JP2002214541A - Zoom telescopic optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zoom telescopic optical system which is capable of suppressing the deterioration in a vibration isolating function accompanying a fluctuation in magnification. SOLUTION: In varying the power, the focal length f0 of an objective lens 10 and the focal length fe of an eyepiece 30 are changed cooperatively in such a manner that the directions of their changes are aligned. More preferably, these focal lengths are so changed that the variation Δf0 of the focal length f0 of the objective lens 10 and the variation Δfe of the focal length fe of the eyepiece 30 are maintained approximately at equal level. The mechanical mid- point of the image side principal point H1 of the objective lens 10 and the object side principal point H2 of the eyepiece 30 is approximately aligned to the center P of the mechanical rotation regardless of a change in the focal length f0 of the objective lens 10 and the focal length fe of the eyepiece 30, by which the vibration isolating conditions are nearly completely satisfied for the entire magnification range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device having an image stabilizing function and a zoom function (for example, binoculars and monoculars).
The present invention relates to a zoom telescope optical system applied to a camera.

[0002]

2. Description of the Related Art When optical devices such as monoculars and binoculars are vibrated, the exit angle of a light beam from an object to be observed with respect to the optical axis fluctuates, so-called "angle blur" occurs, and an observed image is deteriorated. Observation image blur due to this angle blur (image blur)
Is a serious problem particularly in an optical device using a telescope optical system having a high observation magnification. That is, with monoculars, binoculars, and the like, the problem of image blur cannot be ignored because the field of view becomes narrower as the observation magnification increases, and the exit angle of the light beam is expanded by the eyepiece.

In view of the above, various optical devices for preventing image blur due to such vibration and stabilizing the image have been proposed. For example, in Japanese Patent Publication No. 57-37852 and Japanese Patent Laid-Open No. 6-250100, an erect prism is arranged on the optical axis between the objective lens and the eyepiece, and the erect prism is substantially driven regardless of vibration. An image stabilizing device has been proposed in which image blur is prevented by holding the image stabilizing device at the same spatial position. As a method of holding the erect prism at substantially the same spatial position, for example, a method using a rotary inertia body (gyromotor), a method using a combination of an angle detection unit and a control driving unit, and the like are available. In the latter method, the angle deviation is detected by the angle detecting means, and the control driving means controls the angular posture of the erect prism based on the detection result.

Here, the optical image stabilization conditions of the image stabilizing optical system having the erecting prism described above will be briefly described.
It is assumed that the optical elements (the objective lens and the eyepiece) other than the erect prism rotate around a certain point on the optical axis (hereinafter, referred to as “mechanical rotation center”) due to the vibration. At this time, if the mechanical midpoint between the image-side principal point of the objective lens and the object-side principal point of the eyepiece coincides with the mechanical center of rotation, angular image blurring will occur due to the action of the erecting prism. Compensated. That is, the above-mentioned image stabilization condition in the image stabilization optical system is that the mechanical middle point between the image-side principal point of the objective lens and the object-side principal point of the eyepiece coincides with the mechanical rotation center. .

[0005]

Some monoculars and binoculars have a zoom function. As the zoom method, an eyepiece zoom method in which only the focal length of an eyepiece is changed is widely used because it is inexpensive. On the other hand, in the market, development of an anti-vibration optical system having a zoom function is expected. It is thought that an inexpensive zoom anti-shake optical system can be realized by using a zoom eyepiece lens for the above-described anti-shake optical system. There is a problem that the function becomes insufficient.

Hereinafter, a description will be given of an example of a general three-group zoom type eyepiece shown in FIGS. 7A and 7B. In addition,
FIG. 7A shows the lens configuration on the long focal length side (low magnification side in combination with the objective lens), and FIG. 7B shows the lens configuration on the short focal length side (high magnification side in combination with the objective lens). 1 shows a lens configuration. Also, E.I. P indicates an eye point (pupil position). H _W and H _T indicate object-side principal point positions at respective magnifications.

The eyepiece shown in FIG. 1 has a first lens group G1 having a negative refractive power (power) and a positive refractive power from the objective lens side (the direction indicated by the symbol _Zobj in the figure). And a third lens group G3 having a positive refractive power. The zoom eyepiece, by a first lens group G1 and the second lens group G2 moves in opposite directions along the optical axis Z _0, the focal length f _W of the entire eyepiece, f _T is changed. At this time,
By moving the first lens group G1, the focal position F of the entire eyepiece is kept at a predetermined position so as not to move during zooming.

