JPH02120833A - 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, moving the auxiliary lens along an optical axis and variably magnifying the finder. CONSTITUTION:In normal photographing, a rotary mirror 2 retreats outside the optical path to insert the auxiliary lens 11 into the optical path. An image from 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 a normal lens 6, and is further formed in the position of a visual field frame 8. In the case of dummy telescopic photographing, the objective lens 1b moves to an object side, and the auxiliary lens 11b moves to the side of a field lens 4 although the focal length of the objective lens 1 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] [Field of Industrial Application] 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 the objective lens during viewfinder observation to change the magnification of the finder image. Regarding the camera.

[Conventional technology]

As a conventional single-lens reflex camera of this type,
The one described in 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, it is possible to reduce the size of the screen on the focusing board, so it is possible to downsize the pentaprism.
As a result, it is possible to reduce the size, weight, and cost of the entire finder device.

In addition, a camera that can switch the shooting screen between full size and half size was released in 1986-5757.
It is disclosed in No. 7. 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 the enlarged screen size is recorded in a code on a part of the film, and the print is sometimes enlarged based on the code to create a pseudo-telephoto effect. It is something to do.

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

■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 Special 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 as a result, the screen printed on the same size photographic paper is Although the print is enlarged, the viewfinder field of view is smaller than the full-size image (which has the disadvantage of making it 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. Alternatively, in order to overcome this drawback, a complicated viewfinder variable magnification optical system was required, but it was also expensive (and lacked compactness, making it impractical).

[Means for solving problems]

The present invention solves the above-mentioned drawbacks of the conventional example. In a single-lens reflex camera in which the light flux of the objective lens is guided to both the photographing screen and the viewfinder, when the optical system is switched to the viewfinder observation state, the objective lens is An auxiliary lens is inserted into the light beam, and the magnification of the viewfinder is changed by moving the auxiliary lens along the optical axis, making it easy to check the telephoto effect through the viewfinder, even in pseudo-format cameras, for example. be able to.

〔Example〕

An embodiment 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. In both figures,
C is a camera body, l is an objective lens, and 2 is a rotary mirror that can freely rotate around an axis 2a.When the rotary mirror 2 is tilted 45'' with respect to the optical axis as shown in FIG. 4, which will be described later, the objective lens 1 The emitted light beam is bent by 90 degrees and guided to a film 3 arranged parallel to the optical axis (parallel to the plane of the paper). 4 is a field lens provided outside the rotation trajectory of the rotating mirror 2; 5 and 7 are mirrors tilted by 45'' with respect to the optical axis of the objective lens 1, 6 is an erecting lens provided between the mirrors 5 and 7, 8 is a field frame, 9 is a field lens, and lO is a field lens. The eyepiece lens is an auxiliary lens 11 which is retracted out of the optical path during the photographing 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 rotating mirror 2 is retracted out of the optical path (approximately 45 degrees counterclockwise from the state shown in FIG. 4, which will be described later).
° rotation), the auxiliary lens 11 is inserted into the optical path. In the figure, la and lla respectively indicate the objective lens and the auxiliary lens in the normal photographing mode. Furthermore, lb and llb indicate the objective lens and auxiliary lens when switching to pseudo-telephoto mode, which will be explained in detail later. It can be seen that they are spaced apart from each other in the direction.

3 to 6 are diagrams for explaining numerical embodiments of the present invention, in which FIG. 3 is a plan view in a photographing state, FIG. The figure is a plan view when observing through the finder in normal photographing mode, and FIG. 6 is a plan view when observing through the finder in pseudo-telephoto mode.

In FIGS. 3 to 6, the same components as those in FIGS. 1 and 2 are designated by the same reference numerals, and the explanation thereof will be omitted. In FIG. 3, the field lens 4 and the auxiliary lens 11 are held in the same lens barrel (not shown) and are designed to rotate around a point O on the upper left of the mirror 3. That is, when observing through the finder shown in FIGS. 5 and 6, the field lens 4 and the auxiliary lens 11 rotate clockwise around point O from the state shown in FIG.
It is inserted between the objective lens 1 and the mirror 5 on the optical axis.

In this way, by retracting the auxiliary lens 11 into the gap in the finder optical system, space efficiency is improved and the overall camera can be made more compact. In this numerical example, the reduction ratio of the auxiliary lens 11 is 0.5×, and the erecting lens 6 is
The imaging magnification is set at -0.7x. Also, in order to increase space efficiency, the optical path in the Royal Lens System is not bent at a right angle, but at 47 degrees. It is preferable that the angle Q formed by the optical axis be 35° and θ<6o0 (If it is smaller than 35°, the optical paths will overlap greatly and the light rays will be eclipsed by the royal lens, so it is not preferable.

Next, numerical examples of the present invention will be shown. In numerical examples,
f is the focal length, Da is the interval between principal points during normal photography, and Db is the interval between principal points during pseudo-telephotography.

