JPS5833536B2 - High magnification focusing device for reflex cameras - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-magnification focus adjustment device for a reflex camera finder, and particularly to a high-magnification focusing device for a reflex camera finder. To provide a focus adjustment device that not only performs focusing but also reduces shading in a split image type distance measuring section and enables distance measurement of a dark photographic lens.

In a rangefinder camera, the finder's distance measurement ability is proportional to the effective baseline length, which is the product of its baseline length and image magnification, but in the case of a reflex camera, it is proportional to the focus detection ability of the focus plate itself and the eyepiece. The product of the magnification of the lens determines the ranging ability.

Focusing plates can be classified from the perspective of measurement functions: ground glass type, which detects the diameter of the light beam when it is out of focus as blur;
There are two main methods: a split image method or a method that uses a micro prism etc. to detect the amount of out-of-focus as the amount of image shake due to the prism, but the detection ability of both methods depends on the brightness of the photographing lens. There are limits to

In other words, the diameter of the bokeh is determined by the amount of out-of-focus
It is the value divided by the number, and the F number is currently Fl
, is limited to 4 to 1, and it is difficult to increase the distance measurement ability by increasing the blur itself.

When using a split image prism, etc., due to the refraction effect of the prism, the light flux that passes around the shooting lens is used for distance measurement. The base line length of the standard camera is long (it works the same as the standard camera, but in order to avoid shadows in the distance measurement image even when using interchangeable lenses of various brightness, it is necessary to increase the baseline length from 8 degrees to 100 degrees). The prism angle is the limit.

Therefore, efforts are made to increase the magnification of the eyepiece lens, but by securing a viewing angle to see the entire screen and interposing a pentaprism etc. between the screen and the screen, the image magnification when using a standard lens is The limit is 0.8 to 1.0, and the effective baseline length, which is the product of both, is the standard lens (50 mm
) When in use, it is only around 6 degrees, which is about one-eighth of the distance of around 5 degrees for a rangefinder camera (Photography Industry Magazine 197
108 pages of the January 9th issue, "Is it easy to focus with an R-eye reflex camera?")

In fact, it is well known that the distance measurement capabilities of current single-lens reflex cameras are not sufficient, and according to some test data, when shooting at F2, 50 out of 100 frames exceed the allowable depth of focus and are blurry. Even if you stop down and take pictures at F5.6 to F8, 5 out of 100 frames will still be out of focus. reliability").

Considering the current situation, even taking into account the fact that the split image type upper and lower separated images can be easily aligned, it is still necessary to dramatically improve the distance measurement capability by about 5 times. Minor improvements such as improving the magnification of the main eyepiece are completely insufficient, and there is no other way than to incorporate a high-magnification optical system dedicated to distance measurement separately from the main eyepiece.

One such high-magnification optical system dedicated to distance measurement is a method of incorporating a high-magnification optical system into a beam of light that is emitted obliquely to the main optical axis of the finder and is outside the main optical axis.
A method of installing a Galileo-type high-magnification eyepiece system on the side of the main eyepiece (Utility Model Publication 16865-1983),
There are methods such as entering a light beam from off the rear optical axis of a pentaprism into a real-image type high-magnification optical system and making it appear at the bottom of the screen (Utility Model Publication No. 1573-1981), but in these methods, split The reason is that it is difficult to use a focus plate such as an image, and it is limited to the ground glass type.
The position where the light flux on the optical axis entering the main eyepiece passes around the aperture of the photographing lens due to the action of a split prism, and the passage through the photographing lens of a high magnification optical system that uses the light flux in a direction diagonal to the optical axis. Since the positions are not the same, there is a drawback that shadows tend to appear in one of the images.

There is also a method of configuring a high magnification optical system on the main optical axis using variable magnification switching type, zoom type, insert type, etc. One example is a method of inserting a high magnification convex lens on top of a condenser lens ( Utility Model Publication No. 11749 (1974) and a method of constructing a real-image high-magnification finder by inserting a small prism between a pentaprism and the main eyepiece (Utility Model Publication No. 1572 (1972)) are known. In either case, it is necessary to switch between the main finder and the high-magnification optical system, resulting in a lack of quick-shooting performance when photographing moving objects.

