JPH07287174A - Portable binoculars - Google Patents

Abstract

PURPOSE:To obtain a structure of portable binoculars capable of selecting CONSTITUTION:An objective 3 is mounted on an external frame 1 and an power and used according to circumstances. ocular 4 is mounted on an internal frame 2. The internal frame 2 can be extracted while inserted into the external frame 1. The external frame 1 has stop recessed parts 14c, 14d, 14e, 14f, 15c, 15d, 15e, and 15f, and a deflection engagement body 40 formed on the external frame 2 engages them. By this engagement, a state (1) wherein the internal frame 2 is fully stored in the external frame 1, a state (b) wherein the internal frame 2 is fully extracted, a state (c) wherein the internal frame 2 is at an intermediate drawn-out position, and a state (d) wherein the internal frame is at another intermediate drawn-out position are prescribed. The ocular 4 is replaced with other ocular having different focal length and images are formed in the respective states (b)-(d).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to portable binoculars, and in particular, an inner frame is housed inside an outer frame when carrying, and an inner frame is pulled out from the outer frame to secure an optical axis distance when used. And the structure of the binoculars.

[0002]

2. Description of the Related Art Conventional binoculars include an erecting optical system using a roof prism and a Porro prism, and a Galilean optical system using no prism or the like. The former is relatively large and expensive and has a high magnification, while the latter is so-called opera glass, which has a low magnification of about 2 to 3 times and is often inexpensive and has good portability. As the former binoculars, some zoom binoculars that can change the magnification have been commercialized, but the latter low-powered portable binoculars that can change the magnification have not been manufactured.

[0003]

In an ordinary person using binoculars, a case in which 2 to 3 times the opera glasses is sufficient is sufficient, and a case in which the magnification is slightly increased to 5 to 7 times.
Most of the time, it is used twice. Magnifications higher than this are very difficult to use because they narrow the field of view, and even with the zoom type, the high magnification obtained with the zoom type is often unnecessary. Magnification can be made variable with binoculars that employ the erecting optical system described above, but the magnification itself is too high, or the use of a zoom type makes it more expensive. On the other hand, when the zoom type is adopted in the Galileo type binoculars, there is a problem that the manufacturing cost increases, the product becomes large, and the portability deteriorates.
Therefore, the present invention has been made in view of the above problems, and an object thereof is to obtain binoculars capable of selecting a magnification suitable for a use situation and not impairing portability.

[0004]

The present invention has an outer frame equipped with either one of an objective lens and an eyepiece, and an inner frame equipped with the other of the objective lens and the eyepiece. A pair of portable binoculars that can be pulled out in the optical axis direction of the lens while they are inserted into each other, and at least one of the objective lens and the eyepiece can be replaced with another alternative lens having a different focal length. A flexible structure is provided.

In this case, it is desirable that the outer frame and the inner frame are configured to be detachable from each other, and a substitute frame having a substitute lens replaceable with at least one of the outer frame and the inner frame is provided.

Further, a plurality of image forming positions corresponding to the combination of the objective lens and the eyepiece lens are set according to the combination with the alternative lens, and the drawing positions of the outer frame and the inner frame are made to correspond to the plurality of image forming positions. It is preferable to provide a holding structure configured to hold the at a plurality of positions.

Further, a plurality of image forming positions corresponding to the combination of the objective lens and the eyepiece lens are set according to the combination with the alternative lens, and the drawing positions of the outer frame and the inner frame are made to correspond to the plurality of image forming positions. It is preferable to provide a position display configured to display at a plurality of locations.

Further, a plurality of image forming positions corresponding to the combination of the objective lens and the eyepiece lens are set according to the combination with the alternative lens, and the outer frame to the inner frame are maximized in the plurality of image forming positions. It is preferable to include an imaging position corresponding to the pulled out state.

Further, a plurality of image forming positions corresponding to the combination of the objective lens and the eyepiece lens are set according to the combination with the alternative lens, and the inner frame is maximized in the outer frame in the plurality of image forming positions. It is preferable to include an imaging position corresponding to the inserted state.

[0010]

According to the present invention, at least one of the objective lens and the eyepiece lens can be replaced with an alternative lens having a different focal length, and the outer frame and the inner frame can be pulled out when the focal position changes due to the change in magnification. Since it can be dealt with by changing the amount, it is possible to change the magnification appropriately according to the use situation.

