 side via the mirror 5a, the erecting lens 6a, and the mirror 7a, whereas in the pseudo-telephoto shooting state, the light flux that has passed through the field lens 4 is guided to the eyepiece 10 side. The light beam is guided to the eyepiece 10 side via the mirror 5b, the erecting lens 6b, and the mirror 7b. In other words, when transitioning to pseudo-telephoto mode, the erecting lens 6 is moved along the optical axis while changing the distance between the primary imaging plane and the secondary imaging plane, keeping the diopter constant. I try to change the magnification while doing so. According to this configuration, the configuration of the erecting lens can be simplified compared to the first embodiment, and
This has the effect of reducing deterioration in image performance.

In the above embodiments, the present invention is applied to a pseudo-format eye reflex camera, but the present invention is not limited to this, and can be applied to a camera capable of switching the shooting screen between full-size and half-size as described above. can also be applied.

Note that the present invention can also be applied to cameras in which the shooting screen cannot be switched; in this case, the finder is used to close up a part of the screen for accurate focusing, or to obtain a telescope effect. used.

Further, although detailed explanation has been omitted, it goes without saying that in each embodiment, each lens position is configured to change continuously when transitioning from the normal photographing mode to the pseudo-telephoto mode.

Furthermore, the position of the field frame is not limited to the above embodiment. For example, a field frame may be provided at the position of the -th focal plane, or a focusing plate may be provided in the optical path.

As in the third embodiment, in a type in which magnification is changed using an eyepiece, an erecting prism may be used instead of an erecting lens.

[Effects of the Invention] As explained above, according to the present invention, an auxiliary lens is inserted into the optical path of the objective lens when the optical system is switched to the viewfinder observation state, and the auxiliary lens remains fixed and is connected to other lens groups. The magnification of the finder is changed by moving a portion of the lens along the optical axis, so the telephoto effect can be easily confirmed through the finder even in a pseudo-format camera, for example, despite the compact configuration.

Compared to the conventional type that switches between multiple viewfinder field frames or the type that masks the outer edge of the finder field of view, the present invention makes it possible to obtain a continuous viewfinder field of view, including the intermediate state of switching. Furthermore, it is extremely effective because the angle of view of the finder does not become small.

For example, in a camera equipped with both a zoom lens and a pseudo-format function, if we assume that the zoom ratio is 2x and the pseudo-telephoto is cropped by %, a 4x magnification is required on the viewfinder, and the telephoto effect is achieved using the external viewfinder. However, according to the present invention, it is possible to easily realize a single-lens reflex camera equipped with a compact variable magnification finder of the so-called TTL system.

An auxiliary lens that has two types of insertion and retraction on the optical axis,
Since there is no need to move the finder along the optical axis when changing magnification, the structure does not become complicated.

[Brief explanation of the drawing]

1 to 3 show a first embodiment of the present invention,
Figure 1 is a plan view of the camera viewed from above when shooting, Figure 2 is a plan view of the camera viewed from above when observing through the finder.
Fig. 53 is a view of A in Fig. 1, Fig. 4 is a perspective view showing a film trimming signal recording section of a pseudo-format camera, and Figs. 5 and 6 show a second embodiment of the present invention. Fig. 5 is a plan view when photographing, Fig. 6 is a plan view when observing through the finder, Figs. 7 and 8 show the third embodiment of the present invention, and Fig. 7 is a plan view when photographing. A plan view, FIG. 8 is a plan view when observing through the finder, FIGS. 9 and 10 show the fourth embodiment of the present invention, FIG. 9 is a plan view when observing through the finder, and FIG. 10 is a plan view when observing through the finder. FIG. l...Objective lens 2...Rotating mirror 3...Film 10.100...Eyepiece lens 11...Auxiliary lens

Claims (5)

[Claims] (1) In a single-lens reflex camera that guides the light flux of the objective lens to both the photographing screen and the viewfinder, when the optical system is switched to the viewfinder observation state, an auxiliary lens is inserted into the light flux of the objective lens, and the auxiliary lens A single-lens reflex camera characterized in that the magnification of the finder is changed by moving at least one of the other lenses along the optical axis while keeping the lens fixed. (2) The single-lens reflex camera according to claim 1, wherein at least one lens to be moved is located closer to the eyepiece than an auxiliary lens inserted into the optical path. (3) The single-lens reflex camera according to claim 1 or 2, further comprising means for changing the size of the photographic screen or means for instructing enlarged printing by trimming. (4) An erecting lens for performing secondary image formation is provided in the optical path, and the magnification of the finder is changed by moving the erecting lens.
3) Single-lens reflex camera described. (5) The single-lens reflex camera according to claim 1, wherein the objective lens is variable in magnification.