In order to eliminate these drawbacks of the optical system, the present invention uses a high-magnification optical system that eliminates the need for operations such as manual switching, eliminates shadowing of the distance measurement image, and allows distance measurement even at the minimum aperture. This enables quick and accurate focusing.

In Fig. 1, 1 is a focusing plate, 2 is a distance measuring unit such as a split image or microrhythm provided in the center, 3 is a condenser lens, 4 is a pentaprism, and 5 is a focusing plate.
is the main eyepiece, which is the optical system of a normal reflex camera.

In the finder optical system of the present invention, the principal optical axis luminous flux is
The light is reflected by the concave mirror portion 5a on the rear surface of the inclined main eyepiece 5, passes through the front surface 4b of the pentaprism, the roof portion 4a, and exits from the bottom rear portion 4c of the pentaprism, and is reflected by the bottom field reflector of the small distance measuring prism 7. By forming an image with the same magnification as that of the distance measuring section 2 on 7a, and then totally reflecting it on the upper slope of 7 and enlarging it through the distance measuring eyepiece 8 or 8 and the main eyepiece 5, the image shown in FIG. Similarly, a high-magnification ranging image 9 is always displayed at the bottom of the main screen.

According to this configuration, the distance measuring light beam is reflected four times in the vertical direction, is inverted in the horizontal direction by the da... part 4a, and is also inverted 180° by the reflector lens 5c, so that it is completely correct in the up, down, left and right directions. A standing image is obtained, and as shown in the optical path development diagrams FIGS. The distance measurement image magnification is (12 = optical path length from the distance measurement section 2 to the principal point of the reflector lens 5c, from the principal point of 13-50 to the field reflector imaging section 7a). , the optical path length from '+=7a to the principal point of the ranging eyepiece system 8a), and in the design example, it becomes Accuracy is obtained.

Further, the distance measurement image magnification M2-5.18 indicates that when a standard lens is used, the distance measurement image functions as a telescope with a magnification of 5.18 times (51.6 x 5.18 = equivalent to a 267 mm telephoto lens).

In the optical path development diagram in Figure 4, the optical axis center 1 of the photographing lens
Among the light fluxes passing through the split prism 2, considering only the light flux passing above the split prism 2, the light flux is refracted by the prism 2 and deviates from the diameter of the pupil 60 as shown at 12a.

The distance-measuring light flux that enters the pupil passes through a location b away from the optical axis of the photographic lens 10, as shown by diagonal lines, and since the split prisms 2 are placed facing each other, 2b is the distance. Corresponds to the base line length of the total.

Therefore, when the photographic lens 10 is stopped down, the distance measuring light beam 12b
is blocked by the diaphragm 11, and the light beam in the shaded area that reaches the pupil 6 disappears, causing shadows in the split image area, making it difficult to make the base line length 2b sharp.

Currently 15.6-18th (baseline length 2 with 50mm standard lens)
b=7+m) is the limit that can be used for distance measurement.

On the other hand, in the optical system of the present invention, as seen in the optical path development diagram in FIG.
4 is short, an extremely large magnification can be obtained, and at the same time, the aperture angle α2 of the luminous flux entering the pupil is the same as in Fig. 4 (α1), so the main eyepiece 5, which functions as a reflecting mirror lens, is If the diameter of the distance measuring light flux is increased, the radius r2 of the light flux when it passes through the photographing lens 10 will be the relative magnification Ma to the radius r1 of the light flux in FIG.
The size is multiplied by (6, o 3 ).

Here, if r2≧b, the principal optical axis 12 is always within the diagonally lined rangefinding light flux, and even if the aperture 11 is set to the minimum aperture, the rangefinder light flux will not be completely blocked, and the split image image will be Focusing is possible by

As an example, when the angle of the split prism is 8 degrees, the refractive index is n -1.5, the diameter of the pupil is 3 mm, and the other values are the above values, the condition that the main optical axis is included in α2 is r2
=b, the minimum required relative magnification M4 to avoid shadowing
This shows that if the distance measurement image is 2.8 times or more larger than the main screen, there will be no shadowing even at the minimum aperture.
Therefore, in the case of M3=6.03, there is sufficient margin for shadowing, and the angle of the split prism can be increased by that margin.For example, the maximum value of b is 1) -=r2-7.77, but if we leave some margin and widen the baseline length to b=6.5, the angle of the split prism can be increased from 8° to 14°09', and the image separation is 1. It becomes 79 times larger and the image magnification M3=6.
The effective baseline length, which is the product of
．． Since it is 22vrm, the effective baseline length in this case is 6.
22X10.8=67.17mm).