In this case, the objects to be replaced are the outer frame or the inner frame, the focus adjusting moving frame incorporating the eyepiece, the eyepiece lens barrel, and the eyepiece. There is a case where only the lens or only the objective lens is replaced. In addition to the structure described in claim 2, the detachable structure may have a structure in which either the outer frame or the inner frame can be opened and closed, and the internal lens can be taken out. In particular, when the inner frame has a structure that can be opened and closed, a plurality of parts divided by a dividing surface along the pulling direction so that the inner frame can be opened and closed only when the outer frame and the inner frame are separated. It is preferable to form the inner frame with.

According to the second aspect, since the outer frame and the inner frame can be detachably configured and each outer frame or inner frame can be replaced with a substitute frame, detailed work is not required and the replacement work is easy. become.

According to the third aspect of the present invention, since the holding structure capable of holding at a plurality of positions corresponding to a plurality of image forming positions generated in response to the replacement of the alternative lens is provided, the pull-out according to the magnification of the mounted lens is provided. The positions can be easily obtained, and it is possible to prevent the adjustment of the positions of the outer frame and the inner frame from being time-consuming.

According to the fourth aspect, since the position display is provided to display a plurality of positions corresponding to a plurality of image forming positions generated in response to the replacement of the alternative lens, the pull-out position corresponding to the magnification of the mounted lens is provided. Can be easily obtained, and it is possible to prevent the adjustment of the positions of the outer frame and the inner frame from being time-consuming.

According to the fifth aspect, the plurality of image forming positions include an image forming position corresponding to a state where the inner frame is pulled out from the outer frame to the maximum. On the other hand, the size of the binoculars can be efficiently used, and it is possible to improve both the selection range of magnification and the downsizing of the binoculars.

According to the sixth aspect of the present invention, the plurality of image forming positions include the image forming positions corresponding to the state where the inner frame is maximally accommodated in the outer frame. Since it is possible to reduce the number of intermediate positions of the pull-out position among the pull-out positions, the positioning operation of the pull-out position can be easily performed.

In the above holding structure, an elastic engaging claw portion may be provided on one of the outer frame and the inner frame, and an engaging concave portion that can be fitted into the engaging claw portion may be provided on the other.
In this case, by providing at least one of the engaging claw portion and the engaging concave portion at a plurality of positions corresponding to a plurality of image forming positions, it is possible to perform positioning according to the magnification.

Further, although the image forming position changes according to the magnification, it is possible to make a plurality of magnifications correspond to one image forming position by using a combination lens. Since the number can be reduced or unified, the positioning operation can be performed more easily.

[0019]

Embodiments of the portable binoculars according to the present invention will now be described with reference to the drawings. As shown in FIGS. 1A and 1B, in this embodiment, an outer frame 1 on which an objective lens 3 is mounted,
The inner frame 2 is roughly configured from an inner frame 2 on which an eyepiece lens 4 is mounted, and the inner frame 2 is fitted inside the outer frame 1. When not in use, the inner frame 2 is almost completely housed in the outer frame 1 as shown in FIG. 1 (a) to enhance portability, and when not in use, the inner frame 2 is replaced with the outer frame 1 as shown in FIG. 1 (b). The optical axis distance is secured by pulling it out from.

The outer frame 1 and the inner frame 2 are, as shown in FIG.
Each is composed of a pair of upper and lower resin products. The outer frame 1 includes an outer frame half 1a and an outer frame half 1b, and the outer frame half 1a has the same shape as the outer frame half 1b. The inner frame 2 includes an inner frame half 2a and an inner frame half 2b, and the inner frame half 2a has the same shape as the inner frame half 2b. Figure 2
As shown in FIG. 3, a resin-made objective lens 3 in which left and right lens portions are integrally molded is inserted into the housing portion 10 of the outer frame 1. Outer frame halves 1a, 1b, inner frame halves 2a, 2b
Is the contact surface 1 of the wall surfaces 14 and 24 that contact each other.
4a, 24a and contact surfaces 16a, 2 of wall surfaces 16, 26
The left side portion on 6a is provided with a ridge or a protruding shaft,
A groove or hole is provided on the contact surfaces 15a, 25a on the surface 25 and on the right side of the contact surfaces 16a, 26a on the wall surfaces 16, 26. Therefore, the outer frame halves 1a and 1b and the inner frame halves 2a and 2b can be assembled by lightly press-fitting the ridges and the grooves, and the protruding shafts and the recesses, respectively.