Since the principal point of the lens is located at a position apart from the focal position by a focal distance, if the focal position is fixed, as the focal distance changes,
Its position also changes. On the other hand, the anti-vibration condition in the above-described anti-vibration optical system is that a mechanical middle point between the image-side principal point of the objective lens and the object-side principal point of the eyepiece coincides with the mechanical rotation center. . In the image stabilization optical system incorporating the zoom eyepiece, even if the image stabilization condition is satisfied at a certain focal length, if the focal length of the eyepiece changes from that point, the object-side principal point moves, so the objective The midpoint between the image-side principal point of the lens and the object-side principal point of the eyepiece also moves.
Therefore, when zooming, the center point is shifted from the mechanical rotation center and deviates from the image stabilization condition, and the image stabilization function is deteriorated by the magnification.

As described above, complete image stabilization can be achieved only at a specific magnification by simply adopting a zoom eyepiece in the image stabilizing optical system. At other magnifications, image stabilization is performed as the magnification changes. There is a problem that the vibration function becomes insufficient. Therefore, it is desired to develop a telescope optical system that does not deteriorate the image stabilizing function even when the magnification is variable.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a zoom telescope optical system capable of suppressing deterioration of an image stabilizing function due to a change in magnification.

[0011]

SUMMARY OF THE INVENTION A zoom telescope optical system according to a first aspect of the present invention is a zoom telescope optical system used for an apparatus having an image stabilizing function, the objective lens having a variable focal length. And the focal length is configured to be variable,
An eyepiece for observing an image by the objective lens, and an erect prism that is arranged between the objective lens and the eyepiece and that is held at a substantially same spatial position without vibration, and has a focal length of the objective lens and The focal length of the eyepiece is changed in conjunction with the eyepiece so that the direction of change is the same.

In the zoom telescope optical system according to the first aspect of the present invention, at the time of zooming, the focal length of the objective lens and the focal length of the eyepiece change in conjunction with each other so that the direction of the change becomes the same. This compensates for the mechanical midpoint between the image-side principal point of the objective lens and the object-side principal point of the eyepiece moving away from the center of mechanical rotation, as compared to the case of zooming with the eyepiece alone. As a result, deterioration of the optical image stabilizing function is suppressed.

Here, in the zoom telescope optical system according to the first aspect of the present invention, it is preferable that the change amount of the focal length of the objective lens and the change amount of the focal length of the eyepiece obtain a desired image stabilizing function. It is desirable to be configured to be kept substantially the same to the extent possible.

In the zoom telescope optical system according to the first aspect of the present invention, preferably, the mechanical center point between the image-side principal point of the objective lens and the object-side principal point of the eyepiece is adjusted to the focal point of the objective lens. Regardless of the change in the distance and the focal length of the eyepiece, it is desirable that the configuration be such that it substantially coincides with the mechanical rotation center to the extent that a desired image stabilization function can be obtained. With this configuration, the image stabilization conditions are almost completely satisfied at all magnifications.

A zoom telescope optical system according to a second aspect of the present invention is a zoom telescope optical system used for an apparatus having an image stabilizing function, and includes an objective lens having a variable focal length and a variable focal length. An eyepiece for observing an image by the objective lens, and an erecting prism arranged between the objective lens and the eyepiece and held at substantially the same spatial position without vibration. The mechanical midpoint between the image-side principal point and the object-side principal point of the eyepiece substantially coincides with the mechanical center of rotation due to vibration, regardless of changes in the focal length of the objective lens and the focal length of the eyepiece. It is configured as follows.

In the zoom telescope optical system according to the second aspect of the present invention, the mechanical middle point between the image-side principal point of the objective lens and the object-side principal point of the eyepiece lens is changed by mechanical rotation during zooming. It is kept almost coincident with the center. Thereby, the image stabilizing condition is almost completely satisfied at all magnifications, and the deterioration of the optical image stabilizing function due to the magnification change is suppressed as compared with the case where the magnification is changed by the eyepiece alone.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIGS. 1A to 1C and FIG. 2 show the configuration of a zoom telescope optical system according to an embodiment of the present invention. 1A to 1C show lens configurations in a low magnification state, an intermediate magnification state, and a high magnification state, respectively. 1A to 1C also show the moving state of each lens element and the moving state of the principal point position accompanying zooming. FIG. 2 corresponds to the high magnification state shown in FIG. In these figures, the position indicated by reference numeral F ₀ indicates the image forming position by the objective lens 10, P
Indicates an eye point. H1 _W , H1 _M , and H1 _T indicate the image-side principal point positions of the objective lens 10 in the low magnification state, the intermediate magnification state, and the high magnification state, respectively. H2 _W , H
2 _M and H2 _T indicate the object-side principal point positions of the eyepiece 30 in the low magnification state, the intermediate magnification state, and the high magnification state, respectively. In FIG. 2, the reference numeral Ri denotes an ith i-th lens which sequentially increases toward the eye point, with the lens surface closest to the observation object being the first lens, in accordance with the lens data of the embodiment shown in FIG. The figure shows the radius of curvature of the lens surface. The symbol Di also indicates the surface distance on the optical axis between the i-th lens surface and the (i + 1) -th lens surface in accordance with the lens data of the embodiment shown in FIG. Regarding the surface spacing, only the main parts are denoted by reference numerals.