, and regarding the shadow, in the case of FIG. 4, f/2b=7.
12, that is, approximately F7, whereas in this distance measurement image, distance measurement is possible even when the aperture is stopped down to F22.

The above advantages can be achieved in a distant manner by increasing the magnification of the distance-measuring image, which allows a wide beam of light to enter the pupil, but this itself also plays a role in brightening the distance-measuring image.
The higher the magnification, the better the distance measurement accuracy, shadows, and brightness.

In addition, in FIG. 1, FIG. 3, and FIG. 5, the main eyepiece lens 5 has a large aperture, the center portion 5b of the rear surface is a semi-transparent mirror, and the surrounding area 5a is a 100% reflective mirror surface. It constitutes a concave mirror lens.

In this case, the curvature of the concave mirror 5a is not limited by the focal length of the main eyepiece and can be freely set, and has the advantage that it can be used to correct aberrations using each component lens.

Regarding the reflectance of the semi-transparent mirror section in the center, it is not possible to rely entirely on the reflectance of this section in the case of 12a when the aperture is small, and it is not used often, and the split prism section is transparent. Because of this, there is no scattering like in the peripheral ground glass area, and since it is several steps darker, a reflectance of about 20% is sufficient, and the brightness of the main screen is not affected much.

As shown in FIG. 3, this concave mirror section 5a can prevent the main eyepiece from glaring by applying anti-reflection treatment to the pupil side of the peripheral total reflection mirror section 5a. When 5a is placed close to the pupil, the central semi-transparent mirror portion 5b
This has the effect of reducing the amount of light that enters the finder.

Furthermore, this concave reflecting mirror does not necessarily need to be placed in the position shown in FIG. 1; instead, the rear surface 4d of the pentaprism may be a concave mirror as shown in FIG. 7, or a concave mirror 5a may be placed before and after the main eyepiece 50 as shown in FIG. Or, as shown in Figure 6, the main eyepiece 5
It can also be placed diagonally inside.

11 Regarding the setting of the reflection angle, it is possible to tilt only the reflection surface as shown in Figure 6 without tilting the main eyepiece itself, or to utilize the refraction effect of lenses and prisms.
Since the distance measuring light beam has a large spread, it is no problem to shift the optical axis slightly above the optical axis of the main eyepiece 5 as shown in FIG.

Next, in FIGS. 1 and 5, the image on the imaging plane 7a is
It is magnified by the distance measuring eyepiece system 8a to create a high magnification distance measuring image at position 9 in FIG. 2 (M3=6.03).

If its size is 6 x 9 on the main screen, the necessary size of the field lens γa is IXl, which is only a small area of 5 mm, and the required dimension of the bottom rear part 4c of the pentaprism is extremely small. , the small prism T for distance measurement has also become smaller,
It fits almost the same size as the existing pentaprism.

Further, no restrictions are placed on the four-force Lefrein shutter shown by the side line A below it.

In addition, the outline of the high-magnification ranging image 9 is an enlarged view of the field reflector 7a, and since it is located in the imaged image, it can be made to appear at the bottom of the main screen as a clear field frame. Even if the shape of the ranging section 2 at the center of the main screen is circular, its shape can be any size such as a rectangle.

The position of this high-magnification ranging image does not matter where it is displayed as long as it is visible at the same time as the main screen, but it is generally easier to use the lower part of the main screen due to the characteristics of the eye.

As for the distance measuring eyepiece 8, there is no need for the light beam that has passed through it to pass through the main eyepiece 5 again as shown in FIG. There is no problem.

In addition, as shown in Fig. 7, the main eyepiece 5 and the distance measuring eyepiece 8
It is also possible to integrally form it from plastic.