Inside the inner frame 2, a lens moving frame 34, on which the left and right eyepieces 4 are integrally mounted, is arranged so that the eyepieces 4 face the rear opening 20. The lens moving frame 34 is an adjustment wheel 3 rotatably accommodated in the inner frame.
It is connected to 0. The adjusting wheel 30 is configured to be exposed from the upper and lower openings of the inner frame 2, and includes an outer peripheral portion 31 in which knurls are engraved on the surface thereof, and a tubular shaft portion 32 formed in the center. A screw is engraved on the inner peripheral surface of the tubular shaft portion 32, and the drive shaft 33 fixed to the lens moving frame 34 is screwed into the screw. When the adjusting wheel 30 is rotated from the outside, the entire lens moving frame 34 moves back and forth via the drive shaft 33.

The inner frame 2 is integrally formed with a bending engagement body 40 extending forward from the inner side surface on the front side thereof, and the tip end portion 40a of the bending engagement body 40 is bent sideways on the way. , Is projected to the outside through an opening 41 formed in the inner frame 2. The tip portion 40a is adapted to move with the front-back movement of the inner frame 2 while being engaged with the engagement guide surfaces 14b and 15b formed on the inner surface of the outer frame 1. The engagement guide surfaces 14b and 15b have stop recesses 14c and 14d,
14e, 14f, 15c, 15d, 15e, 15f are formed, and the tip end portion 40a of the bending engagement body 40 is formed in the stop recess.
The inner frame 2 is held at a predetermined position by being fitted.

The bending engagement body 40 of the inner frame 2 is engaged with the engagement guide surfaces 14b and 15b of the outer frame 1 with a light force, and when the inner frame 2 is slightly moved back and forth with respect to the outer frame 1, Bending engagement body 4
0 easily gets over the stop recesses on the engagement guide surfaces 14b, 15b. However, as shown in FIG. 3, the stop recesses 14c,
Since 15c has a stop surface S in the pull-out direction of the inner frame 2, the inner frame 2 cannot be detached from the outer frame 1 unless the inner frame 2 is pulled out with a relatively large force. On the other hand, on the side surface portion of the outer frame 1 on the opening side, inclined surfaces 17 and 17 following the engagement guide surfaces 14b and 15b are formed, and the inner frame 2 once removed or a different focal length as described later is provided. Outer frame 1 with another inner frame equipped with an eyepiece
In the case of insertion into, the bending engagement body 40 is pushed inward along the inclined surface 17, so that the outer frame 1 and the inner frame 2 can be inserted and fitted very easily.

On the premise of the portable binoculars having the basic structure as described above, a specific example of the structure of the embodiment will be shown below. Figure 4
Shows an optical system of Example 1 according to the present invention. In the first embodiment, as shown in FIG. 4A, a combined lens including a lens L1 and a lens L2 is used as the objective lens 3, and a concave lens L7 is used as the eyepiece lens 4, so that the total magnification is 7 times. You are getting a magnification. here,
The focal length of the objective lens 3 including the lenses L1 and L2 is 1
25 mm, and the focal length of the eyepiece lens 4 is 17.9 mm. The distance P7 between the principal point of the objective lens 3 and the principal point of the eyepiece lens 4 is 107.1 mm. The position of the image side focus of the objective lens 3 and the position of the image side focus of the eyepiece lens 4 match.

This combination of the objective lens 3 and the eyepiece lens 4 having a magnification of 7 times is used as a basic structure, and further, as an eyepiece lens 4 for replacement, a concave lens L5 shown in FIG.
A concave lens L3 shown in FIG. 4 (c) is prepared. The concave lens L5 has a focal length of 25 mm, and a combination with the objective lens 3 provides a magnification of 5 times. In this case, the distance P5 between the principal point of the objective lens 3 and the principal point of the eyepiece lens 4
Is 100 mm. The focal length of the concave lens L3 is 41.7 mm, and a combination with the objective lens 3 provides a magnification of 3 times. In this case, the distance P3 between the principal point of the objective lens 3 and the principal point of the eyepiece lens 4 is 83.3 m.
m.