A zoom telescope optical system 1 according to the present embodiment.
Is applied to an optical device having an image stabilizing function such as binoculars or monoculars. The zoom telescope optical system 1 includes an objective lens 10 having a variable focal length,
The focal length is variable, and includes an eyepiece 30 for observing an image formed by the objective lens, and an erect prism 20 disposed between the objective lens 10 and the eyepiece 30.

The objective lens 10 has a positive refractive power as a whole, and the first lens group 11
, A second lens group 12 and a third lens group 13 are arranged. The first lens group 11 has, for example, a positive refractive power. The second lens group 12 and the third lens group 13 have, for example, a negative refractive power. The objective lens 10, as shown in FIG. 1 (A) ~ (C) , upon zooming, the lens units, by moving in the same direction along the optical axis Z _0, the total focal length of the It is changing. The first lens group 11 and the second lens group 12 move integrally.

The eyepiece lens 30 has a positive refractive power as a whole, and the first lens group 3 is arranged in order from the objective lens side.
1, a second lens group 32, and a third lens group 33 are arranged. The first lens group 31 has, for example, a negative refractive power. The second lens group 32 and the third lens group 33 have, for example, a positive refractive power. The first lens group 31 and the third lens group 33 are each composed of, for example, a cemented lens. The eyepiece 30 is moved, as shown in FIG. 1 (A) ~ (C) , upon zooming, the first lens group 31 along the second lens group 32 and the optical axis Z ₀ in opposite directions By doing so, the focal length of the entire eyepiece changes.

The erecting prism 20 has a function of inverting the image formed by the objective lens 10. Since the image by the action of the objective lens 10 alone is an inverted image, the action of the erecting prism 20 results in the objective image becoming an erect image. The erecting prism 20 is configured by combining a plurality of prisms having a reflecting surface, for example, as shown in FIG. The erect prism 20 is held at substantially the same spatial position regardless of vibration (irrespective of angular fluctuation).

In the present embodiment, the mechanical means for holding the erect prism 20 at substantially the same spatial position is not particularly limited, and a conventional technique can be used. As a conventional technique, for example, there is a technique using a rotary inertia body, a technique combining an angle detecting means and a control driving means, and the like. In addition, for example,
It is possible to use the technology of the image stabilizing device described in Japanese Patent Application No. -250100.

The zoom telescope optical system 1 is used for zooming.
The focal length f ₀ of the objective lens 10 and the focal length _fe of the eyepiece 30 are changed in conjunction with each other so that the direction of the change becomes the same. That is, when the focal length f _e of the eyepiece 30 is changed to be longer, the focal length f ₀ of the objective lens 10 is also changed to be longer. Conversely, when the focal length f _e of the eyepiece 30 is changed to be shorter, the focal length f ₀ of the objective lens 10 is also changed to be shorter.

The zoom telescope optical system 1 is preferably
It is desirable that the amount of change Delta] f _e of the focal length f _e of variation Delta] f ₀ and the eyepiece 30 of focal length f ₀ of the objective lens 10 is configured to be maintained at substantially the same. Further, in the zoom telescope optical system 1, preferably, the mechanical middle point between the image-side principal point H1 of the objective lens 10 and the object-side principal point H2 of the eyepiece 30 is the focal length f ₀ of the objective lens 10. It is desirable that the eyepiece lens 30 be configured to substantially coincide with the mechanical rotation center P regardless of a change in the focal length _fe of the eyepiece lens 30. With this configuration, the image stabilization conditions described later are almost completely satisfied at all magnifications.

Next, the principle of optical image stabilization by the zoom telescope optical system 1 will be described with reference to FIG. In FIG. 3, each optical element of the zoom telescope optical system 1 is shown in a simplified manner.

First, the objective lens 10 and the erect prism 20
In addition, it is assumed that the eyepiece lens 30 is arranged on the same optical axis while maintaining a normal posture. In this state, light rays parallel to the optical axis Z ₀ that enters the objective lens 10 is emitted as a parallel to the optical axis Z ₀ even after passing through an eyepiece 30. Next, it is assumed that the optical axis Z ₀ is inclined by an angle θ about the mechanical rotation center P due to vibration. In this case, the objective lens 10 and eyepiece 30 is also about a mechanical center of rotation P, so that the rotational movement onto the relative angle θ inclined by an optical axis Z ₀₁ relative to the original optical axis Z ₀ . On the other hand, erecting prism 20 because it is mechanically anti-vibration, and remain in the state keeping the normal posture on the original optical axis Z _0. At this time, the image-side principal point H1 of the objective lens 10 is also set.
And also the object side principal point H2 of the eyepiece 30, and rotational movement about the mechanical rotation center P point on the optical axis Z ₀₁ H11, the H21.

