JPH04147109A - Afocal variable power optical system - Google Patents

Abstract

PURPOSE:To approximate the reference diopter of an image to a diopter with which a person who has general eyesight can easily make an observation and to prevent the image from being defocused owing to power variation by setting the reference diopter of the image minus. CONSTITUTION:The afocal power variation optical system consists of an objective optical system which is positioned on the object side about a visual field ring for prescribing a visual field frame and an ocular optical system which is positioned on the eye side about the visual field ring, and at least part of the ocular optical system is moved to vary the power. Further, the reference diopter of the image which does not vary even by the power variation is set below -1+ or -0.5. Namely, the reference diopter is set to the minus side in consideration of the diopter in use which is set generally to the minus side. Consequently, the afocal optical power variation optical system which hardly varies the diopter of the image owing to power variation is obtained and apparent variation of a visual field such as the defocusing and power variation of the visual field ring is prevented.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an afocal optical system used for double mirrors, single mirrors, etc., and particularly relates to a variable magnification optical system that can change magnification. It is.

(Prior Art) Generally, an eyepiece optical system such as a binocular is provided with a diopter adjustment function so that the focus can be adjusted according to the diopter of the user. Further, in a zoom optical system whose magnification (focal length) can be adjusted, a reference diopter is determined at the time of design, so that the diopter does not change even when the magnification is changed.

When the lens group moved for diopter adjustment and the lens group moved for zooming at least partially overlap,
Changes in diopter due to magnification cannot be suppressed for all diopters. Therefore, the commonly used diopter is determined as the reference diopter, and the lens is designed so that the diopter does not change due to magnification change, at least when the reference diopter is set.

Therefore, if the diopter is set to the standard diopter, the diopter will not change even if you change the magnification, but if the diopter is set to something other than the standard diopter, changing the magnification will not change the diopter. The diopter has changed and it is necessary to adjust the diopter again.

Conventionally, as this type of variable magnification optical system, the Japanese Patent Publication No. 56410
BACKGROUND OF THE INVENTION Eyepiece zoom optical systems described in Japanese Patent Application Laid-open No. 85 and Japanese Patent Application Laid-Open No. 134617/1987 are known. In the eyepiece zoom optical systems described in these publications, the reference diopter is set to 0 dayopter.

(Problem to be Solved by the Invention) However, in the conventional variable magnification optical system described above, the reference diopter was inappropriately set, so there was a problem in that the diopter of the image was easily changed by the variable magnification operation. . In other words, the O diopter, which is the reference diopter of conventional eyepiece zoom optical systems, is the diopter used when viewing objects at infinity, but for people with standard eyesight, it is easier to see objects at 1 meter than to view objects at infinity. It is easier to see objects located within about one tor (-1 dayopter).

Therefore, users often change the diopter from the standard diopter of 0 dayopter to around -1 dayopter, and in this case, even if the diopter is adjusted at a certain magnification, changing the magnification The diopter of the image changes, causing the observed image to be out of focus.

Further, the conventional variable magnification optical system has the problem that the image of the field ring becomes blurred because the position of the field ring for defining the field frame is inappropriate.

If the object side of the optical system to the field ring is the objective optical system, and the field ring to the observation side is the eyepiece optical system, the field ring will be observed only through the eyepiece optical system, and the diopter of the field ring will be Determined by the eyepiece optics. However, in the conventional eyepiece zoom optical system, the diopter of the field ring is also set to 0 dayopter, making it difficult to clearly see the image of the field ring. Moreover, in conventional variable magnification optical systems, the field ring moves together with the eyepiece optical system, so even if the focal length of the eyepiece optical system changes, the position of the field ring does not shift relative to the eyepiece optical system. Therefore, even if the image of the field ring is clearly visible at a certain magnification, the image of the field ring will be out of focus as the magnification is changed.

Furthermore, since it is easier to correct aberrations when zooming is performed on the eyepiece optical system side, conventional zooming optical systems tend to have a lower ratio of the zooming ability of the eyepiece optical system to that of the objective optical system. emphasis is placed on it.

However, if the eyepiece optical system has a high variable magnification ability,
Another problem is that the apparent upper field of view changes as the magnification changes. When using binoculars, the human sense perceives the magnification of an image as the relative relationship between the frame that defines the field of view and the size of the object. Therefore, when the apparent size of the upper field of view is constant and the magnification of an object changes, the user feels that the magnification has changed. However, if the width of the field of view changes with a change in the magnification of an object, as in a conventional variable magnification optical system, this cannot be interpreted as a change in magnification.

(Object of the Invention) The present invention has been made in view of the above-mentioned problems.It is an object of the present invention to provide an afocal variable magnification optical system in which the diopter of an image is difficult to change due to variable magnification, and further, The purpose of the present invention is to provide a variable magnification optical system that can prevent defocusing of a field ring and changes in the apparent upper field of view when changing magnification.