FIG. 6 shows the concave mirror portion 5 of the main eyepiece 5 in FIG.
This is an example in which the distance measuring reflector optical axis 12b is shifted upward from the main screen optical axis 12 by placing the lens a on the bonding surface, and in order to give a deflection angle to the distance measuring optical axis 12b, a split image prism or By adding an angle perpendicularly to the deflection angle of the microprism, as in 2a, and tilting the distance measuring light beam forward, distance measurement can be performed using the light beam centered on the optical axis of the photographing lens. , prevents the appearance of shadows.

The image formed on the field lens 7b at the rear of the bottom of the pentaprism 4 is reflected three times in the small distance-measuring prism 7-1, passes through the triangular prism 7-2, and passes through the distance-measuring eyepiece 8 until it is completely erect. You can see the distance measurement image.

The pentaprism should not be changed (but it is possible, as it has reasonable characteristics due to its structure.

Figure 7 shows an example in which the rear surface 4d of the pentaprism is a concave mirror lens, and the distance measurement image is focused on the field reflector 1b provided at the rear of the focus plate, thereby achieving the simplest configuration. In addition, it is also possible to construct the distance measuring eyepiece integrally with the main eyepiece 5 from plastic as described above.

FIGS. 8 and 9 show an example of incorporating the pentaprism into an erecting optical system.

In FIG. 8, the main optical axis is reflected twice inside the lower prism 16, and then the light is emitted backward at 45°, and the roof portion 17
Two reflections in the upper prism 17 with a lead to the main eyepiece 5.

After the distance measuring light beam is reflected by 5a, it passes through the upper prism 17045.
It is totally reflected on the slope, and after reflection on the da... portion 17a, the front surface 17b, and the bottom portion 17c, an erect image is formed on the ranging field lens 7b.

This is magnified by the distance measuring eyepiece 8 and appears at the bottom of the main screen.

In the acoustic optical system, the upper prism 1T and after are integrated into 4
By rotating 1800 degrees around the 5° optical axis, the high-magnification distance measurement image can also be used as a chest-level finder.

FIG. 9 shows a prism installed in an erecting prism used in a type of camera in which the main eyepiece 5 is located far behind the focus plate 1, and the main optical axis is between the top surface 18b and the bottom surface 1 of the prism.
8c, the roof portion 18a, and the slope 18e to deliver a completely erect image to the main eyepiece lens 5.

The distance measuring light beam reflected by 5a is again transmitted to 18e and 18a.
, 18c , 18b , 18c .

18b, and after being reflected by the light exit surface 18d of the prism, an image is formed on the field reflector 7a of the small prism 7 attached to the lower part of 18e, and this is viewed through the distance measuring eyepiece 8. By effectively utilizing each reflective surface without processing the erecting prism itself, a high-magnification distance-measuring optical system has been completed with a small number of parts.

FIG. 10 is based on the idea of using the main eyepiece 5 instead of the distance-measuring eyepiece 8 shown in FIG. is reflected by the front upper part 4e of the pentaprism, the bottom and rear surfaces, the convex mirror lens 14 at the upper part of the front face, and the oblique plane 4f at the upper rear part of the pentaprism, and a high magnification ranging image is sent to the field reflector 1b at the rear of the focusing plate 1. tie.

Since this distance measurement image is a concave reflecting mirror 1b, when viewed through the pentaprism 4 and the main eyepiece 5, the high magnification distance measurement image can be seen simultaneously on the main screen and below it, as in Figure 2. I can do it.

In the case of FIG. 1, the roof section 4a of the pentaprism is used to erect the distance measurement image left and right, but in the case of FIG. This is no longer necessary because the light passes through the roof part of the pentaprism in between.

1b is not limited to the focus plate, and may be provided at the bottom of a condenser lens or pentaprism.

In this case, the main eyepiece 5, which has a long focal length, is used instead of the distance measuring eyepiece 8, so it cannot be expected that the main eyepiece will enlarge the image.

Therefore, it is necessary to have a sufficient magnification on the imaging section 1b, but by increasing the optical path length by a large number of round trip reflections inside the pentaprism 4 and by introducing a convex mirror lens 14, it is possible to obtain a telephoto image. A large magnification can be obtained by configuring an optical system.

FIG. 12 is a developed view of the distance measuring light beam optical path in FIG. 10.