Such a binocular set has the following modes. First, inner frames 2-5, 2-in which concave lenses L5, L3 as replacement eyepieces are incorporated in advance
This is the case where 3 is prepared. In this case, the inner frame 2 is strongly pulled out and removed from the outer frame 1, and the inner frames 2-5, 2-for replacement are replaced.
By pushing in 3, the exchange of the inner frame is completed easily. Here, the inner frame 2 accommodating the basic concave lens L7
Then, as shown in FIG. 1 (b), the bending engagement body 40 is used in a state in which the tip end portion 40a is fitted into the stop recesses 14c and 15c. In addition, when the inner frame 2-5 is replaced, FIG.
As shown in (c), the inner frame 2 is formed in the stop recesses 14e and 15e.
When it is replaced with -3, as shown in FIG. 1 (d), the bent engaging bodies 40 are fitted into the stop recesses 14f and 15f for use. Here, the stop recesses 14c, 15c, 14
The positions of e, 15e, 14f, and 15f are the distance P between the principal points.
7, P5 and P3 are provided respectively, and by holding the pulling-out amount of the inner frame by the respective stop recesses, it is possible to obtain a magnified view field in which the focus is matched.

In this case, the maximum withdrawal position of the outer frame 1 and the inner frame 2 is the position shown in FIG. 1 (b) where the bending engagement body 40 is fitted in the stop recesses 14c, 15c, and this position is shown in FIG. The size of the binoculars can be efficiently used by associating the image forming positions with the largest distance between the principal points among the image forming positions at the plurality of magnifications. In other words, it is possible to obtain a high magnification, and at the same time, it is possible to achieve the maximum miniaturization within that range. Although different from the present embodiment, FIG.
By associating the maximum storage position of the outer frame 1 and the inner frame 2 shown in (a) with the imaging position where the distance between the principal points is the minimum,
It is possible to reduce the number of intermediate pull-out positions that require positioning work.

As the binoculars set, there may be a case where only the lens moving frame 34 with the concave lenses L7, L5 and L3 attached thereto is prepared. In this case, the inner frame 2 is set in a fitted state without adhering the inner frame halves 2a and 2b, and after the inner frame 2 is removed from the outer frame 1, the inner frame half 2a and the inner frame half 2b are separated. Then, only the lens moving frame 34 is replaced. Here, since the inner frame 2 is divided along the inserting direction and is usually inserted into the outer frame 1, even if it is assembled only in the fitted state, it will not be disassembled during use. .

Further, in this case, only the lens barrel of the eyepiece lens 4 may be replaced. Here, the concave lenses L7, L
A lens barrel to which 5 and L3 are attached is prepared, and at the time of replacement, the lens moving frame 34 is taken out and only the left and right lens barrels are replaced. The mounting structure of the lens barrel of the eyepiece 4 with respect to the lens moving frame 34 employs a combination of a radially elastically deformable pawl and an engaging portion that engages with the pawl, screwing, or light press-fitting. Can be done.

Further, only the eyepiece lens 4 may be replaced. Here, the concave lenses L7, L5, L3 are prepared respectively, and at the time of replacement, the lens moving frame 34 is taken out and the concave lenses mounted on the left and right lens barrels are replaced. The concave lens attachment structure to the lens barrel can be configured, for example, such that the concave lens is housed in a concave portion formed in the lens barrel, and a lens pressing member that is fixed to the lens barrel by screwing or press fitting is covered from above. .

Next, a second embodiment according to the present invention will be described with reference to FIG. In the second embodiment, the eyepiece lens 4 is a common concave lens L7 and the focal length of the objective lens 3 is changed. The objective lens 3 is basically composed of the lenses L1 and L2 shown in FIG. 5A, but as an interchangeable lens, a lens L1 having a focal length of 89.5 mm is used.
5 and L25, and focal length 53.7m
A lens group consisting of m lenses L13 and L23 is prepared. The combined lens including the lenses L15 and L25 is combined with the concave lens L7 serving as the eyepiece lens 4 to realize a magnification of 5 times. In this case, the distance P55 between the principal points of the objective lens 3 and the eyepiece lens is 71.6 mm. The combined lens composed of the lenses L13 and L23 is combined with the concave lens L7 to realize a magnification of 3 times. In this case, the distance P33 between the principal points of the objective lens 3 and the eyepiece lens is 35.8.
mm.