(Means for Solving the Problem) In order to achieve the above object, the present invention is characterized in that the reference diopter DIO of the image is set to less than O diopter. Considering that the diopter during use is generally set to the minus side, by setting the reference diopter to the minus side, it is possible to suppress diopter deviation during zooming.

In addition to the above configuration, the diopter of the field ring at high magnification is D.
ST, when the diopter of the viewing ring at low magnification is DSW, it is characterized by satisfying DST≦DIO≦DSIII. Since the change in the diopter of the field ring during magnification changes extends to both sides of the reference diopter, which takes a negative value, even if the diopter of the field ring changes, the amount of out-of-focus will be small.

Note that if the position of the field ring is moved so that DST=DSW=DIO at this time, there is no change in the diopter of the field ring due to zooming, and defocus of the field ring can be prevented.

Furthermore, it is characterized in that the variable power ratio of the eyepiece optical system is set to 1.30 or less. By keeping the magnification ratio of the eyepiece optical system low, it is possible to suppress changes in the apparent upper field of view, and when changing the magnification, only the size of the image changes within a fixed field of view, making it difficult for the observer. This makes it easier for people to understand the changes in magnification. When the variable power ratio of the eyepiece optical system becomes larger than 1.30,
When changing the magnification, the apparent change in the upper field of view increases, making it even more interesting to observe.

(Example) The present invention will be explained below based on the drawings.

FIRST EMBODIMENT> FIGS. 1, 3, and 5 are lens diagrams showing the first embodiment of the variable magnification optical system of the present invention, respectively. The figure shows the image at medium magnification, and FIG. 5 shows the image at high magnification.

The specific numerical structure is shown in Table 1. In addition, the symbols in the tables in all Examples are as follows: r is the radius of curvature of the lens surface, and d
is the lens thickness or lens spacing, n is the refractive index of the lens, ν
is the number of lenses, fl is the focal length of the objective optical system,
fe is the focal length of the eyepiece optical system.

is the half angle of view.

In this embodiment, the magnification is changed by changing d7, d9, and d14, and the numerical structure thereof is shown in Table 2. The fourth to seventh surfaces are the surfaces of the erecting prism.

Various aberrations due to this configuration are shown in FIG. 2 at low magnifications, FIG. 4 at medium magnifications, and FIG. 6 at high magnifications.

Table 1 63.811 38.439 117.465 70.480 28.398 322.719 11.419 23.749 55.560 21.238 35.161 54.737 At low magnification 100,00 16.69 3,50 ” 23.27 7.03 12, 28 Table 2 4.79 1.31 23.76 33.26 1.58 30.09 Variable 1.31 Variable 1.31 5.82 0.17 3.72 Variable 2. 56 1.51633 1.62004 1.56883 1.56883 1.51633 1.80518 1.71300 1.51633 1.51633 64.1 36.3 56.3 56.3 64.1 25.4 53.8 64 .1 64.1 Medium magnification 133, 95 15, 02 2.566 14.41 21, 13 7.04 High magnification 158, 93 13, 36 2.08' 10.30 31, 71 0.57 Low magnification The magnification ratio between the focal length few of the eyepiece optical system at the time and the focal length fet of the eyepiece optical system at high magnification is few/fe
Since t·1.25 is obtained, it is possible to suppress changes in the apparent field of view due to variable magnification.

When the standard diopter DIO is set to 11 day opters, if the diopter adjustment is set to 11 day opters as shown in Table 3, of course no diopter deviation will occur, and the diopter will be 12 on the low magnification side.
Even when adjusting the diopter to a diopter, the amount of shift can be kept to just under 3 diopters.

Table 3 At low magnification At medium magnification At high magnification -4,0-7,7-12,9 -2,0-3,2-5,0 1,0-1,0-1,0 Q, O+l, 2 +3.0+2.
0 +5.7 +
10.9 In the case of an optical system in which the field ring moves together with the variable power lens group, the diopter of the field ring changes with the change in power. When the field ring is moved together with the variable magnification lens group, in the first embodiment, the diopter of the field ring is DS'w.-0.4 diopters on the low magnification side, and DST.-5.8 diopters on the high magnification side. , DST≦DIO≦DSW is satisfied.

The field ring is independently moved so that the diopter of the field ring is constant, and the condition of DST = D 0 = DSW = -1 is satisfied so that the diopter of the field ring is the same as the reference diopter. In order to achieve this, the distance from the most object-side surface (rlo) of the eyepiece optical system to the field ring can be changed as shown in Table 4. With this configuration, the diopter of the image and the field of view can be adjusted regardless of magnification. The diopters of the rings match, which prevents the viewing ring from going out of focus and from changing the apparent field of view, making it easier to observe.