[0028] Here, as the image side principal point H1 of the objective lens 10, and consider the light beam incident parallel to the optical axis Z _0. This light, after exiting the objective lens 10, passes through the point Z _B on the optical axis Z ₀ at Z _A and the exit surface point on the optical axis Z ₀ at the incident surface of the erecting prism 20, an eyepiece 30 through the object-side principal point H2 of the eye point E.30. P
Leads to. On the other hand, consider the rays 41 incident at an oblique through the image side principal point H11 of the objective lens 10A of the state, and the original optical axis Z ₀ parallel to the height h. The light 41, since a ray passing through the image-side principal point H11 of the objective lens 10A, remain parallel to the original optical axis Z ₀ even after exiting the objective lens 10A, on the entrance surface of the erecting prism 20 The point Z _A1
Incident on.

[0029] At this time, the height of the point Z _A on the incident point Z _A1 and the original optical axis Z ₀ When Z _A Z _A1, rays 41 by the action of the erecting prism 20, the optical axis Z ₀ Incident point Z _A1
On the opposite side to a point Z at a height that is a distance Z _A Z _A1 away
From _B1, it is emitted in parallel to the original optical axis Z _0. In this case, when the height of the point Z _B on the emission point Z _B1 and the original optical axis Z ₀ and Z _B Z _B1, a _{Z A Z A1 = Z B Z} B1. If the light beam 42 emitted in this state passes through the object-side principal point H21 of the eyepiece 30A in an inclined state, the eyepiece 3
After passing through the 0A, light 42 is emitted while maintaining a parallel state with respect to the original optical axis Z _0. In this state,
The height from the object side principal point H2 of the eyepiece 30 before tilting to the object side principal point H21 of the eyepiece 30A after tilting is H
When 2H21, the H2H21 = Z _B Z _B1. Further, since it is _{Z B Z B1 = Z A Z} A1 = H11H12, H2
H21 = H1H11 = h (H1H11 is the height from the image-side principal point H1 of the objective lens 10 to the image-side principal point H11 of the objective lens 10A). In this case also, the center of the objective image by the objective lens 10 before tilting, from the point F ₀ on the optical axis Z _0, (rather than the point R on the optical axis Z ₀₁ after tilt) rays 42
This means that an image is formed at the upper point _F01 . Point F ₀₁ is the point R
Are located at a distance of f _e · theta from (f _e is the focal length of the eyepiece 30).

The above condition is satisfied if the mechanical center point between the image-side principal point H1 of the objective lens 10 and the object-side principal point H2 of the eyepiece 30 coincides with the mechanical rotation center P. .
That is, a mechanical distance H1P between the image-side principal point H1 of the objective lens 10 and the mechanical rotation center P, and a mechanical distance PH between the mechanical rotation center P and the object-side principal point H2 of the eyepiece 30.
2 and is, well if a value equal L ₀ (H1P = P
H2 = L ₀ ), which is a necessary and sufficient condition for optical vibration isolation. The installation position of the erect prism 20 may be optically any position between the objective lens 10 and the eyepiece 30. The erect prism 20 can be installed, for example, at a position that is most convenient mechanically (for example, a mechanical center of gravity position). In the state where the above optical vibration isolation conditions are satisfied,
Even if the optical axis Z ₀ is inclined by θ, the ray 41 that passes through the image-side principal point H11 of the objective lens 10A and is incident at a height h in parallel with the original optical axis Z ₀ maintains its parallel state. The light exits from the eyepiece 30A at the height h. That is, since there is no change in the emission angle of the light beam from the eyepiece lens 30 before and after the vibration, angular image blur is compensated and a good image is observed.

FIG. 4 shows an example of the configuration of the erect prism 20. As the erecting prism 20, for example, an erecting prism of Schmidt, an erecting prism of Abbe, an erecting prism of bauern fend, an erecting prism of Polo and the like can be used. it can.
Here, a Schmidt erect prism will be described as an example.

The Schmidt erect prism has two prisms 21 and 22, as shown in FIG. First
Prism 21 has three optically active surfaces 21A, 21A.
B, 21C. The surface 21A is a light incident surface. The surfaces 21B and 21C are provided at a predetermined angle with respect to the incident surface 21A. The second prism 22 is a roof prism and has a roof (Dach) surface 22C composed of two reflection surfaces orthogonal to each other. 4, the line denoted by reference numeral 22C ₁ shows a ridge of the roof surface 22C. The prism 22 also has two optically active surfaces 22A and 21B. Prism 2
1 and the prism 22 are separated from each other by a predetermined air space.
And the surface 22A are arranged so as to face each other.