The distance measuring light beam forms an image on the focal plane 2 by the photographing lens 10.

Then, it passes through the pentaprism 4, passes through the reflector lens system 5c provided in the main eyepiece 5, and the convex mirror reflector lens 14 located at a distance of 15 mm, and reaches the field reflector section 1b separated by 16 mm. The light enters the pupil 6 through the main eyepiece 5.

Here, the relative magnification M5 of the distance measurement image with respect to the main screen when the convex mirror reflecting lens 14 is not used is the principal point of the reflecting mirror lens system 5c when the convex mirror reflecting lens 14 is then inserted to form a telephoto optical system. When the telephoto lens 15 is moved to the position of the lens 15, the relative magnification M3 of the distance measurement image can be enlarged, and this can be freely set depending on the arrangement of the powers of the telephoto lens systems 5c and 14.

- For example, this means that with telephoto optics the magnification is 1
．． This shows that the increase is from 90 to 5.00 times, which is very effective.

As described above, this method has the advantage of being strong with a small number of components and being very easy to see because the high magnification distance measurement image is formed on the same plane as the main screen.

Furthermore, since no parts are interposed between the condenser lens and the pentaprism, there is no problem when using the finder as a prism exchange type.

In FIG. 11, the distance-measuring light beam reflected by the reflecting mirror lens 5a is divided into the front upper part of the pentaprism 4e, the bottom surface of the pentaprism, the rear surface of the pentaprism, the bottom surface of the pentaprism, the rear surface of the pentaprism, the bottom surface of the pentaprism, the rear surface of the pentaprism, the upper part of the rear surface of the prism, and the front surface of the pentaprism as shown in FIG.
After repeated reflections, the image emerges from the bottom rear part 4c, forms an enlarged image on the bottom of the small ranging prism 7 and the same field of view reflector imaging section 7a, and then - after being reflected from the bottom of the upper slope, the rear part 4c
The light enters obliquely and vertically, and reaches the pupil via the pentaprism 4 and the main eyepiece 5, similar to the main screen.

With such a configuration, the optical path length of the ranging light beam inside the pentaprism becomes extremely long, and in the design example, a relative magnification of 3.6 times with respect to the main screen (M3) is obtained, making a telephoto optical system necessary. However, if the convex reflecting mirror 14 in FIG. 10 is placed at the 4f position, M3=8 is possible.

Note that since the small prism 7 is located on the image forming plane, the accuracy of the reflecting surface has little influence on the image (and can be manufactured at low cost because it is made of plastic.

FIG. 13 shows a method of forming a high-magnification distance measurement image using a virtual image method, in which the distance measurement light beam reflected by the reflector lens 5a is reflected at the front upper part 4e of the pentagonal prism, and then reflected at the 40-degree angle at the rear of the bottom surface of the pentaprism.
It enters the small prism 7 for distance measurement, is reflected twice, passes through the eyepiece lens 8 for distance measurement, and reaches the pupil.The reflector lens 5a and the negative eyepiece lens 8 for distance measurement Configure a telescope and enlarge the distance measurement image.

Compared to the real image system shown in FIG. 1, although the field frame is not clear, there is no need to invert the distance measuring light beam left and right at the roof, there is no need for a field reflector, and the structure is simple.

FIG. 14 shows an optical path development diagram in the case of FIG. 13, and if the focal length f--10 mrn of the distance-measuring eyepiece system 8a is used, a relative magnification of about M3-5 can be obtained.

FIG. 15 is a simplified version of FIG. 13, and a Galilean telescope is configured by a reflecting mirror lens 5a and a convex mirror lens 14 arranged at the lower front of the pentaprism, and the distance measurement image is magnified.

The distance-measuring light flux that enters the pupil from the convex mirror lens 14 does not necessarily have to pass through the main eyepiece 5 (although it may be allowed to enter the pupil directly through the lower part of the main eyepiece lens 5), by which higher magnification can be obtained.

In FIG. 16, as in FIG. 15, a convex reflector 14 with weak power is placed at the lower front of the pentaprism, and a negative distance measuring eyepiece 8 is placed between the pentaprism and the main eyepiece 50. , which has the advantage of increasing the telephoto effect.