Table 4 At low magnification At middle magnification At high magnification 6, 54 -7.24 -7.83For comparison, the change in diopter when the reference diopter is set to 0 dayopter in the configuration of the first example is shown. It is shown in Table 5. For example, when the observation diopter is set to -1 dayopter on the low magnification side, the diopter becomes =3.6 dayopter on the high magnification side due to the power change.

Furthermore, when the diopter is adjusted using -2 diopters, the high magnification side is off by 5 diopters or more compared to the low magnification side.

Table 5 At low magnification At medium magnification At high magnification 4, 0
-8.6 -14.4-2.0 -4.3
~7.2-1.0 -2.1 -
3.6 o, o o, o o,
.

+2.0 +4.3
+7.2 (Second Embodiment) Figures 7, 9, and 11 are lens diagrams showing the second embodiment of the variable magnification optical system of the present invention, and Figure 7 is the one at low magnification. , FIG. 9 shows the image at medium magnification, and FIG. 11 shows the image at high magnification. Note that the specific numerical structure is shown in Table 6. Further, in this embodiment, the magnification is changed by changing d7, d9, and d14, and the numerical structure thereof is as shown in Table 7.

Various aberrations due to this configuration are shown in FIG. 8 at low magnification, FIG. 10 at medium magnification, and FIG. 12 at high magnification.

57.232 36.823 116.590 41.540 26.168 55.235 10.857 -22.194 145.117 -28.719 19.391 141.943 At low magnification 100, 00 16, 45 2.67 @14,. 31 10, 23 13, 37 Table 6 4.99 1.45 25, 89 29, 93 1.81 29, 93 Variable variable 1.18 5.62 0.36 2.63 Variable 2.36 Table 7 1.51633 1.62004 1.56883 1.56883 1.51633 1.80518 1.71300 1.51633 1.51633 Medium magnification 131.84 14, 6111 1.94°7.77 22, 23 7.90 64.1 36 .3 56.3 56.3 64.1 25.4 53.8 64.1 64.1 At high magnification 155, 83 13, 14 1.58° 4.61 31, 36 1, 93 Eyepiece at low magnification The magnification ratio between the focal length few of the optical system and the focal length fet of the eyepiece optical system at high magnification is few/fe
Since t = 1.25, changes in the apparent field of view due to variable magnification can be suppressed.

Table 8 shows the change in diopter due to magnification when the standard diopter is set to 11 dayopters.

Table 8 Low magnification Medium magnification High magnification -4,0-7,6-12,5 2,0-3,2-4,8 1,0-1,0~1.0 0.0 ÷1 .2 +2.8+2.0
+5.6 +1
0.5 The field ring is moved independently so that the diopter of the field ring is constant, and the condition of DST = DIO = DSW = -1 is set so that the diopter of the field ring is the same as the reference diopter. In order to satisfy this requirement, the distance between the surface (rlo) of the eyepiece optical system closest to the object and the viewing ring may be changed as shown in Table 9.

Table 9 Low magnification Medium magnification High magnification 7.25 -7.79 -8.
33 For comparison, the reference diopter DI with the configuration of the second embodiment is
Table 1 shows the change in diopter when O is set to 0 dayopter.
(shown in l.

Table 10 Low magnification Medium magnification High magnification 4.0 -8.8 -15.4-2.0
-4.4 -7.71, 0 -2.
2 -3.8o,o o,o
o.

+2.0 +4.4 +7.7 3rd
Embodiment> Fig. 13, Fig. 15, and Fig. 17 are lens diagrams showing a third embodiment of the variable magnification optical system of the present invention, Fig. 13 at low magnification, and Fig. 15 at medium magnification. Figure 17 shows the image at high magnification. Note that the specific numerical structure is shown in Table 11. In this example, among the five lenses of the eyepiece optical system, the lens closest to the object and the fourth lens are resin lenses.

Various aberrations caused by this configuration are shown in Figure 14 at low magnification.
The image at medium magnification is shown in Figure 16, and the image at high magnification is shown in Figure 18.
Shown in the figure.

Table 11 64.573 -33.786 95.352 L60.979 14.802 -63.592 14.263 17.104 50.744 27.452 24.422 186.044 At low magnification 100, 00 16.66 2 .67' 12, 35 9.55 12, 51 5.24 1.52 28.57 32.38 1.91 28.57 Variable 1.24 Variable 1.24 6.57 0.38 3.52 Variable 2. 67 Table 12 1.51633 1.62004 64.1 36.3 1.56883 56.3 1.56883 56.3 1.492 57.4 1.80518 1.71300 25.4 53.8 1.492 57. 4 1.51633 64.1 Medium magnification 136, 95 15.28 1.94° 5.78 21, 55 7.07 High magnification 165, 18 13, 96 1.58" 2.75 30, 82 0. 84 The zoom ratio between the focal length few of the eyepiece optical system at low magnification and the focal length fet of the eyepiece optical system at high magnification is few/
fet·1.19, it is possible to suppress changes in the apparent field of view due to variable magnification.