Numerical Example Objective Lens 1 f=28.736 Da=9.254
Db=26.454 Auxiliary lens 11 f=19
．． 482 Da=9.741 Db=2.043 Field lens 4 f=17.581 Da=3
0.588 Db=30.588 erect lens 6 f
=12.595 Da=21.412 Db=21.
412 field lens 9 f=20.363
0a=16.5 Db=16.5 Eyepiece 10
f=16.5 Photographing in the pseudo-telephoto mode described above will be described below.

FIG. 7 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. 20 and 21 are light emitting diodes that imprint a trimming signal, which will be described later, between the perforations of the film 3. SWI.

SW2 is a switch that controls the light emitting state of the light emitting diodes 20 and 21, respectively. When photographing is performed in the standard state, the SWI is turned on, the light emitting diode 20 lights up, and only one dot image is imprinted at a predetermined position between the perforations of the film 3. When this negative film is placed on a specific enlarger after development, the enlarger detects this dot image, recognizes that the image was taken under the standard conditions of a pseudo-format camera, and crops the entire screen. (Enlarging.) Next, when shooting in a pseudo-telephoto state, both SWI and SW2 are turned on, light-emitting diodes 20 and 21 light up, and two dot images are imprinted at predetermined positions between the perforations of 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 cropping, and enlarges the image at a higher magnification than the standard state. (Thus, when shooting in a pseudo-telephoto state, a print with a larger magnification than that taken in a standard state can be obtained, achieving the desired purpose.

Furthermore, when the present invention is applied to a camera that switches the screen between full size and half size, the enlargement is performed to the same print size according to the screen size of the image without applying a trimming signal. In this case, 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 state with reference to FIGS. 1, 3, and 4, the light beam emitted from the objective lens 1 is bent by 90 degrees by the rotating mirror 2I tilted at 45 degrees with respect to the optical axis, and is guided to the film 3. Then, the shooting 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 poses a problem because subsequent printing can produce regular prints through processing. There isn't.

Furthermore, to explain the viewfinder observation state with reference to FIGS. 2, 5, and 6, first of all, in the case of normal photography, the rotating mirror 2 is retracted out of the optical path as described above, and the auxiliary lens 11 is
is inserted into the optical path. 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 then becomes an erect image by the mirrors 5, 7 and the erecting lens 6. field of view frame 8
The image is formed at the position of At this time, it is better to set the imaging magnification of the erecting lens 6 to be reduced to a value of -0.8x to -〇.25x and relayed on the field frame to make the finder system thinner and more compact. It is effective. Field of view frame 8
The image formed at the position is observed through the field lens 9 and the eyepiece lens 10. The reduction ratio of the auxiliary lens 11 is preferably in the range of 0.7x to 0.3x; if it is larger than 0.7x, the finder system will become large, and in order to make it smaller than O, aX, the power of the auxiliary lens 11 must be strengthened. This is not preferable because it becomes difficult to remove spherical aberration and astigmatism of the finder system.

Next, in the case of pseudo-telephoto shooting, although the focal length of the objective lens 1 is the same as in normal shooting, the objective lens 1b is on the object side and the auxiliary lens 11b is on the field lens 4 side, as shown in FIG. By moving to , you can change the magnification of the finder while keeping the finder diopter constant. Therefore, the telephoto effect can be visually confirmed when observing through the finder.

8 and 9 show a second embodiment of the present invention,
FIG. 8 shows a photographing state, and FIG. 9 shows a viewfinder observation state. According to this embodiment, the auxiliary lens 11a and the erecting lens 6 in the normal shooting mode are shown in FIG.
a are located close to the mirror 7 on the objective lens 1 side. On the other hand, in the pseudo-telephoto mode, the auxiliary lens llb moves toward the field lens 4, and the erecting lens 6b moves toward the mirror 5, making it easy to change the magnification of the finder. According to this configuration,
The objective lens 1, which is the heaviest in weight, is fixed, and only the auxiliary lens 11 and the erecting lens 6, which are lighter in weight, need to be moved, so the lens driving force is small, and the shock when moving the lens is small. There are advantages.

10 and 11 show a third embodiment of the present invention, in which FIG. 1O shows a photographing state and FIG. 11 shows a viewfinder observation state. According to this embodiment, the eleventh
In the figure, when the auxiliary lens in the normal shooting mode is 11a, the field frame is 8a, and the eyepiece is 10a, in the pseudo-telephoto mode, the field frame 8b and the eyepiece 10b are moved in the direction in which the auxiliary lens 11b approaches the field lens 4. They are adapted to move in the direction of the optical axis away from the field lens 9 (to the right in FIG. 11), and the finder magnification can be changed while keeping the diopter constant. According to this configuration, as in the second embodiment, the objective lens l, which has the largest weight, is fixed, and the auxiliary lenses 11. Since it is only necessary to move the field frame 8 and the eyepiece lens 10, the lens driving force can be small. Another advantage is that there is less shock when moving the lens. or,
The eyepiece 1O is located at the outermost part of the camera body C and is very small.
It is easy and most efficient to dispose the mechanism for moving 0 inside the camera body C.