In the erecting prism having such a configuration, FIG.
As shown in the figure, there is an input-output coaxial where the incident optical axis 51 and the output optical axis 52 are on the same straight line. Such an incident optical axis 5
In an erect prism that can take the exit optical axis 52 on the same straight line as the light beam 41, the light ray 41 incident parallel to the incident optical axis 51 at a height h is first incident on the entrance surface 2 of the prism 21.
1A and then reflected at surface 21B toward surface 21C. The light ray incident on the surface 21C is reflected on the surface 21C again toward the surface 21B. Light rays incident on the surface 21B from the surface 21C pass through the surface 21B, and then pass through the surface 22A of the prism 22. Light rays that have passed through the surface 22A are then reflected at the surface 22B toward the roof surface 22C. The light rays incident on the roof surface 22C are again reflected on the surface 22A.
Reflected toward. The light beam incident on the surface 22A is
At 2A, the light is reflected again toward the surface 22B,
The light exits at a height h on the side opposite to the time when the light enters the emission optical axis 52 from the light source.

As described above, in the erecting prism, the light beam 41 incident at a height h with respect to the incident optical axis 51 is
2 at the height h on the opposite side to when it is incident on
Light is emitted while maintaining the parallel state. Therefore, in this erecting prism, the incident image is inverted up and down. Also,
In this erecting prism, the incident image is reversed right and left by the action of the roof surface 22C. As a result, in the erecting prism, the incident image is inverted up, down, left, and right, and an inverted image of the upright image is obtained.

Next, with reference mainly to FIGS. 1 (A) to 1 (C) and FIG. 2, the optical action and effect brought about by the present zoom telescope optical system 1 having the above configuration will be described.

The zoom telescope optical system 1 according to the present embodiment
In this case, the light beam from the observation target passes through the objective lens 10 to form an objective image. At this time, an image formed by the action of the objective lens 10 alone is an inverted image. The inverted image passes through the erecting prism 20 and is converted into an erect image. The objective lens 10 and the erect prism 2
0 is the erect objective image formed by the eyepiece 30
Is observed by

In the zoom telescope optical system 1, upon zooming, the focal length f ₀ of the objective lens 10 and the focal length _fe of the eyepiece 30 are changed in conjunction with each other so that the direction of the change is the same. . For example, when the focal length _fe of the eyepiece 30 is changed to be longer in order to obtain the low magnification state shown in FIG. 1A, the focal length f ₀ of the objective lens 10 is also changed to be longer. Here, assuming that the focal lengths of the objective lens 10 and the eyepiece 30 in the low magnification state are f ₀ 1 and f _e 1, and the amounts of change of the focal lengths are Δf ₀ and Δf _e , respectively, the zoom telescope optical system 1 is given by “f ₀ 1 / f _e 1 = f ₀ + Δ
the _{f 0 / (f e + Δf} e) ". At this time, the zoom telescope optical system 1, preferably, it is desirable to keep the amount of change Delta] f _e of the focal length f _e of variation Delta] f _e and the eyepiece 30 of focal length f ₀ of the objective lens 10 to be substantially the same . At this time, assuming that the same change amount is Δf, the magnification is “f _{0
1 / f e 1 = f 0} + Δf / (f e + Δf) becomes ".

As already described with reference to FIG. 3, the optical image stabilizing condition of the zoom telescope optical system 1 is determined by the image-side principal point H1 of the objective lens 10 and the object-side principal point H2 of the eyepiece 30. The mechanical center point coincides with the mechanical rotation center P, the mechanical distance H1P between the image-side principal point H1 of the objective lens 10 and the mechanical rotation center P, the mechanical rotation center P and the eyepiece. And the mechanical distance PH2 between the object side principal point H2 and
That is, they have the same value. Now, for example, FIG.
The anti-vibration condition in an intermediate magnification state shown in (B) are completely made up _{(H1 M P = PH2 M =} L M), also intended to mechanical center of rotation P is in a fixed position. Only by changing long focal length from the state e.g. eyepiece 30, when subjected to scaling to a low magnification state, the object side principal point H2 _M is moved to a point H2 _W eyepoint side. Therefore,
In this case, the mechanical midpoint of the object side principal point H2 _W of the image-side principal point H1 _W and the eyepiece 30 of the objective lens 10 in the low magnification state, the eye point side than in the intermediate magnification state It moves and moves away from the mechanical rotation center P. As a result, as the magnification is changed to the low magnification state, the image stabilization condition is deviated, and the optical image stabilization function is deteriorated.