Table 13 shows the change in diopter due to magnification when the standard diopter is set to 11 dayopters.

Table 13 Low magnification Medium magnification High magnification 4.0 -7.7 -12.82, 0
-3.2 -4.91.0 -1.0
-1.00.0 +1.2
+2.9+2.0 +5.7 +10
．． 8 To independently move the field ring so that the diopter of the field ring is constant, and to satisfy the condition of DST = DIO = DSW = -1 so that the diopter of the field ring becomes the same as the reference diopter. For this purpose, the distance between the surface (rlQ) of the eyepiece optical system closest to the object and the field ring may be changed as shown in Table 14.

Table 14 At low magnification At middle magnification At high magnification = 7.00 -7.52 -8.01 For comparison, change in diopter when the reference diopter is set to 0 dayopter in the configuration of the third embodiment above are shown in Table 15.

Table 15 Low magnification Medium magnification High magnification 4.0 -9.0 -15.72, 0
-4.5 -7.91.0 -2.2
-3.9o,o o,o
o.

+2.0 44.5
+7.9 (Effect) As explained above, according to the present invention, by setting the standard diopter of the image to the negative side, the standard diopter can be set to a diopter that is easy for people with normal eyesight to observe. This allows the lens to be brought closer and prevents the image from becoming out of focus due to magnification changes.

[Brief explanation of drawings]

1 to 6 show a first embodiment of the afocal variable magnification optical system according to the present invention. FIG. 1 is a lens diagram at low magnification, and FIG. 2 is a lens diagram at low magnification. Diagrams of various aberrations. Figure 3 is a diagram of the lens at medium magnification, Figure 4 is a diagram of various aberrations at medium magnification, Figure 5 is a diagram of the lens at high magnification, and Figure 6 is a diagram of various aberrations at high magnification. be. 7 to 12 show a second embodiment of the afocal variable magnification optical system according to the present invention. FIG. 7 is a lens diagram at low magnification, and FIG. 8 is a lens diagram at low magnification. Various aberration diagrams, Figure 9 is a lens diagram at medium magnification, Figure 10 is a diagram of various aberrations at medium magnification, Figure 11 is a lens diagram at high magnification, and Figure 12 is a diagram of various aberrations at high magnification. be. 13 to 18 show a third embodiment of the afocal variable magnification optical system according to the present invention. FIG. 13 is a lens diagram at low magnification, and FIG. 14 is a lens diagram at low magnification. Various aberration diagrams,
FIG. 15 is a lens diagram at medium magnification, FIG. 16 is a diagram of various aberrations at medium magnification, FIG. 17 is a lens diagram at high magnification, and FIG. 18 is a diagram of various aberrations at high magnification. Part 1 Figure 2 Spherical aberration Lateral chromatic aberration Astigmatism 1. ! ! ;! Differential Distortion Fig. 3 Fig. 5 Fig. 6 Spherical Aberration Chromatic Aberration Magnification Chromatic Aberration Astigmatism Distortion Fig. 7 Fig. 8 Spherical Aberration Compression Magnification e Aberration Astigmatism Distortion Fig. 9 Fig. 10 Spherical Aberration Convex Sword = @ Scientific Aberration Astigmatism Distortion Figure 13 Figure 14 Spherical Aberration Chromatic Aberration @ Rate Acupuncture and Lens Point 92 Months Doo Distortion Aberration Procedure Correction (Spontaneous) August 19, 1991

Claims (5)

[Claims] (1) Consisting of an objective optical system located on the object side of the field of view ring and an eyepiece optical system located on the eye side of the field of view with a field of view environment for defining the field of view frame, at least the eyepiece optical system 1. An afocal variable magnification optical system characterized in that magnification is changed by moving a part of the afocal lens, and a reference diopter of an image that does not change even with magnification is set to less than 0 diopter. (2) The afocal variable power optical system according to claim 1, wherein the reference diopter is set to be changeable. (3) When the reference diopter is DIO, the diopter of the field ring at high magnification is DST, and the diopter of the field ring at low magnification is DSW, the following condition is satisfied. Afocal variable magnification optical system described in . DST≦DIO≦DSW (4) The afocal variable magnification optical system according to claim 3, wherein the field ring is moved in response to variable magnification so that DST=DSW=DIO is satisfied. (5) the focal length of the eyepiece optical system at low magnification is few;
2. The afocal variable magnification optical system according to claim 1, wherein the following condition is satisfied when the focal length of the eyepiece optical system at high magnification is fet. few/fet≦1.30