JPH095644A - Zoom magnifier - Google Patents

Abstract

PURPOSE: To enable an observer to continuously observe an observing object by changing a magnification rate without parting the eyes from the observing part of this object by consisting the above zoom magnifier of lens groups of positive, negative and positive first to third groups, successively from the object side, and varying power by moving at least the two groups near and apart to and from each other along the optical axis, thereby maintaining the specified diopter. CONSTITUTION: This zoom magnifier has the positive first lens group L11, the negative second lens group L12 and the positive third lens group L13. The positive first lens group L11 consists of a combined lens which consists, successively from the object side, of positive lens, positive lens and negative lens and is positive as a whole and a positive lens. The first lens group L11 and the second lens group L12 move near and apart to and from each other relatively along the optical axis, thereby constituting a moving lens which varies the power (zooming) by maintaining the specified dipoter. The third lens group L13 is formed as a stationary group to eliminate the observer's need for moving the positions of his eyes. The zoom magnifier has a diopter adjusting function in order to adjust the individual differences of the diopters.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom magnifying glass for magnifying and observing an object at a close range.

[0002]

2. Description of the Related Art A magnifying glass places an observation object in the vicinity of the object-side focal point of a positive lens system, and brings an eye closer to the positive lens system from the opposite side to observe a magnified virtual image of the observation object. To do. The lens system of the conventional magnifying glass is
It was a so-called fixed focal length, and the magnification could not be changed. Therefore, in order to observe the same observation object with different magnifying powers, it is necessary to prepare a plurality of magnifying mirrors having different magnifying powers and switch to a magnifying glass having a desired magnifying power.

In order to eliminate such inconvenience, a magnifying glass provided with a variable power lens system is proposed in, for example, Japanese Patent Laid-Open No. 5-134193, but this conventional example has the following problems. It was

This conventional lens has positive, negative, and
Among the five lens groups of positive, positive, and positive, only the second lens group on the eye side is moved to change the magnification. With such movement of only the second group, the diopter change was large (maximum 1.4 D). aberration,
Especially, the distortion was large. For example, distortion occurs at a high magnification of about 6% and at a low magnification of about 10%. Further, this conventional lens has a noticeable color blur in the periphery.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a zoom magnifying glass capable of continuously observing by changing the magnifying power without keeping an eye on the observing portion of an observing object. With the goal. A further object of the present invention is to provide a zoom magnifying glass which has a small diopter change, distortion and color fringing and has a large zoom ratio.

[0006]

SUMMARY OF THE INVENTION The invention according to claim 1 for achieving the above object is a lens system comprising a positive first lens group, a negative second lens group, and a positive third lens group in order from the object side. It is characterized in that at least two groups are moved toward and away from each other along the optical axis to keep the diopter constant and to change the magnification.

The invention described in claim 2 is characterized in that the first group and the second group are movable lenses which are moved close to and away from each other along the optical axis to keep the diopter constant and to change the magnification. Have.

The invention described in claim 3 is characterized in that the third lens group has at least one lens movable along the optical axis to have a diopter adjusting function.

According to the fourth aspect of the present invention, at least one surface of the first group is an aspherical surface in which the lens thickness is thicker in the periphery than in the paraxial spherical surface, so that the distortion aberration is reduced.

According to a fifth aspect of the present invention, the first group is further composed of, in order from the object side, a positive lens, a positive cemented lens composed of a positive lens and a negative lens as a whole, and a positive lens in that order. The Abbe number ratio of the combined lens is ν _p / ν _n ≧ 1.8 where ν _{p is} the Abbe number of the positive lens of the cemented lens ν _n : By satisfying the condition of the Abbe number of the negative lens of the cemented lens, Reduced color fringing.

[0011]

The zoom magnifying glass of the present invention will be described below with reference to the illustrated embodiments. Here, r is the radius of curvature of each surface of the lens, d is the lens thickness or lens spacing, n is the refractive index for the d-line, and ν is the Abbe number.

[Embodiment 1] FIGS. 1 and 3 are views showing the lens structure of Embodiment 1 of the present invention at a high magnification and a low magnification, and FIG. 2 is a high magnification shown in FIG. D at time
FIG. 4 is a diagram showing various aberrations of the line, g-line and C-line, and FIG. 4 is a diagram showing various aberrations at the low magnification shown in FIG.

The first embodiment includes a positive first lens unit L11, a negative second lens unit L12, and a positive third lens unit L13 from the object side. The first positive lens unit L11 includes, from the object side, a positive lens, a positive cemented lens including a positive lens and a negative lens as a whole, and a positive lens. The first lens unit L11 and the second lens unit L12 constitute a movable lens that relatively moves closer to and away from the optical axis to keep the diopter constant and to perform zooming. Here, the third lens group L13 is a fixed group so that the observer does not have to move the eye position even when zooming,
It also has a diopter adjustment function to adjust individual differences in diopter.

The specific lens construction of Example 1 is shown in Table 1 below.

[Table 1] Focal length (mm) f = 16.32 to 43.34 Magnification ratio (times) 16 to 6 Diopter (Dpt.) -1.05 -0.98 NO. R d n ν 1 83.585 8.30 1.69680 55.5 2 -42.112 8.74 3 56.463 1.50 1.80518 25.4 4 18.362 12.00 1.65160 58.5 5 -57.676 0.10 6 25.331 5.50 1.67000 57.4 7 87.425 17.74 〜 2.16 8 -43.754 0.70 1.69680 55.5 9 29.379 2.00 10 -11.775 0.70 1.64250 58.4 11 -65.028 2.85 〜 10.42 13 -21.844.722 1.40 11.653-

[Embodiment 2] FIGS. 5 and 7 are views showing a lens structure of Embodiment 2 of the present invention in a state of high magnification and low magnification, and FIG. 6 is a view of high magnification shown in FIG. D in
FIG. 8 is a diagram showing various aberrations of the line, g line, and C line, and FIG. 8 is a diagram showing various aberrations of the d line, g line, and C line at the low magnification shown in FIG.