On the other hand, in this zoom telescope optical system 1, an eyepiece
The focal length f of the objective lens 10 as well as the lens 30₀
So that the direction of the change is the same as that of the eyepiece 30.
By interlocking with the change, the deterioration of the anti-vibration function is suppressed.
It is. That is, when zooming to a low magnification state,
Like the eye lens 30, the focal length f of the objective lens 10 ₀
Change for a long time. At this time, the main image side of the objective lens 10 is
Point H1_MIs the object-side principal point H2 of the eyepiece 30_MHow to move
Point H1 on the observation object side in the direction opposite to the direction_WGo to this
Lower than when zooming with the eyepiece alone
Image-side principal point H1 of objective lens 10 in a magnification state_WContact with
Object-side principal point H2 of eye lens 30_WThe mechanical midpoint with
The distance from the mechanical rotation center P is compensated,
Deterioration of typical anti-vibration function is suppressed. At this time,
Focal length f₀Change amount Δf_eAnd the eyepiece 30
Focal length f_eChange amount Δf_eAnd the same, the objective lens
Ten image-side principal points H1_WAnd the object side principal point H of the eyepiece 30
2_WWith the mechanical center of rotation P
(H1_wP = PH2_w= L_W), Low magnification state
In this case, the anti-vibration conditions can be completely maintained.

Conversely, a description will be given of a case where a high magnification state is set. For example, when the focal length f _e of the eyepiece 30 is changed to be shorter in order to obtain the high magnification state shown in FIG. 1C, the focal length f ₀ of the objective lens 10 is also changed to be shorter. Here, assuming that the focal lengths of the objective lens 10 and the eyepiece 30 in the high magnification state are f ₀ 3 and f _e 3, respectively, and the amounts of change of the focal lengths are Δf ₀ and Δf _e , respectively, the zoom telescope optical system 1 is given by “f ₀ 1 / _fe 1 = f ₀ −Δf ₀ / (f _e −Δ
f _e ) ". At this time, the zoom telescope optical system 1
Preferably, the variation of the focal length f _e of variation Delta] f _e and the eyepiece 30 of focal length f ₀ of the objective lens 10 Delta] f _e
Is desirably kept substantially the same. At this time, assuming that the same change amount is Δf, the magnification is “f ₀ 1 / f _e 1 = f
₀₋ Δf / ( _fe− Δf) ”.

Now, for example, in the intermediate magnification state shown in FIG. 1B, the anti-vibration condition is completely satisfied (H1 _M P = P
H2 _M = L _M ), and the mechanical rotation center P is at a fixed position. Only short changing the focal length from the state e.g. eyepiece 30, when subjected to scaling to high power state, a point on the object side principal point H2 _M is the observation object side H2 _T
Go to Therefore, in this case, the mechanical midpoint of the object side principal point H2 _T of the image-side principal point H1 _T and the eyepiece 30 of the objective lens 10 is in a high magnification state, observation object than in the intermediate magnification state Side and move away from the mechanical rotation center P. As a result, as the magnification is changed to the high magnification state, the vibration proof condition is deviated, and the optical vibration proof function is deteriorated.

On the other hand, in the present zoom telescope optical system 1, the focal length f ₀ of the objective lens 10 is changed to be short as in the case of the eyepiece lens 30 when the magnification is changed to the high magnification state.
At this time, the image-side principal point H1 _M of the objective lens 10, the moving direction of the object side principal point H2 _M eyepiece 30 is moved to a point H1 _T eyepoint side in the opposite direction. Thus, as compared with the case of variable power eyepiece alone, the image-side principal point H1 _T and the eyepiece of the objective lens 10 in a high magnification state 30
Mechanical midpoint of the object side principal point H2 _T of, it is compensated away from the mechanical center of rotation P, the deterioration of the optical image stabilization function is suppressed. In this case, the focal length variation Delta] f _e and the eyepiece 30 of focal length f ₀ of the objective lens 10 f _e
Maintaining the amount of change Delta] f _e to the same, mechanical midpoint of the object side principal point H2 of the image side principal point H1 and the eyepiece 30 of the objective lens 10, by matching the mechanical center of rotation P ( H1 _T P = PH 2 _T = L _T ), and the image stabilizing conditions can be completely maintained even in the high magnification state.

As described above, according to the zoom telescope optical system 1 of the present embodiment, the objective lens 1
Focal length f ₀ of 0 and the eyepiece 30 and a focal length f _e,
By interlockingly changing the direction of the change so as to be the same, the image-side principal point H1 of the objective lens 10 at each magnification is changed.
And the mechanical center point between the object-side principal point H2 of the eyepiece 30 and the object-side principal point H2 is compensated for moving away from the mechanical rotation center P,
It is possible to suppress deterioration of the optical image stabilizing function due to a change in magnification. Thereby, a sufficient image stabilizing function can be obtained at all magnifications, and good observation with little image blur can be performed.

[Embodiment] Next, the present zoom telescope optical system 1
Specific numerical examples will be described. The cross-sectional structure of the zoom telescope optical system according to the present embodiment and the zoom method are the same as those of the zoom telescope optical system 1 shown in FIGS. 1A to 1C and FIG.