Such a binocular set includes the following modes. First, there is a case where the outer frames 1-5 and 1-3 in which the lenses L15 and L25 and L13 and L23 as the objective lenses for replacement are incorporated in advance are prepared. In this case, the inner frame 2 is strongly pulled out to be removed from the outer frame 1, and the outer frames 1-5 and 1-3 for replacement are pushed in, whereby the outer frame is easily replaced. Here, the basic lens L1
In the outer frame 1 accommodating L2 and L2, as shown in FIG.
Used in the state of being fitted to c. Further, when the outer frame 1-5 is replaced, as shown in FIG.
e and 15e, when the outer frame 1-3 is replaced,
As shown in (d), the bending engaging bodies 40 are fitted into the stop recesses 14f and 15f for use.

Here, the stop recesses 14c, 15c, 14
The positions of e, 15e, 14f, and 15f are the distance P between the principal points.
7, P55 and P33 are provided respectively, and by holding the pulling-out amount of the inner frame by the respective stop recesses, it is possible to obtain a magnified view field in which the focus is matched. In this case, although all the stop recesses shown in FIG. 1 may be provided in each of the outer frames 1, 1-5, 1-3 as described above, the stop recesses 14c, 15c, 14d, 15d are provided in the outer frame 1. Only the outer frame 1-5 has stop recesses 14d, 15d, 14e,
15e, and the stop recesses 14d, 15 on the outer frame 1-3.
By providing only d, 14f, and 15f, respectively, it is possible to define the relationship between the outer frame and the inner frame at the image forming position corresponding to each outer frame without selecting a plurality of positions.

In the binocular set, only the objective lens 3 may be replaced. In this case, the outer frame 1 is kept in a fitted state without adhering the outer frame halves 1a and 1b, and the inner frame 2
After removing from the outer frame 1, the outer frame half 1a and the outer frame half 1b are separated. Here, in addition to the lenses L1 and L2,
The lenses L15 and L25, the lenses L13 and L23 are prepared, and the housing portion 10 for the outer frame half 1a and the outer frame half 1b is prepared.
Replace the lens group inserted in. Then, the outer frame 1 is fitted and assembled, and the inner frame 2 is inserted into the outer frame 1.

Next, a third embodiment according to the present invention will be described with reference to FIG. In the third embodiment, as the objective lens 3, a combined lens including lenses L1 and L2 is commonly used. As in the first embodiment, the eyepiece lens 4 uses the concave lens L3 when the magnification is 3 times and the concave lens 5 when the magnification is 5 times. However, when the magnification is 7 times, the lens L7A is arranged near the concave lens L7B as the eyepiece lens 4. With this lens L7A, a magnification of 7 times can be obtained with an optical axis distance substantially similar to the case of the magnification of 5 times shown in FIG. Here, the lens L7A is the objective lens 3 including the lenses L1 and L2.
The focal length as a three-lens combination lens is 70
mm, the focal length of the eyepiece L7B is 10 mm, and the principal point distance P77 between the objective lens 3 (consisting of the lenses L1, L2, and L7A) and the eyepiece 4 (concave lens L7B).
Is 60 mm.

In the third embodiment, since the optical axis distance for obtaining high magnification (7 times) is reduced, the total length of the binoculars can be shortened both in use and when not in use. Also,
Since the stop recesses used when using the 5 × and 7 × optical systems shown in FIGS. 6A and 6C can be made common, the number of stop recesses can be reduced, and the selection of the stop recesses can be reduced. Less confusing.

As described above, in each of the above-described embodiments, at least one of the objective lens and the eyepiece lens can be replaced with a lens having a different focal length, so that the magnification can be changed according to the situation. For example, it is about 3 times in the case of a theater, about 5 times in the case of watching sports, and about 7 times in the case of bird watching. In this case, in this embodiment, since the stop concave portions are provided at a plurality of image forming positions corresponding to the respective magnifications, the lens, the lens barrel, the lens moving frame, the inner frame,
Can be used without any trouble even if the outer frame is replaced. In this case, in the above embodiment, the positioning between the outer frame and the inner frame is performed by utilizing the fitting between the engaging body and the stop recess, but, for example,
A mark corresponding to the image forming position may be displayed on the outer surface of the outer frame or the inner frame, and the mark may be positioned according to this mark.

In this embodiment, the outer frame and the inner frame can be easily attached and detached, so that the outer frame and the inner frame can be easily replaced. Also, separate the outer and inner frames,
It is also possible to use either one alone. For example, when carrying out the present embodiment for bird watching, it is possible to use only the outer frame as a map magnifying glass alone. Here, in the above embodiment,
The case of exchanging a plurality of prepared inner frames and the case of exchanging a plurality of prepared outer frames have been described separately, but a plurality of both inner frames and outer frames are prepared so that different magnifications can be obtained by combining these. May be.