To summarize the effects of incorporating the focus adjustment device of the present invention, (1) The high magnification image for distance measurement is always visible at the bottom of the main screen,
You can achieve high-precision focusing simply by moving your line of sight without taking your eyes off the viewfinder screen.

Unlike commercially available magnifiers, there is no need to install or remove it, and it is especially effective for focusing when shooting hand-held.

(2) An extremely high magnification of the distance measurement image, 3 to 10 times that of the main screen, can be obtained.

(3) A high-magnification distance measurement image can be measured without any problem even if the number of photographing lenses is set to the minimum number.

(4) Since the high-magnification distance measurement image is less likely to be obscured, the degree of image separation by the split prism or microprism can be increased.

Combined with high magnification, the effective baseline length is dramatically expanded.

(5) The distance measurement image is bright.

This is because the outer diameter of the reflecting mirror lens is large (the opening of the light beam entering the pupil is dog-shaped), and the reflecting lens is close to the pupil, so the central semi-transparent mirror portion can be made small.

In addition, since the light flux used for distance measurement passes through the split prism part, the light flux is not scattered like it would be on a ground glass surface, and the image is naturally much brighter than the surrounding image.

(6) The field of view is clear.

The high magnification distance measurement image is an enlarged image of the field reflector imaging area, and stands out as a clear outline in the dark area at the bottom of the main screen.

Its shape can be any shape regardless of the shape of the distance measuring section 2.

(7) Effective as a portable telescope.

When using a camera, such as when traveling, a telescope is often required, and its incorporation has great utility value.

In particular, being able to see the entire image on the main screen while also seeing an enlarged central image at the bottom makes it easier to follow the image, making it more convenient than binoculars for viewing various sports and horse races. It can also be used as an astronomical telescope by replacing it with something like this.

(8) There is no problem even if the pentaprism and focusing glass are interchangeable.

This is because the optical system for distance measurement was completed after the pentaprism, so the focus plate and condenser lens are unrelated to the pentaprism.

(9) A high-magnification ranging image can be used in the chest-level finder.

Normally, a magnifier cannot be attached to a right-angle angle finder, but this finder has a high-magnification distance measurement image as part of the screen.
A right-angle angle finder can also be used when high-precision focusing is required, such as for close-up photography or copying.

(10) Since a reflector lens is used to condense the light beam for distance measurement, it is possible to compact a lens with a large aperture, short focal length, and little chromatic aberration, and it can be used in combination with the main eyepiece. It can be made cheaper.

(11) The distance measuring optical system hardly protrudes below the bottom surface of the pentaprism, and there is no dimensional restriction on the focal plane shutter which occupies the rear part of the reticle, making it easy to incorporate.

α Since there are few optical parts and it is a solid fixed type, it is less likely to go awry due to shocks etc.

(L3) In order to make the distance measurement image a completely erect image, the image is rotated 1800 degrees by the imaging lens, or left/right reversal by the roof section is effectively used, and a roof prism is not particularly required as the distance measurement optical system. Therefore, the overall cost is low.

(14) Since the imaging reflector lens 5a is placed close to the pupil, the area of the central semi-transparent mirror portion 5b is small;
There is little effect on photometric elements etc. due to reverse incident light.

(15) As shown in Figure 6, by overlapping the deflection prism 2a on the split prism part, shadows can be reduced even when the optical axis of the ranging optical system is placed outside the main optical axis. I can do it.

116) Warn about camera shake.

This means that even if the camera moves slightly or the subject does not move, on the viewfinder screen that is close to life-size with a standard lens,
You won't notice camera shake because the field of view frame appears to be moving, but with this finder, the high-magnification distance measurement image moves violently compared to the stationary main screen, similar to when using a super telephoto lens, so there is a camera pre-warning. It functions as a device, and as a result of careful photography, it combines with improved focusing accuracy to produce sharp photos with less blur.

(17) When the distance measurement image is magnified at a high magnification, the separation of the distance measurement image such as a split image or a micro prism increases, but this is not only to solve the out-of-focus problem of improving distance measurement accuracy, but also to actually improve the distance measurement accuracy. When used, the matching speed of the separated image with respect to the rotation angle of the helicoid becomes several times faster, which has the psychological effect of allowing the user to focus more quickly, without tiring the nerves.