FIGS. 12 and 13 show a fourth embodiment of the present invention, with FIG. 12 showing a photographing state and FIG. 13 showing a finder observing state, respectively. According to this embodiment, an erect image is obtained using the prism 12 and the prism 13 without using the above-mentioned erecting lens or a plurality of mirrors.

Incidentally, the prism 12 and the prism 13 are disposed in a space behind the rotating mirror 2 so as not to prevent rotation of the rotating mirror 2 when the rotating mirror 2 rotates. moreover,
14 is a mask placed in front of the prism 12.

In FIG. 13, the objective lens la and the auxiliary lens 11a, which are close to each other in the normal shooting mode, move in the opposite direction along the optical axis in the pseudo-telephoto mode, and the objective lens lb
, the auxiliary lens Ilb can be moved to positions separated from each other to change the magnification of the finder. According to this embodiment, the photographing optical axis and the finder optical axis can be set coaxially, which is effective in reducing the size of the camera body C. Incidentally, the finder magnification can be set higher in a finder that uses a royal lens to obtain secondary imaging as in the above embodiment than in the case of using a prism as described above.

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 zoom in on a part of the screen for accurate focusing, or to obtain a telescope effect. used for.

Further, although detailed explanation has been omitted, it goes without saying that each embodiment is configured such that the position of each lens changes 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. Furthermore, a focusing plate may be provided in the optical path.

Unlike the above embodiment, the auxiliary lens is composed of a plurality of lens groups, and the auxiliary lens is inserted into the optical path of the objective lens during viewfinder observation, and when switched to pseudo-telephoto mode, the optical axis direction is different. By moving the lens with the light beam, it is possible to change the magnification of the viewfinder while keeping the diopter constant. With such a configuration, a compact variable magnification finder can be realized.

〔Effect of the invention〕

As explained above, according to the present invention, when the optical system is switched to the viewfinder observation state, the auxiliary lens is inserted into the optical path of the objective lens, and by moving the auxiliary lens along the optical axis, the viewfinder Since the magnification is changed, the telephoto effect can be easily confirmed in 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 viewfinder field of view, according to the present invention, it is possible to obtain a continuous viewfinder field of view including the intermediate state of switching, Furthermore, the angle of view of the viewfinder is small (it does not become narrow), so it is extremely effective.

For example, in a camera equipped with both a zoom lens and a pseudo format function, the zoom ratio is 2X.

Assuming 1/2 cropping is done with a pseudo-telephoto lens, 4x magnification is required on the viewfinder, which is undesirable as it increases the size of the lens if you try to check the telephoto effect using an external viewfinder. In contrast, according to the present invention, it is possible to easily realize a single-lens reflex camera equipped with a so-called TTL type compact variable magnification finder.

[Brief explanation of drawings]

1 to 6 show a first embodiment of the present invention,
Figures 1 and 3 are top views of the camera when photographing, Figures 2, 5, and 6 are top views of the camera when observing through the finder, and Figure 4 is a top view of the camera when observing through the finder. 3 is a perspective view of A in FIG. 3, FIG. 7 is a perspective view showing the film and trimming signal recording section of a pseudo-format camera, and FIGS. 8 and 9 show a second embodiment of the present invention. The figure is a plan view when photographing, FIG. 9 is a plan view when observing through the finder, FIGS. 10 and 11 show a third embodiment of the present invention, and FIG. Figure 11 is a plan view when observing through the finder, Figures 12 and 13 show a fourth embodiment of the present invention, Figure 12 is a plan view when photographing, and Figure 13 is a plan view when observing through the finder. It is. l ・・・・・・・・・・・・・・・Objective lens 2・
・・・・・・・・・・・・Rotating mirror 3・・・・
・・・・・・・・・・・・Film 10・・・・・・
・・・・・・・・・Eyepiece 11 ・・・・・・・・・
・・・・・・・・・Auxiliary lens l

Claims (4)

[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 finder observation state, an auxiliary lens is inserted into the light flux of the objective lens, and the light flux of the objective lens is guided to both the shooting screen and the finder. A single-lens reflex camera characterized by changing the magnification of the finder by moving an auxiliary lens along the optical axis. (2) The single-lens reflex camera according to claim (1), further comprising means for changing the size of the photographic screen or means for instructing enlarged printing by trimming. (3) The single-lens reflex camera according to claim 1 or 2, wherein the objective lens and the auxiliary lens are moved in opposite directions along the optical axis to change the magnification. (4) A single-lens reflex camera according to claim (1) or (2), characterized in that the auxiliary lens and some lenses in the finder optical system are moved in the optical axis direction to change the magnification. .