Since the outer frame and the inner frame of this embodiment are composed of two halves having exactly the same shape, it is possible to reduce the manufacturing cost. Further, since each half is assembled by fitting the convex line and the concave groove formed on the abutting surface of the wall surface and the protruding shaft and the concave hole, it is possible to easily disassemble and assemble. Therefore, it is easy to disassemble the outer frame and the inner frame and replace only the inner lens, the lens barrel, and the movable frame.
In this case, since each of the contact surfaces of the wall surfaces 14, 15, 16 and 26 is formed with a ridge or a groove along the outer periphery thereof, distortion, light leakage and the like on the contact surfaces are prevented.

[0040]

As described above, according to the present invention, the objective lens and the eyepiece lens are constructed so that the outer frame and the inner frame respectively equipped with the objective lens and the eyepiece lens can be drawn out in a mutually inserted state. Since at least one of the
A change in the focus position due to a change in magnification can be dealt with by changing the amount of pulling out of the outer frame and the inner frame, so that the magnification can be appropriately changed and used according to the usage situation.

[Brief description of drawings]

FIG. 1 is a side view of the portable binoculars according to the present invention when carried, (a), a side view when fully pulled out (b),
It is the side view (c) at the time of intermediate drawing, and the side view (d) at the time of another intermediate drawing.

FIG. 2 is a cross-sectional view showing an internal structure in an embodiment of the portable binoculars according to the present invention by disassembling an outer frame and an inner frame.

FIG. 3 is an enlarged view showing an engaging structure of an outer frame and an inner frame in the embodiment of the portable binoculars according to the present invention.

FIG. 4 is explanatory diagrams (a), (b), and (c) showing an optical system in Example 1 of the portable binoculars according to the present invention.

5A to 5C are explanatory views (a), (b), and (c) showing an optical system in Example 2 of the portable binoculars according to the present invention.

6A to 6C are explanatory views (a), (b), and (c) showing an optical system in Example 3 of the portable binoculars according to the present invention.

[Explanation of symbols]

1 Outer Frame 2 Inner Frame 3 Objective Lens 4 Eyepieces 14b, 15b Engagement Guide Surfaces 14c, 14d, 14e, 14f, 15c, 15d, 1
5e, 15f Stop concave portion 40 Bending engagement body 40a Tip portion

Claims (6)

[Claims] 1. A state in which an outer frame equipped with one of an objective lens and an eyepiece lens and an inner frame equipped with the other of the objective lens and an eyepiece lens are provided, and the outer frame and the inner frame are inserted into each other. The portable binoculars are attached so that they can be pulled out in the optical axis direction of the lens, and are equipped with a detachable structure in which at least one of the objective lens and the eyepiece lens can be replaced with another alternative lens having a different focal length. For binoculars. 2. The alternative frame according to claim 1, wherein the outer frame and the inner frame are configured to be detachable from each other, and the alternative lens is attached to replace at least one of the outer frame and the inner frame. Portable binoculars characterized by being provided. 3. The image forming position according to claim 1 or 2, wherein a plurality of image forming positions corresponding to a combination of the objective lens and the eyepiece lens are set according to a combination with the alternative lens, and the plurality of image forming positions are set. Correspondingly, a holding structure configured to hold the drawn-out positions of the outer frame and the inner frame at a plurality of places is provided. 4. The image forming position according to claim 1 or 2, wherein a plurality of image forming positions corresponding to the combination of the objective lens and the eyepiece lens are set according to the combination with the alternative lens, and the plurality of image forming positions are set. Correspondingly, a position indicator configured to display pull-out positions of the outer frame and the inner frame at a plurality of positions is provided, and portable binoculars. 5. The image forming position according to claim 1 or 2, wherein a plurality of image forming positions corresponding to a combination of the objective lens and the eyepiece lens are set according to a combination with the alternative lens, and the plurality of image forming positions are The portable binoculars including an imaging position corresponding to a state where the inner frame is pulled out to the maximum extent from the outer frame. 6. The image forming position according to claim 1 or 2, wherein a plurality of image forming positions corresponding to a combination of the objective lens and the eyepiece lens are set according to a combination with the alternative lens, and the plurality of image forming positions are The portable binoculars characterized by including an imaging position corresponding to a state in which the inner frame is maximally inserted into the outer frame.