FIGS. 5A and 5B show specific numerical examples of the zoom telescope optical system according to the present embodiment.
FIG. 5A shows basic lens data.
(B) shows data of the variable surface interval as described later.
The surface number Si in FIG. 5A indicates the number of the lens surface that sequentially increases toward the eye point, with the lens surface closest to the observation object being the first. Refractive index Ne
i and the Abbe number νei are e-line (wavelength λe =
546.1 nm). The radius of curvature Ri is
Like the reference symbol Ri shown in FIG. 2, the radius of curvature of the i-th lens surface from the observation object side is shown. FIG. 5 (A),
The surface distance Di in (B) is the same as the reference numeral Di shown in FIG. 2 and indicates the surface distance on the optical axis between the i-th lens surface Si and the (i + 1) -th lens surface Si + 1 from the observation object side. The unit of the value of the radius of curvature Ri and the surface interval Di is millimeter (mm). In the figure, the radius of curvature R
A lens surface in which i is described as “INFINITY” indicates that the surface shape is flat.

In the lens data of FIG. 5A, surface numbers S1 to S6 indicate the objective lens 10, and surface numbers S12 to S19 indicate the eyepiece lens 30. The surface number S11 indicates an objective image by the objective lens 10. The surface number S20 indicates an eye point by the eyepiece lens 30. FIGS. 1A to 1C and FIG. 2 show only the entrance surface and the exit surface of the entire erect prism, but in the present embodiment, the erect prism 20 is a 2
It is composed of two prisms. In the lens data of FIG. 5A, the constituent surface of the erect prism 20 is the surface number S
7 to S10.

FIG. 5B shows a low magnification state (10.0).
×), the intermediate magnification state (13.0 ×) and the high magnification state (19.9 ×) in each variable surface distance D4.
D6, D11, D14, and D16 are shown.

In this embodiment, the objective lens 1 is used for zooming.
The first lens group 11 0 and the second lens group 12 is moved along the optical axis Z ₀ together. Third lens group 1
3 also moves along the optical axis Z _0. For this reason, in the present embodiment, the surface distance D4 between the second lens group 12 and the third lens group 13 in the objective lens 10 and the surface distance D6 between the third lens group 13 and the erecting prism 20 are determined. Is a variable surface interval. In this embodiment, also, during zooming, the first lens group 31 of the eyepiece 30 and the second lens group 32 is moved in opposite directions along the optical axis Z _0. For this reason, in the present embodiment, the first lens group 31 in the eyepiece lens 30 is used.
A surface distance D14 between the first lens group and the second lens group 32 and a surface distance D16 between the second lens group 32 and the third lens group 33 are variable surface distances. In the present embodiment, the position of the objective image is substantially constant during zooming.
0, the first lens group 31 moves, so that the objective image plane S11 and the surface S1 of the first lens group 31 closest to the observation object side
2 is also a variable surface distance.

FIG. 6 shows the actual field of view (°) and the objective lens 10.
The values of the focal length f ₀ and the focal length f _e of the eyepiece 30 are shown for each magnification. FIG. 6 also shows the value of the back focal point of the objective lens 10 from the exit surface S10 of the erecting prism 20 and the eyepiece 30 from the objective image surface S11.
Are also shown.

As can be seen from FIG. 6, in the present embodiment, the focal length f ₀ of the objective lens 10 and the focal length f _e of the eyepiece 30 are changed by substantially the same amount during zooming.
Thus, at each magnification, the mechanical middle point between the image-side principal point H1 of the objective lens 10 and the object-side principal point H2 of the eyepiece 30 is compensated for moving away from the mechanical rotation center P, and magnification fluctuation is compensated. The deterioration of the optical anti-vibration function due to the above is suppressed.

Note that the present invention is not limited to the above embodiment, and various modifications can be made. For example, the radius of curvature R, surface interval D, refractive index N, and Abbe number ν of each lens component
Is not limited to the values shown in the above numerical examples, and may take other values. Further, the number of lenses and the power distribution of the objective lens 10 and the eyepiece 30 are not limited to those described in the above embodiment, and other configurations can be adopted.

The zoom method is not limited to the one described in the above embodiment, but may be another method. For example, in the above embodiment, the eyepiece 30 is
Although the group zoom method is used, the present invention is applicable to eyepieces other than the three-group zoom method. Further, in the above-described embodiment, an example has been described in which the focal position of the eyepiece lens 30 does not change during zooming. However, the present invention is also applicable to a case where the focal position of the eyepiece lens 30 moves according to magnification. In this case, the focal length and the focal position of the objective lens 10 may be changed in accordance with the movement of the focal position of the eyepiece 30 so as to satisfy the image stabilization condition.