The second embodiment includes, from the object side, a positive first lens unit L11, a negative second lens unit L12, and a positive third lens unit L13. The positive first lens unit L11 is composed of a positive lens, a positive lens, and a negative lens as a whole, and a positive cemented lens and a positive lens from the object side. In Example 2, the second surface of the first lens unit L11 (surface NO.
The feature is that 2) is an aspherical surface. In Example 1, the coma aberration is generated in the periphery because the distortion aberration is reduced, and the distortion aberration returns, so that the image appears distorted. However, as in Example 2, the first lens group L11 By making the two surfaces aspherical, coma at the peripheral portion was suppressed and distortion was reduced. In addition, there is no return to distortion. Further, in the second embodiment, similarly to the first embodiment, the first lens unit L11 and the second lens unit L12 relatively move toward and away from each other along the optical axis to zoom (zoom) while keeping the diopter constant. It constitutes a movable lens. Here, the third lens group L13 is a fixed group so that the observer does not have to move the eye position even during zooming, and also has a diopter adjustment function for adjusting individual differences in diopter. have.

The specific lens construction of the second embodiment is shown in Table 2 below.

[Table 2] Focal length (mm) f = 15.63 to 41.02 Expansion rate (times) 16 to 6 Diopter (Dpt.) -1.00 -1.00 NO. R d n ν 1 64.627 8.30 1.69680 55.5 * 2 -29.916 6.23 3 2766.022 1.50 1.80518 25.4 4 21.196 12.00 1.65160 58.5 5 -38.596 0.10 6 31.587 5.50 1.67000 57.4 7 -171.823 15.48 ~ 1.55 8 35.932 0.70 1.69680 55.5 9 11.262 2.00 10 -12.260 0.70 1.64250 58.4 11 1.973.959 3.09 -9.40 12.65 -50.353 14.765-However, * is aspherical surface Aspherical shape is expressed by the following formula. ^{x = CY 2 / (1+ (} 1- (1 + K) C 2 Y 2) 1/2)
+ A4Y ⁴ (C is the curvature (1 / r), Y is the height from the optical axis, K is the conic coefficient) Aspheric surface data NO. 2: K = 0.00000 A4 = 0.13783 × 10 ^-4

Further, in the above-mentioned Embodiments 1 and 2,
The first lens unit L11 includes, from the object side, a positive lens, and a positive cemented lens composed of a positive lens and a negative lens as a whole,
And a positive lens. Furthermore, the Abbe number ratio of the cemented lens is ν _p / ν _n ≧ 1.8, where ν _{p is} the Abbe number of the positive lens of the cemented lens, and ν _{n is} the Abbe number of the negative lens of the cemented lens. This reduces color fringing in the surrounding area. In both Examples 1 and 2, ν _p / ν _n = 58.5
/25.4≈2.30≧1.8.

[0019]

As described above, according to the present invention, the diopter is constant, the distortion is small, the color fringing in the periphery is small, the zoom ratio is large, and the magnification ratio is continuously maintained without taking the eye away from the observed object. It is possible to obtain a zoom magnifying glass that can be continuously observed by changing its shape.

[Brief description of drawings]

FIG. 1 is a lens configuration diagram showing a first embodiment of a zoom magnifying glass according to the present invention in a high magnification state.

FIG. 2 is a diagram of various types of aberration of the zoom magnifying glass of FIG.

FIG. 3 is a lens configuration diagram showing Embodiment 1 of the zoom magnifying glass according to the present invention in a low magnification state.

FIG. 4 is a diagram of various types of aberration of the zoom magnifying glass of FIG.

FIG. 5 is a lens configuration diagram showing a second embodiment of the zoom magnifying glass according to the present invention in a high magnification state.

FIG. 6 is a diagram of various types of aberration of the zoom magnifying glass of FIG.

FIG. 7 is a lens configuration diagram showing a second embodiment of the zoom magnifying glass according to the present invention in a low magnification state.

FIG. 8 is a diagram of various types of aberration of the zoom magnifying glass of FIG. 7.

[Explanation of symbols]

 L11 First lens group L12 Second lens group L13 Third lens group

Claims (5)

[Claims] 1. A positive first group and a negative second group in order from the object side.
A zoom magnifying lens, characterized in that, in a lens system composed of a lens unit and a lens unit of a positive third lens unit, at least two lens units move close to and away from each other along the optical axis to keep the diopter constant and perform zooming. . 2. The movable lens according to claim 1, wherein the first lens group and the second lens group are movable lenses that move closer to and away from each other along the optical axis to keep the diopter constant and to change the magnification. Zoom magnifier to do. 3. The zoom magnifying glass according to claim 2, wherein the third group has at least one lens movable along an optical axis and has a diopter adjusting function. 4. The zoom magnifying glass according to claim 1, wherein at least one surface of the first group is an aspherical surface having a shape in which the lens thickness is thicker in the periphery as compared with a paraxial spherical surface. 5. The cemented lens according to claim 1, wherein the first group is composed of, in order from the object side, a positive lens, a positive cemented lens composed of a positive lens and a negative lens as a whole, and a positive lens. The Abbe number ratio of ν _p / ν _n ≧ 1.8 where ν _p : Abbe number of the positive lens of the cemented lens ν _n : Satisfies the condition of the Abbe number of the negative lens of the cemented lens Zoom magnifier.