This usability is experienced in the ease of focusing in a rangefinder camera with a long effective baseline length.

With a reflex camera, when using a wide-angle lens, the pitch of the helicoid is so loose that it feels like it is difficult to focus, and when using a telephoto lens, the matching speed is fast (this is the same effect as making it easier to use).

[Brief explanation of drawings]

1 and 7 are cross-sectional views of the optical system when a type using a distance-measuring eyepiece is applied to a pentaprism among the real image systems according to an embodiment of the present invention, and FIG. 2 is a viewfinder field diagram; FIG. 3 is a reflection view of the eyepiece part, FIGS. 4 and 5 are optical path development diagrams in the embodiment of FIG. 1, and FIG.
Figures 6-A and 6-A are cross-sectional views of the optical system when a type using a distance-measuring eyepiece is applied to a pentaprism, and Figures 8 and 9 are enlarged views of the same. Figures 10 and 11 are cross-sectional views of the optical system when a high-magnification optical system is incorporated into another erecting prism, and Figures 10 and 11 show a method using the main eyepiece instead of the distance-measuring eyepiece in the East real image method. Optical system cross-sectional view, Figure 11-A is the 11th
12 is a developed optical path diagram in the embodiment shown in FIG. 10, FIG. 13 is a sectional view of the optical system in the virtual image method, and FIG. 14 is a developed optical path diagram in FIG. 15 and 16 are cross-sectional views of the optical system in the virtual image method.

Claims (1)

[Scope of Claims] 1. A reflective lens having a semi-transparent part in the center is installed on the exit surface of an erecting prism of a reflex camera, or on the main eyepiece, or on the optical axis light beam of the photographing lens in front and behind it. , the reflective mirror lens is inclined with respect to the optical axis so that the light beam reflected by the reflective mirror lens repeatedly reflects within the erecting prism and then reaches near the lower part of the main screen of the finder; A magnifying optical system is installed in the reflected light beam to reach the pupil, and the magnified image for distance measurement is constantly observed within the same field of view as the main screen. By making the optical axis light flux of the lens large enough to condense the light flux deflected by the split prism, the magnified image for distance measurement is not obscured even when the aperture of the photographic lens is narrowed down. High magnification focusing device for reflex cameras. 2. In the device according to claim 1, in the distance measuring optical system in which the optical axis of the reflecting mirror lens is arranged outside the optical axis of the eyepiece, the split prism or the micro prism A high magnification focusing device for a reflex camera, characterized in that a declination angle is added to so that the light beam for distance measurement is directed toward the center of the optical axis of the reflecting mirror lens. 3. In the apparatus according to claim 1 or 2, the distance measuring light beam is reflected back and forth within the erecting prism by the reflecting mirror lens, and is reflected on the roof surface at least once, and High magnification for a reflex camera, characterized in that a distance measurement image is re-formed near the lens, and the image is observed as a completely erect magnified image through a distance measurement eyepiece placed below the eyepiece. Focusing device. 4. In the device according to claim 1 or 2, the distance measuring light beam is reflected back and forth within the erecting prism by the reflecting mirror lens, so that the optical path length from the focus plate to the reflecting mirror lens is Obtaining an optical path length of 100cm, forming a high magnification image in substantially the same plane as the main screen, and observing this again as a completely erect magnified image through the erecting prism and the main eyepiece. A high-magnification focusing device for reflex cameras featuring: 5. In the device according to claim 4, a convex mirror reflecting lens or a concave lens is disposed in the middle of the distance measuring optical path from the reflecting mirror lens to the same plane, so that the principal point of the reflecting mirror lens is A high-magnification focusing device for a reflex camera, which moves toward the screen side and magnifies the magnified distance-measuring image at a higher magnification. 6. In the device according to claim 1 or 2, after the distance measuring light beam is reflected back and forth within the erecting prism by the reflecting mirror lens, it is emitted from near the bottom of the main eyepiece of the erecting prism. For a reflex camera, the lens is guided to the pupil, and a convex mirror reflecting lens or a concave lens is used in the middle of the distance measuring optical path to construct a Galileo-type high magnification optical system to obtain a fully erect magnified image for distance measuring. High magnification focusing device.