[0053]

As described above, claims 1 to 3 are described.
According to the zoom telescope optical system according to any one of the above,
An objective lens with a variable focal length, a variable focal length, an eyepiece for observing an image by the objective lens, and an eyepiece between the objective and the eyepiece, which are substantially independent of vibration An erecting prism held at the same spatial position is provided, and the focal length of the objective lens and the focal length of the eyepiece are changed in conjunction with each other so that the direction of the change is the same. As compared with the case where the magnification is changed, the deterioration of the optical image stabilizing function due to the magnification change can be suppressed. Thereby, good observation with little image blur can be performed at each magnification.

In particular, according to the zoom telescope optical system according to the third aspect, in the zoom telescope optical system according to the first or second aspect, the mechanical relationship between the image-side principal point of the objective lens and the object-side principal point of the eyepiece lens. The center point is approximately the same as the mechanical center of rotation due to vibration, regardless of the change in the focal length of the objective lens and the focal length of the eyepiece. Is done. This allows
A sufficient image stabilizing function is obtained at each magnification, and good observation with almost no image blur can be performed.

According to the zoom telescope optical system of the fourth aspect, an objective lens having a variable focal length,
An eyepiece for observing an image formed by the objective lens, which has a variable focal length, and an erecting prism disposed between the objective lens and the eyepiece and held at substantially the same spatial position regardless of vibration. Provided, the mechanical midpoint between the image-side principal point of the objective lens and the object-side principal point of the eyepiece, regardless of changes in the focal length of the objective lens and the focal length of the eyepiece,
Since it is configured so that it substantially coincides with the center of mechanical rotation due to vibration, the anti-vibration conditions are almost completely satisfied at all magnifications,
Compared with the case where the magnification is changed by the eyepiece alone, it is possible to suppress the deterioration of the optical image stabilizing function due to the magnification change.
As a result, a sufficient anti-vibration function is obtained at each magnification,
Good observation with almost no image blur can be performed.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a lens configuration in a low magnification state, an intermediate magnification state, and a high magnification state in a zoom telescope optical system according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a configuration of a zoom telescope optical system according to one embodiment of the present invention.

FIG. 3 is an explanatory diagram showing the principle of vibration isolation.

FIG. 4 is a sectional view showing an example of an erect prism.

FIG. 5 is an explanatory diagram showing specific numerical examples of the zoom telescope optical system according to one embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a focal length value of an objective lens, a focal length value of an eyepiece, and the like in the zoom telescope optical system according to the embodiment shown in FIG. 5;

FIG. 7 is an explanatory diagram showing an eyepiece zoom method.

[Explanation of symbols]

_{H1 (H1 W, H1 M,} H1 T) ... the image side principal point of the objective _{lens, H2 (H2 W, H2 M} , H2 T) ... object side principal point, P ... mechanical rotation center of the eyepiece, Z ₀ ... Optical axis, 1 ... Zoom telescope optical system, 10 ... Objective lens, 20 ... Erect prism, 30 ... Ocular lens.

Continued on the front page F term (reference) 2H039 AA05 AB15 AB22 AB32 AB54 2H087 KA16 KA17 LA11 NA07 PA03 PA17 PA19 PB03 PB05 PB08 QA02 QA03 QA06 QA07 QA12 QA14 QA22 QA25 QA26 QA37 QA38 QA41 QA42 SA12 SA12 SAB SA26

Claims (4)

[Claims] 1. A zoom telescope optical system used in an apparatus having an image stabilizing function, comprising: an objective lens having a variable focal length; and an objective lens having a variable focal length for observing an image by the objective lens. An eyepiece lens, and an erect prism disposed between the objective lens and the eyepiece lens and held in substantially the same spatial position regardless of vibration, and the focal length of the objective lens and the eyepiece lens A zoom telescope optical system, wherein the focal length is changed in conjunction with the changing direction so that the direction of change is the same. 2. The zoom telescope according to claim 1, wherein the amount of change in the focal length of the objective lens and the amount of change in the focal length of the eyepiece are kept substantially the same. Optical system. 3. A mechanical midpoint between the image-side principal point of the objective lens and the object-side principal point of the eyepiece lens, regardless of a change in the focal length of the objective lens and the focal length of the eyepiece lens. 3. A zoom telescope optical system according to claim 1, wherein said zoom telescope optical system is configured to substantially coincide with a center of mechanical rotation caused by vibration. 4. A zoom telescope optical system used in an apparatus having an image stabilizing function, comprising: an objective lens having a variable focal length; and a variable focal length configured to observe an image formed by the objective lens. And an erecting prism disposed between the objective lens and the eyepiece lens and held at substantially the same spatial position without vibration, wherein an image-side principal point of the objective lens and the eyepiece are provided. A mechanical center point between the object side principal point of the lens and the focal length of the objective lens and the focal length of the eyepiece are configured to substantially coincide with a mechanical center of rotation due to vibration regardless of a change in the focal length of the objective lens and the focal length of the eyepiece. A zoom telescope optical system.